This document provides an overview of neuroendocrinology in insects and crustaceans. It describes the key components of their neuroendocrine systems, including neurosecretory cells located in the brain and ganglia that produce neurohormones. These neurohormones are released into the circulatory system and regulate various physiological processes such as growth, reproduction, color changes, and moulting. The document also discusses specialized endocrine glands like the corpora allata in insects and the X-organ complex in crustaceans that help control these processes through the hormones they secrete.
Insects' life processes are regulated by their neural and endocrine systems. There are three main types of hormones: brain hormones which regulate various bodily events, moulting hormones which are responsible for moulting and growth, and juvenile hormones which ensure larval growth and prevent metamorphosis. These hormones control insect development and can be targeted for pest control by disrupting or blocking their biosynthesis.
Hormones play an important role in controlling the growth and development of insects. Key hormones include the prothoracicotropic hormone (PTTH) secreted by neurosecretory cells that activates the prothoracic glands to secrete ecdysone, the moulting hormone. The corpora allata gland secretes juvenile hormone which inhibits metamorphosis and allows moults to successive larval stages. Together these hormones and their coordinated secretions regulate the moulting process, metamorphosis, diapause, reproduction and other physiological functions in insects.
Taxonomic Collections, Preservation and Curating of InsectsKamlesh Patel
Taxonomy: Taxonomy is the science of defining and naming groups of biological organisms on the basis of shared characteristics.
The classification of organisms is according to hierarchal system or in taxonomic ranks (eg; domain, kingdom, phylum class, order, family, genus and species) based on phylogenetic relationship established by genetic analysis.
Taxonomic Collection : Biological collection are typically preserved plant or animals specimens along with specimen documentations such as labels and notations.
Dry Collection - Dry collections consist of those specimens that are preserved in a dry state.
Wet Collection - Wet collections are specimens kept in a liquid preservative to prevent their deterioration.
The document discusses the urinogenital system in vertebrates. It begins by defining the urinogenital system and its components, which include the kidneys, urinary ducts, gonads, and genital ducts. It then describes the evolution and development of the kidney structures in vertebrates, from the primitive pronephros to the more advanced metanephros. Key points include that the kidney evolves from the intermediate mesoderm and progresses through pronephric, mesonephric, and metanephric stages. The metanephros is the definitive kidney structure in amniotes. The document also discusses kidney structure and blood supply in different vertebrate groups.
1) Fish possess various adaptive structures like electric organs, poison glands, and sound producing organs. This document focuses on bioluminescence organs.
2) Bioluminescence involves the production of light by living organisms through a chemical reaction between luciferin and luciferase enzymes. It is common in marine life.
3) Fish bioluminescence can involve symbiotic bacteria or intrinsic photophores. Photophores are light-emitting organs that vary in structure and function between fish species.
The corpora cardiaca are a pair of endocrine glands located behind the brain in insects. They are closely associated with the aorta and contain neurosecretory cells whose axons project from the brain. The corpora cardiaca serve as neurohemal organs that store and release several hormones into the haemolymph (blood) to control functions like heart rate and trehalose levels. They contain intrinsic secretory cells that produce the adipokinetic hormone and other peptides of unknown function. In some insect groups, the corpora cardiaca become separated from the aorta in later development.
Origin of the Lateral Line System
Lateral line is a canal along the side of a fish containing pores that open into tubes supplied with sense organs sensitive to low vibrations.
Robert H. Denison explained the origin of the lateral line system. He explained that early vertebrates had a pore-canal system in the dermis which functioned as a primitive sensory system in detecting water movement.
Through the evidences from fossils, embryology and comparative anatomy, Denison (1966) established that the inner ear is closely related to the lateral line system. He found a distinct relationship between the pore canal system and the lateral line in Osteotraci.
The inner ear and the lateral line are developed from ectodermal thickenings, called dorso-lateral placodes. These have a number of similarities, including receptors with sensory hairs, and are both innervated by fibers in the acoustico-lateral area of the brain.
The pore canal system is present and developed in Osteostraci (ostracoderm).
It is also present in Heterostraci which is another group of ostracoderms and includes early vertebrates such as lungfishes and crossopterygians.
As its presence is extensive, it is reasonable to suggest that the pore canal system was a primitive character in early vertebrates .
In transverse sections also , it is very difficult to differentiate the pore canal system from a lateral line canal.
Structure of the Lateral Line System
Epidermal structures called neuromasts form the peripheral area of the lateral line.
Neuromasts consist of two types of cells, hair cells and supporting cells.
Hair cells have an epidermal origin and each hair cell has one high kynocyle (5-10 μm) and 30 to 150 short stereocilia (2-3 μm).
The number of hair cells in each neuromast depends on its size, and they can range from dozens to thousands.
Hair cells can be oriented in two opposite directions with each hair cell surrounded by supporting cells.
At the basal part of each hair cell, there are synaptic contacts with afferent and efferent nerve fibers. Afferent fibers, transmit signals to the neural centres of the lateral line and expand at the neuromast base. The regulation of hair cells is achieved by the action of efferent fibers.
Stereocilia and kinocilium of hair cells are immersed into a cupula and are located above the surface of the sensory epithelium.
The cupula is created by a gel-like media, which is secreted by non-receptor cells of the neuromast.
Metamorphosis in amphibians involves dramatic changes initiated by thyroid hormones that transform aquatic larvae into terrestrial adults. These changes include remodeling of tissues and organs like development of lungs and loss of gills to transition from aquatic to terrestrial respiration. Changes in skin, digestive system and other organs prepare the amphibian for life on land. The process is controlled by thyroid hormones which activate receptors that turn on genes driving tissue remodeling and metamorphosis.
Insects' life processes are regulated by their neural and endocrine systems. There are three main types of hormones: brain hormones which regulate various bodily events, moulting hormones which are responsible for moulting and growth, and juvenile hormones which ensure larval growth and prevent metamorphosis. These hormones control insect development and can be targeted for pest control by disrupting or blocking their biosynthesis.
Hormones play an important role in controlling the growth and development of insects. Key hormones include the prothoracicotropic hormone (PTTH) secreted by neurosecretory cells that activates the prothoracic glands to secrete ecdysone, the moulting hormone. The corpora allata gland secretes juvenile hormone which inhibits metamorphosis and allows moults to successive larval stages. Together these hormones and their coordinated secretions regulate the moulting process, metamorphosis, diapause, reproduction and other physiological functions in insects.
Taxonomic Collections, Preservation and Curating of InsectsKamlesh Patel
Taxonomy: Taxonomy is the science of defining and naming groups of biological organisms on the basis of shared characteristics.
The classification of organisms is according to hierarchal system or in taxonomic ranks (eg; domain, kingdom, phylum class, order, family, genus and species) based on phylogenetic relationship established by genetic analysis.
Taxonomic Collection : Biological collection are typically preserved plant or animals specimens along with specimen documentations such as labels and notations.
Dry Collection - Dry collections consist of those specimens that are preserved in a dry state.
Wet Collection - Wet collections are specimens kept in a liquid preservative to prevent their deterioration.
The document discusses the urinogenital system in vertebrates. It begins by defining the urinogenital system and its components, which include the kidneys, urinary ducts, gonads, and genital ducts. It then describes the evolution and development of the kidney structures in vertebrates, from the primitive pronephros to the more advanced metanephros. Key points include that the kidney evolves from the intermediate mesoderm and progresses through pronephric, mesonephric, and metanephric stages. The metanephros is the definitive kidney structure in amniotes. The document also discusses kidney structure and blood supply in different vertebrate groups.
1) Fish possess various adaptive structures like electric organs, poison glands, and sound producing organs. This document focuses on bioluminescence organs.
2) Bioluminescence involves the production of light by living organisms through a chemical reaction between luciferin and luciferase enzymes. It is common in marine life.
3) Fish bioluminescence can involve symbiotic bacteria or intrinsic photophores. Photophores are light-emitting organs that vary in structure and function between fish species.
The corpora cardiaca are a pair of endocrine glands located behind the brain in insects. They are closely associated with the aorta and contain neurosecretory cells whose axons project from the brain. The corpora cardiaca serve as neurohemal organs that store and release several hormones into the haemolymph (blood) to control functions like heart rate and trehalose levels. They contain intrinsic secretory cells that produce the adipokinetic hormone and other peptides of unknown function. In some insect groups, the corpora cardiaca become separated from the aorta in later development.
Origin of the Lateral Line System
Lateral line is a canal along the side of a fish containing pores that open into tubes supplied with sense organs sensitive to low vibrations.
Robert H. Denison explained the origin of the lateral line system. He explained that early vertebrates had a pore-canal system in the dermis which functioned as a primitive sensory system in detecting water movement.
Through the evidences from fossils, embryology and comparative anatomy, Denison (1966) established that the inner ear is closely related to the lateral line system. He found a distinct relationship between the pore canal system and the lateral line in Osteotraci.
The inner ear and the lateral line are developed from ectodermal thickenings, called dorso-lateral placodes. These have a number of similarities, including receptors with sensory hairs, and are both innervated by fibers in the acoustico-lateral area of the brain.
The pore canal system is present and developed in Osteostraci (ostracoderm).
It is also present in Heterostraci which is another group of ostracoderms and includes early vertebrates such as lungfishes and crossopterygians.
As its presence is extensive, it is reasonable to suggest that the pore canal system was a primitive character in early vertebrates .
In transverse sections also , it is very difficult to differentiate the pore canal system from a lateral line canal.
Structure of the Lateral Line System
Epidermal structures called neuromasts form the peripheral area of the lateral line.
Neuromasts consist of two types of cells, hair cells and supporting cells.
Hair cells have an epidermal origin and each hair cell has one high kynocyle (5-10 μm) and 30 to 150 short stereocilia (2-3 μm).
The number of hair cells in each neuromast depends on its size, and they can range from dozens to thousands.
Hair cells can be oriented in two opposite directions with each hair cell surrounded by supporting cells.
At the basal part of each hair cell, there are synaptic contacts with afferent and efferent nerve fibers. Afferent fibers, transmit signals to the neural centres of the lateral line and expand at the neuromast base. The regulation of hair cells is achieved by the action of efferent fibers.
Stereocilia and kinocilium of hair cells are immersed into a cupula and are located above the surface of the sensory epithelium.
The cupula is created by a gel-like media, which is secreted by non-receptor cells of the neuromast.
Metamorphosis in amphibians involves dramatic changes initiated by thyroid hormones that transform aquatic larvae into terrestrial adults. These changes include remodeling of tissues and organs like development of lungs and loss of gills to transition from aquatic to terrestrial respiration. Changes in skin, digestive system and other organs prepare the amphibian for life on land. The process is controlled by thyroid hormones which activate receptors that turn on genes driving tissue remodeling and metamorphosis.
There are three types of insect development: holometabolous (complete metamorphosis from larva to pupa to adult), hemimetabolous (partial metamorphosis from nymph to adult), and ametabolous (no metamorphosis from pronymph to adult). In holometabolous insects, imaginal cells develop into adult structures during the pupal stage through programmed cell death of larval cells and differentiation of imaginal discs, controlled by the hormones ecdysone and juvenile hormone. Ecdysone triggers molting and metamorphosis while juvenile hormone prevents metamorphosis and ensures additional larval stages; in the final larval stage, low juvenile hormone allows ecdysone to
ELECTROGENESIS IN FISHES By ABDUR ROUF SAMIMSYED ASSIM HAQ
This document summarizes electrogenesis in fishes. It describes that electrogenesis refers to the production of electrical impulses in living organisms, observed in fishes, reptiles, and mammals. There are two types of electric fishes - strongly electric fishes like torpedo and electrophorus, and weakly electric fishes like raja and gymnotus. Electric organs are specialized organs that produce electric fields outside the body, built from electroplates embedded in connective tissue. The location of electric organs varies between species, and electric organ discharges can be monophasic, biphasic, or polyphasic pulses. Electric organs are used for food procurement, defense, communication and other functions.
Comparative Anatomy of Respiratory System of VertebratesRameshPandi4
The document discusses the comparative anatomy of the respiratory systems of various vertebrates. It describes how respiration occurs through the skin, gills, lungs, and gas bladders in different organisms. It explains key differences in respiratory structures between cartilaginous fishes, bony fishes, and jawless fishes. Mechanisms of gas exchange are covered for fishes, as well as respiratory organs and processes for amphibians, reptiles, birds, and mammals.
Ostracoderms were early jawless vertebrates that lived from the Cambrian to the late Devonian period. They were covered in bony plates and resembled modern hagfish and lampreys. While some evidence suggests they lived in freshwater, their habitat is still debated. Later in the Devonian, jawed fish evolved from ostracoderms and outcompeted them, contributing to their extinction by the end of the period. Ostracoderms were divided into two main groups and played an important role in the early evolution of vertebrates.
1. The document discusses various methods for studying animal behavior, including ad libitum observation, focal animal observation, scanning/instantaneous sampling, all occurrences sampling, and one-zero sampling.
2. It provides examples of how to create an ethogram to catalog an animal's behaviors and create a time budget to track how much time an animal spends on different behaviors like hunting, eating, sleeping, and grooming.
3. The procedure outlines observing a single animal for an hour, recording its behaviors and the time spent on each one in order to analyze which behaviors are most and least frequent.
Vittelogenesis is a word developed from Latin vitellus-yolk, and genero-produce
Vitellogenesis (also known as yolk deposition) is the process of yolk formation via nutrients being deposited in the oocyte, or female germ cell involved in reproduction of lecithotrophic organisms. In insects, it starts when the fat body stimulates the release of juvenile hormones and produces vitellogenin protein.
Yolks is the most usual form of food storage in the egg.
Yolks appear in the oocyte in the secondary period of their growth called vittelogenesis.
Thus,the formation and deposition of yolks is known as vittelogenesis
Characteristic
Yolks is a complex variable assembled component.
The principle component are protein,phospholipid and fats in different combination.
Depending upon these component yolks is distinguished into protein yolks and fatty acid
For eg- the avian contain 48.19% water , 16.6 % protein, 32.6% phospholipids and fats and 1% carbohydrates.
Parental care in amphibians provides benefits to offspring survival. There are various types of parental care exhibited by different amphibian species, including selecting protected nesting sites, defending eggs or territories, directly transporting tadpoles to water, gluing or carrying eggs attached to the body, and even viviparity in some species. Parental care improves offspring chances of survival by protecting eggs from predators and ensuring young amphibians safely reach water once hatched.
Primate social organizations can generally be categorized into two types: 1) solitary foragers or dispersed polygyny where females forage alone and males monopolize access to females, and 2) where females forage together in female-bonded groups that are larger and contain multiple males. Group structures range from one-male harems to multi-male/multi-female groups. The type of social structure adopted depends on factors like the nature of resources and how defendable or monopolizable they are.
Amphibian metamorphosis is initiated by thyroid hormones that travel through the bloodstream and induce changes in organs and tissues. This includes the growth of adult structures like limbs, remodeling of larval structures like the intestine and nervous system, and programmed cell death of larval structures like gills and tail. The levels of thyroid hormones regulate the timing and progression of metamorphosis through different stages from pre-metamorphosis to metamorphic climax. While some tissues proliferate and differentiate in response to thyroid hormones, other tissues are instructed to degenerate, allowing the transition from aquatic larva to terrestrial adult.
1. There are four main types of regeneration: stem cell mediated, epimorphosis, morphallaxis, and compensatory regeneration.
2. Epimorphosis involves de-differentiation of cells forming a blastema which then re-differentiates, as seen in salamander limb regeneration.
3. Morphallaxis involves re-patterning of existing tissues with little new growth, as seen when hydra fragments regenerate entire organisms.
Social organization and social behaviour in insectsPoojaVishnoi7
Introduction
Properties of a society
Advantages of a society
Disadvantages of a society
Social organisation and social behaviour in insects:-
1. Termites
2.Honeybees
3.Ants
4.Yellow wasp
Regeneration involves the reactivation of development to restore missing tissues through various mechanisms. Epimorphic regeneration occurs when differentiated cells dedifferentiate to form an undifferentiated blastema which then proliferates and redifferentiates into the new structure. Salamanders regenerate limbs through epimorphosis by forming a blastema beneath the wound epidermis/apical ectodermal cap. Blastema cells require both nerves and growth factors from the apical ectodermal cap to proliferate. Patterning molecules like retinoic acid and Hox genes help reestablish proximal-distal patterning in the regenerating limb.
This document summarizes flightless birds. It begins by defining flightless birds as belonging to the superorder Palaeognathae, characterized by a Palaeognathous plate. These birds are flightless, with small heads, rudimentary wings, and well-developed legs adapted for running rather than flying. The document then discusses four orders of flightless birds - ostriches, emus, cassowaries, and kiwis. Examples are provided for each, describing their physical characteristics and habitats. In closing, the document briefly mentions penguins as another type of flightless bird found in cold southern climates.
Fishes, amphibians, reptiles, and birds have paired pharyngeal ultimobranchial glands that secrete the hypocalcemic hormone calcitonin. The corpuscles of Stannius, unique glandular islets found only in the kidneys of bony fishes, secrete a peptide called hypocalcin.
This document discusses adaptive radiation in reptiles. It defines adaptive radiation as the diversification of a single ancestor into an array of species occupying different ecological niches. Reptiles underwent adaptive radiation, evolving from ancestral reptiles into terrestrial herbivores and carnivores, burrowing reptiles, aquatic reptiles, and flying reptiles. Specific examples discussed include the adaptive radiation of turtles, Caribbean anoles lizards, pygopodid lizards, and crocodilians. Adaptive radiation is driven by the availability of new resources and ecological niches following mass extinction events or the evolution of new traits that allow entry into new environments.
1. In vertebrates, primordial germ cells (PGCs) arise early in development and migrate into developing gonads to form germ cells.
2. The mechanism of PGC migration varies between species, with frogs and zebrafish migrating chemotactically in response to signaling proteins, while birds and reptiles migrate through the bloodstream.
3. In mammals, PGCs form in the posterior epiblast and migrate directly into the endoderm and then genital ridges over successive days of development.
The vertebrate brain
The vertebrate brain is the main part of the central nervous system. The brain and the spinal cord make up the central nervous system,
In most of the vertebrates the brain is at the front, in the head. It is protected by the skull and close to the main sense organs.
Brains are extremely complex and the part of human and animal body. The brain controls the other organs of the body, either by activating muscles or by causing secretion of chemicals such as hormones and neurotransmitters.
Muscular action allows rapid and coordinated responses to changes in the environment.
The brain of an adult human weights about 1300–1400 grams .
In vertebrates, the spinal cord by itself can cause reflex responses as well as simple movement such as swimming or walking. However, sophisticated control of behaviour requires a centralized brain.
The structure of all vertebrate brains is basically the same.
At the same time, during the course of evolution, the vertebrate brain has undergone changes, and become more effective.
In so-called 'lower' animals, most or all of the brain structure is inherited, and therefore their behaviour is mostly instinctive.
In mammals, and especially in man, the brain is developed further during life by learning. This has the benefit of helping them fit better into their environment. The capacity to learn is seen best in the cerebral cortex.
Three principles
The brain and nervous system is essentially a system which makes connections. It has input from sense organs and output to muscles. It is connected in several ways with the endocrine system, which makes hormones, and the digestive system and sex system. Hormones work slowly, so those changes are gradual.
The brain is a kind of department store. It has, all inter-connected, departments which do different things. They all help each other gather senses.
Much of what the body does is not conscious. Basically, much of the body runs on automatic (breathing, heart beat, hungry, hair growth) adjusted by the autonomic nervous system. The brain, too, does much of its work without a person noticing it. The unconscious mind refers to the brain activities which are hardly ever noticed.
This document discusses regeneration in living organisms. It defines regeneration as the ability to replace or renew damaged or lost body parts after embryonic development. Regeneration involves growth, morphogenesis, and cell differentiation regulated by signaling pathways like WNT and FGF. There are three main types of regeneration: physiological regeneration which replaces regularly lost cells; reparative regeneration which repairs wounds or lost parts; and autotomy where animals self-detach parts when threatened. Regeneration abilities vary across vertebrates, from restricted tissue regeneration in mammals to full limb regeneration in salamanders and fish fin regeneration. The process of limb regeneration occurs in three phases: wound healing, blastema formation from progenitor cells, and redifferentiation of the blastema into
Neuroendocrine system and NeurosecretionLekhan Lodhi
The neuroendocrine system allows the hypothalamus to regulate endocrine glands and maintain homeostasis. It does this through the hypothalamic-pituitary portal system, which connects the hypothalamus and anterior pituitary via blood vessels. The hypothalamus secretes releasing and inhibiting hormones that stimulate or suppress hormone production in the anterior pituitary, which then regulates other endocrine glands. Key axes include the HPT, HPA, and HPG axes that control thyroid function, stress response, and reproduction respectively. Neurosecretory cells in the hypothalamus also secrete oxytocin and vasopressin into the bloodstream and posterior pituitary for storage and release.
Electric organs are found in about 250 species of fish and are composed of electroplates, which are stacks of electrocytes that discharge electricity. The organs vary in voltage output between species from 4-550 volts and serve functions like catching prey, defense, communication, and territory maintenance. Electric organs are thought to have evolved from muscle tissue, with different fish lineages co-opting different muscle groups for electrocyte differentiation during development.
The Endocrine System and Chemical MessengersNaveedAkhtar58
This document discusses the endocrine system and chemical messengers. It begins by comparing the nervous and endocrine systems, noting that the endocrine system uses slower chemical messengers. It then describes the evolution of these messengers and the five major types: local chemical messengers, neurotransmitters, neuropeptides, hormones, and pheromones. The document provides examples of these messengers in both invertebrates and vertebrates. It also explains the mechanisms of hormone action, feedback control systems, and gives specific examples of endocrine systems in groups like molluscs, arthropods, and crustaceans.
There are three types of insect development: holometabolous (complete metamorphosis from larva to pupa to adult), hemimetabolous (partial metamorphosis from nymph to adult), and ametabolous (no metamorphosis from pronymph to adult). In holometabolous insects, imaginal cells develop into adult structures during the pupal stage through programmed cell death of larval cells and differentiation of imaginal discs, controlled by the hormones ecdysone and juvenile hormone. Ecdysone triggers molting and metamorphosis while juvenile hormone prevents metamorphosis and ensures additional larval stages; in the final larval stage, low juvenile hormone allows ecdysone to
ELECTROGENESIS IN FISHES By ABDUR ROUF SAMIMSYED ASSIM HAQ
This document summarizes electrogenesis in fishes. It describes that electrogenesis refers to the production of electrical impulses in living organisms, observed in fishes, reptiles, and mammals. There are two types of electric fishes - strongly electric fishes like torpedo and electrophorus, and weakly electric fishes like raja and gymnotus. Electric organs are specialized organs that produce electric fields outside the body, built from electroplates embedded in connective tissue. The location of electric organs varies between species, and electric organ discharges can be monophasic, biphasic, or polyphasic pulses. Electric organs are used for food procurement, defense, communication and other functions.
Comparative Anatomy of Respiratory System of VertebratesRameshPandi4
The document discusses the comparative anatomy of the respiratory systems of various vertebrates. It describes how respiration occurs through the skin, gills, lungs, and gas bladders in different organisms. It explains key differences in respiratory structures between cartilaginous fishes, bony fishes, and jawless fishes. Mechanisms of gas exchange are covered for fishes, as well as respiratory organs and processes for amphibians, reptiles, birds, and mammals.
Ostracoderms were early jawless vertebrates that lived from the Cambrian to the late Devonian period. They were covered in bony plates and resembled modern hagfish and lampreys. While some evidence suggests they lived in freshwater, their habitat is still debated. Later in the Devonian, jawed fish evolved from ostracoderms and outcompeted them, contributing to their extinction by the end of the period. Ostracoderms were divided into two main groups and played an important role in the early evolution of vertebrates.
1. The document discusses various methods for studying animal behavior, including ad libitum observation, focal animal observation, scanning/instantaneous sampling, all occurrences sampling, and one-zero sampling.
2. It provides examples of how to create an ethogram to catalog an animal's behaviors and create a time budget to track how much time an animal spends on different behaviors like hunting, eating, sleeping, and grooming.
3. The procedure outlines observing a single animal for an hour, recording its behaviors and the time spent on each one in order to analyze which behaviors are most and least frequent.
Vittelogenesis is a word developed from Latin vitellus-yolk, and genero-produce
Vitellogenesis (also known as yolk deposition) is the process of yolk formation via nutrients being deposited in the oocyte, or female germ cell involved in reproduction of lecithotrophic organisms. In insects, it starts when the fat body stimulates the release of juvenile hormones and produces vitellogenin protein.
Yolks is the most usual form of food storage in the egg.
Yolks appear in the oocyte in the secondary period of their growth called vittelogenesis.
Thus,the formation and deposition of yolks is known as vittelogenesis
Characteristic
Yolks is a complex variable assembled component.
The principle component are protein,phospholipid and fats in different combination.
Depending upon these component yolks is distinguished into protein yolks and fatty acid
For eg- the avian contain 48.19% water , 16.6 % protein, 32.6% phospholipids and fats and 1% carbohydrates.
Parental care in amphibians provides benefits to offspring survival. There are various types of parental care exhibited by different amphibian species, including selecting protected nesting sites, defending eggs or territories, directly transporting tadpoles to water, gluing or carrying eggs attached to the body, and even viviparity in some species. Parental care improves offspring chances of survival by protecting eggs from predators and ensuring young amphibians safely reach water once hatched.
Primate social organizations can generally be categorized into two types: 1) solitary foragers or dispersed polygyny where females forage alone and males monopolize access to females, and 2) where females forage together in female-bonded groups that are larger and contain multiple males. Group structures range from one-male harems to multi-male/multi-female groups. The type of social structure adopted depends on factors like the nature of resources and how defendable or monopolizable they are.
Amphibian metamorphosis is initiated by thyroid hormones that travel through the bloodstream and induce changes in organs and tissues. This includes the growth of adult structures like limbs, remodeling of larval structures like the intestine and nervous system, and programmed cell death of larval structures like gills and tail. The levels of thyroid hormones regulate the timing and progression of metamorphosis through different stages from pre-metamorphosis to metamorphic climax. While some tissues proliferate and differentiate in response to thyroid hormones, other tissues are instructed to degenerate, allowing the transition from aquatic larva to terrestrial adult.
1. There are four main types of regeneration: stem cell mediated, epimorphosis, morphallaxis, and compensatory regeneration.
2. Epimorphosis involves de-differentiation of cells forming a blastema which then re-differentiates, as seen in salamander limb regeneration.
3. Morphallaxis involves re-patterning of existing tissues with little new growth, as seen when hydra fragments regenerate entire organisms.
Social organization and social behaviour in insectsPoojaVishnoi7
Introduction
Properties of a society
Advantages of a society
Disadvantages of a society
Social organisation and social behaviour in insects:-
1. Termites
2.Honeybees
3.Ants
4.Yellow wasp
Regeneration involves the reactivation of development to restore missing tissues through various mechanisms. Epimorphic regeneration occurs when differentiated cells dedifferentiate to form an undifferentiated blastema which then proliferates and redifferentiates into the new structure. Salamanders regenerate limbs through epimorphosis by forming a blastema beneath the wound epidermis/apical ectodermal cap. Blastema cells require both nerves and growth factors from the apical ectodermal cap to proliferate. Patterning molecules like retinoic acid and Hox genes help reestablish proximal-distal patterning in the regenerating limb.
This document summarizes flightless birds. It begins by defining flightless birds as belonging to the superorder Palaeognathae, characterized by a Palaeognathous plate. These birds are flightless, with small heads, rudimentary wings, and well-developed legs adapted for running rather than flying. The document then discusses four orders of flightless birds - ostriches, emus, cassowaries, and kiwis. Examples are provided for each, describing their physical characteristics and habitats. In closing, the document briefly mentions penguins as another type of flightless bird found in cold southern climates.
Fishes, amphibians, reptiles, and birds have paired pharyngeal ultimobranchial glands that secrete the hypocalcemic hormone calcitonin. The corpuscles of Stannius, unique glandular islets found only in the kidneys of bony fishes, secrete a peptide called hypocalcin.
This document discusses adaptive radiation in reptiles. It defines adaptive radiation as the diversification of a single ancestor into an array of species occupying different ecological niches. Reptiles underwent adaptive radiation, evolving from ancestral reptiles into terrestrial herbivores and carnivores, burrowing reptiles, aquatic reptiles, and flying reptiles. Specific examples discussed include the adaptive radiation of turtles, Caribbean anoles lizards, pygopodid lizards, and crocodilians. Adaptive radiation is driven by the availability of new resources and ecological niches following mass extinction events or the evolution of new traits that allow entry into new environments.
1. In vertebrates, primordial germ cells (PGCs) arise early in development and migrate into developing gonads to form germ cells.
2. The mechanism of PGC migration varies between species, with frogs and zebrafish migrating chemotactically in response to signaling proteins, while birds and reptiles migrate through the bloodstream.
3. In mammals, PGCs form in the posterior epiblast and migrate directly into the endoderm and then genital ridges over successive days of development.
The vertebrate brain
The vertebrate brain is the main part of the central nervous system. The brain and the spinal cord make up the central nervous system,
In most of the vertebrates the brain is at the front, in the head. It is protected by the skull and close to the main sense organs.
Brains are extremely complex and the part of human and animal body. The brain controls the other organs of the body, either by activating muscles or by causing secretion of chemicals such as hormones and neurotransmitters.
Muscular action allows rapid and coordinated responses to changes in the environment.
The brain of an adult human weights about 1300–1400 grams .
In vertebrates, the spinal cord by itself can cause reflex responses as well as simple movement such as swimming or walking. However, sophisticated control of behaviour requires a centralized brain.
The structure of all vertebrate brains is basically the same.
At the same time, during the course of evolution, the vertebrate brain has undergone changes, and become more effective.
In so-called 'lower' animals, most or all of the brain structure is inherited, and therefore their behaviour is mostly instinctive.
In mammals, and especially in man, the brain is developed further during life by learning. This has the benefit of helping them fit better into their environment. The capacity to learn is seen best in the cerebral cortex.
Three principles
The brain and nervous system is essentially a system which makes connections. It has input from sense organs and output to muscles. It is connected in several ways with the endocrine system, which makes hormones, and the digestive system and sex system. Hormones work slowly, so those changes are gradual.
The brain is a kind of department store. It has, all inter-connected, departments which do different things. They all help each other gather senses.
Much of what the body does is not conscious. Basically, much of the body runs on automatic (breathing, heart beat, hungry, hair growth) adjusted by the autonomic nervous system. The brain, too, does much of its work without a person noticing it. The unconscious mind refers to the brain activities which are hardly ever noticed.
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Electric organs are found in about 250 species of fish and are composed of electroplates, which are stacks of electrocytes that discharge electricity. The organs vary in voltage output between species from 4-550 volts and serve functions like catching prey, defense, communication, and territory maintenance. Electric organs are thought to have evolved from muscle tissue, with different fish lineages co-opting different muscle groups for electrocyte differentiation during development.
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This document discusses the endocrine system and chemical messengers. It begins by comparing the nervous and endocrine systems, noting that the endocrine system uses slower chemical messengers. It then describes the evolution of these messengers and the five major types: local chemical messengers, neurotransmitters, neuropeptides, hormones, and pheromones. The document provides examples of these messengers in both invertebrates and vertebrates. It also explains the mechanisms of hormone action, feedback control systems, and gives specific examples of endocrine systems in groups like molluscs, arthropods, and crustaceans.
The document discusses the endocrine system and chemical messengers. It begins by comparing the nervous and endocrine systems, noting that the endocrine system uses slower chemical messengers. It then discusses the evolution of these messengers in single-celled organisms and their conservation over hundreds of millions of years. The document outlines the five major types of chemical messengers - local, neurotransmitters, neuropeptides, hormones, and pheromones - and provides examples of each. It also examines the endocrine systems of various invertebrate phyla and how hormones regulate functions like growth, reproduction, and molting in these groups.
The document summarizes key aspects of the endocrine system, including:
1. The endocrine system regulates growth, development and metabolism through chemical messengers called hormones. It acts more gradually than the nervous system.
2. Major endocrine glands include the pituitary, thyroid, parathyroid, adrenal, pancreas and gonads.
3. The hypothalamus acts as the link between the nervous and endocrine systems by stimulating the pituitary gland.
4. The pituitary gland secretes hormones that regulate other glands and body functions. Its posterior lobe stores and releases oxytocin and antidiuretic hormone.
The document discusses various types of chemical messengers in the body including hormones, neurotransmitters, neuropeptides, pheromones, and local chemical messengers. It then provides details on the endocrine system, describing how it works with the nervous system to regulate various bodily functions through chemical signals called hormones, which travel through the bloodstream and control the actions of cells and organs. Feedback control systems that help maintain homeostasis through monitoring changes and making adjustments are also examined.
This document provides an overview of general physiology and cell physiology concepts. It discusses homeostasis and how the body maintains stable internal conditions through negative feedback loops. Key organelles like the mitochondria, Golgi complex, endoplasmic reticulum, lysosomes, and nucleus are described. The structure and function of the plasma membrane, including the fluid mosaic model, transport proteins, and passive transport mechanisms like diffusion and facilitated diffusion are also summarized.
The document discusses the endocrine system and its role in regulating and maintaining body functions. It describes the major areas of control, including responses to stress and reproduction. It provides details on the anatomy of the endocrine system, including the locations and functions of the major endocrine glands like the pituitary, thyroid, adrenals, and others. The document also covers the physiology of the endocrine system, including the classes of hormones, hormone properties, and the homeostatic feedback mechanisms that help regulate hormone levels.
Cells and organisms communicate through chemical signals called hormones. Hormones can stimulate the cell that releases them (autocrine), nearby cells (paracrine), or distant cells (endocrine). They are classified by their target and include steroid hormones, peptides, proteins, fatty acid derivatives, and gases. Hormones act as chemical messengers in the body at very low concentrations and can stimulate or inhibit target organs through membrane receptors or intracellular receptors to regulate many physiological processes. Major endocrine glands include the hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid gland, thymus gland, adrenal gland, pancreas and gonads.
Human Anatomy and Physiology-II:
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Classification of hormones, mechanism of hormone action, structure and functions of pituitary gland, thyroid gland, parathyroid gland,
adrenal gland, pancreas, pineal gland, thymus and their disorders.
1) The document discusses the Ayurvedic concept of Granthi Sharira (nodular masses in the body) and compares it to modern anatomy.
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3) The endocrine system, which includes glands like the pituitary, thyroid, and pancreas, plays an important role in bodily functions and is comparable to the Ayurvedic concept of Granthi Sharira.
This document provides information on gametogenesis, fertilization, and early embryonic development. It discusses how the male and female gametes, or germ cells, undergo maturation into sperm and eggs. It describes the process of ovulation, fertilization within the fallopian tubes, and the first few cell divisions following zygote formation to create a morula. The key events summarized are gamete formation through meiosis, capacitation and acrosome reaction in sperm, penetration and fusion of sperm with the egg, and early cleavage divisions up to the morula stage.
The document discusses various types of chemical signals in the body including hormones, neurotransmitters, and pheromones. It describes where these signals are produced, how they travel to target cells, and the responses they elicit by binding to receptors. Specific examples covered include hormones secreted by the hypothalamus, pituitary gland, thyroid gland, adrenal glands, ovaries/testes, and posterior pituitary. The roles and mechanisms of various hormone types such as peptides, steroids, and eicosanoids are also summarized.
The document discusses endocrine glands, specifically the endocrine gland. It defines endocrine glands as groups of secretory cells surrounded by an extensive network of capillaries that facilitates the diffusion of hormones directly into the bloodstream. Some key endocrine glands discussed include the pituitary gland, thyroid gland, and hypothalamus. The pituitary gland regulates other endocrine glands and is divided into the posterior and anterior pituitary. The hypothalamus produces hormones that regulate the anterior pituitary. The thyroid gland produces thyroid hormones that increase metabolism.
Chemical Coordination and Integration_NEET_XI_NCERT-1.pptxsaabitkhan280
The document discusses human physiology related to endocrine glands and hormones. It describes that endocrine glands secrete hormones which act as chemical messengers. The major endocrine glands discussed include the hypothalamus, pituitary gland, thyroid gland, parathyroid gland, adrenal gland, pancreas, gonads and pineal gland. It provides details on the hormones secreted by each gland and their functions in regulating other glands and target organs. Disorders related to some glands like pituitary are also mentioned.
The document summarizes key aspects of the human endocrine system. It describes the main endocrine glands including the hypothalamus, pituitary gland, thyroid gland, parathyroid gland, pineal gland, thymus gland, adrenal gland and pancreas. It provides details on the hormones produced by each gland and their functions in regulating processes like growth, metabolism, sexual development and the immune system. The hypothalamus and pituitary gland play central roles in controlling the other endocrine glands through releasing and inhibiting hormones.
The endocrine system is made up of glands that produce hormones, which are chemical messengers that influence cells and organs throughout the body. There are four principal ways cells communicate: gap junctions, neurotransmitters, paracrines, and hormones. The pituitary gland located in the brain secretes several important hormones including follicle-stimulating hormone, luteinizing hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, prolactin, and growth hormone from its anterior lobe. Its posterior lobe secretes antidiuretic hormone and oxytocin. Other endocrine glands include the pineal gland, thyroid gland, pancreas, ovaries, testes, and adrenal glands.
The endocrine system maintains homeostasis through chemical messengers called hormones. The hypothalamus controls the endocrine system and pituitary gland. The pituitary gland regulates other endocrine glands and releases hormones in response to signals from the hypothalamus. Major endocrine glands include the thyroid, parathyroid, adrenal, pancreas, ovaries/testes, which regulate processes like metabolism, growth and development, and reproduction.
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2. 1 Introduction
Neurosecretions are the main sources of hormone in the
invertebrates.
Neurosecretion is the storage, synthesis and release
of hormones from neurons.
These neurohormones, produced by neurosecretory cells,
are normally secreted from nerve cells in the brain that
then circulate into the blood.
These neurohormones are similar to non-
neural endocrine cells and glands in that they also
regulate both endocrine and non-endocrine cells.
3. Neurosecretion cells synthesize and package their
product in vesicles and exocytose them at axon
endings just as normal neurons do, but release their
product fartheir from their target than normal neurons
(which release their neurotransmitters short distances
at synapses), typically releasing their neurohormones
into the circulatory system to reach their distant targets.
In invertebrate neurosecretions appear to regulate
growth, regeneration, metamorphosis and reproductive
activities.
4. Neuroendocrine system in Crustacea
A typical crustacean, the neuro-endocrine system has
the following components.
1. Neurosecretory cells: In crustaceans, neurosecretory
cells are located in the brain, portions of the optic
lobe and all the ganglia of the ventral nerve cord.
2.The neurosecretory X-organ or organ of Bellonci and
its associated three neurohemal organ:
i)The sinus gland. Both an X-organ and a sinus
gland are located in each eyestalk, and together they
are termed the eyestalk complex.
5. They made up of axon termini from the neurosecretory
cells of brain and optic ganglia. They receive storage
and release hormones secreted from neurosecretory cells
in brain and the optic lobe. Sinus gland contains
chromatophorotropin hormone and moult-inhibiting
hormone.
(ii)The post commisure organ located immediately
posterior to the oesophagus and receiving axon from
the brain. It serves as a centre for storage and
release of secretion from the posterior part of the
brain(tritocerebraum). It affects the colour changes
(chromatophorotropin hormone).
6. (iii)The pericardial organ located in the wall of the
pericardium. They consist of neurosecretory cells and
axon terminals from various ventral ganglia. The
secretions of the organs are concentrated with the
increased heart beat and also responsible for the
regulation of gas transport and exchange.
7. 3. There are three non-neural endocrine glands
namely:
(i) The Y-organ located within antennary or
maxillary segments. It secretes a hormone that
influences moulting. It secretion is regulated by the X-
organ complex. An eye stalk hormone appears to
inhibit production of Y-organ hormone.
(ii) Androgenic gland found in male crustaceans. Its
secretion is responsible for development of male
secondary sexual characters. The gland located on the
wall of the vasdeferens. It is performed by interstitial
cells of the testes.
(iii) Ovaries found in female. Its secretion is
responsible for female secondary sexual characters.
8. Role of neuroendocrine system
The various physiological process regulated by the
neuroendocrine system is divided into three groups
namely, kinetic, morphological and metabolic process.
The kinetic process includes somatic pigmentation,
retinal pigment migration and cardiac regulation.
9. Colour changes or somatic pigmentation
The neurohormones known as chromatophorotropins
secreted by the pigment cells (chromatophores) have
been found in the eyestalk complex and almost all part
of the nervous system that regulate colour changes.
The best known are the light-adapting hormone and
the red-pigment-concentrating hormone.
Regulation of the chromatophores allows an animal to
adapt to different backgrounds by changing colours or
by becoming lighter or darker.
10. Control of retinal pigment
movements
Crustacean eye is a compound structure compost of
many units called ommatidia.
The ommatidium consists of three sets of pigments
namely, proximal retinal pigment, distal retinal pigments
and reflecting pigment.
The movement of pigments are under the control of
the hormone of the eye-stalk and brain.
11. Cardiac regulation
In most crustaceans, the heart is neurogenic with
elongated dorsal cardiac ganglion acting as the
pacemaker.
Heart rate is accelerated in crustaceans by a factor
called Myotropic factor released from the pericardial
organs.
Extracts of these organs found to contain 5–hydroxyl-
tryptamine which increased heart rate and also regulates
gas transport and exchange.
12. Moulting
Growth is discontinuous process in arthropods.
Increase in size being restricted to the period between
loss of the old exoskeleton and expansion and
hardening of the new one.
Moulting may be a seasonal or continuous process and
it is influenced by a great variety of environmental
factors.
Externally moulting may be appear sloughing off of the
hard exoskeleton to allow internal growth, internally it is
a complex metabolic adjustments and a well coordinated
neuro-endocrine mechanism operates this complex
process.
In crustaceans, molt cycle occurs in four stages.
Pre-moult, moult, post-moult and inter-moult.
13. Premoult (proecdysis)
Pre-moult (proecdysis) stage occurs just prior to
exuviation, and is characterized by separation of the
old exoskeleton from the underlying epidermal layer.
The old exoskeleton is partly reabsorbed, and energy
reserves are mobilized from the midgut gland.
Pre-moult begins with an increase in concentration of
moulting hormone in the hemolymph.
The first indication that the prawn is entering proecdysis
is the withdrawal of the epidermis from the old cuticle
(apolysis).
14. Later the epidermis starts to hypertrophy and cells,
which appear to have a storage function, accumulate
in it.
As the prawn proceeds through this stage, the
epidermis starts to secrete a new epicuticle and
exocuticle.
Feeding starts to decline and has completely ceased
by the end of the proecdysis.
Oxygen consumption increases, glycogen is deposited
in the hypodemic tissue of the old cuticle and lost
limbs are regenerated rapidly.
The materials for cuticle synthesis are derived from
two sources: accumulated reserves due to feeding and
resorption from the old cuticle.
15.
16. Moult or Ecdysis
Ecdysis, as a stage, only lasts a few minutes.
It begins with the old exoskeleton opening at
the dorsal junction of the thorax and abdomen
in decapod crustaceans, and is completed when
the animal escapes from its confines.
Moult is sloughing off of the old cuticle.
This is accompanied by a marked increase in
size which accounts for rapid absorption of
water immediately after removal of the old
cuticle and the cuticle hardens appreciably
within a few hours afterwards.
17. The steroid hormone ecdysone secreted from the Y-
organ stimulates moulting.
After it is released into the blood, ecdysone is
converted to a 20-hydroxyecdysone, which is the
active moulting hormone.
Edysone is blocked by a neurohormone called moult-
inhibiting hormone, produced by the eyestalk complex.
In moult of the crustacean, the ablation of eyestalk
bring about accelerate the moulting cycle.
18.
19. Post-moult (postecdysis)
Post-moult is the stage just following exuviation
(shedding of the old exoskeleton).
It is the period when the exoskeleton expands due to
increased hemolymph volume from water influx.
Water influx occurs across the epidermis, gills, and gut.
After several hours or days (depending upon total
length of the molt cycle), the new exoskeleton hardens
and retains its rigidity.
Immediately after ecdysis, the only layers present are
the epicuticle and exocuticle.
Within a few hours the epidermis starts to secrete the
endocuticle.
20. Most of the cuticle must be derived from materials
stored in the epidermis, as feeding does not begin until
the prawn is well into the inter-moult stage.
This secretion continues until the prawns are in the
inter-moult condition, when the three layers are fully
formed
21. Inter-moult
During inter-moult the exoskeleton becomes much
harder through mineral and protein deposition.
Shrimp exoskeleton is relatively thin and soft compared
to crabs and lobsters (Chang, 1992).
The volume, as well as the weight of the whole prawn
increases by 3-4% during the intermoult period.
This increase may be due to extension of the thin
intersegmental connections of the abdomen, and
supports the concept that growth in penaeids is a more
continuous process than in the heavily armoured
decapods, which moult relatively infrequently.
22. The X-organ sinus gland complex and Y-organ regulate
the process of moulting.
The Y-organ performs a positive role in this process.
Internal and external environmental conditions influence
the moulting pattern by either affecting the production of
MIH in the X organ or it release from the sinus gland.
The function of Y organ is under the control of
circulating titters of MIH.
During moulting phase concentration of MH higher and
the moulting is switched on.
On other hand, when concentration of MIH increases it
inhibit Y-organ to synthesis MH and inhibition of
moulting process.
The time and duration of each period may be varies
according to geographical distribution, environmental
condition age and sex of the animals.
23.
24. Reproduction
Most of the crustaceans are bisexual with clear cut
sexual dimorphism.
sex is determined genetically, but the morphological and
functional expression are under the control of hormone.
At the younger stages the sexes cannot be
distinguished however, the sexual differentiation
progressed with successive moults and continuous up to
the gonadal maturity and complete development of
secondary sexual characters.
25. Male reproductive hormone:
The male sex hormone is produced by a pair of
androgenic glands located end of the each vasdeferens.
In a genetic female, they fail to develop. But in male
the gland enlarged to form solid strand of cells, folded
several times and become functional androgenic glands.
It is a holocrine gland, that is secretes total content
into the blood.
The peptide hormone secreted by the androgenic glands
influence the normal development of testes and
subsequent spermatogenesis and expression of secondary
sexual characteristics
26. In addition to this, injection of extract from the sub-
oesophageal and thoracic ganglia accelerate the gonadal
development.
This indicates that, some gonads accelerating factor
present in these ganglia.
It is experimentally proved that, in shrimps and other
crustaceans the removal of androgenic glands or their
testes tent to function like ovaries.
They spontaneously develop oocytes from primary germ
cells instead of sperms.
When the androgenic glands are removed such
operation leads to either partial or complete castration of
a male individual.
From this concluded that, the normal functional state of
testes and maintenance of secondary sexual character is
controlled by the male sex hormone secreted by the
androgenic glands.
Testes as an organ however, have no endocrine role.
27. Female reproductive hormone:
The normal functional state of the ovary and female
secondary sexual characters are controlled by two
hormones released from X organ sinus gland complex
of the eye stalk and the ovary.
The eyestalk complex appears to produce a
neurohormone called ovary inhibiting hormone
that inhibits enlargement of ovary and vitellogenesis by
the fat body and blocks vitellogenin (yolk) deposition
in the oocytes in the ovary.
Older follicles in the ovary, however, may secrete a
vitellogenin-stimulating hormone that overrides the effects
of the eyestalk neurohormone.
28. During moulting, the ovarian inhibition hormone is
produced in large quantities thereby inhibiting
reproductive phase.
On the other hand, during reproductive phase moult
inhibiting hormone is secretes in large quantities this
preventing the process of moulting.
29. Osmoregulation
There are four known sources of factors that influence
water and ionic balance (osmoregulation) in
crustaceans.
The brain factor is known to regulate function of the
antennal glands (paired “kidneys” located at the base
of each antenna), the intestine, and the gills.
The thoracic ganglion factor affects the stomach,
intestine, and gills.
Both the antennal glands and the gills are affected by a
factor from the eyestalk complex.
Finally, the pericardial organs (neurohemal glands
located in the pericardial cavity) influence salt and water
metabolism by heart muscle and gills.
30. Neuroendocrine system in Insects
In insect, various life process like growth, metabolism,
colour adaptation and reproduction are controlled by well
coordinated endocrine system.
The neuro-endocrine system of a typical insect is
compost of both aggregation of neurosecretory nuclei in
different regions of the nervous system and specialized
non neural endocrine glans.
Insects contains two neurosecretory nuclei namely,
cerebral ganglia and corpora cardiaca, the non-neural
organs namely, corpora allata and prothoracic gland or
ecdysial gland.
31. Cerebral ganglions are the important neurosecretory
centre of insects.
It has two median ganglions and two lateral ganglions.
Axons from the median ganglions cross each other and
emerging from the brain forming a pair of nerves called
Nervi Corporis Cardiaci-I (NCC-I) extend to a
neurohaemal organ corpora cardiac.
The lateral ganglia or B-cells are usually smaller in size
and fewer in numbers then the median cells or ganglia.
From these a paired nerves directly emerged out and
joint with corpora cardiaca that is called nervicorporis II
(NCC-II).
Cerebral ganglia
32. They located lateral to the NCC-I. In some cases the
third group of trito-cerebral nuclei are present.
From this the axons directly enter to the corpora
cardiac via NCC-III.
These are the cerebral ganglions or cells found in the
various groups of insects.
In addition to this, neurosecretory cells also found in
sub-oesophageal and other ganglia of ventral nerve
cords.
The presence of neurosecretory cells in the sub-
oesophageal ganglia is a characteristic feature of
throughout the insect order.
33.
34. Corpora cardiaca
Corpora cardiaca are the principal neurohaemal organs
located just below the brain.
They are small paired structure, bluish in appearance.
The nerve trunks from cerebral ganglia (NCC-I, II and
III) are end in the corpora cardiaca. Each corpora
cardiaca is again connected to its corresponding corpora
allatum by a single nerve nervous corpora allati.
Corpora allati composed of axons originating from the
brain.
The corpora cardiaca can be considered as a modified
nerve ganglia functioning as a neurohaemal organ.
Moreover, some nerve cells located in it may function
as neurosecretory cells.
35. A large portion of the cardiacum is composed of axons
terminals of the brain neurosecretory cells.
The neurosecretion of the cerebral nuclei may be
stored here or released directly into the haemolymph.
But the secretory cells have been identified in cardiaca
from many species that function is not yet understood.
36. Corpoa allata
The corpora allata are a non neural endocrine gland
located immediately below the corpora cardiaca.
It is an ectodermal in origin, appeared as a solid
structure and ovoid in shape.
The allata receive a pair of nerves from corpora
cardiaca which are primarily the extensions of the nervi
corporis cardiaci-I.
Thus the allata becomes the segment of the
protocephalic neurosecretory pathway that extends from
the protocerebrum through the corpora cardiaca into the
allata.
The corpora allata is the sources of juvenile hormone
(JH) or neotensis which play an important role in the
life cycle of insect particularly in the process of
moulting.
37. Prothoracic gland or Ecdysial gland
Prothoracic gland is a second non neural endocrine
gland arising from the ectodermal cells.
The gland usually in pair and their location is varies in
different group of insects.
Mainly it found in prothorax hence, it is called
prothoracic gland.
It plays an important role in the process of moult or
ecdysis.
The functioning of the scdysial gland is controlled by a
tropic hormone released from the corpora cardiacum.
The ecdysial gland secretes a steroid hormone called
ecdysone.
It plays an important role in the process of growth and
development.
38. Endocrine control of moulting and
metamorphosis
The endocrine systems in insects control growth and
development.
In insects growth is a discontinuous process that leads
towards maturity through stages or instars.
A key feature of insects is that they have exoskeletons.
For an insect to grow, at the end of each instar
moulting occurs.
During moulting the old binding exoskeleton is shed with
the formation of new one to providing space for further
growth of body.
This shedding process is called moulting or ecdysis.
39. The life of an insect consists of a series of discrete steps:
growing followed by moulting, then more growing followed by
moulting, and so on.
However, the rigid exoskeleton cannot change shape between
moults.
In the moult cycle, final moult is the very important changes
because it is the period during which the adult characters
are formed with the concurrent loss of specific juvenile
structure. This means that all the changes of external
shape in the life of an insect must occur during
moulting.
This transformation from an immature juvenile to a
mature adult is termed as metamorphosis.
In this way, the moulting process is intimately
connected to both growth and morphological
development.
40. The process of growth and development is controlled by
three endocrine sources namely, the brain, ecdysal
gland and corpora allata.
There are three hormones regulates growth and
development they are first one is prothoracicotropic
hormone (PTTH), a peptide tropic hormone secreted by
brain neurosecretory cells.
The second is ecdysone, a steroid secreted by non-
neural endocrine cells in the pro-thoracic glands.
PTTH controls secretion of ecdysone. Juvenile hormone
(JH) is the third hormone of primary importance in the
control of moulting.
It is secreted into the general circulation by non
neural endocrine cells in the corpora allata
41. Neurosecretory cells in the brain secretes
prothoracicotropic hormone or ecdysiotropin hormone
which is stored in the corpora cardiaca.
The brain has a computational power to determine
when each moult will occur.
The neurosecretory cells that secrete PTTH is receive
synaptic inputs from other, ordinary brain neurons that
control when the neurosecretory cells will secrete their
hormone.
On stimulation from the ventral nerve cord to the brain
via the axons of the brain the corpora cardiaca release
the PTTH to blood (haemolymph).
42. During each episode of PTTH secretion, the flow of
blood carries the PTTH to the two pro-thoracic glands,
where it stimulates to secrete ecdysone hormone.
As the ecdysone circulates, it undergoes peripheral
activation to form 20-hydroxyecdysone, a hormone that
primarily affects the insect’s epidermis, the layer of
living tissue just inside the exoskeleton.
The epidermis secretes the exoskeleton. The hormone,
being a steroid, enters the epidermal cells.
There it combines with intracellular receptors, which
alter gene transcription patterns.
43. As a result, the epidermal cells secrete enzymes that
loosen their connection with the old exoskeleton,
allowing the old exoskeleton to be shed.
Then the epidermal cells synthesize a new, larger
exoskeleton and differentiation of tissue.
In other words, a moult occurs.
44.
45. At that time, Juvenile hormone (JH) is secreted into the
general circulation by non-neural endocrine cells in the
corpora allata .
It is lipid-soluble and enters target cells to starts life
as a larva (caterpillar), retains its larval form for
several moults, and then metamorphoses into an adult.
It is observed that, each cell of the body has
multiple sets of genes which transfer the body into
immature or mature characters.
Some insects, such as moths and butterflies, undergo
a complete metamorphosis during their development.
In this respect JH play an important role in retaining
juvenile characters after each moult.
46. When a larva moults, it retains its larval form if JH is
at high concentration in the blood during the moulting
process.
During the early life of an individual, the blood
concentration of JH is high.
Moulting thus results in a series of larger and larger
larval forms .
Later in life, however, JH secretion is reduced, and
the JH concentration in the blood falls to a low level.
At that point, when moulting occurs, the juvenile form
is not retained.
Instead, the insect enters a resting stage of distinctive
body form, called a pupa.
During the inactive pupal stage, the insect’s
47. During the inactive pupal stage, the insect’s body is
extensively remodelled inside the pupal exoskeleton.
Then, when the insect moults yet again without a high
concentration of JH in the blood, the individual emerges
as an adult.
48. Hormonal regulation of
Reproduction
The initiation and termination of some reproductive
events often depend on environmental factors, such
as temperature, humidity, photoperiod, or availability
of food or a suitable egg-laying site.
Additionally, these external influences may be modified
by internal factors such as nutritional condition and the
state of maturation of the oocytes.
Copulation also may trigger oocyte development,
oviposition, and inhibition of sexual receptivity in the
female via enzymes or peptides transferred to the
female reproductive tract in male accessory gland
secretions.
49. Regulation of reproduction is complex and involves
sensory receptors, neuronal transmission, and integration
of messages in the brain, as well as chemical
messengers (hormones) transported in the hemolymph
or via the nerve axons to target tissues or to other
endocrine glands.
Certain parts of the nervous system, particularly
neuro-secretory cells in the brain, produce
neurohormones or neuropeptides (proteinaceous
messengers) and also control the synthesis of two
groups of insect hormones — the ecdysteroids and the
juvenile hormones (JH).
Neuropeptides, steroid hormones, and JH all play
essential roles in the regulation of reproduction,
50. Juvenile hormones and/or ecdysteroids are essential
to reproduction, with JH mostly triggering the functioning
of organs such as the ovary, accessory glands, and fat
body, whereas ecdysteroids influence morphogenesis
as well as gonad functions.
Neuropeptides play various roles at different stages
of reproduction, as they regulate endocrine function
(via the corpora allata and prothoracic glands) and
also directly influence reproductive events, especially
ovulation and oviposition or larviposition.
51. The role of neuropeptides in control of reproduction
is an expanding area of research, made possible
by new technologies, especially in biochemistry and
molecular biology.
To date, most studies have concentrated on the
Diptera (especially Drosophila, mosquitoes, and
houseflies), the Lepidoptera (especially the tobacco
hornworm, Manduca sexta), locusts, and cockroaches.
52. Examples of some important insect physiological
processes mediated by neuropeptides.
53. Neuropeptide Action
Growth and development
Allatostatins and allatotropins Induce/regulate juvenile hormone (JH)
production
Bursicon Controls cuticular sclerotization
Crustacean cardioactive peptide (CCAP) Switches on ecdysis behaviour
Diapause hormone (DH) Causes dormancy in silkworm eggs
Pre-ecdysis triggering hormone (PETH) Stimulates pre-ecdysis behaviour
Ecdysis triggering hormone (ETH) Initiates events at ecdysis
Eclosion hormone (EH) Controls events at ecdysis
JH esterase inducing factor Stimulates JH degradative enzyme
Prothoracicotropic hormone (PTTH) Induces ecdysteroid secretion from
prothoracic gland
Puparium tanning factor Accelerates fly puparium tanning
54. Reproduction
Antigonadotropin (e. g. oostatic
hormone, OH)
Suppresses oocyte development
Ovarian ecdysteroidogenic
hormone (OEH = EDNH)
Stimulates ovarian ecdysteroid
production
Ovary maturing peptide (OMP) Stimulates egg development
Oviposition peptides Stimulate egg deposition
Prothoracicotropic hormone (PTTH) Affects egg development
Pheromone biosynthesis activating
neuropeptide
Regulates pheromone production
(PBAN)
55. Homeostasis
Metabolic peptides (= AKH/RPCH
family)
Adipokinetic hormone (AKH) Releases lipid from fat body
Hyperglycemic hormone Releases carbohydrate from fat body
Hypoglycemic hormone Enhances carbohydrate uptake
Protein synthesis factors Enhance fat body protein synthesis
56. Diuretic and antidiuretic peptides
Antidiuretic peptide (ADP) Suppresses water excretion
Diuretic peptide (DP) Enhances water excretion
Chloride-transport stimulating
hormone
Stimulates Cl− absorption (rectum)
Ion-transport peptide (ITP) Stimulates Cl− absorption (ileum)
Myotropic peptides
Cardiopeptides Increase heartbeat rate
Kinin family (e. g. leukokinins and
myosuppressins)
Regulate gut contraction
Proctolin Modifies excitation response of some
muscles
58. The transition from ecdysterone production by the pre-
adult prothoracic gland to the adult ovary varies
between taxa. (After Raabe 1986)
In summary, reproduction in different class of insects is
controlled by a well defined neuroendocrine
phenomenon, in which central nervous system plays a
key role.
Even though various external and internal stimuli
regulates on it, set a series of neuro-endocrine
adjustments leading to the development of gonads and
switching on the secondary reproductive behavioural
adjustment.
The experimental evidences prove that, main endocrine
sources controlling reproduction are brain, corpora allata
and pro-thoracic gland.
59. DIAPAUSES
Diapauses, is a resting phase in the life cycle of an
insect as a result of arrested development.
It is a condition of reduced metabolism and various
other changes like decreased body water and
responsiveness to external stimulus.
The temporary adjustments to avoid death, otherwise
possible due to unfavourable conditions, involve a
change in the neuro-endocrine regulation.
Diapauses may occur at any stage of the life cycle
from egg to the adult.
60. The females emerging from eggs exposed to long
photoperiods and high environmental temperature
produces diapauses egg to avoid the environmental
stress during post embryonic development.
A definite neroendocrine are controls the production of
these eggs.
In Bombyx mori, it is observed that, the diapauses
hormone is synthesised and released from the nero-
secretory cells in the sub-oesophageal ganglion.
The hormone acts upon the eggs when they are still
in the genital tract.
61. As compared to eggs, larval or nymphal diapauses
have received little attention.
Pupa diapauses generally terminate following the period
of reduced temperature.
During this phase proto-cerebral neurosecretory cells of
the diapausing pupa regain their activities.
The neruo-hormone released from the cells stimulates
the ecdysial gland to release ecdysone which terminates
the diapauses.
Many insects are able to enter the diapauses condition
at an adult stage but very little is known about the
neuroendocrine regulation of this phenomenon.
62. Hormonal control of
osmoregulation
Insects and other arthropods, such as crayfish and
crabs, have elaborate endocrine systems.
For example, many insects have anti-diuretic and
diuretic hormones that control excretion of water by the
insect organs that serve kidney functions.
Diuretic hormones promote excretion of a high volume
of water.
Some of the blood-sucking insects secrete diuretic
hormones immediately after each blood meal.
These hormones promote rapid excretion of much of
the water in the blood, thereby concentrating the
nutritious part of the meal (e.g., the blood proteins)
in the gut.
63. Colour adaptation
In insects, both morphological and physiological colour
changes are occurs.
In general, physiological colour changes are influenced
by two endocrine principal originating from sub-oesophageal
ganglion and tritocerebrum and a weaker effect substance
from corpora cardiaca.
Generally, under the influence of them darkening of the
epidermis is brought about.
The environmental stimulus which influence the activity of
nerosecretory cells in light.
Morphological colour changes usually occur during ontogenetic
development and hormones must be modifying the metabolic
pathway involved in synthesis of different indegumentary
pigments.
Generally, coloration of the environment influences the body
colour in response to ecdysial gland.