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[BIO102] Control and Integration (Nervous and Endocrine Systems)

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a ppt/pptx about the nervous and endocrine systems presented for BIO102 course (Fundamentals of Animal Biology)

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[BIO102] Control and Integration (Nervous and Endocrine Systems)

  1. 1. NERVOUS & ENDOCRINE SYSTEMS
  2. 2. • NERVOUS SYSTEM •Rapid communication by neural mechanisms • ENDOCRINE SYSTEM •less rapid communication by hormonal mechanisms
  3. 3. • Originated from irritability – a fundamental property of life; the ability to respond to environmental stimuli • Neural signaling has higher specificity and is relatively faster than hormonal signaling. • Some nerve impulses travel at 120 meters per second (about 400 km/h) • Basic plan is to: 1. Receive information from both external and internal environments 2. Encode this information 3. Transmit this information
  4. 4. • Neuron – functional unit of nervous systems – has many types depending on function and location – transmit nerve signals to and from the brain
  5. 5. • Cell body (or soma) – has nucleus • Dendrites – branch from the cell body The soma and dendrites are the neuron’s receptive apparatus. • Axon – a long fiber, may be meters in length in the largest mammals – conducts nerve signal In vertebrates and some complex invertebrates, the axon is often covered with myelin – an insulating sheath that accelerates transmission – consists of 70-80% lipids and 20-30% protein • Nodes of Ranvier – parts of the axon that are not coated with myelin • Axon terminals – transmitters • Synapse – gap between axon terminals and the receiving cell
  6. 6. Neuroglial Cells (or simply glial cells) – surround neurons • Schwann’s cells – manufactures myelin in the peripheral nervous system • Oligodendrocytes – manufacture myelin in the central nervous system • Astrocytes – star-like shape – serve as nutrient and ion reservoirs for neuron – provide scaffold during brain development – essential for regenerative process • Microglial cells – smaller than astrocytes – essential for regenerative process
  7. 7. • Afferent (or Sensory) Neurons – connected to receptors • Receptors function to convert external and internal environmental stimuli into nerve signals which are carried by afferent neurons into the CNS • Efferent (or Motor) Neurons – carry nerve signals to effectors • Effectors are organs, tissues, or cells that become active upon stimulation. • Interneurons – interconnect neurons
  8. 8. Stimulus Receptor Sensory Neuron CNS Motor Neuron Effector
  9. 9. • In vertebrates, nerve processes (usually axons) are often bundled together in a wrapping of connective tissue to form a nerve. • Cell bodies of these nerve processes are located either in the central nervous system or in ganglia (bundles of nerve-cell bodies located outside CNS)
  10. 10. • Nerve Net – forms an extensive network in and under the epidermis all over the body – radially symmetrical animals, sea anemones, hydras, jellyfishes, comb jellies, etc
  11. 11. • Bilateral Nervous System • Flatworms have the simplest bilateral nervous system
  12. 12. • Bilateral Nervous System • Annelids’ nervous system consist of a bilobed brain, a double nerve cord with segmental ganglia and distinct afferent and efferent neurons
  13. 13. • Bilateral Nervous System • Molluscan nervous system • Vary among groups • Squids and octopi have well-centralized nervous systems
  14. 14. • Bilateral Nervous System • The nervous system of arthropods resembles the annelids’, but arthropods have larger ganglia and better developed sense organs • Mushroom bodies – brain region associated with learning; largest in social instects
  15. 15. Vertebrates • Encephalization – the process of the great elaboration of size, configuration, and functional capacity of the brain • Fast responses • Great capacity for information storage • Enhanced complexity and flexibility of behavior • The ability to form associations between past, present, and (at least in humans) future events
  16. 16. • Composed of the spinal cord and the brain
  17. 17. • Early vertebrates had three (3) principal brain divisions: 1. Prosencephalon or forebrain – smell 2. Mesencephalon or midbrain – vision 3. Rhombencephalon or hindbrain – hearing and balance
  18. 18. Pon s
  19. 19. • Human brain is the most complex, even though it is not the largest nor the most convoluted. • Contains 35 billion neurons, each of which may receive information from 10 000 synapses at one time • May be so complex that it will never be able to understand its own function!
  20. 20. • Spinal cord – long, tubular bundle of nerves extending from the brain • Wrapped in three layers of membranes called meninges • Two (2) Zones: 1. Zone of Gray Matter – inner zone – butterfly shaped – consists of the cell bodies of motor neurons and interneurons 2. Zone of White Matter – outer zone – contains bundles of axons and dendrites linking different levels of the cord with each other and with the brain
  21. 21. Three (3) Major Functions: 1. Conduit for motor information Motor information travel down 2. Conduit for sensory information Sensory information travel up 3. Center for coordination of
  22. 22. • Composed of all nerves not included in the CNS
  23. 23. 1. Sensory (or Afferent) Division • brings sensory information to the central nervous system 2. Motor (or Efferent) Division • conveys motor commands to muscles and glands • Two (2) Components of the Efferent Division 1. Somatic Nervous System – skeletal muscles 2. Autonomic Nervous System – smooth muscles, cardiac muscles, glands • Two (2) Subdivisions of the Autonomic Nervous System 1. Parasympathetic System
  24. 24. • Composed of glands that produce hormones that regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things • Hormonal signaling is relatively much slower than neural signaling. • Endocrine control is expected when a sustained effect is required.
  25. 25. • Hormones – chemical messengers – chemical compounds released into the blood in small amounts and transported by the circulatory system throughout the body to distant target cells – may act as a neurotransmitter or as a parahormone • Endocrine glands – small, well-vascularized ductless glands • Target cell – where a hormone initiate physiological responses
  26. 26. • Neurosecretory cells – specialized nerve cells capable of synthesizing and secreting hormones - principal source of hormones in many metazoan phyla • The most common hormones among different invertebrate groups are peptides and neuropeptides. • Cardioactive peptide – increases heart rate in crustaceans • Crustacean hyperglycaemic hormone family (CHH) – regulate metabolism in crustaceans • Adipokinetic hormone family – regulate metabolism in insects • Molting and metamorphosis are primarily controlled by the interaction of these two hormones: 1. Molting hormone or ecdysone
  27. 27. • The major human endocrine glands
  28. 28. • Hypothalamus – contains groups of neurosecretory cells that manufacture releasing hormones and/or release- inhibiting hormones • These hormones then either stimulate or inhibit release of various anterior pituitary hormones. • Pituitary gland (or hypophysis) – a two-part gland 1. Anterior Pituitary (adrenohypophysis) 2. Posterior Pituitary (neurohypophysis) – connected to the hypothalamus by a stalk called infundibulum
  29. 29. • Pineal Gland – produces the hormone melatonin • Melatonin secretion is strongly affected by the presence of light. • Lowest during daylight hours, highest at night • In nonmammalian vertebrates, the pituitary gland is responsible for maintaining circadian rhythms – 24-hour long rhythms; a circadian rhythm serves as a biological clock for many physiological processes that follow a regular pattern • In mammals, the suprachiasmatic nucleus (an area of the hypothalamus) is the primary circadian pacemakers, although the pineal gland still produces melatonin nightly and serves to reinforce the circadian rhythm of the suprachiasmatic nucles.
  30. 30. • Thyroid gland – a large endocrine gland located in the neck of all vertebrates • Triiodothyronine (T3) and Thyroxine (T4) • Most important functions: • Promote normal growth and development of the nervous system of growing animals • Stimulate metabolic rate
  31. 31. Three (3) Hormones that Maintain Blood Calcium Level: 1. Parathyroid hormone (PTH) – stimulates release of calcium when blood calcium level decreases from normal level - produced by the parathyroid glands 2. 1,25-dihydroxyvitamin D3 – active calcium absorption by the gut - hormonal form of vitamin D3 3. Calcitonin – protects the body against blood calcium level increase - produced by thyroid gland
  32. 32. • Adrenal Gland – composed of the cortex (outer region of adrenocortical cells) and medulla (inner region of specialized cells) • Corticosteroid hormones are classified in two (2) groups: Long-term stress responses 1. Glucocorticoids – influence food metabolism, inflammation, and stress • include cortisol and corticosterone – gluconeogenesis 2. Mineralocorticoids – regulate salt balance • include aldosterone which promotes tubular reabsorption of sodium and tubular secretion of potassium by the kidneys • Hormones secreted by adrenal medullary cells: • Epinephrine (adrenaline) • Norpinephrine (nonadrenaline) These hormones and the sympathetic nervous system have the same general effects on the body. • “Fight or flight” (short-term stress) responses
  33. 33. • Pancreas – both an exocrine and an endocrine organs • Islets of Langerhans – small islets of tissue scattered within the exocrine portion • Several hormones are secreted by different cell types within the islets: • Beta cells – insulin (promotes entry of glucose into body cells; lowers blood glucose level) and amylin • Alpha cells – glucagon (increases blood glucose level) • Delta cells – somatostatin (inhibit secretion of other pancreatic hormones) • Gamma cells – pancreatic polypeptide (reduces appetite)
  34. 34. • Gonads: • Testes (male) • Ovary (female) • Gonads produce most of the body’s sex hormones: androgens, estrogens, progestins, etc.
  35. 35. • Tropic hormones – hormones that influence the action of another hormone or an endocrine gland

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