Secretin is a hormone that controls the secretions into the duodenum , and also separately, water homeostasis throughout the body. It is produced in the S cells of the duodenum in the crypts of Lieberkühn .  Its effect is to regulate the pH of the duodenal contents via the control of gastric acid secretion and buffering with bicarbonate from the centroacinar cells of the pancreas as well as intercalated ducts. It is notable for being the first hormone to be identified
General psych neurobiobases part 2
GENERAL PSYCHOLOGY Neurobiological Basis of Psychology (2) Endocrine System Sensation & Perception
The Neuron – basic unit if the nervous system. Responsible in making body necessary responses or actions.
3 major parts of neuron : 1.Dendrites – neuron fiber carrying impulse to nerve cell body from synapse.
2. Cell body – the compact central portion of a neuron 3. Axon – carries the nerve impulse away from the cell body and into the end brush.
<ul><li>*Types of Neurons* </li></ul><ul><li> </li></ul><ul><li>Afferent or Sensory Neuron </li></ul><ul><li>– carry messages towards the central nervous system from the receptors such as the eyes, ears and other sense organs. </li></ul>
2.Efferent or Motor Neurons – these carry messages from the central nervous system to the muscles and glands. 3.Connecting or Association Neurons – these are ‘middle-men’ between neurons. They are between the sensory and motor neurons. Most of them are found within the central nervous system.
Glia Cell or Neuroglia – other cells in the central nervous system. It is smaller than neurons. Their function is to provide support to the neurons.
Synapse – the only way that a neuron can communicate with other neurons. It is a microscopic gap, about eighteen-millionths of an inch wide, between the axon of one neuron and the dendrites of another neuron.
Nerve Impulse – is a wave of electro-chemical disturbance propagated along a nerve fiber.
<ul><li>Two Main Divisions: </li></ul><ul><li>Central Nervous System </li></ul><ul><li>– composed of the brain and the spinal cord. </li></ul>
A. Brain – is that portion of the nervous system that is encased in the cranial bones.
It composed of soft nerve tissues covered by three membranes together known as meninges.
Three Major Sub–Divisions of the Brain 1. Hindbrain – within the hindbrain are the medulla oblogata, cerebellum, and pons varoli.
Medulla oblongata – the lowest portion of the brain. It connects the spinal cord. It contains center that regulate heart beat, blood pressure, and breathing and it controls the activities of the internal organs.
Cerebellum – is situated at the back of and above the medulla. It controls body balance.
Pons Varoli – contains nerves fibers that connect both hemispheres of the cerebellum with each other as well as with nerve fibers that transmit neutral impulses upward and downward within the nervous system.
2. Midbrain – contains nerve tracks that connect the cerebrum with the brain stem and the spinal cord. It also contains neurons that are important for visual and auditory functions.
3. Forebrain – the highest part of the brain, is divided into three main parts: the thalamus, the limbic system, and the cerebrum.
Thalamus – is the brain’s major relay station connecting the lower the lower structures of the brain and the spinal cord with cerebrum. - In the thalamus lie the cell bodies of important connecting neurons for the various senses.
Limbic System – includes such areas as the amygdala, the hippocampus, the septum and portions of the hypothalamus and thalamus is a complex organization of neutral structures and pathways carrying messages between the lower and higher parts of the brain. It receives sensory messages from the visceral organs and helps control activities.
Amygdala – which is connected with the hippocampus seems to be the main area involved with emotions. It is fundamental for self- preservation. Hippocampus – involved with memory, especially the formation of long-term memory.
Cerebrum – the largest part of the brain. It is divided into two halves called the cerebral hemispheres. These hemispheres contain the center for sensory integration and for voluntary motor activities. - They also play important roles in governing memory and intelligence.
<ul><li>Peripheral Nervous System </li></ul><ul><li>- Composed of nerves that connect the brain and spinal cord to the periphery of the body. </li></ul><ul><li>- This nerves, called the peripheral nerves are found outside the central nervous system. They connect to the skin, muscles, and glands. </li></ul>
Afferent nerves - the nerves carrying sensory input to the central nervous system Efferent nerves – the one’s carrying motor output away from the nervous system.
B. Spinal Cord The spinal cord is composed mainly of nerve connections running between the brain and the various parts of the body. It is long, tapering tube which occupy the hollow interior of the vertebral column, through the opening of which the spinal nerves enter and emerge from the cord. There are 31 pairs of spinal nerves.
<ul><li>*Two sub- Division of the Central Nervous System* </li></ul><ul><li>Somatic Nervous System </li></ul><ul><li>– form by the efferent nerves leading to the skeleton muscles. Somatic motor nerves control most of what we called behavior. </li></ul>
<ul><li>Autonomic Nervous System </li></ul><ul><li>– regulates the automatic actions of the viscera necessary to keep the body in operation and to reproduce the species. It is the mainly responsible for the activation of the smooth muscles , the glands, and in part, the heart muscles. </li></ul>
Hormones <ul><li>Secreted by the endocrine glands. </li></ul><ul><li>Chemicals that circulate via the bloodstream to specific parts of the body and affect their functioning and growth. </li></ul><ul><li>Not all hormones are secreted by glands.Ex:secretin. </li></ul><ul><li>Not all hormones are proteins. </li></ul><ul><li>They can be peptides, steroids, amino acids </li></ul><ul><li>and derivatives of catecholamine. </li></ul>
Endocrine Glands Hormones – glands which are compose of cells that specialize in secreting highly complex chemical substance. Duct glands – glands that pour out their secretion trough tubes. Ex. milk glands, salivary glands, gastric glands on the walls of the stomach and the liver.
The major endocrine glands: ( Male left, female right) 1 Pineal gland 2 Pituitary gland 3 Thyroid gland 4 Thymus 5 Adrenal gland 6 Pancreas 7 Ovary 8 Testes Endocrine System
Ductless glands - glands secrete hormones directly into bloodstream. 1. Pituitary Glands It is found below the brain stem and is only a little larger than a pea. It is sometimes called the master glands because its secretes hormones that act on particular endocrine and stimulates their growth and activity.
For example, it sends hormones to the thyroid, adrenals, gonads in order to stimulates them to produce their own hormones. The pituitary gland has two lobes, an anterior lobe and a posterior lobe. The anterior lobe secretes several hormones, one of these are growth hormones which promotes and control normal increase in size of the body.
2. The Thyroid Glands It is located in the neck produce the hormone thyroxin which influences the rate of the body metabolism especially oxidative or respiratory processes in all cells of the body.
Thyroid gland <ul><li>Located at the base of the neck on either side of the wind pipe. </li></ul><ul><li>Necessary for optimal development and growth of CNS and other body systems. </li></ul><ul><li>Secretes thyroxin-regulates the rate of metabolism. </li></ul>
<ul><li>Hypothyroidism </li></ul><ul><li>-cretinism-retarded physical and mental growth, poor body proportions, low metabolic activity, a broad nose, dry skin, poor mental activity. </li></ul><ul><li>-Myxoedema-thick, puffy skin, dry, brittle hair, sluggish mental activity, increased body fat and weight. </li></ul><ul><li>Hyperthyroidism -nervousness, irritability, fatigue, fast heart beat, weight loss. </li></ul>
<ul><li>Goiter or grave’s disease </li></ul><ul><li>Enlarged thyroid gland characterised by swelling under the skin at the front of the neck. </li></ul><ul><li>Increased heart beat and metabolism, reduction in weight, high blood pressure </li></ul><ul><li>-overactive, unstable, tense, nervous. </li></ul><ul><li>-insomnia. </li></ul>
3.Parathyroid Glands - The parathyroid glands are located on the thyroid. They secrete parathormone, a hormone necessary to control the balance of various minerals in the blood stream especially calcium. It is essential to the maintenance of proper level of calcium in the blood and for the control of calcium metabolism in the cells.
<ul><li>Located on either side of TG </li></ul><ul><li>regulates calcium absorption and metabolism. </li></ul><ul><li>Secretes parathormone hormone. </li></ul><ul><li>-regulates calcium level in the blood. </li></ul><ul><li>-small variations-muscles and nerve impairment, affects behavior. </li></ul><ul><li>-necessary for cartilage models to become bones. </li></ul><ul><li>-under secretion or over secretion affects skeletal bones and teeth. </li></ul><ul><li>-removal-tremors, cramps, convulsions and muscular twitching. </li></ul>
<ul><li>Located in the region where the throat joins the chest. </li></ul><ul><li>Large gland at childhood starts shrinking around puberty and reduces to the minimum during adulthood. </li></ul><ul><li>Stimulates the vertical growth and withholds premature sexual development. </li></ul><ul><li>Plays an important role in the development of the child’s immune system. </li></ul>
Adrenal glands <ul><li>Play an important role in determining a person’s mood, energy level and ability to cope with stress. </li></ul><ul><li>Located above kidneys. </li></ul><ul><li>- Each gland has: </li></ul><ul><li>Adrenal medulla (inner) </li></ul><ul><li>Adrenal cortex (outer) </li></ul>
<ul><li>Adrenal medulla : </li></ul><ul><li>Helps cope with physical and emotional stress. </li></ul><ul><li>Closely related to the sympathetic nervous system, control physical reactions induced by emotion. </li></ul><ul><li>Secretes-epinephrine (adrenalin)-increase heart rate, facilitates blood flow to muscles and brain, relaxation of smooth muscles, conversion of glycogen to glucose in the liver. Norepinephrine (noradrenalin)-stimulates to release adrenocortical hormone. </li></ul>
<ul><li>Adrenal cortex : </li></ul><ul><li>Secretes a number of hormones-aidosterone, cortisol (minor aches and pains), cortisone (rheumatoid arthritis), 17-ketosteroids (sex hormones) etc. </li></ul><ul><li>Secreted more under stress. </li></ul><ul><li>Destruction-Addison’s disease-irritability, increased fatigue, loss of appetite. </li></ul>
5. The Adrenals Located on the upper end of each kidney. Each adrenal has two parts: the medulla(inner part), which secretes adrenalin also known as epinephrine and nor-adrenalin or nor-epinephrine, the cortex or outer part which considered as an amazing endocrine factory since it produces very many different hormones.
- This gland continues to grow in size from infancy to puberty but after puberty, it slowly shrinks and is almost none existent in all age. The thymus gland therefore inhibits sexual development during childhood, but ceases to function after. - Sometimes called gland of childhood.
* Adrenalin - referred to as the emergency hormone because it enables the individual to cope with emergency situations. 6. Islets of Langerhans This are a group of cells located in the pancreas. They secrete insulin which is needed in the regulation of blood sugar by the cells. Its primary function is to control the metabolism of glucose.
This photograph shows a mouse pancreatic islet, an often spherical group of hormone-producing cells . Insulin is labelled here in green, glucagon in red, and the nuclei in blue. Islets of Langerhans
7. The Gonads This refer to the ovaries in the female and testes in the male which produce sex hormones. The ovaries produce estrogen and progesterone. The testes produce the male sex hormone testosterone. These hormones influence the appearance of the secondary sex characteristics, the maturation of the reproductive organs, and the sex drive.
<ul><li>RECAP: </li></ul><ul><li>Different parts of your brain share information and organize plans for action through a code system. </li></ul><ul><li>Chemicals called neurotransmitters are emptied from tiny sacs into the space between nerve cells. </li></ul><ul><li>These chemicals cross that space and bind to receptors on other nerve cells. </li></ul><ul><li>The binding process triggers an electrical stimulus in the receiving cells. </li></ul>
<ul><li>A hormone is a substance that is secreted by an organ or part of the body, into the blood stream, and is thereby transported to another body part (or it may act on the organ that secreted it), to illicit an action. </li></ul><ul><li>A neurotransmitter is any specific </li></ul><ul><li>chemical that crosses a synaptic </li></ul><ul><li>space after being transmitted from </li></ul><ul><li>a presynaptic cell, and acts on a </li></ul><ul><li>post-synaptic cell. </li></ul>
<ul><li>Hormone is a compound produced by an endocrine gland and released into the bloodstream where it can find it's target cells at some distance from it's actual site of release. </li></ul><ul><li>A neurotransmitter is a compound </li></ul><ul><li>released from a nerve terminal. These </li></ul><ul><li>nerve terminals are in direct apposition </li></ul><ul><li>with their target cells to ensure rapid </li></ul><ul><li>and specific delivery of the signal. </li></ul>
ASSIGNMENT: IS ADRENALIN (or Adrenaline) A HORMONE OR A NEUROTRANSMITTER? (1/2 crosswise yellow sheet)
Stimulus – any from of energy capable of exiting the nervous system like light waves, sound waves, and the chemical energy that causes the sensation taste and smell. Receptor – is a specialized nerve ending capable of responding to energy. Senses – mechanisms which convert stimulus energy into neutral energy.
*Five Human Senses* 1.VISION The organ for vision is the eye. It is stimulated by light waves that strike the retina where the photo-sensitive cells- the rod and the cones- are located. The rods and cones are the receptor for vision.
<ul><li>Structure </li></ul><ul><li>Globe - shaped and has a diameter of approximately one inch. </li></ul><ul><li>Composed of three coats: </li></ul><ul><li>Sclera - the outer layer, a tough opaque layer of connective tissue used to protect the inner structures of the eye. Helps maintain the shape of the eyeball, in front, this layer becomes the cornea which is thin and transparent. </li></ul>
Choroid Coat - the middle layer, a pigmented layer. It contains some of the blood vessels that supply the eye with blood. It also absorbs imperfectly focused light rays. In the front part of the eye, it becomes modified to from the iris and the cilliary blood. Pupil – the central opening of the iris
Iris – a circular arrangement of muscles that contract and expand to change the size of the pupil depending upon the intensity of illumination called light or dark adaptation. The color of the eye is due to the pigment in the iris Accommodation – the process when the lens become thinner to bring faraway objects into focus and thickens to focus on nearly objects.
<ul><li>Defects of Vision </li></ul><ul><li>Presbyopia </li></ul><ul><li>– a special form of farsightedness which occurs with advancing age. The presbyopic person cannot focus clearly on near objects. </li></ul>
<ul><li>Farsightedness or Hyperopia </li></ul><ul><li>– is caused by a shortened eyeball, making the distance from the lens to the retina too short. The lens will focus at a point behind the retina. A farsighted person is able to see far objects clearly but not near ones. </li></ul>
<ul><li>Nearsightedness or Myopia – near objects are not seen clearly but lens is unable to thin enough to bring far objects into clear focus. </li></ul>
<ul><li>Astigmatism </li></ul><ul><li>– a structural defect of the eye generally caused by an irregularity in the shape of the cornea. </li></ul>
<ul><li>Colorblindness </li></ul><ul><li>– Poor color vision can be cause by an inherited lack of one or another of the three types of cones. </li></ul>
<ul><li>2. HEARING </li></ul><ul><li>It is the most vital channel of interaction with the environment. </li></ul><ul><li>The stimuli fro hearing are soundwaves. </li></ul><ul><li>Three dimensions describing the sound stimulus are : </li></ul><ul><li>Intensity </li></ul><ul><li>Frequency </li></ul><ul><li>Complexity </li></ul>
Structure of the ear. The ear is divided into three parts: The outer ear - it is the visible part of the ear, composed of the pinna, the auditory canal, and the tympanic membrane commonly called eardrum.
The middle ear – an air- filled chamber that is connected to the pharynx by the eustachian tube.
This connection of the middle ear to the pharynx serves to equalize the pressure on the two sides of the eardrum. The middle ear structure is composed of tree small bones or ossicles: the mallleus (hammer), the incus (anvil), and the stapes (stirrup). These bones are hanging into the system of levers, so that the movement of the eardrum is transmitted to a membrane called the oval window.
The inner ear – can find a cochlea which is a fluid- filled bony structure shaped like a snail shell. It is the organ of hearing. There are three canals in the cochlea–the cochlear canal, the tympanic canal, and the vestibular canal.
<ul><li>Hearing Defects </li></ul><ul><li>Conduction Deafness – deafness due to inability to transmit vibrations through the external and middle ear. </li></ul><ul><li>Nerve Deafness – this kind of deafness results from damage to the nerves themselves or to the delicate parts of the cochlea. </li></ul>
3. SMELL - The receptors for smell are found at the olfactory epithelium located at the very top of the nasal passages. -They are sensitive only to gases and to volatile substances that have been dissolved in the air.
4. TASTE Much of the sensation depends on other factors-on warmth, coldness, the mild irritation caused by certain spices, and above all, on smell. When our nostrils are stuffed because of colds. Food seems almost tasteless. The tastebuds are the receptors for taste. They respond to four qualities of taste: sweet, sour, salty, and bitter.
5. THE SKIN SENSES The skin has four separate senses: pain, pressure, cold, and warmth. The receptors fro the skin senses are nerve endings which come in four general forms: free nerve endings, globular bulbs, egg- shaped corpuscles, and “baskets” surrounding root hairs.
KINESTHESIS This is the sense of bodily movements. Its receptors are nerve endings found in muscles, tendons, and linings of joints. EQUILIBRIUM This is also called as the Static Sense. Two kinds of receptors give information about movements of the head and permit a sense of balance of the body.
These are in the semicircular canals and the vestibular canal. Both are located in the inner ear next to cochlea. THE ORGANIC SENSE This give s the result of the sensitivity of the visceral and other internal organs oft he body. Among the visceral organs are the stomach, intestines, sex structure, throat, hear and lungs.
PERCEPTION Chaplin defines perception as the process of knowing objects and objective events by means of senses. This sensory input consists of nerve impulses. They carry a sort of raw, undigested information about the environment. The individual must convert it into a meaningful information. Perception, then, is the organization of sensory input into meaningful experiences.
PERCEPTUAL CONSTANCY The perception of an object and all of its properties as constant and unchanging in spite of the continuously changing sensations of these properties outline the scope of object constancies. Our perceptual organization remains relatively stable even though some aspects of the pattern within the optical array undergo great changes.
<ul><li>ORGANIZATION IN PERCEPTION </li></ul><ul><li>Figure and ground – when we perceive an object, usually one part tends to stand out while the rest seems to remain in the background. The part which stands out is called the figure and the rest of the stimulus pattern is called the ground. </li></ul>
<ul><li>Grouping – we are concerned more with the figure than with the ground. </li></ul><ul><li>* The principles of similarity – stimuli which are similar tend to be perceived as forming a group. </li></ul>
* The principle of proximity – there is a tendency to perceive stimuli which are near one another as belonging together.
*The principle of closure – when fragmentary stimuli form enough of a familiar figure, we tend to perceive the whole figure, ignoring the missing part of parts.
*The principles of continuity – stimuli which from a continuous pattern are perceived as a whole, the pattern they make generally appears as a figure apart from the ground.
ATTENTION AND PERCEPTION Perception is selective. The direction of perception toward selected objects is called attention. A number of stimulus conditions help determine the direction of attention
DEPTH PERCEPTION This is the ability to see three- dimensional space and accurately judge distances. A study of perception would be incomplete without considering perceiving the third dimension- distance and depth.
<ul><li>PERSONAL FACTORS IN PERCEPTION </li></ul><ul><li>Motives </li></ul><ul><li>Emotions </li></ul><ul><li>Attitudes </li></ul><ul><li>Frames of reference </li></ul>
<ul><li>ERRORS IN PERCEPTION </li></ul><ul><li>Illusion – a perception which is common but usually considered mistaken. This is an error which depends on stimulus conditions and occur in normal individuals. </li></ul><ul><li>Hallucinations – are false perceptions that occur under abnormal conditions. </li></ul>