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Chapter 4

Week 4 - Sept 19-24 - Chapter 4 - PSYCH 3M03
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Department
Biochemistry
Course
BIOCHEM 2B03
Professor
Denys Decatanzaro
Semester
Fall

Description
LECTURE 4 PSYCH 3M03 Chapter 4: Physiology September 19-24, 2013 Supplemental Notes on Hormones and Neurochemistry  Subcortical – focus not on the cortex; start in the periphery of the body (highly conserved), move into the subcortical central nervous system  New structures built on old (conserved) – basic biological dries and emotions cannot be understood by human evolution exclusively; must look at primate predecessors; predecessor structures observed in humans, but tweaked  Structure reflects evolution – homologous structures of brain in many mammals  Cortex can drive our motivation; more with maturing and learning  Impulses from more primitive structures can conflict with cortex  Autonomic system accounts for emotion – o Many peripheral nerves o Sympathetic – stress, fear, intense emotions, exhilaration,  Great deal of tissue, goes to every organ of the body  Sympathetic nerve ganglia o Parasympathetic  Cervical lumbar area of spine  Activates organs; causes reversal of reflexes  Involved in resting, digestion  Nervous tissue Sympathetic NS Reflexes  Arousal and energy generation: o Increases heart and respiratory rate o Increases blood pressure o Inhibits digestion  Stress inhibits proper digestion o Less blood flow to digestive tract, skin  Less blood to skin – “green” o More blood flow to muscles, lungs  Blood to muscles – dealing with primitive forms of danger (that you have to run from) or aggression o Dilates pupils  Better intake of visual information; can focus  Intense arousal o Piloerection – hair standing on end; goose bumps o Spontaneous urination and defecation o Can lead to hyperventilation, fast heart rate o Involuntary reflexes  Sympathetic chain ganglia (clusters of cell bodies and often synapses – paralleled to spinal cord in the thorax o Avoidance of danger, confronting danger o Ancient emotions  Fires quickly and massively in arousal – danger needs immediate attention Parasympathetic NS  Decreases heart and respiratory rate  Increases blood flow to digestive tracts  Promotes calming of the nerves  Constriction of the pupil stimulates salivary gland secretion + other digestive structures  Involved in sleep and sexual response  Fires slowly, reflex by reflex – unwinding takes time Adrenal Glands  Produces epinephrine, norepinephrine hormones that go to the blood stream that go to the junctions of the sympathetic NS o Hormones boost sympathetic reflexes  Located on top of the kidney  Adrenal cortex (outer layer) produce steroid hormones  Medulla (NOT medulla oblongata) in the core o Secretes catecholamine’s in response to sympathetic NS o Controlled by nerves 1 LECTURE 4 PSYCH 3M03 o Overgrown ganglion of the sympathetic NS; secretes hormones into blood in conjunction with firing in the sympathetic NS o Hormones go through flood to junctions of sympathetic nerves with target organs (except brain) and enhance reflexes o Enhancer of sympathetic reflexes produced by nerves  Cortex (outer layer) o Secretes steroids (eg/ cortisol, DHEA corticosterone, androgens, progesterone) in response to chemical stimulation (especially ACTH from pituitary)  More stressed = more active adrenal glands Brain  Hypothalamus o Responsive to:  Light (photoperiod)  Olfactory stimuli (including pheromones)  Steroids (gonadal and adrenocortical)  Neural information from the viscera  Autonomic inputs  Various peptide hormones and other substances from blood o Controlling influences upon:  Autonomic nervous system  Hormones from the pituitary gland  Aspects of bodily homeostasis  Basic biological drives (hunger, thirst, sexual drive maternal behavior, fear, rage, thermal regulation o Consists of a number of nuclei o Surround third ventricle of brain; peptides and hormones in ventricles o Controls pituitary gland – thus controls chemicals that affect other systems  Limbic system important for emotional behaviour o Amygdala – balance of fear and rage; sexual inhibition, appropriateness of social behaviour (approach, avoid, aggression, fear, withdrawal) o Septum – reward processes, contains the nucleus accumbens o Hippocampus – spatial awareness, learning and memory;  Ventricular System o Medium for chemical control o Fourth ventricle – pain, o FAPs elicited due to peptide interaction with ventricles  Pituitary Gland o Anterior Pituitary – produces several hormones  ACTH released in stress in response to CRF from hypothalamus  Causes stretching, yawning, sexual behaviour if put in brain  Stimulates adrenal cortex in stress to produce more steroids General Definitions  Hormone – substance released into the bloodstream that communicates with receptors at some distant site(s)  Neurotransmitter – substance released into the synapse when a presynaptic neuron fires, is then picked up by a receptor on the dendrite membrane of the post synaptic neuron, affecting the probability that it will fire; there can be excitatory or inhibitory induces on the postsynaptic neuron Basic Chemical Forms 1) Steroids  Mainly from testes/ovaries, adrenal cortex  Generally small, fat soluble molecules that pass readily throughout the system including the brain, where there are receptors in the limbic system o Receptors have organizational behaviour  Functions – reproduction, stress, metabolism  Relatively slow acting (depends on which steroid; hours, days, months)  Generally lipid (fat) soluble (depends on which steroid)  May bind to carrier proteins in blood  Receptors in various peripheral sites; in the brain predominantly in limbic system 2 LECTURE 4 PSYCH 3M03  Testes, Ovaries o Androgens (eg/ testosterone) o Estrogens (eg/ estradiol) o Progesterone  Adrenal Cortex o Aldosterone o Progesterone o Cortisol, corticosterone o Androgens (eg/ DHEA, testosterone o Estrogens 2) Peptides  Consists of various chains of amino acids; can be a few or hundreds of AA  Generally, water soluble, fragile, short-acting/rapid action (milliseconds, seconds, minutes)  Don’t get passed the Blood Brain Barrier  Produced all over the body; the ones most relevant to behaviour come from hypothalamus and pituitary  Peptides from the pituitary control the gonads, adrenal cortex, and thyroid; also have actions of their own  The anterior pituitary is controlled chemically by peptides in local circulation from the hypothalamus  There are many peripheral peptides with relevance to behaviour (eg/ insulin and glucagon from pancreas, CCK from gut, leptin from adipose cells) o Those produced in periphery may not reach the brain  Do not flow freely to all parts of the body, often because of large molecular size o Hypothalamus o CRF/CRH – cause panic; also found in amygdala o GnRH – gonadotropin releasing hormone; causes release of gonadotropins which affect gonads and o NPY – neuropeptide Y;  Pituitary o Anterior  ACTH – controls adrenal cortex; sets off great production in hormones during stress  B-endorphin – released in stress; cause analgesia (causes you to not notice pain when in stress); affect, emotion  LH, FSH – Luteinizing hormone  Prolactin – related to maternal behaviour o Posterior  Oxytocin – emotional bonding  Vasopressin (ADH)  Brain o Ventricles relay many hypothalamic and pituitary hormones o Peptide dynamics in limb
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