OVERVIEW Neurotransmission Neurotransmitters Endocrine System Hormones Feedback Systems
OVERVIEW • • • Neurotransmission Neurotransmitters Endocrine System Hormones Feedback Systems
NEUROTRANSMISSION
THE NEURON Multipolar: more than two processes from cell body Unipolar: one process from cell body Bipolar: two processes from cell body Interneurons: short or no axons Supportive cells: glial cells, satellite cells, astrocytes, oligodendrocytes, Schwann cells http: //www. utexas. edu/research/asrec/synapse_m. html
COMMUNICATION. . con’t
COMMUNICATION • Action potentials: Ionic basis • Conduction of Action Potentials • Chemical Transmission at the Synapse
ACTION POTENTIALS m. V = millivolts http: //artsci-ccwin. concordia. ca/psychology/psyc 358/Lectures/actpotent 1. htm
MEMBRANE POTENTIAL • • Random motion Electrostatic pressure Membrane permeability Sodium-potassium pumps
http: //web. psych. ualberta. ca/~msnyder/Academic/Psych 104/ch 6/lec 2/P 104. 6. 2. html
When NTs bind to postsynaptic receptors… • Depolarize: Excitatory Postsynaptic Potentials (EPSP) • Hyperpolarize: Inhibitory Postsynaptic Potentials (IPSP) • Action potential: reversal of membrane potential
ACTION POTENTIALS m. V = millivolts http: //artsci-ccwin. concordia. ca/psychology/psyc 358/Lectures/actpotent 1. htm
http: //luna. cas. usf. edu/~husband/expsych/fig_axon. htm
http: //luna. cas. usf. edu/~husband/expsych/fig_axon. htm
NEUROTRANSMITTERS & HORMONES
CHEMICAL COMMUNICATION • • • Intracrine mediation: intracellular Autocrine mediation: feedback loops Paracrine mediation: adjacent cells Endocrine mediation: bloodstream Ecotcrine mediation: pheromones
HOW THEY DIFFER. . NEUROTRANSMITTERS • DF HORMONES • KJH
NEUROTRANSMITTERS
STEPS OF NT ACTION • Released NTs bind • NTs are synthesized with autoreceptors and from precursors inhibit more release • NTs are stored in • Released NTs bind to vesicles postsynaptic receptors • Leaking NTs are • Released NTs are destroyed deactived by reuptake • Action potentials cause or enzymatic NTs to bind degradation presynaptic membrane & be released into synapse
http: //www. nipissingu. ca/saari/slides/pinel 13/sld 023. htm
AGONISTIC EFFECTS • Agonist: drug that facilitates the effects of a particular neurotransmitter – ex. Cocaine: dopamine & norepinephrine • • Increases synthesis of NTs Destroys degrading enzymes Increases release of NTs Blocks inhibitory effects of NTs • Activates postsynaptic receptors or increases effects of NTs • Blocks degradation or reuptake
ANTAGONISTIC EFFECTS • Antagonist: drug that inhibits the effects of a particular neurotransmitter – ex. Curare: cholinergic receptors • Blocks synthesis of NTs • Causes NTs to leak from vesicles & to be destroyed by degrading enzymes • Blocks release of NTs into synapse • Activates autoreceptors & inhibits NT release • Blocks postsynaptic receptors
UPREGULATION Http: //www. utexas. edu/research/asrec/dopamine. html
DOWNREGULATION Http: //www. utexas. edu/research/asrec/dopamine. html
CLASSES OF NTs Amino Acids Catecholamines Dopamine Epinephrine Norepinephrine Indolamines Serotonin Monoamines Glutamate Aspartate Glycine GABA Soluble Gases Nitric Oxide Carbon Monoxide Acetylcholine Neuropeptides Hormones*
Http: /web. indstate. edu/thcme/mwking/aminoacidderivatives. htm#tyrosine
DOPAMINE • found primarily in the limbic system, parts of the hypothalamus, the frontal cortex, and forebrain (basal ganglia) • thought disorders • motor disorders • pleasure & pain • role in addiction
http: //www. nipissingu. ca/saari/slides/pinel 13/sld 033. htm
SEROTONIN • high concentrations in the brain stem and thalamus • sleep/wake cycle • sensory perception • emotional behaviour: depression, impulsive behaviour, aggression
NOREPINEPHRINE • high concentrations in the cortex and limbic system • Also works as hormone • respiration • activity, stimulation, and arousal • rate of metabolism
http: //www. nipissingu. ca/saari/slides/pinel 13/sld 030. htm
ACETYLCHOLINE • Major NT of the motor system – found at neuromuscular junction • Learning and Memory – memory loss of Alzheimer’s patients • Sleep • Nicotinic and muscarinic receptors
http: //www. nipissingu. ca/saari/slides/pinel 13/sld 024. htm
GABA/GLUTAMATE • • GABA: inhibitory effects Glutamate: excitatory effects scatter throughout the brain Unique because: – # of synapses using G/G > than any other NT combined – important functions in the body, not only the brain
THE ENDOCRINE SYSTEM
GENERAL FEATURES. . 1. Endocrine glands are ductless 2. Endocrine glands have a rich blood supply 3. Hormones are secreted into the bloodstream 4. Hormones can travel to every cell in the body 5. Hormone receptors are specific binding sites
ENDOCRINE GLANDS • • Hypothalamus Pituitary Gland Thyroid Gland Pancreas Gastrointestinal Tract Adrenal Glands Pineal Gland Gonads: Testes & Ovaries • Placenta* http: //www. ama-assn. org/ama/pub/printcat/7157. html
biological clock STI MULI HYPOTHALAMUS CRH Gn. RH GHRF TRH ANTERIOR PITUITARY ACTH ADRENALS (Cortisol) MIF Somatostatin PIF TSH THYROID (Thyroid H) PRL GH MSH OTHER TISSUE FSH&LH TESTIS OVARIES (T) (Estrogen)
HYPOTHALAMUS • Releasing hormones • produced by various nuclei of the hypothalamus • involuntary body functions • many simple body functions http: //www. cwru. edu/dental/web/neuro/ghts. html
PITUITARY GLAND
THYROID GLAND • Thyroglobulin: converted to T 3 & T 4 • almost all cells are target of THs • calcitonin • metabolic rate, growth & development TRH: Thyroid-releasing hormone http: //www. vivo. colostate. edu/hbooks/pathphys/endocrine/hypopit/tsh. html
PANCREAS • digestive enzymes • islets secrete insulin & glucagon • release dependent on level of glucose in blood
GASTROINTESTINAL • hormones that aid with digestion – gastrin – enterokinin – secretin – cholecystokinin (CCK) – glucose dependent insulinotropic hormone – vasoactive
ADRENAL GLAND
PINEAL GLAND • biological rhythms • Melatonin – – receptors in SCN night reproduction, sleep Seasonal Affective Disorder http: //www. crystalinks. com/thirdeyepineal. html
GONADS: TESTES & OVARIES TESTES • produce sperm androgens • LH & FSH OVARIES • produce ova, estrogen, and progesterone • LH & FSH • menstrual cycle
HORMONES • Grouped into 3 classes, based on structure: – steroids – peptides – amines
STEROIDS http: //www. emc. maricopa. edu/faculty/farabee/BIOBK/Bio. Book. ENDOCR. html
HORMONES • Grouped into 3 classes, based on structure: – steroids – peptides – amines • Mechanisms: – Nonsteroid: second messenger systems – Steroid: hormone-receptor complex, DNA, & protein production
ESTROGEN • released by ovary • controlled/controls feedback • sexual behaviour, maternal behaviour, menstrual cycle • memory & neurogenesis http: //www. vivo. colostate. edu/hbooks/pathphys/endocrine/hypopit/lhfsh. html
PROGESTERONE • produced by ovaries • works in conjunction with estrogen: – – menstrual cycle pregnancy maternal behaviour sexual behaviour http: //www. wisc. edu/ansci_repro/lec_11/lec 11 fig. html#figure%205
FSH & LH • essential for reproduction • Luteinizing Hormone: stimulates secretion of sex steroids; health of ovary • Follicle-Stimulating Hormone: maturation of ovarian follicles; sperm production http: //www. vivo. colostate. edu/hbooks/pathphys/endocrine/hypopit/lhfsh. html
TESTOSTERONE • maintains spermatogenesis • act of skeletal muscle • secondary sex characteristics • reproductive behaviour • aggression http: //www. vivo. colostate. edu/hbooks/pathphys/endocrine/hypopit/lhfsh. html
OXYTOCIN & VASOPRESSIN • Vasopressin: antidiuretic hormone; conserve water; reproductive function; social behaviour • Oxytocin: birth & lactation; anti-amnestic; maternal behaviour, social behaviour • Stress? http: //www. vivo. colostate. edu/hbooks/pathphys/endocrine/hypopit/oxytocin. html
NEUROPEPTIDE Y & LEPTIN NPY • regulation of circadian rhythms, sexual functioning, anxiety, stress response, feeding behaviour • neuropeptide • synthesized in arcuate nucleus LEPTIN • appetite regulation? • ob/ob mice: leptin replacement • decreases NPY expression
PROLACTIN • closely related to GH • major target: mammary glands – many tissues contain receptors • • milk production reproductive behaviour immune function maternal behaviour * regulated by DA, TRH, Gn. RH, E http: //www. vivo. colostate. edu/hbooks/pathphys/endocrine/hypopit/prolactin. html
GROWTH HORMONE • Direct effects: target receptors in fat; protein, lipid, & carbohydrate metabolism • Indirect effects: mediated by insulin-like growth factor-1 (IGF-1) ; muscle & bone growth GHRH: growth hormonereleasing hormone SS: somatostatin http: //www. vivo. colostate. edu/hbooks/pathphys/endocrine/hypopit/gh. html
HORMONES • needed for the immediate onset of maternal behaviour • progesterone • estrogen • prolactin • oxytocin • glucocorticoids
THE HPA AXIS: POSTIVE & NEGATIVE FEEDBACK SYSTEMS
Brain here Cingulate Cx. Frontal Cx. Inferior Temporal Cx. Amygdala Hippocampus Septum Hypothalamus Pituitary Gland
THE HPA AXIS Stimulus LIMBIC SYSTEM (Hippocampus) +ve HYPOTHALAMUS (Paraventricular Nucleus) CRH PITUITARY GLAND (Anterior Pituitary) ACTH Glucocorticoid ADRENAL GLAND (Adrenal Cortex) -ve
THE HPA AXIS LIMBIC SYSTEM Stimulus +ve HYPOTHALAMUS (Paraventricular Nucleus) CRH PITUITARY GLAND (Anterior Pituitary) ACTH Glucocorticoid ADRENAL GLAND (Adrenal Cortex) -ve
INPUTS TO THE LIMBIC SYSTEM Stimulus Modality specific areas Amygdala Entorhinal cortex Hippocampus Association areas Frontal association areas & Inferior temporal association areas
THE HPA AXIS Stimulus LIMBIC SYSTEM (Hippocampus) +ve HYPOTHALAMUS CRH PITUITARY GLAND (Anterior Pituitary) ACTH Glucocorticoid ADRENAL GLAND (Adrenal Cortex) -ve
LIMBIC INPUTS TO THE HYPOTHALAMUS CINGULATE CORTEX HIPPOCAMPUS FORNIX SEPTUM AMYGDALA STRIA TERMINALIS MEDIAL FOREBRAIN BUNDLE HYPOTHALAMUS
OTHER INPUTS • MEDULLA: via the nucleus solitarius (baroreceptor information) • MIDBRAIN: via the reticular formation; directly and indirectly through the thalamus (chemoreceptor information) • BRAINSTEM: monoaminergic inputs (physiological stress)
EFFECTS OF CRH (Corticotropin. Releasing Hormone) Epi NE ACh 5 -HT STRESS RESPONSE + ve • activity, aggression, CRH food intake, fear, - ve anxiety, sexual & maternal behaviour CRH GABA opioids GC • metabolism & circulation found in brainstem, midbrain, striatum, hippocampus, cerebral cortex, spinal chord, sympathetic ganglia, & adrenal gland
THE HPA AXIS Stimulus LIMBIC SYSTEM (Hippocampus) +ve HYPOTHALAMUS (Paraventricular Nucleus) CRH PITUITARY GLAND ACTH Glucocorticoid ADRENAL GLAND (Adrenal Cortex) -ve
EFFECTS OF ACTH (Adrenocorticotropic Hormone) STRESS RESPONSE • attention, motivation, learning, & memory • aggression, grooming, sexual & social behaviour • neurotrophic? ANTERIOR PITUITARY POMC ACTH beta-lipotropin beta-endorphin
THE HPA AXIS Stimulus LIMBIC SYSTEM (Hippocampus) +ve Specific Organs HYPOTHALAMUS (Paraventricular Nucleus) CRH PITUITARY GLAND (Anterior Pituitary) ACTH Glucocorticoid ADRENAL GLAND -ve
EFFECTS OF GLUCOCORTICOIDS STRESS RESPONSE • heart rate, blood pressure, respiration, digestion, growth, reproduction, immune function • learning, cognition, emotional response, other behaviours GC-R I & II • hippocampus, septum, hypothalamus, amygdala, & nucleus tractus solitarius * mobilizes energy resources for adaptation to stressor
HIPPOCAMPUS • Negative Feedback: mechanism? • Mineralocorticoid & Glucocorticoid Receptors: ratio • Species differences • Chronic Stress = Neuronal Death * lack of brain “food” HIPPOCAMPUS glutamate BNST GABA HYPOTHALAMUS (PVN)
Endocrine-related problems • Overproduction of a hormone – Cushing’s Syndrome • Underproduction of a hormone – Diabetes • Nonfunctional receptors that cause target cells to become insensitive to hormones – Growth Hormone Insensitivity
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