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Physiology 2130 Chapter Notes -Alpha Motor Neuron, Olfactory Receptor, Sympathetic Nervous System

Course Code
Kim Luton

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Hypothalamus functions
Body temperature regulation
Body energy balance and exchange
Water balance and exchange
Sodium balance and exchange
Control of autonomic system
Neuroendocrine control (posterior pituitary, catecholamine released
from adrenal medulla) interaction between nervous system and
endocrine glands
Drives and emotions (ex feeding, attack)
Circadian rhythms
Reproduction (behavior and pituitary function)
Parasympathetic (fast + specific)
Sympathetic (slow, low specificity)
Saliva secretion watery (parasympathetic), mucus, thick (sympathetic)
Bladder contraction contraction (direct), vasoconstriction cause urine to squeeze
out of bladder
Pupil constrict
Pupil dilation
Bronchiole constrict
Bronchiole dilate
Stimulate peristalsis, secretion, and
release of bile
Inhibition of peristalsis, secretion
Conversion of glycogen to glucose
Secretion of adrenaline and
Hypothalamic control of pituitary gland
Anterior pituitary
Hormone secreted by basomedial hypothalamus through
circulatory system hypophyseal portal system
Posterior pituitary
Supraoptic (SON) and paraventricular nuclei (PVH) (both
part of hypothalamus) have AVP neurons that produce ADH
(vasopressin - VP) and oxytocin and are directly released to
posterior pituitary through their axons connection
(hypothalamic hypophyseal tract) where they are
temporarily stored in neurohypophysis ADH and oxytocin
are both made in the hypothalamus and released into
Neural-endocrine reflex a stimulation to sensory neuron sends signal to the
brain, which then respond through endocrine system release of hormone
(ex. Oxytocin release- stimulate mammary gland hypothalamus

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posterior pituitary release oxytocin back to mammary gland allow milk
Positive feedbacks
More sucking on breast, more oxytocin is produced to create milk
More pressure exerted in uterus, the more oxytocin is produced
Negative feedback response to salt ingestion
Hypothalamus produce ADH to increase water reabsorption in the
kidney (conserve water)
Cause thirst (to drink and obtain more water)
Ways hypothalamus is stimulated to release ADH (VP)
Hypothalamic osmoreceptor osmolarity greater than 280 mOsM
Atrial stretch receptor low blood volume
Cartotid and aortic baroreceptor decreased blood pressure
60% men obese, 38% female obese in Canada
Why do we eat (environment and lifestyle)
Taste and smell palatability
Cost/reward optimization
Internal clock
Cues and social habits
Individual predisposition for obesity (Genetics)
Early life events
High fat and sugar diets contribute to development of obesity
Adipose tissues release leptin hormone that provides satiety signal (high
leptin = high fat = satiation, low leptin = low fat = hunger)
Oxrexin (peptide) formed in lateral hypothalamus neurons helps induce
Interferences with Satiety Centre
Chronic secretion of leptin (too much leptin release) increase leptin
resistance no longer have satiety signal SNS (sympathetic
nervous system) hypertension
Ablation (lesion) of Arcuate/VMH hypothalamic nuclei damage
satiety center never feel full GAIN WEIGHT (ex. Obesity)
Interference with Hunger Center
Ablation of lateral hypothalamic nucleus LOSS WEIGHT (ex.
Metabolic syndrome- collection of signs and symptoms that are associated
with metabolic disorder and cardiovascular disease

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Anorexia & obesity involves genetic, neurochemical, psycho-developmental,
and socio-cultural factors ALL involve hypothalamus
Melatonin (produced in pineal gland) is suppressed in the presence of light
Circadian rhythm 24 hr cycle in which biological rhythm is found (ex.
Corticosterone, LH, melatonin release all follow 24 hr pattern)
Suprachiasmatic nucleus (SCN) biological clock control the following
circadian rhythms
Sleep (melatonin)
Food and water intake
Urine production
Blood pressure (spike in the morning)
Platelet aggregation
White blood cell production
Body temperature change
Hormone release (corticosterone, luteinizing hormone, melatonin)
Menstrual cycle
Heat is produced through
Radiation (sun)
Muscle contraction (skeletal) most heat produced and highest
* blue indicates external heat inputs
Heat is lost through
At low temperature activate posterior hypothalamus Sympathetic
adrenergic muscle contraction (somatic neurons stimulate skeletal
muscle)+ vessel constriction (increase blood pressure)+ sweat gland inactive
RAISE temp
At high temperature activate anterior hypothalamus Sympathetic
cholinergic vessel dilation + inhibit heat conserving mechanism + sweat
gland activate LOWER temperature
Brown fat produce heat through chemical process
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