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2 ways in which hypothalamus activiates the adrenals
-neural
-hormonal
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where are the adrenal glands located?
just above the kidneys
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2 portons of adrenal glands
cortex and medulla
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(adrenal glands)What does cortex secrete?
hormones cortisol, androgens, and estrognes
*hormonal
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(adrenal glands) what does the medulla secrete?
secretes norepinephrine and epinephrine
*neural
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when does negative feedback occur?
when the system responds in an opposite direction to the perturbation
*maintains homeostasis
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(result of activation of adrenals) Cortisol
-increases blood presusre
-increases blood sugar level
-Supresses immune function
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(result of activation of adrenals) Epineprine and norepinphrine
-increase heart rate
-increase blood pressure
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Chronic stress and health
-chronic stress can hamper ones body
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(health) Immune system is responsible for...
- protecting us against foreign agents
- *bacteria
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(stress can effect immune activity) Short term stressors
- can enhance immune function
- *public speaking, athletic contest
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(stress can effect immune activity) Long term stressors
- can depress immune function
- *unemployment, over-crowding)
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example of restraint stress on health
-increase in circulating levels in glucocorticoids (cortisol)
-chronic elevations in glucocoricoids will suppress immune fucntion and allow the abcteria to increase and promotoe stomach ulcers
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Control reduces...
stress
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predictability reduces
stress
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What is the hippocampus capable of generating?
new, functioning neurons called neurogenesis
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(stress effects) Stress and Neurogenesis
- -stress appears to reduce neurogenesis
- *ex) fox odor exposure to rats, reduced the birth of new cells in hippocampus
- -*effect is likely mediated by glucocorticoids
- ***removal of adrenal glands eliminates the effect of stress on nuerogenesis
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Hippocampus is critical for...
-learning and memory as well as providing negative feedback to the HPA axis
-they also contain neurons that express glucocorticoids receptors
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Ghrelin hormone
-stomach hormone
-it has been linked to hunger
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Ghrelin and feeding behavior
-ghrelin levels rise and peak before the onset of a meal
- -ghrelin levels fall after meal consumption
- *data indicates that there is correlation between ghrelin levels and feeding behavior
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When animals get injected with ghrelin...
they eat
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(sections of hypothalamus) Supraoptic nucleus and paraventricular nucleus
make and package oxytocin and vasopressin
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(sections of hypothalamus) medial preoptic nucleus
-male sexual behavior
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(sections of hypothalamus) Ventromedial nucleus
female sexual behavior
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(sections of hypothalamus) Arcuate nucleus
-feeding behavior
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(arcuate hypothalamus-ghrelin) Ghrelin acts on and excites 2 neurons that stimulate feeding behavior
-Agrp and
-NPY
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Characteristics of OB/OB mouse
-ate voraciously
-incredibly obese
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(hormones and feeding-satiety) experiment D
-2 lean mice
- *normal insulin
- *normal blood sugar
- * <fat pad size
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(hormones and feeding-satiety) experiment c, OB/OB + lean
- Obese
- - < food intake
- - < insulinemia
- - < blood sugar
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(hormones and feeding-satiety) experiemtn A, DB/DB + lean
- DB
- - >body weight
- - > adipose tissue mass
- lean
- - < food intake
- - < insulimenia
- - < blood sugar
- ***death by starvatiion
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(experiments on hormones and feeding) OB/OB mice
failed to make and release leptin
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(experiments on hormones and feeding) db/db mice
failed to express leptin receptors but made leptin
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Leptin deleivered to the periphery or the central nervous system ...
decreases feeding and body weight
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2 sets of hormones in arcuate hypothalamus
-leptin
-ghrelin
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(arcuate hormones) Leptin
- -works on the other set of neurons to shut off feeding behavior
- *inhibits
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(arcuate hormones) Ghrelin
stimulates feeding behavior
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(more to it than ghrelin and leptin) 3 other reasons for feeding?
-neural signals
-learning
-reward
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(more to it than ghrelin and leptin) 3 other hormones associated with satiety
-CCK
- insulin
-GLP-I
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(more to it than ghrelin and leptin) 3 other reasons that make satiety happen?
-neural signals
- stomach stretching
-other hormones in play besides leptin
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(body fluid homeostasis) What organ carefully monitors blood pressure and sodium levels?
kidneys
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(body fluid homeostasis) if our body fluid becomes too concentrated...
- we drink more water
- and concentrate our urine
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(body fluid homeostasis) If our body become too diluted...
we are drive to consume sodium
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(body fluid homeostasis) Our kidneys carefully monitor...
- osmolarity
- *osmoles of solute/liter of solution
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(body fluid homeostasis) Changes in blood pressure can trigger...
the release of enzymes and hormones
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if perfusion of kidney decreases...
juxtaglomerular cells secrete renin
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