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2 ways in which hypothalamus activiates the adrenals
where are the adrenal glands located?
just above the kidneys
2 portons of adrenal glands
cortex and medulla
(adrenal glands)What does cortex secrete?
hormones cortisol, androgens, and estrognes
(adrenal glands) what does the medulla secrete?
secretes norepinephrine and epinephrine
when does negative feedback occur?
when the system responds in an opposite direction to the perturbation
(result of activation of adrenals) Cortisol
-increases blood presusre
-increases blood sugar level
-Supresses immune function
(result of activation of adrenals) Epineprine and norepinphrine
-increase heart rate
-increase blood pressure
Chronic stress and health
-chronic stress can hamper ones body
(health) Immune system is responsible for...
- protecting us against foreign agents
(stress can effect immune activity) Short term stressors
- can enhance immune function
- *public speaking, athletic contest
(stress can effect immune activity) Long term stressors
- can depress immune function
- *unemployment, over-crowding)
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
What is the hippocampus capable of generating?
new, functioning neurons called neurogenesis
(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
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
-it has been linked to hunger
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
When animals get injected with ghrelin...
(sections of hypothalamus) Supraoptic nucleus and paraventricular nucleus
make and package oxytocin and vasopressin
(sections of hypothalamus) medial preoptic nucleus
-male sexual behavior
(sections of hypothalamus) Ventromedial nucleus
female sexual behavior
(sections of hypothalamus) Arcuate nucleus
(arcuate hypothalamus-ghrelin) Ghrelin acts on and excites 2 neurons that stimulate feeding behavior
Characteristics of OB/OB mouse
(hormones and feeding-satiety) experiment D
-2 lean mice
- *normal insulin
- *normal blood sugar
- * <fat pad size
(hormones and feeding-satiety) experiment c, OB/OB + lean
- - < food intake
- - < insulinemia
- - < blood sugar
(hormones and feeding-satiety) experiemtn A, DB/DB + lean
- - >body weight
- - > adipose tissue mass
- - < food intake
- - < insulimenia
- - < blood sugar
- ***death by starvatiion
(experiments on hormones and feeding) OB/OB mice
failed to make and release leptin
(experiments on hormones and feeding) db/db mice
failed to express leptin receptors but made leptin
Leptin deleivered to the periphery or the central nervous system ...
decreases feeding and body weight
2 sets of hormones in arcuate hypothalamus
(arcuate hormones) Leptin
- -works on the other set of neurons to shut off feeding behavior
(arcuate hormones) Ghrelin
stimulates feeding behavior
(more to it than ghrelin and leptin) 3 other reasons for feeding?
(more to it than ghrelin and leptin) 3 other hormones associated with satiety
(more to it than ghrelin and leptin) 3 other reasons that make satiety happen?
- stomach stretching
-other hormones in play besides leptin
(body fluid homeostasis) What organ carefully monitors blood pressure and sodium levels?
(body fluid homeostasis) if our body fluid becomes too concentrated...
- we drink more water
- and concentrate our urine
(body fluid homeostasis) If our body become too diluted...
we are drive to consume sodium
(body fluid homeostasis) Our kidneys carefully monitor...
- *osmoles of solute/liter of solution
(body fluid homeostasis) Changes in blood pressure can trigger...
the release of enzymes and hormones
if perfusion of kidney decreases...
juxtaglomerular cells secrete renin