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what are the main functions of the hypothalamus?
- cardiovascular regulation
- uterine contractility and milk ejection from breasts regulation
- temperature regulation
- body water regulation
- gastrointestinal and feeding regulation
- endocrine regulation
stimulating what part of the hypothalamus increases HR and arterial pressure?
posterior and lateral hypothalamus
stimulating what part of the hypothalamus decreases HR and arterial pressure?
preoptic area of hypothalamus
how and where in does the hypothalamus regulate uterine contractility?
- paraventricular nuclei
- stimulation cuases secretion of oxytocin at the end of pregnancy
stimulating what part of the hypothalamus regulates body temperature?
the anterior part, especially preoptic
- incr temp of blood flowing in this area increases the activity
- dec temp of blood flowing in this area decreases the activity
how does the hypothalamus regulate body fluid levels?
- 1. regulating thirst
- 2. regulating excretion of water
how does the hypothalamus (and where) regulate thirst?
- thirst center in lateral hypothalamus
- when fluid electrolytes are too concentrated, animal develops sense of thirst to bring concentration back to normal
how doe sthe hypothalamus (and where) regulate excretion of water?
- supraoptic nuclei
- if body fluids become too concentrated, neurons stimulated which then stimulate post pituitary gland to secrete ADH (vasopressin) which is transported via blood to kidneys causing increased reabsorption of water
how and where in does the hypothalamus regulate breast milk excretion?
when baby suckles, reflex to post hypothalamus which causes oxytocin release which stimulates contraction of myoepithelial cells surrounding the alveoli of the breasts
where in the hypothalamus is hunger stimulated?
lateral hypothalamic area
where in the hypothalamus is the feeling of full stimulated?
ventromedial nuclei, called the satiety center
where in the hypothalamus is the overall control of GI activity located?
- mamillary bodies (kinda posterior)
- some control over feeding reflexes like licking lips and swallowing
what happens if the lateral hypothalamus is stimulated?
- inc thirst
- inc hunger
- inc general activity level of animal
- can lead to overt rage and fighting
what happens if the ventromedial hypothalamus is stimulated?
- dec hunger (feeling of satiety)
- dec activity (tranquility)
what happens if a thin zone of periventricular nuclei (adjacent to 3rd ventricle) in the hypothalamus is stimulated?
fear and punishment reactions
where is the sexual drive most stimulated in the hypothalamus
- anterior and posterior
- but can be stimulated from several areas
where are the major reward centers located?
- along the course of the medial forebrain bundle
- esp in lateral and ventrormedial nuclei of hypothalamus
- (there are less potent rewards centers located elsewhere)
where are the major punishment centers located?
- central gray area surrounding the aqeduct of Sylvius in mesencephalon and extending upward into the periventricular zones of the hypothalamus and thalamus
- (less potent centers are located elsewhere)
true or false, fear and punishment can take precedenc over pleasure and reward?
true or false, in the same area of the brain, weak stimuli give a sense of reward and stronger ones a sense of punishment?
true in many areas but not an absolute