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Cognition & Senses - wk 1 > hypothalamus > Flashcards

hypothalamus Flashcards

1
Q

what is homeostasis

A

balanced functioning of physiological processes and maintenance of an organism’s internal environment within a narrow range

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2
Q

what is the hypothalamus and what does it do

A
  • specialized sensory neurons measure the regulated parameter and deviations from optimal range are detected
  • coordinates the necessary compensatory mechanims
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3
Q

what are the 3 things that the hypothalamus controls

A
  1. autonomic nervous system (sympathetic and parasympathetic)
  2. endocrine system (anterior and posterior pituitary gland)
  3. motivated homeostatic behaviors (feeding, drinking) (connections with forebrain, limbic system, brainstem and spinal cord)
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4
Q

what are the 3 divisions of the hypothalamic nuclei from medial to lateral

A
  1. periventricular area
  2. medial hypothalamic area
  3. lateral hypothalamic area
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5
Q

what are the 4 regions of the medial hypothalamic area from rostral to caudal

A
  1. preoptic area
  2. anterior (supraoptic) region
  3. middle (tuberal) region
  4. posterior (mammillary) region
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6
Q

magnocellular neurosecretory cells located in the supraoptic nucleus and paraventricular nucleus do what?

A

secrete two hormones into a capillary bed in the posterior pituitary

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7
Q

what are the two hormones that the magnocellular neurosecretory cells secrete

A
  • oxytocin
  • vasopressin
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8
Q

what does oxytocin do

A
  • uterine contractions
  • milk letdown reflex
  • love hormon e
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9
Q

what does vasopressin do

A
  • ADH
  • regulated blood volume
  • salt concentration
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10
Q

what do parocellular neurosecretory cells do and where are they located

A
  • paraventricular nucleus
  • secrete releasing hormones and inhibiting hormones into the hypothalamic-pituitary portal circulation
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11
Q

biological stress is created by the brain in response to real or imagined stimuli and this leads to:

A

the release of cortisol during “stress response”

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12
Q

what does cortisol do

A
  • released glucose into your bloodstream
  • increases blood pressure for increased physical activity such as running
  • stimulates brain for more intense awareness
  • immune system activity is reduced to save energy for physical activity
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13
Q

what are the 5 steps of the HPA axis

A
  1. stress (physiological stess or anxiety)
  2. parvocellular neurosecretory neurons
  3. anterior pituitary releases ACTH
  4. ACTH acts on adrenal cortex
  5. cortisol inhibits CRH release
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14
Q

what are the two NT of the sympathetic and parasympathetic system

preganglionic and postganglionic

A

sympathetic

  • pre - ACh
  • post - NE

parasympathetic

  • pre -ACh
  • post - ACh
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15
Q

what is anabolism

A

when blood is filled with nutrients

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16
Q

what are the two forms that energy is stored in

A
  • glycogen in liver and skeletal muscle
  • triglycerides in adipose tissue
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17
Q

what is catabolism

A
  • during fasting; between meals
  • stored glycogen and triglycerides are broken down to provide body with a continuous supply of molecules for fuel
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18
Q

what does the ob gene code for

A

a protein called leptin which is released by adipocytes

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19
Q

what is leptin

A

a hormone that communicates with the brain about fat reserves

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20
Q

elevated leptin levels in blood activates:

A

hypothalamus and decreases feeding behavior

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21
Q

decreased leptin leptin levels in blood activates:

A

hypothalamus and increases feeding behavior

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22
Q

what is parabiosis

A

anatomical and physiological union of two animals - share blood supply

23
Q

leptin released by adipocytes activate leptin receptors in ____ ____ of the hypothalamus

A

arcuate nucleus

24
Q

arcuate nucleus

A
  • sense leptin levels
  • controls paraventricular nuc
  • controls lateral hypothalamus area
25
Q

paraventricular nucleus

A
  • ANS (increase sympathetic tone)
  • endocrine system (leads to release of ACTH and TSH)
  • both increase metabolism and energy expenditure
26
Q

lat. hypothalamic area

A

activates homeostatic motivated behavior (feeding behavior)

27
Q

arcuate neurons responding to elevated leptin release the peptide transmitters:

A
  • alpha MSH
  • CART
28
Q

anoretic peptides

A
  • increase alphaMSH and CART in arcuate nucleus
  • inhibit feeding behavior
  • increase metabolism
  • increase energy expendature
29
Q

arcuate neurons responding to decreased leptin release the peptide transmitters:

A
  • NPY
  • AgRP
30
Q

orexigenic peptides

A
  • increase NYP and AgRP in arcuate nucleus
  • stimulate feeding behavior
  • decrease metabolism
  • decrease energy expenditure
31
Q

what are the peptides involved in short term regulation of feeding bahvior

A
  • ghrelin
  • gastric distension
  • cholecystokinin (CCK)
  • insulin
32
Q

what do serotonin levels in the hypothalamus do

A
  • rise at the sight or smell of food
  • peak during a meal, especially in reponse to carbs
  • elevates mood - especially during stress
33
Q

depression and anxiety are linked to:

A

lowered brain serotonin levels

34
Q

low serotoning levels reduce ____

A

satiety

35
Q

antidepressent drugs that elevate brain ____ levels, are and effective treatment for ____ ____

A

serotonin; bulimia nervosa

36
Q

what are circumventricular organs

A
  • highly vascularized structures located around the third and fourth ventricles lack of a blood-brain barrier (BBB)
  • points of communication between the blood, the brain, and the CSF
37
Q

what is drinking behavior stimulated by

A

hypovolemia and hypertonicity

38
Q

what is hypovolemia

A

decrease in blood volume (volumetric thirst)

39
Q

steps of hypovolemia

A
  • detected by pressure receptors in the cardiovascular system
  • signals ascend to nucleus of the solitary tract via vagus nerve
  • solitary nucleus prokects to paraventricular nucleus of hyothalamus
  • vasopressin (ADH) released by posterior pituitary
  • ADH acts on kidney to increase water retention and inhibit urine production
  • hypothalamus activates sympathetic division of ANS to constrict blood vessels
  • reduced blood flow to kidneys causes release of renin to the blod
  • in the liver, renin converts angiotensinogen to angiotensin I which breaks down to angiotensin II
40
Q

what does angiotensin II do

A
  • acts on the neurons of the subfornical organ, which stimulate neurons in the paraventriculat nucleus causing release of ADH by posterior pituitaty
  • ADH acts on kidney to increase water retention and inhibit urine production
  • subfornical organ projects to lateral hypothalamus which produces thirst that motivates drinking behavior
41
Q

what is hypertonicity

A

increase in blood salt (osmometric thirst)

42
Q

what are the steps in hypertonicity

A
  • hypertonicity of the blood is sensed by neurons in the vascular organ of the lamina terminalis (OVLT)
  • OVLT projects to the paraventricular nucleus of the hypothalamus
  • posterior pit. secretes vasopressin
  • ADH acts on kidney to increase water retention and inhibit urine production
  • OVLT projects to the lateral hyothalamus
  • lateral hyothalamus stimualtes osmometric thirst, the motivation to drink water when dehydrated
43
Q

neurons in the ____ ____ transduce small changes in blood temperature to changes in firing rate

A

anterior hypothalamus

44
Q

cold-sensitive neurons of the anterior hypothalamus project to:

A

medial preoptic area of the hypothalamus

45
Q

medial preoptic area projects to parvocellular neruons of the:

A

paraventricular nucleus -> anterior pit.

46
Q

thyroid stimulating hormone, TSH is released by:
and this leads to:

A

anterior pit; release of thyroid hormone thyroxin

47
Q

what does thyroxin do

A

increases metabolism

48
Q

medial preotpic nucleus activity activates sympathetic division of ANS and this causes:

A

blood vessels in skin to constrict and piloerection

49
Q

cold-sensitive neurons of the anterior hypothalamus projects to:
this leads to:

A

lateral hypothalamus; shivering and to seek warmth

50
Q

warm-sensitive neurons of the anterior hypothalamus projects to:

A

medial preoptic area of hypothalamus

51
Q

medial preoptic area projects to parocellular neurons of the:

A

paraventriculat nucleus -> anterior pituitary

52
Q

parvocellular neurons signal anterior pituirary to:

A

stop secreting TSH and metabolism is slowed

53
Q

medial preoptic nucleus activity activates:

A

sympathetic divistion of ANS and blood is shunted to the periphery to dissipate heat

54
Q

activity in the lateral hypothalamus causes behavior of:

A

seeking shade, panting, and in humans - sweating

Cognition & Senses - wk 1 (13 decks)

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