hypothalamus pituitary

Question 1

pituitary gland is stimulated by what

Answer 1

hypothalamus

Question 2

Differentiate anterior and posterior pituitary based on what they are composed of

Answer 2

• anterior pituitary: composed of endocrine tissue
  
  • devoid of nervous innervation
• posterior pituitary: composed predominately of nervous tissue

Question 3

how does hypothalamus and anterior lobe communicate

Answer 3

• hypothalamus releases hypothalamic releasing and release-inhibiting hormones that enter the hypothalamic-hypophysial portal vessels of the anterior lobe

Question 4

hormones are transferred down axons, stored in vesicles within this pituitary gland and then released in a neurocrine manner

Answer 4

posterior pituitary

Question 5

in what method are hormones released by posterior and anterior pituitary glands

Answer 5

• posterior: neurocrine
• anterior: endocrine

Question 6

each anterior pituitary hormone is secreted by a different cell type. Name the 5 cell types

Answer 6

• gonadotroph
• thyrotroph
• somatotroph
• lactotroph
• corticotroph

Question 7

hypothalamus and anterior pituitary participate in what type of feedback mechanism

Answer 7

negative feedback

Question 8

where are the hormones of the posterior pituitary synthesized

Answer 8

• hypothalamic neuronal cell bodies

Question 9

hormones of the posterior pituitary are neuropeptides. what does this mean?

Answer 9

• stored in vesicles
• transported in axons
• secreted at nerve terminals (located in posterior pituitary)
• released into pituitary capillaries upon stimulation

Question 10

What are the hormones of the posterior pituitary

Answer 10

antidiuretic hormone (ADH) and oxytocin

Question 11

how is ADH formed in the hypothalamus

Answer 11

• Prepropressophysin is cleaved into propressophysin and packaged into vesicles to travel down the hypothalamic-hypophyseal tract to the posterior pituitary

Question 12

function of ADH

Answer 12

• regulates plasma osmolarity
  
  • secreted in response to an increase in plasma osmolarity or hypovolemia
  • causes reabsorption of water from distal tubule and collecting duct

Question 13

what is central diabetes insipidus

Answer 13

• deficiency of ADH release; levels of ADH low
• caused by disease or damage of ADH neurons
• result
  
  • collecting ducts are impermeable to water
  • diluted urine
• treatment: exogenous ADH

Question 14

what is nephrogenic diabetes insipidus

Answer 14

• posterior pituitary normal, ADH levels elevated
• collecting ducts unresponsive to ADH
  
  • defect in V2 receptor, G protein, or intracellular signaling
  • dilute urine

Question 15

how does oxytocin stimulate milk production

Answer 15

• promotes milk “letdown” from lactating breasts
  
  • causes contraction of myoepithelial cells lining milk ducts
  • continued suckling further stimulates synthesis and release of oxytocin
• during suckling, oxytocin causes uterine contractions during first weeks of lactation

Question 16

is suckling required for secretion of milk

Answer 16

• no
  
  • conditioned responses to the sight, smell, sound of infant also stimuli

Question 17

sensory receptors in the nipple generate impulses that reach the hypothalamus. and synapses discharge oxytocin from the posterior pituitary

Answer 17

• afferent
• cholinergic

Question 18

what is oxytocin used for theraputically

Answer 18

used to induce labor

Question 19

name the three effects of oxytocin

Answer 19

1. promotes milk letdown from lactating breasts
2. causes uterine smooth muscle contraction before delivery
3. released during orgasm in both sexes