hypothalmus and pituitary

Question 1

what system is the hypothalamus a part of and what does it act as an interface to?

Answer 1

is a part of the CNS and acta as an interface between the brain and endocrine system

Question 2

what gland do the hypothalmus control

Answer 2

controls the pituitary

Question 3

what type of tissues is the pituitary composed of and why

Answer 3

distinct neural and endocrine tissue bc it recieves both neural and endocrine signals from the hypothalmus

Question 4

what are the 3 modes of hypothalmic control over the endocrine system

Answer 4

1) hypothalmic neurons secrete regulatory hormones that control the release of a 2nd hormone from the anterior pituitary
2) hypothalmic neurons release hormones directly into the blood via the posterior pituitary ( ADH and oxytocin)
3) hypothalmus exerts direct neural control over the endocrine cells of the adrenal medulla (secretion of epinephrine and nor epinephrine)

Question 5

what do pituitary hormones directly regulate

Answer 5

metabolic rate, body growth, water balance, lactation

Question 6

what other glands do pituitary hormones regulate

Answer 6

• thyroid
• adrenal
• repro glands

Question 7

what is considered the master gland and why

Answer 7

• the hypothalmus and pituitary system functions as a master gland
• bc they release hormones that regulate the output of several other endocrine glands

Question 8

how does the the hypothalmus/ pituitary affect peripheral tissues
- give an example

Answer 8

• directly affect other tissues
• ex) prolactin in regulation of milk production

Question 9

2 parts of the pituitary

Answer 9

• posterior pituitary (neurohypophysis)
• anterior pituitary ( adenohypophysis)

Question 10

what is the origin of the posterior pituitary and how is it in communication with the hypothalmus

Answer 10

it is of neuralectoderm origin and has axons that project from the hypothalmus to nerve terminals that release hormones into the blood

Question 11

what is the origin of the anterior pituitary and how is the anterior pituitary in communication with the hypothalmus

Answer 11

-oral ectoderm origin
-contains endocrine cells regulated indirectly by neuroendocrine signals from the hypothalamus that are released in the median eminence

Question 12

how do the regulatory hormones from the hypothalmus get to the anterior pituitary

Answer 12

• axons from the hypothalamus terminate in the neurovascular region, the median eminence, where they secrete regulatory hormones into local circulation and deliver it to the anterior pituitary.
• 2ndary hormones are then released from the anterior pituitary to the blood

Question 13

what is the function of the posterior pituitary and where are hormones stored and released

Answer 13

• store hormones produced by the hypothalamus at nerve terminals and released into a separate blood supply then the posterior pituitary

Question 14

what are the types of hormones that are released by the hypothalamus to the anterior pituitary and how are they transported there

Answer 14

releasing and inhibitory hormones are secreted in the median eminence and pass-through the portal vein to the anterior pituitary

Question 15

2 major neurohormones stored in the posterior pituitary and their role

Answer 15

vasopressin (adh) regulate body fluid by increases water retention in the kidney

oxytocin- stimulate the release of milk from the mammary gland and stimulate the contraction of the uterus

Question 16

what are the 2 modes in which increased osmolality in the ECF can be decreased

Answer 16

• increased thirst» increase water intake&raquo_space; dilutes ECF = decreased osmolality
• increased vasopressin > water retention > dilutes ECF = increased osmolality

Question 17

what is the role of vasopressin

Answer 17

maintains osmolality of ECF

Question 18

3 ways oxytocin is stimulated to be released by the posterior pituitary

Answer 18

• suckling stimulates release via afferent neurons which then causes milk secretion
• in pregencancy, stimulated by uterine contractions and distention of the cervix to enhance contractions
• important in social behavior and increases maternal bonding

Question 19

what affect do releasing hormones have on the anterior pituitary

Answer 19

act on the PM receptors of specific pituitary endocrine cells to stimulate exocytosis and synthesis of hormones

Question 20

what is the affect of inhibiting hormones on the anterior pituitary

Answer 20

reduce secretion and synthesis of pituitary hormones at their target cells

Question 21

what are the target cells of TRH , what pituitary hormone is released, what is the affect(2)

Answer 21

thyrotroph, thryropin (TSH) released, increased thyroid hormone secretion and enlarges thyroid gland

mamotroph, increases prolactin

Question 22

what is the target cell of GnRH, what pituitary hormone is released, what is the affect

Answer 22

• gonadotroph, LH and FSH,
• LH = ovulation and testosterone secretion in males
• FSH = ovarian follicle growth and estrogen secretion in females and spermatogenesis in males

Question 23

what is the target cell of corticotropin releasing hormone (CRH), what pituitary hormone is released and what is the affect

Answer 23

corticotroph, adrenocorticotropic hormone (ACTH), hormone secretion and cell growth in the adrenal cortex

Question 24

what is the target cell of growth hormone releasing hormone ( GHRH), what pituitary hormone is released, what is the affect

Answer 24

somatotroph, increases growth hormone (somatotropin), causes body growth

Question 25

what is the target cell of somatostatin ( growth hormone inhibiting hormone), what pituitary hormone is released and what is the affect(2)

Answer 25

• somatotroph, decresases GH (somatotropin)
• Thyrotroph, decreases thyroptropin (TSH)

Question 26

what is the target cell of prolactin inhibiting factor (PIF,DOPAMINE), what pituitary hormone is affected, what are the affects

Answer 26

mamotroph, decreases prolactin, milk secretion

Question 27

how is the pituitary gland regulated

Answer 27

via negative feedback by peripheral hormones on the pituitary and hypothalamus

Question 28

what type of hormone is GH and what cells is it secreteted by

Answer 28

is a polypeptide hormone secreted by somatotrophs cells in the anterior pituitary

Question 29

what are the roles of GH

Answer 29

development in children and regulating metabolism in children and adults

Question 30

what is GHregulated by

Answer 30

regulated by GHRH ( somatotropin)and inhinitory GHIH (somatostatin)

Question 30

what does the GH stimulate the secretion of in the liver what is its function

Answer 30

somatomedian (IGF) exerts negactive feedback on GH by inhibiting GHRH and enhancing GHIH

Question 31

how does GH indirectly act on tissues

Answer 31

via secondary hormones ( somatomedins also knows as insulin like growth factors, IGF-1 and IGF-2)

Question 32

what do somatomedins (IGFs)do to tissues

Answer 32

stimulate anabolic response to bone, muscle , and other organs to increase protein synthesis and increase growth

Question 33

how is GH diabetogenic

Answer 33

• oppose actions of insulin by inhibiting glucose uptake and enhances lipolysis( decreases adiposity)

Question 34

major difference btwn Gh and somatomedian

Answer 34

Gh decreases glucose uptake and somatomedin increases it

Question 35

what are the 3 hormones important for growth

Answer 35

-GH importnat throughout growth
- thyroid hormone important in early growth
- androgens and estrogen important during puberty

Question 36

what is the result of too much and too little GH

Answer 36

• gigantism and pituitary dwarfism

Question 37

what is acromegaly
-cause
- sympotoms
- treatment
- what other disease may occur

Answer 37

• caused by hypersectrtion of GH from a pituitary somatotroph tumor
• causes widening bones, accumulation of soft tissue, thickening skin, large hands nad feet, large jaw
• diabetes may occur
• treated by surgery or somatostatin

Question 38

affects of prolactin when do levels increase

Answer 38

stimulate breast development and milk production
increase during pregnancy and nursing

Question 39

how is PRL regulated

Answer 39

regulated by dopamine (PIF) and negative feedback on the hypothalamus by dopmaine release

Question 40

what does high estrogen do to prolactin

Answer 40

increases ints production by directly acting on mamotrophs in the anterior pituitary

Answer 41