the pituitary gland

Question 1

define a hormone

Answer 1

a messenger that is carried from the organ where they are produced to the organ which they affect by means of the blood stream

Question 2

compare the synthesis of steroid and peptide hormones

Answer 2

peptide:
synthesised as prohormones requiring further processing

steroid:
synthesised in a series of reactions from cholesterol

Question 3

compare the storage of peptide and steroid hormones

Answer 3

peptide:
stored in vesicles (regulatory secretion)

steroid:
released immediately (constitutive secretion)

Question 4

compare the receptors for peptide and steroid hormones

Answer 4

peptide:
bind to receptors on the cell membrane and transduce signal using 2nd messenger systems

steroid:
bind to intracellular receptors to change gene expression directly

Question 5

where does the pituitary gland sit?

Answer 5

in the sella turcica of sphenoid bone

it is inferior to the hypothalamus and optic chiasm

Question 6

what is the name of the neurons that regulate anterior pituitary function?

Answer 6

hypothalamic parvocellular neurons

Question 7

describe hypothalamic parvocellular neurons

Answer 7

short
terminate on median eminence
release hypothalamic releasing/inhibitory factors into capillary plexus in median eminence

Question 8

what is the name of the system that moves factors from hypothalamus to the pituitary?

Answer 8

the hypophyseal-pituitary portal system

Question 9

is the anterior pituitary anatomically continuous or distinct to the hypothalamus?

Answer 9

distinct

Question 10

what are the 5 types of cell that make up the anterior pituitary?

Answer 10

somatotrophs
lactotrophs
corticotrophs
thyrotrophs
gonadotrophs

Question 11

outline the 4 steps of hormone secretion from anterior pituitary

Answer 11

1: axon terminals of hypothalamic neurosecretory cells release hormones (RHs and IHs) into the hypothalamo-pituitary portal system
2: the RHs and IHs travel in the portal system to the anterior pituitary
3: the RHs and IHs stimulate or inhibit the release of hormones from the anterior pituitary cells
4: anterior pituitary hormones leave via the blood

Question 12

what hormone do the somatotrophs release?

Answer 12

growth hormone (somatotrophin)

Question 13

what hormone do lactotrophs release?

Answer 13

prolactin

Question 14

what hormone do thyrotrophs release?

Answer 14

thyroid stimulating hormone (TSH)

thyrotrophin

Question 15

what hormone do gonadotrophs release?

Answer 15

luteinising hormone (LH)
follicle stimulating hormone (FSH)

Question 16

what hormone do corticotrophs release?

Answer 16

adrenocorticotrophic hormone (ACTH)
(corticotrophin)

Question 17

how is growth hormone production regulated?

Answer 17

releasing- growth hormone releasing hormone

inhibiting- somatostatin

Question 18

how is prolactin production regulated?

Answer 18

inhibiting- dopamine (only inhibition only)

Question 19

how is thyroid stimulating hormone (TSH) / thyrotrophin regulated?

Answer 19

releasing- thyrotrophin releasing hormone

Question 20

how is luteinising hormone (LH) and follicle stimulating hormone (FSH) production regulated?

Answer 20

releasing- gonadotrophin releasing hormone

Question 21

how is adrenocorticotrophic hormone (ACTH) / corticotrophin production regulated?

Answer 21

releasing- corticotrophin releasing hormone

Question 22

where are the receptors for growth hormone?

Answer 22

general body tissue, especially the liver

Question 23

where are the receptors for prolactin?

Answer 23

breasts (lactating women)

Question 24

where are the receptors for thyrotrophin?

Answer 24

thyroid

Question 25

where are the receptors for gonadotrophins?

Answer 25

testes (males)

ovaries (females)

Question 26

where are the receptors for adrenocorticotrophic hormone?

Answer 26

adrenal cortex

Question 27

what is bitemporal hemianopia?

Answer 27

loss of the outside half of your vison

Question 28

why do pituitary tumours cause bitemporal hemianopia?

Answer 28

the optic chiasm gets squashed only the peripheral fibres cross here so the transmission of sensory information is prevented from lateral visual fields to the occipital lobe

Question 29

what are the mechanisms of growth hormone action

Answer 29

to liver gets used or turned into insulin-like growth factor(IGF-1 and IGF-2)
then growth hormone and the IGFs act on body tissues promoting growth and development

Question 30

what are the symptoms of acromegaly (excess growth hormone in adults)

Answer 30

coarsening of facial features
macroglossia- large tongue
prominent nose
prognathism- large jaw
increased hand and feet size
sweatiness
headache
(no increase in height)

Question 31

what hormones does the posterior pituitary hormones?

Answer 31

arginine vasopressin(AVP)/ anti-diuretic hormone
oxytocin

Question 32

is the posterior pituitary gland anatomically distinct or continuous from the hypothalamus?

Answer 32

continuous

Question 33

describe the hypothalamic magnocellular neurons

Answer 33

long originate in the supraoptic(AVP) and paraventricular (oxytocin) hypothalamic nuclei
nuclei —> stalk —> posterior pituitary

Question 34

outline the regulation of the posterior pituitary gland

Answer 34

1: two sets of hypothalamic neurosecretory cells produce AVP and oxytocin and transport them to the posterior pituitary
2: excitation of these hypothalamic magnocellular neurons stimulates release of AVP or oxytocin into the posterior pituitary where they diffuse into the blood capillaries
3: then leave the posterior pituitary via the blood

Question 35

outline the physiological action of vasopressin

Answer 35

anti-diuretic hormone (diuresis- production of urine)

stimulates water reabsorption in the renal collecting duct
concentrates urine
acts through the V2 receptor in the kidney
vasoconstrictor V1 receptor
stimulates ACTH release from anterior pituitary

Question 36

how does vasopressin concentrate urine?

Answer 36

AVP binds to V2
chain of reactions causes vesicles with aquaporin-2 proteins to fuse with the membrane (on the tubule side)
this allows more water to flow into the cell and out of the aquaporin-3 proteins bringing water into the blood

Question 37

what are the physiological actions oxytocin?

Answer 37

contraction

for baby delivery or milk ejection