Disorders of the pituitary gland

Question 1

List the hormone produced by the anterior pituitary gland

Answer 1

GH
ACTH
LH/FSH
TSH
Prolactin

Question 2

What is the function of growth hormone (GH)?

Answer 2

acts on every cell of the body
stimulated by GHRH, inhibited by somatostatin
for skeletal growth, metabolsim (quicker), cardiac function, bone density, quality of life, muscle strength
highest during night, too much = acromegly
GH deficiency: short stature (kids), subtle changes in adults

Question 3

What is the function of ACTH?

Answer 3

CRH (cortisol releasing hormone) & ACTH: secreted in pulses
CRH: positive control (hypothalamic)
ACTH: released when STRESSED, peak in morning, reduced in evening (stimulates cortisol)

Question 4

What is the function of LH/FSH?

Answer 4

GnRH stimulates pituitary gland (positive)
FEMALES: LH cause oestrogen release (follicular phase) - cause progesterone release, LH/FSH surge - positive feedback (ovulation)
MALES: LH drives testosterone secretion, FSH drives sperm production

Question 5

What is the function of TSH (thyroid stimulating hormone)?

Answer 5

stimulate pituitary to release TSH to circulation
TSH activates follicular cells of thyroid to produce T3 & T4
Hypothalamus –> TRH –> pituitary (secondary gland) –> TSH –> thyroid (primary gland) –> T3/T4

T3/T4 neg feedback hypothalamus & pituitary (suppress)

Question 6

What happens in primary gland failure in pituitary thyroid release? what is it called?

Answer 6

primary gland = thyroid releasing T3/T4

1. end organ hormone low (T3/T4)
2. pituitary hormone high (TSH) - lack of negative feedback
   e. g. primary hypothyroidism - lowered thyroid function

Question 7

What happens in secondary gland failure of pituitary thyroid?

Answer 7

secondary gland = pituitary gland releasing TSH

end organ hormone (T3/T4) & pituitary hormone low (TSH)

Question 8

What is primary hyperthyroidism?

Answer 8

excess T4 production by thyroid, suppressed TSH & TRH

Question 9

What is the function of prolactin?

Answer 9

initiates & maintain lactation
acts on peripheral tissues - no target gland
high levels = lactation & menstrual disturbance (women)

Question 10

What inhibits and stimulates prolactin levels?

Answer 10

inhibit: dopamine
stimulate: minor +ve control by TRH, increased by oestrogen
slightly increased at night

Question 11

Cause of high prolactin levels?

Answer 11

5P’s

1. physiological
2. pregnancy
3. pharmacological
4. pituitary (+ve control from TRH from hypothalamus)
5. Polycystic ovaries - hormone imbalance in women

Question 12

Describe in general terms, the structure of the steroid hormones

Answer 12

1. number of C-atoms (C27, 21,19,18)
2. presence of functional groups
3. distribution of C=C

Question 13

How is the pituitary the master of endocrine glands?

Answer 13

pituitary releases number of trophic hormones
TSH –> thyroid
ACTH –> adrenal
GH –> liver production of somatomedins
LH –> ovary & testis hormone production
FSH –> ovary & testis function

Question 14

Describe the role of hypothalamus in control of pituitary function

Answer 14

hypothalamus release: releasing / inhibiting hormones on anterior pituitary cells e.g. TRH
inhibiting hormones travel via hypophyseal portal vessels to pituitary releasing / inhibiting hormones allow brain to control pituitary hormone secretion

Question 15

Examples of hypothalamus in the control of pituitary function

Answer 15

TRH –> stimulates TSH release
CRT –> stimulates ACTH release
SRH –> stimulates GH release
somatostatin –> inhibits GH release

Question 16

List the hormone produced by the posterior pituitary gland and their functions

Answer 16

ADH: reabsorb water in kidneys - prevent dehydration
oxytocin: cause lactation & contraction