Introduction To Endocrine Physiology

Question 1

Endocrine secretions have …..effects while exocrine have….

Answer 1

Intracellular
Extracellular

Question 2

Liver secretes…..while kidney secretes……with respect their endocrine function

Answer 2

Erythropoietin, somatomedins
Calcitriol, renin, erythropoietin

Question 3

An example of autocrine hormones…..while paracrine is…..

Answer 3

Prostalglandins
Histamine

Question 4

Enumerate:
1. Amino acid derived hormones
2. Lipophilic hormones

Answer 4

1. CAs, thyroid hormone, melatonin
2. All steroid hormones + thyroid hormones + eicosanoids & retinoids

Question 5

Enumerate determinants of strength of response to hormonal secretions

Answer 5

1. Blood level of hormone
2. Relative number of hormonal receptors on or in target cells (up/down regulation)
3. Affinity of hormone & receptor

Question 6

Enumerate possible Mechanisms of action of hormones

Answer 6

1. Ion channel activation
2. Direct activation of transcription (lipophilic)
3. Through 2nd messenger (IP3, DAG, Ca++, cAMP)
4. Activation of tyrosine kinase

Question 7

Define each if the following with giving example:
1. Permissiveness
2. Synergism
3. Antagonism

Answer 7

1. One hormone is needed for another hormone to exert its full effect. Thyroid hormone upregulated epinepherine receptors on its target cells thus increasing its effectiveness.
2. Actions of Several hormones are complementaryand their combines effect is greater than the sum of their separate effects. FSH & testosterone are both required for normal rate of sperm production.
3. One hormone causes loss of receptors of another hormone. Progesterone causes loss of estrogen receptors from uterine wall muscle decreasing its responsiveness to estrogen during pregnancy.

Question 8

Mention methods of control of hormonal secretion

Answer 8

1. Feedback (+/-)
2. Neuroendocrine reflexes
3. Circadian rhytyms (controlled by SCN)

Question 9

2ry hyposecretion of endo.gland occurs because of……

Answer 9

Deficiency of its tropic hormone

Question 10

Production of melatonin is stimulated by activity of……via……

Answer 10

SCN
Sympathetic neurons in superior sympathetic ganglion that innervate pineal gland

Question 11

Describe function of melatonin

Answer 11

Postulated to have the ability to inhibit pituitary+gonad axis (inhibit GnRH secretion or the response of ant pitutary to it)