endocrine system

Question 1

give an example of a chemical messenger that may be either a hormone or neurotransmitter depending on its source and mode of delivery to target cells. how does it work?

Answer 1

norepinephrine as its released as a neurotransmitter by nerve fibres into the synaptic cleft and binds to alpha adrenergic receptors or as a hormone by the adrenal medulla

Question 2

what is a tropic hormone and give two examples

Answer 2

a hormone that has as its primary function the regulation of hormone secretion by another endocrine gland e.g. TRH snd TSH

Question 3

what is a non tropic hormone and give an example

Answer 3

a hormone that exerts its effects on non-endocrine target tissue e.g. thyroid hormone

Question 4

Give three classes of hormones depending on their biochemical structure

Answer 4

-peptides
-amines
-steroids

Question 5

how does the solubility of hormones affect their function?

Answer 5

-hydrophillic peptide hormones are transported simply dissolved in the plasma
-hydrophobic steroid hormones circulate in the blood to their target cells reversibly bound to plasma proteins

Question 6

how do hydrophilic hormones cross through plasma membranes?

Answer 6

by binding to specific receptors on the outer plasma membrane surface of the target cells triggering a signalling cascade

Question 7

give the process of a signalling cascade triggered by hydrophilic hormones (check slide 8-9). Use the example of adrenaline regulating blood glucose

Answer 7

adrenaline regulating blood glucose:
1. Adrenaline binds to the transmembrane protein receptor in the cell surface membrane of the liver cell
2. Tertiary structure of protein receptor changes shape activating adenyl cyclase enzyme inside the membrane
3. Converts ATP to cAMP (cyclic AMP) which acts as a second messenger
4. cAMP changes the tertiary protein structure shape and activates kinase enzyme
5. Active kinase catalyses conversion of glycogen to glucose

Question 8

how do hydrophobic hormones cross through the plasma membrane, what happens once they pass through?

Answer 8

via simple diffusion and bind to specific intracellular receptors, the receptors then become activated causing the formation of new intracellular proteins whcih in turn produce the desired effect

Question 9

give examples of where the endocrine system controls activities that need duration instead of speed (slide 12)

Answer 9

-regulation of metabolism and water and electrolyte balance
-changes to help the body cope with stressful situations
-promotes smooth and sequential growth and development
-regulates red blood cell production
-controls and integrates both circulation and digestion and absorption of food

Question 10

name the major endocrine glands (slide 13)

Answer 10

-pineal gland
-pituitary gland
-parathyroid gland
-thyroid gland
-pancreas
-adrenal glands
-ovaries and testes

Question 11

what functions does the hypothalamus have? (slide 14)

Answer 11

-control centre for many autonomic functions of the peripheral nervous system
-influences some emotional responses as part of the limbic system structure
-mainains homeostasis

Question 12

where is vasopressin and oxytocin released from?

Answer 12

the posterior side of the pituitary gland

Question 13

what pituitary hormone secretions does the blood vessel connections between the hypothalamus and pituitary gland allow?

Answer 13

-CRH stimulates ACTH
-TRH stimulates release of TSH and prolactin
-GnRH stimulates release of FSH and RH
-GHRH stimulates release of GH
-GHIH inhibits GH and TSH
-PIH inhibits prolactin

Question 14

what does the anterior pituitary release?

Answer 14

-TSH
-ACTH
-prolactin
-growth hormone
-LH
-FSH

Question 15

what does the posterior pituitary release?

Answer 15

vasopressin and oxytocin

Question 16

what does the pineal gland do?

Answer 16

produces and secretes several important hormones including melatonin

Question 17

what does melatonin do?

Answer 17

helps to keep the body’s circadian rhythms in synch with the light-dark cycle by regulation of activity levels over the course of the day

Question 18

how does exposure of melatonin to light supress melatonin secretion by the pineal gland?

Answer 18

1. melanopsin-expressing intrinsically photosensitive retinal ganglion cells innervate the hypothalamic suprachiasmatic nucleus (SCN)
2. The SCN relays the message to the pineal gland
3. melatonin release is suppressed

Question 19

what does the thyroid do?

Answer 19

secretes thyroxine which regulates the body’s overall metabolism

Question 20

what does the parathyroid do?

Answer 20

secrete parathormone which controls calcium and phosphate in the blood and tissue fluid hence affecting the excitability of the nervous system

Question 21

what do the adrenal glands do?

Answer 21

-maintain salt levels in the blood
-maintain blood pressure
-help control kidney function
-control overall fluid conc in the body

Question 22

what part of the adrenal gland can be removed with no life threatening effects? what part of the adrenal glad is needed?

Answer 22

medulla can be removed, adrenal cortex is essential

Question 23

what are mineralcorticoids? where are they secreted from? What is the principle one? what does it do?

Answer 23

-a type of steroid
-secreted by the outermost region of the adrenal cortex
-aldosterone
-acts to conserve sodium ions and water in the body

Question 23

what are all cortical hormones sythesised from? what is another name for cortical hormones?

Answer 23

cholesterol, steroids

Question 24

what happens when vasopressin receptors in arterioles are triggered by vasopressin?

Answer 24

vasoconstriction of the arterioles to help regulate blood pressure

Question 25

what does oxytocin do?

Answer 25

-stimulates contraction of the uterine smooth muscle in childbirth
-stimulates the mammary glands to trigger milk ejection during breast feeding

Question 26

what are two issues that can arise when there is dysfunction in the thyroid? what are their symptoms for each?

Answer 26

-hypothyroidism causing drowsiness and slower metabolism
-hyperthyroidism causing reduced concentration and irritability

Question 27

what are glucocorticoids? where are they secreted from? What is the principle one? what does it do?

Answer 27

-a type of steroid
-secreted by the middle region of the adrenal cortex
-cortisol
-increases blood glucose levels

Question 28

what are gonadocorticoids? where are they secreted from? What is the principle one? what does it do?

Answer 28

-a type of steroid
-innermost region of the adrenal cortex
-androgens for males and estrogens for females
-sex hormones but their effect is usually masked by the hormones from the testes and ovaries

Question 29

what hormones are released from the adrenal glands? when are the secreted?

Answer 29

-adrenaline = epinephrine and noradrenaline = norepinephrine
-secreted in response to stimulation by sympathetic nerves particularly during stressful situations

Question 30

What are the effects of adrenaline and noradrenaline?

Answer 30

-increased heart rate
-increased blood pressure
-increased blood vessel constriction in the skin and gastrointestinal tract
-bronchiole dilation
-increased metabolism

Question 31

what causes hypersecretion of adrenal glands?

Answer 31

a prolonged or continual sympathetic response

Question 32

what is Grave’s disease? how does Grave’s disease affect the eyes?

Answer 32

-a type of hyperthyroidism
-causes bulging of the eyes as a result of inflammation and swelling of eye muscles and fat behind the eyes within the orbits

Question 33

give some general treatment methods off grave’s disease

Answer 33

-use of anti-thyroid drugs that specifically interfere with thyroid hormone synthesis
-surgical removal of a portion of the oversecreting thyroid gland
-administration of radioactive iodine as it selectively destroys thyroid glandular tissue by being concentrated in the thyroid gland by the iodine trap