Endocrine Glands and Hormones​

Question 1

History​

Answer 1

in 1889, Prof. Brown-Séquard, aged 72:​
​
Self-administration – 5 injections of dog testicle extract … 5 more from guinea pig testicle extract ….. “rejuvenated … increased his physical strength, improved his intellectual capacity, and increased his sexual potency”​
​
Brown-Séquard. Lancet 1889 ​

Question 2

Glands

Answer 2

are epithelial tissue derivatives specialised for secreting​

Question 3

Secretion

Answer 3

is the biochemical release from a particular type of cell upon stimulation​
​

Question 4

Endocrine​

Answer 4

endo’- internal crine’ - secretion…. Secretions enter bloodstream … ductless gland​
compare with Exocrine (gland with ducts that channels its secretion)​

Question 5

Hormones definition

Answer 5

‘Chemical messengers’ secreted into blood by endocrine glands in response to an appropriate signal, and exerting their effects on target cells that have receptors that bind with the hormone.​

Question 6

classification of Hormones​

Answer 6

• Based on their solubility​
  1. Hydrophilic or Water soluble ​
  Peptides (e.g insulin) and catecholamines (adrenaline & noradrenaline)​
  2. Lipophilic or Lipid soluble ​
  Steroids (e.g cortisol) and thyroid hormone​
• Based on their structure​
  1. Peptides – chain of specific amino acids​
  2. Amines - derivatives of amino acids, tryptophan or tyrosine (indoleamines, catecholamines, thyroid hormones)​
  3. Steroids – cholesterol derived lipids​
  ​

Question 7

PEPTIDES​

Answer 7

Produced by normal protein synthesis machinery​
Travel in blood in solution​
Cannot enter cells ​
(lipid bilayer cell membrane)​
Bind to cell surface receptor​
Trigger event on inside surface of membrane​
(second messenger system)​
Fast acting​

Question 8

STEROIDS ​

Answer 8

Produced by modification of cholesterol molecule by enzymes​
Travel in blood bound to plasma proteins​
Enter cells easily​
Intracellular receptor ​
Act on DNA to alter cell function​
Slow acting (transcription delay)​

Question 9

Contraceptive pills and patches

Answer 9

contain oestrogen and progesterone which are steroids and can be absorbed through the skin and get into systemic circulation without being broken down in the GI tract ​

Question 10

Thyroid hormones

Answer 10

are amines and are not broken down by enzymes in the GI tract and hence can be taken as tablets ​

Question 11

Insulin

Answer 11

is a peptide hormone and should be administered through intravenous, subcutaneous or intramuscular routes​

Question 12

Human Endocrine Organs​

Answer 12

Question 13

Overall regulatory role of endocrine system​

Answer 13

Metabolism, water and electrolyte balance​
Stress response​
Growth & development​
Reproduction​
Red cell production​
Coordination of circulation​
Coordination of digestion

Question 14

Pituitary

Answer 14

Pea Size (1 cm2)​
​
Weight 1g​
​
Two lobes (anterior and posterior)​
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Connects to the hypothalamus via the pituitary stalk​

Question 15

all the HP- different axis

Answer 15

Question 16

THE HYPOTHALAMUS, ANTEROR/ POSTEROIR PITUITORY GLANDS

Answer 16

Question 17

HPG Axis ​

Answer 17

Hypothalamus-Pituitary- Gonad Axis ​
Gonads – male and female reproductive organs that secrete hormones and are sites of sperm and ova production ​

Question 18

Testes

Answer 18

Question 19

Ovaries

Answer 19

Question 20

function of testes

Answer 20

Question 21

function of ovaries

Answer 21

Question 22

HPG Axis – Regulation of Testicular Function ​

Answer 22

Question 23

negative feedback

Answer 23

Question 24

HPT Axis

Answer 24

Hypothalamus- Pituitary- Thyroid Gland​

Question 25

Thyroid Gland

Answer 25

Located in the neck area, over the trachea, and just below the larynx. ​ ​ It is made of two lobes of endocrine tissue joined by an isthmus, a narrow part of the gland. ​ ​ The hormone-secreting cells are arranged in hollow spheres called follicles. ​

Question 26

Thyroid Hormones​

Answer 26

Two hormones - Thyroxine (T4) and Triiodothyronine (T3)​ The main ingredients are amino acid tyrosine and iodine (should come from diet)​ Functions: ​ Increasing metabolic rate and heat production (calorigenic effect)​ Sympathomimetic effect (permissive action)​ Effect on cardiovascular system​ Effect on growth and nervous system​

Question 27

Regulation of Thyroid Hormones​

Answer 27

Question 28

Parathyroid Hormone (PTH)​

Answer 28

Calcium metabolism​ Raises free plasma Ca2+​ mobilises bone store​ reduces urine loss​ increases gut absorption​ ​

Question 29

HPA Axis

Answer 29

Hypothalamus- Pituitary- Adrenal Gland​

Question 30

Adrenal Glands​ (Suprarenal Glands)​

Answer 30

- kidney secrets a hormone and hence is an endocrine gland. - here are two adrenal glands and they are located one above each kidney and embedded in a capsule of fat. ​

Question 31

Hormones Secreted By Adrenal Glands​

Answer 31

The adrenal gland consists of two functionally different regions;​ ​ Adrenal Cortex ​ steroid hormones (cortisol, aldosterone and androgens)​ ​ Adrenal Medulla ​ catecholamines (adrenaline and noradrenaline)​

Question 32

adrenal cortex and medulla summaries

Answer 32

Question 33

HPA Axis – Controls only Cortisol production from Adrenal Cortex​

Answer 33

Question 34

Integrated Stress Response​

Answer 34