Introduction (1)

Question 1

What is a hormone?

Answer 1

Chemical messenger released from one tissue carried in the blood circulation
→ producing a specific receptor mediated change in another tissue

Question 2

What do hormones regulate?

Answer 2

Development
→ proliferation, growth, differentiation, organogenesis
Metabolism
→ energy storage, metabolic rate, temperature
Reduction
→ sexual maturity, behaviour, pregnancy, lactation
Fluid homeostasis
→ water balance, salt levels, blood volume and pressure

Question 3

What are some endocrine glands?

Answer 3

Tissues with endocrine functions:
Brain
Pituitary
Thyroid
Thymus
Adrenal
Pancreas
Kidney
Testes
Ovary
Uterus

Question 4

What hormones does the pituitary gland release?

Answer 4

Anterior pituitary → growth hormone, thyroid-stimulating hormone. adrenocorticotropic hormone, follicle-stimulating hormone, luteinising hormone, prolactin
Intermediate pituitary → melanocyte-stimulating hormone
Posterior pituitary → oxytocin, vasopressin, oxytocin (stored), anti-diuretic hormone (stored)

Question 5

What hormones does the hypothalamus release?

Answer 5

Thyrotropin-releasing hormone, dopamine, growth hormone-releasing hormone, somatostatin, gonadotropin-releasing hormone, corticotropin-releasing hormone, oxytocin, vasopressin

Question 6

What hormones does the thyroid release?

Answer 6

Triiodothyronine
Thyroxine

Question 7

What hormones does the liver release?

Answer 7

Insulin-like growth factor (somatomedin)
Angiotensinogen
Angiotensin
ThrombopietinW

Question 8

What hormones does the stomach release?

Answer 8

Gastrin, gherkin, neuropeptide Y, somatostatin, histamine, endothelin

Question 9

What hormones does the pancreas release?

Answer 9

Insulin
Glucagon
Somatostatin
Pancreatic polypeptide

Question 10

What hormones does the ovary release?

Answer 10

Progesterone
Androstenedione
Oestrogens
Inhibit

Question 11

What are the endocrine organs of the brain?

Answer 11

Hypothalamus
Pineal gland
Pituitary gland

Question 12

What are the 4 types of signalling?

Answer 12

Autocrine → self signalling
Paracine → signalling over short distance
Endocrine → signalling over longer distance via blood stream,
Neurocrine → via blood stream, involving neurone

Question 13

What are the 2 derivations of hormones?

Answer 13

Derived from amino acids
Derived from lipid precursors

Question 14

What are the characteristics of peptide and catecholamine hormone systems?

Answer 14

Changes in [plasma] → rapid
Plasma half life → short
Type of receptor → cell membrane
Mechanism → activate preformed enzymes secretory granules, constitutive + bursts
Speed of effect → rapid

Question 15

What are the characteristics of steroids and thyroid hormones?

Answer 15

Changes in [plasma] → slow fluctuations
Plasma half-life → long (mins to days)
Type of receptors → intracellular
Mechanism → stimulate protein synthesis, direct rapid passage, related to secretion rate
Speed of effect → slow (hours to days)

Question 16

How are hormones synthesised?

Answer 16

1 → Proteins are formed on the ribosomes attached to the ER.
2 → These nascent protein are then transferred into the ER.
3 → From here they go to the Golgi complex.
4 → In the Golgi complex the proteins are concentrated and transformed into zymogen granules.
5 → The zymogen granules released from the Gogli complex migrate to the surface of the cell.

Question 17

Name 3 hormones formed from tyrosine?

Answer 17

Dihydroxyphenylalanie
Dopamine
Norepinephrine

Question 18

What does a pre-pro-PTH consist of?

Answer 18

Pre-pro-peptide/protein hormone

N- signal sequence - pro sequence - biologically active sequence - c-terminal fragment sequence -C

Question 19

How are steroid hormones synthesised?

Answer 19

More complicated than peptide
→ comes from cholesterol
→ occurs in discrete sub-cellular environments

1. hydrolysis of esters and release of cholesterol
2. cholesterol to pregnenolone
3. processing
4. diffusion

Question 20

What are feedback mechanisms?

Answer 20

Systems in place to stop hormones working
→ positive/negative

Question 21

What are tropic hormones?

Answer 21

Act on another endocrine gland to drive hormone secretion

Question 22

What are trophic (non-tropic) hormones?

Answer 22

Stimulate growth of a target tissue
→ growth, metabolism or other functions

Question 23

Can hormones have both tropic and trophic roles?

Answer 23

Yes

Question 24

Why are hormones receptors important?

Answer 24

Hormones levels in circulation are low
→ hormone effects are mediated by specific, high affinity receptors
→ receptors are presents inside the cell or on the cell membrane
→ one molecule can effect through amplification

Question 25

What are some endocrine disorders?

Answer 25

Excess secretion of a hormone
Deficient secretion of a hormone
Failure to response to a hormone
(due to a malfunction/defect of a receptor, or down-stream signalling)

Question 26

What are some endocrine diseases?

Answer 26

Diabetes mellitus → insulin deficiency or insensitivity
Thyroid disease → too little or too much
Infertility → hypothalamic, pituitary, gonadal
Obesity → leptin