Endocrine System

Question 1

Which tissues are glucose dependent?

Answer 1

CNS, brain

Question 2

What is hypoglycaemia?

Answer 2

When blood glucose <3.0mM

Question 3

What are the acute effects of hypoglycaemia?

Answer 3

Trembling, weakness, tiredness, headache, sickness, sweating, tingling around lips, palpitations, changes in mood, slurred speech, staggering walk

Question 4

What is hyperglycaemia?

Answer 4

When blood glucose is >7.0mM

Question 5

Which systems can be affected in hyperglycaemia?

Answer 5

CNS, CVS and renal systems

Question 6

What are the effects of hyperglycaemia?

Answer 6

Polyuria, polydipsia, increased non-enzymatic glycosylation of plasma proteins

Question 7

What are the effects of insulin?

Answer 7

Increases glucose uptake, promotes glycogenesis, promotes lipogenesis, promotes amino acid uptake

Question 8

What are the effects of glucagon?

Answer 8

Gluconeogenesis is stimulated, glycogenolysis is stimulated, lipolysis is stimulated

Question 9

What are the metabolic effects of feeding?

Answer 9

Absorption of glucose, amino acids and lipids - increased levels in blood. Stimulates release of insulin

Question 10

What are the metabolic effects of fasting?

Answer 10

Insulin secretion depressed, glucagon secretion stimulated

Question 11

How is secretion of hormones controlled?

Answer 11

Change in a parameter regulated by the hormone, concentration of hormone itself or another hormone.

Question 12

What is the role of osmoreceptors?

Answer 12

Monitor osmolality and Na+ conc

Question 13

What does the magnitude of response to a hormone rely on?

Answer 13

Concentration of active hormone, responsiveness of target tissues, receptor number

Question 14

What types of hormones are there?

Answer 14

Polypeptide, glycoprotein, amino acid derivatives and steroids

Question 15

Where are hormones inactivated?

Answer 15

In the liver, kidney and in some target tissues.

Question 16

Define the term hormone

Answer 16

Chemical messenger that travels via the bloodstream

Question 17

What types of hormones are there?

Answer 17

Polypeptide, glycoprotein, amino acid derivatives and steroid hormones

Question 18

Describe and give examples of polypeptide hormones

Answer 18

Short or long chain(s) of amino acids e.g. insulin, glucagon, growth hormone etc

Question 19

Describe and give examples of glycoprotein hormones

Answer 19

Large protein molecules with carbohydrate side chains. e.g. anterior pituitary hormones (LH, FSH, TSH)

Question 20

Describe and give examples of amino acid derivative hormones

Answer 20

Small molecules synthesised from amino acids e.g. adrenaline, and thyroid hormones

Question 21

Describe and give examples of steroid hormones

Answer 21

Derived from cholesterol e.g. cortisol, aldosterone, testosterone, oestrogen

Question 22

What effects can hormones have?

Answer 22

Can change the activity of enzymes or other functional proteins (e.g. membrane transport) , can effect gene expression

Question 23

Describe the binding of a hydrophilic hormone

Answer 23

Binds to receptors on the surface of the cell which can trigger a second messenger (e.g. cAMP)

Question 24

Describe the basic outline of a negative feedback mechanism

Answer 24

Effector opposes the stimuli - when the hormone levels rises in the blood then it’s production will be inhibited.

Question 25

How can one hormone control the release of another?

Answer 25

Controlling hormone is called the trophic hormone - mostly secreted from anterior pituitary gland

Question 26

What are the main hormones that the anterior pituitary gland secretes?

Answer 26

TSH, ACTH, GH, LH, FSH, prolactin

Question 27

Where do releasing or inhibiting hormones come from?

Answer 27

Nerve cells in the hypothalamus and travel to the gland via hypophyseal portal vessels

Question 28

Give examples of hormones that the hypothalamus releases

Answer 28

TRH, CRH, SRH, somatostatin

Question 29

How are steroid hormones inactivated?

Answer 29

Relatively small change in chemical structure which increases their water solubility thus enabling them to be excreted from the body in the urine or via bile

Question 30

How are protein hormones inactivated?

Answer 30

Undergo extensive chemical changes and are degraded to amino acids that are reused

Question 31

How is insulin stored?

Answer 31

In beta-cells storage granules as a crystalline-zinc complex

Question 32

What are the short term effects of insulin?

Answer 32

Anabolic - clears absorbed nutrients from the blood following a meal

Question 33

How is glucagon synthesised?

Answer 33

Pre-proglucagon - undergoes post-translational processing to produce glucagon.

Question 34

What are the short term effects of glucagon?

Answer 34

Catabolic - binds to a G-protein coupled receptor (GPCR) thus activating adenylate cyclase which increases cAMP intracellularly. High levels of cAMP activate PKA - phosphorylates shizz

Question 35

What are the long term effects of insulin?

Answer 35

Effects cell growth/cell division which relates to its ability to stimulate protein synthesis and DNA replication.

Question 36

How is insulin synthesised?

Answer 36

Pre-proinsulin has its signal peptide removed in ER - pro-insulin goes to trans surface of Golgi - storage vesicles - proteolysis removes a C-peptide from near the middle (good indicator of insulin)

Question 37

Describe the structure of insulin

Answer 37

2 polypeptide chains, covalently linked by two disulphide bridges, 3rd disulphide bond is in the A chain

Question 38

Describe the structure of glucagon

Answer 38

Single chain polypeptide, flexible 3D structure that takes up active conformation on binding to receptor