Extracellular Signalling - Diseases

Question 1

What are the 5 problems that can cause diseases?

Answer 1

1. Signal is lost / no longer sent
2. Target ignores the signal
3. Signal doesn’t reach target
4. Too much signal
5. Multiple breakdowns

Question 2

What occurs during type 1 diabetes compared to what should happen?

Answer 2

What should happen:

1. Glucose in blood
2. Beta cells in pancreas release insulin
3. Insulin binds to insulin receptors on muscle cell which triggers movement of glucose transporter (GLUT4) to cell surface and triggers uptake of glucose

Type 1 Diabetes:

1. Pancreas becomes damaged
2. Beta cells no longer produce insulin
3. Sugar in bloodstream not taken up into muscle cells
4. Elevated blood sugar levels

Question 3

What occurs during Type 2 diabetes?

Answer 3

Insulin produced and insulin and glucose in bloodstream
BUT
Defective insulin receptor:
1. Insulin binds to receptor but signal not sent
2. Glucose transporter doesn’t move to surface –> no uptake
3. High levels of insulin AND glucose in blood

Question 4

What occurs during multiple sclerosis?

Answer 4

Signal (nerve impulse) doesn’t reach target due to breakdown of myelin sheath surrounding neurone

Question 5

What occurs during brain damage (excitotoxicity)?

Answer 5

1. Blood clot in blood vessel starves brain of O2 leading to damage of neurones
2. Neurotransmitters releases when neurones die and can over activate surrounding cells

Question 6

What is cancer caused by?

Answer 6

Too much signalling causing proliferation of cells

1. Cells invading signals that suppress growth and resist apoptosis
2. Causes breakdown of multiple communication pathways