Lecture 10- Signalling Between Cells I

Question 1

Why do cells need to communicate?

Answer 1

1) process information- sensory stimuli
2) self preservation- ID dangers–> Spinal reflex/ SNS
3) voluntary movement
4) homeostasis- thermoregulation, glucose homeostasis

Question 2

List examples of intercellular and intracellular signalling

Answer 2

Intercellular- pancreas to liver to maintain glucose glucose levels
Intracellular- between a and B cells within the is,eats of langerhans

Question 3

List 4 types of signalling

Answer 3

Endocrine
Paracrine
Autocrine
Signalling by membrane attached proteins

Question 4

Define endocrine signalling and give examples

Answer 4

Hormone travels in bloodstream to act on distant target cells

1) glucagon acts on liver
2) insulin from pan crease acts on liver, muscle and adipose tissue
3) adrenaline produced in adrenal glands acts on trachea

Question 5

Define paracrine signalling and give examples

Answer 5

Hormone acts on adjacent cells

1) insulin inhibits glucagon production in alpha cells in pancreas
2) Nitric oxide produced by endothelial cells act on vascular smooth muscle
3) osteoclasts activating factors produced by adjacent osteoblasts

Question 6

Define autocrine signalling and give examples

Answer 6

Signalling molecules act on the same cell

1) IL-2 and TCR
2) acetylcholine–> presynaptic muscarinic M2 receptors
3) growth factors from tumour cells –> mitogenesis

Question 7

Give examples of membrane attached proteins involved in cell signalling

Answer 7

1) a blood borne virus is digested by an APC and expressed MHC class II on its surface and then T cells bind to the MHC molecule using TCR

Question 8

What are the two physiological responses to hypoglycaemia?

Answer 8

1) glycogen breakdown (glycogenolysis)

2) gluconeogenesis

Question 9

How is glycogenolysis and gluconeogenesis brought about when you are hypoglycaemic?

Answer 9

1) glucagon is secreted by alpha cells of the islets of langerhans in the pancreas
2) glucagon secreted into bloodstream
3) glucagon stimulates glycogenolysis and gluconeogenesis in the liver causing bs to rise

Question 10

What are the 3 physiological responses to hyperglycaemia

Answer 10

1) glucose uptake
2) reduced gluconeogenesis
3) reduced glycogenolysis

Question 11

How are the physiological responses to hyperglycaemia brought about?

Answer 11

1) increased blood glucose–> insulin secreted by B-cells in islets of Langerhans
I) has paracrine effect on a-cell glucagon secretion
II) has endocrine effect on liver