8. Signalling between cells I

Question 1

4 Reasons cells need to communicate

Answer 1

1.	Process information 
Sensory stimuli (e.g. sight, sound)
2.	Self-preservation
Spinal reflexes and Sympathetic nervous system
3.	Voluntary movement
Daily activities
4.	Homeostasis
Thermoregulation and Glucose homeostasis

Question 2

4 Modes of intercellular signalling

Answer 2

Endocrine
Paracrine
Autocrine
Signalling by membrane attached proteins

Question 3

Endocrine signalling

Answer 3

Hormone travels within blood vessels to act on a distant target cell e.g. Glucagon from pancreas, Adrenaline

Question 4

Paracrine signalling

Answer 4

Hormone acts on an adjacent cell e.g. Insulin within pancreas, Nitric Oxide

Question 5

Signalling between membrane attached proteins

Answer 5

Plasma membrane proteins on adjacent cells interacting e.g. APC’s and T-lymphocytes

Question 6

Autocrine signalling

Answer 6

Signalling molecule acts on same cell

e.g. IL-2 on T-lymphocytes