Week 4 Physiology

Question 1

What are the three muscle types?

Answer 1

Skeletal
- Under voluntary control by the brain
- Allows movement and postural control
- Contributes to temperature regulation

Cardiac
- Responsible for the contractility of the heart

Smooth
- Found in the walls of blood vessels and many internal organs
- Contractioin not under voluntary control

Question 2

What do the three muscle types have in common

Answer 2

• Excitability: muscle cell membranes can generate action potentials
• Contractility: muscle cells can shorten and hence exert a force on the structures the muscles are attached to. Using ATP, the muscle contracts by activating motor proteins (actin and myosin) that interact and slide past each other, shortening the cell.
• Calcium ions: contraction is triggered when the concentration of free calcium ions in the cytosol increase. Ca2+ ions can enter from extracellular space or from intracellular storage compartement (sarcoplamic reticulum).