Question

Module 7 Worksheet (Muscles)

BIO 326

1. What are the three main muscle types and describe their characteristics (striated or not, duration of muscle twitch, purpose).

b. Describe how skeletal muscle contracts. What ion is important and what happens when it increases in abundance inside the cell? How does the muscle relax again?

c. Why do t-tubules need to be closely associated with the sarcoplasmic reticulum?

d. Describe how the pacemaker (auto rhythmic) cells generate a repetitive series of action potentials.

e. Why is cardiac muscle not prone to tetanus

Answer 1

Ans. 1 (a)

The three main types of muscles are:

1. Skeletal muscle - it is connected at either or both ends to a bone

2.smooth - muscles found in walls of internal organs such as stomach and intestine

3.cardiac - muscle tissue of the heart

Characterstics of skeletal

• It is composed of long cells and have a striated appearance
• It has a brief, contractile response that elicited by a single maximal volley of impulses in the neurons.
• It moves bones by contracting and relaxing in response to voluntary messages from the nervous system.

Characterstics of smooth:

• These are nonstriated and involuntary
• These respond slowly to stimuli then again are capable of long time sustained contractions.
• These are meant for providing power for regulating internal environment related to digestion, circulation, secretion and excretion.

Characterstics of cardiac:

• striated
• syncytium, myogenic (initiates its own contraction), have longer contraction
• they are meant for automatic rhythmic contractions for long period of time.

Ans 1(b)