Module 5- Muscles

Question 1

what are the 3 kinds of muscle types

Answer 1

1) skeletal muscle
2) smooth muscle
3) cardiac muscle

Question 2

what are the 3 purposes of muscle function

Answer 2

1) body movement
2) heat production
3) support of the skeleton (aka posture)

Question 3

outline the levels of muscle tissue structure

Answer 3

a) whole muscle made of bundles of FASCICULI
b) each faciculi made of bundles of muscle cells
c) muscle cell made of bundles of myofibrils
d) myofibrils made of thick/thin myofilaments
- THIN are made of actin
- THICK are made of myosin

Question 4

do muscle cells have one nucleus or several?

Answer 4

they have more than one nucleus

Question 5

what is the sarcolemma

Answer 5

a membrane that transmits APs to the muscle cells

-use TRANSVERSE TUBULES to extend down into the cells to transmit

Question 6

what surround the myofibrils?

Answer 6

sarcoplasmic reticulum (SR) 
-mesh with ca to stim contraction

Question 7

where are the terminal cisternae located?

Answer 7

at the ends of the SR (sarcoplasmic reticulum)

Question 8

which myofilament is made of actin?

Answer 8

thin myofilaments

• has a binding site for myosin from the thick filament
• TROMYOSIN covers the binding site when not active

Question 9

what are the 3 subunits of TROPONIN

Answer 9

• troponin A–> binds to actin
• troponin C–> binds to ca
• troponin T–> binds to tropomyosin
• when ca binds to trop C it pulls tropomyosin off myosin

Question 10

what is a sarcomere?

Answer 10

the length of a THIN myofil stretch (from z disk to z disk)

-thin lines called I bands

Question 11

what are the lines/bands for thick myofils called?

Answer 11

• thick myofils go from m lines to m lines

- the thick bands are called A bands

Question 12

what is the theory of contraction/sliding filament theory?

Answer 12

• the head of myosin attaches to binding site on actin, creating the CROSSBRIDGE
• myosin changes shape and swings the head, creating the POWERSTROKE

Question 13

how does an AP trigger the powerstroke?

Answer 13

• ap opens ca channels along the SR
• ca binds to troponin c, which uncovers binding site of myosin on actin…
• special ca pumps more ca into SR (uses ATP against mgrad), so tropomyopsin can cover the binding site and relax

Question 14

if there is ca present in the muscle cell, will it be able to relax?

Answer 14

nop

Question 15

what are the two ways to increase the force of contraction?

Answer 15

1) recruiting motor units
- motor units can cover many muscle cells at once
2) summary twitch contractions
- add twitches on top of each other by ^ ap per sec