Skeletal Muscle Structure and Function

Question 1

What are the 3 types of muscle

Answer 1

Skeletal
Cardiac
Smooth

Question 2

Where can you find smooth muscle

Answer 2

contractile cells of the viscera and blood vessels

Question 3

Describe the appearance of smooth muscle

Answer 3

No Striations
Spindle shaped
Central nucleus

Question 4

What does contraction cause to happen to the cell

Answer 4

shorten and round up

Question 5

What does calcium from the ECF bind to in smooth muscle

Answer 5

Calmodulin

Question 6

What activates myosin heads to bind to actin

Answer 6

calmodulin

Question 7

What 3 things regulate smooth muscle contraction

Answer 7

Autonomic Nervous System
Hormones
Local physiological conditions
nothing is under voluntary control

Question 8

What happens to smooth muscle in asthma

Answer 8

Smooth muscle proliferates and contracts airways

Question 9

What is Leiomyoma

Answer 9

A benign smooth muscle neoplasm

Question 10

Describe the appearance of cardiac muscle

Answer 10

Striations - actin and myosin in regular arrangement
Central nucleus
Long branched cardiac fibres formed by linking cardiac muscle cells end to end
Intercalated disks connect cells, these are specialised junctional systems

Question 11

Why can’t cardiac muscle regenerate after damage

Answer 11

It has no stem cells

Question 12

Contraction of cardiac muscle is similar to skeletal muscle, what controls its contraction

Answer 12

Autonomic control of cardiac muscle

Question 13

Describe the appearance of skeletal muscle

Answer 13

Striated - actin + myosin in regular arrangement
Multinucleated fibres - many individual cells fused together
Fibres 10cm in length
nucleus peripheral
contains stem cells for repair

Question 14

What is a sarcomere made up of

Answer 14

Parallel interdigitating thick and thin myofilaments.
Thick = myosin
Thin = actin

Question 15

What is a sarcolemma in skeletal muscle

Answer 15

Muscle cell plasma membrane

Question 16

What are T-Tubules

Answer 16

These are extensions of the sarcolemma that extend transversely into the muscle cell and surround each myofibril at the junction of A and I bands

Question 17

How are the myosin binding sites revealed

Answer 17

Calcium binding to troponin = conformational change and this removes tropomyosin from the binding site

Question 18

What is the role of a T-Tubule

Answer 18

They carry the depolarisation of the muscle fibre membrane into the muscle fibre

Question 19

Where is calcium released from in the muscle cell and where does it bind to

Answer 19

Released from sarcoplasmic reticulum and binds to troponin

Question 20

After myosin binding site exposure how does skeletal muscle contract

Answer 20

Myosin binds and hydrolyses ATP and change the shape of the myosin head
Stored energy is released and ADP and inorganic phosphate
This myosin head pulls the actin and contracts the muscle
Myosin then lets go of actin and allows muscle relaxation

Question 21

Upon muscle damage what repairs the muscle if the sarcolemma is intact

Answer 21

Satellite cells activate and repair muscle

Question 22

Upon muscle damage what repairs the muscle if the sarcolemma is damaged

Answer 22

region of damage is replaced with fibrocollagenous tissue

Question 23

What type is slow twitch and what is fast twitch

Answer 23

type 1 = slow

type 2 = fast