Lecture 7 - Muscle Histology

Question 1

______is a single mature muscle cell.

Answer 1

Myofiber or muscle fiber or myocyte

Question 2

the muscle cell membrane

Answer 2

Sarcolemma

Question 3

the cytoplasm of the muscle cell

Answer 3

Sarcoplasm

Question 4

smooth endoplasmic reticulum (sER) known as what in muscle

Answer 4

Sarcoplasmic reticulum

Question 5

dense connective tissue sheath covering the entire muscle.

Answer 5

Epimysium

Question 6

derives from epimysium and surrounds the bundles or fascicles of muscle cells

Answer 6

Perimysium

Question 7

delicate layer of reticular fibers and extracellular matrix surrounding each muscle cell

Answer 7

Endomysium

Question 8

Sarcomere extends from where to where

Answer 8

Z line to Z line, consits of 1/2 I band, complete A band, 1/2 I band

Question 9

The A band is bisected by a light region called the _______

Answer 9

H band

Question 10

The major component of H band is the enzyme _________ , which catalyzes the formation of ATP from creatine phosphate and ADP .

Answer 10

Creatine Kinase

Question 11

Running through the middle of the H band is the ________

Answer 11

M line

Question 12

Thick filaments known as

Thin filaments known as

Answer 12

Myosin

Actin

Question 13

Regulatory proteins on actin

Answer 13

tropomyosin and troponin

Question 14

Triad consists of what

Answer 14

2 Terminal cisternae and 1 T tubules

Question 15

What does the triad do?

Answer 15

depolarization of sarcolemma in a T tubule to affect the sarcoplasmic reticulum and trigger release of Ca⁺⁺ ions into the cytoplasm around the thick and thin filaments , which initiate contraction of the sarcomeres

Question 16

Is an autoimmune disorder in which antibodies are produced against acetylcholine receptors.
Antibodies bind to the receptor , preventing the binding of acetylcholine .
This blocks the normal nerve – muscle interaction and results in progressive muscle weakness .
The extra ocular muscles of the eye are commonly affected first .

Answer 16

Myasthenia gravis

Question 17

Each muscle spindle has concentric layers of flattened cells , containing interstitial fluid and a few thin muscle fibers , called

Answer 17

Intrafusal fibers (Sense changes in length and send infot to spinal cord

Question 18

much smaller encapsulated structures that enclose the sensory axons penetrating the collagen bundles at the muscle – tendon junction .
They detect changes in tension within tendons produced by muscle contraction and act to inhibit motor activity if tension becomes excessive.

Answer 18

Golgi tendon organs

Question 19

are adapted for slow contractions over long periods without fatigue. They have many mitochondria , rich capillary network and much myoglobin ( dark fibers or red fibers)

Answer 19

Slow oxidative muscle fibers

Question 20

specialized for rapid , short term contraction , have few mitochondria , few capillaries and depend largely on anaerobic metabolism of glucose from stored glycogen. These fibers appear white and they fatigue rapidly

Answer 20

Fast glycolytic fibers

Question 21

have physiological and histological features intermediate between those of other 2 types

Answer 21

Fast oxidative – glycolytic fibers

Question 22

• are of considerable significance in muscle maintenance, repair and regeneration .
• are mitotically quiescent in adults , but can resume self – renewal and proliferation in response to stress or trauma. This is the basis of stem cell therapy of a number of muscle injuries and degenerative diseases including muscular dystrophies.

Answer 22

Satellite cells