Muscle Histology

Question 1

What is the function of muscles?

Answer 1

Direct, integrated movement

Question 2

Muscles are made up fo mycocytes, myofibrils and muscle fibres. What is a muscle fibre?

Answer 2

Muscle cell

NOT made of CT like normal fibres

Question 3

What are the components of connective tissue found in muscles? What is the function of this CT?

Answer 3

Blood vessels
Nerves
Provide mechanical support

Question 4

What are the 3 types of muscle and which are striated?

Answer 4

Skeletal - striated
Cardiac - striated
Smooth - non-striated

Question 5

Skeletal muscle, what are the two types of fibre found and what contractions are associated with each?

Answer 5

Dark fibre -tonic contractions

Pale fibre - phasic contractions

Question 6

What are the 3 layers of skeletal muscle? WHat does the innermost layer do?

Answer 6

Epimysium
Perimysium
Endomysium - electrical insulation

Question 7

Contraction of each sarcomere is all or nothing, so how are contractions varied?

Answer 7

Number of fibres contracting

Question 8

Skeletal muscles have a neuromuscular spindle. What is this? What does it do?

Answer 8

Modified muscle fibre

Sends sensory information about muscle tension to the CNS

Question 9

What are motor end plates? Which neurotransmitter is released here?

Answer 9

Folds in sarcolemma at the post synaptic membrane

Acetylcholine

Question 10

Which cells are responsible for myogenesis?

Answer 10

Mesenchymal cells and myoblasts

Question 11

During myogenesis, myoblasts fuse to form what?

Answer 11

Myocytes and satellite cells

Question 12

What are satellite cells?

Answer 12

Bipotent muscle stem cells

Question 13

What is atrophy? What could this be due to?

Answer 13

Loss of myofibrils and nuclei

Interrupted nerve supply

Question 14

What cells are responsible for regeneration of skeletal muscle?

Answer 14

Satellite cells

Question 15

Which muscle layer is the holding base for sutures?

Answer 15

Epimysium

Question 16

What are terminal cisternae?

Answer 16

Enlarged areas of sarcoplasmic reticulum

Surrounding T-tubules

Question 17

Where is cardiac muscle found?

Answer 17

Heart

Large vessels near the heart

Question 18

Describe the nuclei and and endomysium of cardiac muscle

Answer 18

Centrally placed nuclei

Abundant endomysium containing blood vessels

Question 19

Are there visible striations in cardiac muscle? How are fibres arranged?

Answer 19

Yes

Loose arrangement of fibres

Question 20

What are intercalated discs?

Answer 20

Junctions between cardiomyocytes which allow synchronised cardiac muscle contraction
(Rapid spread of wave)

Question 21

Which feature is missing from cardiac muscle which is found in the 2 other muscle types?

Answer 21

Terminal cisternae

Question 22

Describe the presence of mitochondria in the different types of muscles

Answer 22

Smooth - least
Skeletal - more
Cardiac - most

Question 23

Is cardiac myogenesis possible?

Answer 23

No - lost soon after birth

Question 24

How are cardiac muscle fibres repaired?

Answer 24

Cannot regenerate cells after birth

Repair by increasing connective tissue

Question 25

What are purkinje fibres? Where are they found? WHat do they do?

Answer 25

Specialised cardiac muscle | Carry electrical impulse from left and right bundle branch

Question 26

How do purkinje fibres stain? Why?

Answer 26

Pale staining | High glycogen levels

Question 27

Which species have more prominent Purkinje fibres in the heart?

Answer 27

Sheep | Dogs

Question 28

Where is smooth muscle found?

Answer 28

All organs | Tunica media

Question 29

Describe the shape of smooth muscle cells and their nuclei

Answer 29

Spindle shaped cells | Central nuclei - only 10% visible in transverse section

Question 30

Do smooth muscle cells have striations? Do they have connective tissue present within fibres?

Answer 30

No striations | yes - CT within fibres

Question 31

Smooth muscles have no striations. They also have no.... and few...

Answer 31

No T-tubules | Few sarcoplasmic reticulum

Question 32

What are pericytes?

Answer 32

Undifferentiated muscle cells

Question 33

What is the name of the huge multi nuclear engined cells that can be several centimetres in length?

Answer 33

Syncytium

Question 34

What are striations comprised of?

Answer 34

Ends of sarcomeres arranged in parallel rows

Question 35

Which is the thin filament found here? Which is the thick?

Answer 35

Thin- actin | Thick - myosin

Question 36

Why do skeletal muscles have multiple nuclei?

Answer 36

They are made up of fused myoblasts