Muscle Tissue

Question 1

Define muscle tissue:

Answer 1

Elongated cells that use energy from the hydrolysis of ATP to generate force

Question 2

What is the result of muscle contraction?

Answer 2

Heat, movement, posture

Question 3

How do muscle cells appear under the microscope?

Answer 3

Striated (stripy pattern, cylindrical), multinucleated with many peripheral nuclei pushed to the side.

Question 4

What is the smallest muscle in the body and what is its function?

Answer 4

The stapedius which resides in the inner ear. It changes the tension on bones that conduct sound from the eardrum (so loud sounds don’t deafen us)

Question 5

What happens if there is a nerve malfunction in the stapedius?

Answer 5

The facial nerve becomes paralysed temporarily and the person will hear loud sounds when talking. It is called Bells palsy and is also considered hyperacusis.

Question 6

What is the longest muscle in the body?

Answer 6

The sartorius connects hip flexor to knee lateral rotator

Question 7

What causes striations in muscle cells?

Answer 7

Myofibrils (myofibrilis) that fill the sarcoplasm of the muscle fibre, they are tubular structures

Question 8

What are the two filaments in myofibrils and what protein are they made up of?

Answer 8

Thick filaments (made up of actin)
Thin filaments (made up of myosin)

Question 9

Myofilimants are arranged in compartments called:

Answer 9

Sarcomeres (basic functional unit of a myofibril)

Question 10

What separates sarcomeres?

Answer 10

Z discs

Question 11

What does the epimysium surround?

Answer 11

Anatomical muscles (helps incase muscles so they don’t stick to each other)

Question 12

What does the perimysium surround?

Answer 12

Fascicles (a group of cells)

Question 13

What does the endomysium surround and what do they provide?

Answer 13

Muscle cells, provide a layer for capillaries/nerves

Question 14

What is the sarcolemma?

Answer 14

Actual cell plasma membrane

Question 15

What is the sarcoplasm?

Answer 15

The cell cytoplasm

Question 16

When thick and thin myofilaments overlap, they produce what in myofibril?

Answer 16

Striations

Question 17

What is the A band in the myofibril and what type of filaments does it have?

Answer 17

The dark middle part, contains thick filaments

Question 18

What type of filaments does the I band have?

Answer 18

Thin filaments

Question 19

What is the H zone and what filaments does it have?

Answer 19

It is found where the I band disappears, and contains thick filaments

Question 20

What is the M line? And what filaments does it hold together?

Answer 20

The middle of the sarcomere, it holds thick filaments together

Question 21

What are Z discs and what are they made of?

Answer 21

Discs that pass through the I band, made of actinins that link filaments of adjacent sarcomeres

Question 22

What is titin?

Answer 22

It links Z discs to the M line, provides resting tension in I band (molecular spring)

Question 23

What does cardiac muscle look like under the microscope?

Answer 23

Striated, branched with a single central nucleus

Question 24

Where is cardiac muscle located?

Answer 24

In the heart (involuntary control)

Question 25

Fibres in cardiac muscle join end to end through what?

Answer 25

Intercalated discs

Question 26

What two cell junctions are found in cardiac muscle?

Answer 26

Gap junctions and Desmosomes

Question 27

What is the function of gap junctions in cardiac muscle?

Answer 27

Communication, coordination

Question 28

What is the function of desmosomes in cardiac muscle?

Answer 28

Bind the intermediate filaments, provide adhesion in contraction

Question 29

Does smooth muscle have striations?

Answer 29

No

Question 30

Where is smooth muscle located?

Answer 30

Walls of hollow internal structures e.g intestine, blood vessel walls

Question 31

Is smooth muscle voluntary or involuntary?

Answer 31

Involuntary

Question 32

What shape are the cells in smooth muscle?

Answer 32

Small, spindle shape, short, thick in the middle

Question 33

Smooth muscle is not striated but still has bundles of actin and myosin. Why is this?

Answer 33

So the muscle is able to contract

Question 34

In smooth muscle cells, actin attaches to:

Answer 34

Dense bodies (major protein = actinin)

Question 35

What is the role of intermediate filaments in smooth muscle cells?

Answer 35

When the cell contracts, the cell screws down on itself