Muscle Histology Flashcards

1
Q

A muscle _______is a cell, while muscle ________ and muscle ________ are structures within the cell.

A

Fiber
Fibril
Filament

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2
Q

What are the histology names for muscle fibers, fibrils, and filaments?

A

Myofiber
Myofibril
Myofilament

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3
Q

Muscle forms the flesh of the body, and over __% of body weight

A

40%

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4
Q

Muscle is specialized for ________.

A

Contraction

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5
Q

Muscles transform _____ into mechanical _______.

A

ATP

Energy

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6
Q

What are the 4 functions of skeletal muscle?

A

Create movement
Stabilize joints
Maintain posture
Create heat

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7
Q

In embryo, ________ elongate and fuse together

A

myoblasts

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8
Q

Nuclei in muscle cells are pushed to the side by many ________ proteins.

A

Contractile proteins

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9
Q

Postnatally, muscles increase in ________, not _______.

A

Size

Number

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10
Q

What is the plasma membrane of muscle cell?

A

Sarcolemma

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11
Q

What is the cytoplasm of a muscle cell?

A

Sarcoplasm

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12
Q

What two things of note are in sarcoplasm?

A

Glycogen

Myoglobin

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13
Q

What is myoglobin?

A

A red pigment that binds O2 until its needed

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14
Q

What CT surrounds a myofiber?

A

Endomysium

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15
Q

What CT surrounds a fascicle of fibers?

A

Perimysyium

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16
Q

What CT surrounds the whole muscle?

A

Epimysium

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17
Q

How is tendon formed?

A

All three of these CTs meet at the ends of muscles to form the tendon

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18
Q

What does a tendon do? What shape is it?

A

Connects muscle to bone, is round in shape

19
Q

What is aponeurosis?

A

A sheet of CT (dense regular) connecting a muscle to the part it moves

20
Q

What is an example of aponeurosis?

A

Found on the skull and in the abdomen

21
Q

What color are the markings on skeletal muscle?

A

Skeletal muscle has alternating dark and light bands

This are not surface markings, involve total fiber thickness

22
Q

What is a myofibril?

A

Inside the cell, are long, rod-like contractile elements, most of cell volume

23
Q

What are myofibrils made of?

A

Myofilaments

24
Q

What two components make myofibrils?

A

Actin: A thinner filament of protein
Myosin: A thicker filament of protein

25
Q

What is the A band?

A

The dark overlap of actin and myosin

26
Q

What is the I band?

A

The light band, only actin is present

27
Q

In 3-D, 6 ______ surround 1 ______.

A

Actin

Myosin

28
Q

What is the functional unit of skeletal muscle?

A

The sarcomere

29
Q

What is the smallest contractile unit of the muscle?

A

The sarcomere

30
Q

What are the Z lines?

A

They define the sarcomere; are a disc that anchors the myofilaments

31
Q

What is the H zone?

A

In the middle of the sarcomere, only visible in relaxed muscle

32
Q

What is the M line?

A

Fine stabilizing threads that interconnect the myosin filaments

33
Q

Which muscle zone can only be seen when the muscle is at rest?

A

The H zone

34
Q

What is the sarcoplasmic reticulum?

A

Interconnecting tubules that surround each myofibril, like the sleeve of a sweater

35
Q

In the sarcoplasmic reticulum, which way do most tubules run?

A

Longitudinally

36
Q

What is the terminal cisternae? Where is it found?

A

Perpendicular channels formed at the A-I band junction

37
Q

What is a T tubule?

A

A tube that travels through the muscle fiber and out the other side
This elongated tubule is called the T (transverse) tubule, and contains ECF

38
Q

Where is the T tubule located?

A

At the A-I band junction

39
Q

The T tubule is an __________ of sarcolemma into the cell interior.

A

Invagination

40
Q

How does the T tubule assist with signal transmission?

A

This tremendously increases the muscle fiber’s surface area
When the sarcolemma is depolarized, the signal goes along the surface and down into the interior through the T tubule- and is very efficient

41
Q

The T Tubules encircle each _______, and pass from one myofibril to the next

A

myofibril

42
Q

What fluid do T tubules contain?

A

ECF

43
Q

What is the triad?

A

Each T tubule is between 2 terminal cisternae

44
Q

The signal to contract will go down the T tubule and release stored ______ out into the sarcoplasm

A

Ca++