Chapter 9 Flashcards Preview

Anatomy-Exam 3 (CH. 9, 10) > Chapter 9 > Flashcards

Flashcards in Chapter 9 Deck (72):
1

What are the three types of muscle tissue in the body?

Skeletal, Cardiac and Smooth

2

Which types of muscle cells are referred to as muscle "fibers"?

Long muscle cells of skeletal and smooth muscle tissue

3

What characteristics of long muscle cells of skeletal and smooth muscle tissue cause them to be referred to as muscle "fibers"?

Because they are very long cells compared to other cells in the body

4

What are the two types of myo-filaments?

Actin (thin filament) and Myosin (thick filaments)

5

Define "Sarcolemma"

Plasma membrane of a muscle cell.

6

Define "Sarcoplasm"

Cytoplasm of a muscle cell.

7

What does the sarcoplasm contain?

unusually large amounts of glycosomes and myoglobin

8

What are "glycosomes"?

granules of stored glycogen that provide glucose during muscle cell activity

9

What is "myoglobin"?

A red pigment that stores oxygen

10

What prefixes always refer to "muscle" in anatomy?

Myo- and Mys (and sarco- is used as well, but not exclusively for muscle)

11

What are the characteristics of "skeletal" muscle?

-longest muscle cells
-multi-nucleated
-striated
-cylindrical
-voluntarily controlled

12

What is the function of "skeletal" muscle?

Responsible for overall body mobility. It can contract rapidly, but it tires easily and must rest after short periods of activity. Nevertheless, it can exert tremendous power.

13

What are the characteristics of "smooth" muscle?

-non-striated
-elongated cells
-one central nucleus
-involuntary

14

What is the function of "smooth" muscle?

Its role is to force fluids and other substances through internal body channels. Its contractions are slow and sustained.

15

Where is "smooth" muscle located?

It is found in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passages.

16

What are the characteristics of "cardiac" muscle?

-striated
-involuntary
-single nucleus
-short, fat, and branched cells
-lots of mitochondria

17

What is the function of "cardiac" muscle?

body's blood pump

18

Where is "cardiac" muscle located?

Only in the heart

19

What are the four special characteristics of muscle tissue?

Excitability, Contractility, Extensibility and Elasticity.

20

What is "excitability"?

Also termed "responsiveness".
Is the ability to receive and respond to stimulus, that is, any change in the environment either inside or outside the body.

21

What is "contractility"?

Is the ability to shorten forcibly when adequately stimulated. This ability sets muscle apart from all other tissue types

22

What is "extensibility"?

Is the ability to extend or stretch beyond resting length, when relaxed.

23

What is "elasticity"?

is the ability of a muscle cell sot recoil and resume its resting length after stretching.

24

What are the four important functions of muscle?

It produces movement, maintains posture, stabilizes joints and generates heat.

25

What tissues make up "skeletal" muscle?

Skeletal muscle fibers predominately, blood vessels, nerve fibers, and substantial amounts of connective tissues

26

What are the three connective tissue sheaths?

Epimysium, Perimysium, and Endomysium

27

What is "epimysium"?

It is an "overcoat" of dense irregular connective tissue that surrounds the whole muscle

28

What is "perimysium"?

A fibrous connective tissue that surrounds the fascicles (muscle fiber bundles)

29

What is "endomysium"?

is a wispy sheath of connective tissue that surrounds each individual muscle fiber (fine areolar connective tissue)

30

Describe the nervous and blood supply to skeletal muscles.

There is one nerve that brings electrical signal to each muscle, one artery bringing blood (oxygen and nutrients) to each muscle and there may be more than one vein taking blood (carbon dioxide and wastes) away from each muscle.

31

What is the "origin" of skeletal muscle?

The end of the muscle that is on the bone that will move least in the action

32

What is the "insertion" of skeletal muscle?

The end of the muscle on the bone that will move most in the action. Hint: the insertion will always move toward the origin in the action.

33

What is the general microscopic anatomy of a muscle fiber?

Multi-nucleated cell with a specialized plasma membrane called a sarcolemma and cytoplasm called sarcoplasm (contains glycosomes and myoblobin).
They are also very long (several centimeters) and not very wide (several micrometers).

34

Why is a muscle fiber considered a "syncytium"?

Cells fuse together during fetal development to form muscle fibers so they "work together" = Syncitium

35

What is the cytoplasm of a muscle cell called?

Sacroplasm

36

Define "myofibril".

A cylindrical unit packed with myofilaments (actin and myosin) and fill the muscle fibers

37

What is considered the smallest contractile unit of a muscle?

Sarcomere

38

What is the general structure of a sarcomere?

Defined from z-disc to z-disc and contains overlapping actin and myosin proteins for contraction.

39

Define "Z-disc".

Sheets of protein that span the myofibril and form the boundaries of the sarcomeres

40

Define "A band".

"Dark Bands". Contains myosin with overlapping actin.

41

Define "I band".

"Light Bands". Contain actin only

42

Define "H zone"

Myosin only

43

Define "M line"

Formed by myomesin up the center of the sarcomere

44

What attaches actin and myosin to the z disc?

Actin is attached by "nebulin".
Myosin is attached by "titin".

45

Actin is also referred to as?

Thin filament

46

Myosin is also referred to as?

Thick filament

47

What is the sarcoplasmic reticulum of a muscle cell?

It is a modified smooth endoplasmic reticulum.

48

What is the function of the sarcoplasmic reticulum in a muscle fiber?

It specifically stores and releases calcium into the sarcoplasm for muscle contraction.

49

What is "terminal cisternae"?

The ends of the sarcoplasmic reticulum (SR) that are coupled to the t-tubule to form triads. The calcium is released from this part, which is triggered by electricity coming down the t-tubule.

50

What is a "t-tubule"?

Indentations of the sarcolemma

51

What is the function of a "t-tubule" in a muscle cell?

It carries the electric signal deep into the muscle fiber and triggers the SR to release its calcium for muscle contraction

52

What is a "triad"?

2- terminal cisternae and 1-T-tubule between them at the A-I junctions of the myofibrils

53

How do the components of the triad work together in muscle contraction?

The t-tubule carries the electric signal to the terminal cisternae, which then are triggered to release calcium into the sarcoplasm for muscle contraction.

54

Describe the "sliding filament model of contraction".

During muscle contraction, actin is pulled by myosin towards the center of the sarcomere, so actin "slides" past myosin.

55

How do the actin and myosin interact in the sliding filament model?

the myosin heads "grab" actin to form a cross bridge. Then the myosin heads change shape in a way that pulls actin towards the center of the sarcomere. This action is called a power stroke.

56

What type of neurons stimulate skeletal muscle?

Motor neurons

57

Describe the structure of a neuromuscular junction

The motor neuron ending contains vesicles filled with the neurotransmitter acetylcholine. The portion of the muscle sarcolemma across from the motor neuron ending is called the motor end plate and contains receptors for acetylcholine. The space between the motor end plate and the motor neuron is called the synaptic cleft.

58

What is a "synaptic vesicle"?

A lipid "bubble" formed by a phospholipid bilayer

59

What neurotransmitter will always stimulate skeletal muscle?

Acetylcholine

60

What is the space between the axonal endings and the motor end plate of the muscle cell called?

Cleft

61

What process releases the neurotransmitter from the axonal terminal?

Exocytosis

62

How is the neurotransmitter destroyed?

An enzyme called acetylcholinesterase.

63

Why does the neurotransmitter need to be destroyed?

As long as it is in the cleft it can bind to the receptors and cause muscle contraction. To be able to relax the muscle the neurotransmitter must be removed.

64

Define "motor unit".

A motor neuron and all od the muscle fibers that it innervates

65

What is the general structure of a smooth muscle fiber?

spindle shaped cells with only one nucleus. Not striated even though it still has actin and myosin. The actin and myosin are arranged in a cris-cross pattern. There is only a little bit of endomysium.

66

Compare and contrast the structure and function of smooth muscle and a skeletal muscle cell.

Skeletal muscle cells are cylindrical and centimeters long whereas smooth muscle cells are spindle and a couple of hundred micrometers long. Skeletal muscle cells contract to move the body and things in the environment whereas smooth muscle cells contract to move substances through hollow organs.

67

Define "peristalsis"?.

Wave-like contractions of smooth muscle in the walls of hollow organs to move substances through them

68

How does smooth muscle receive neurotransmitter since they lack a neuromuscular junction?

Bulbous swellings called varicosities release neurotransmitter over many smooth muscle cells at once

69

How are the actin and myosin arranged in a smooth muscle cell?

In a cris-cross pattern through the cell. This pattern allows the cell to twist and shorten during contraction.

70

What are the "intermediate filaments" and "dense bodies" in a smooth muscle cell?

Intermediate filaments are actin and myosin and dense bodies hold them together when they cross in the cell.

71

List and describe the unique characteristics of smooth muscle?

Sarcoplasmic reticulum is less developed.
Indentations called calveoli hold calcium from extracellular fluid for contraction.
There are no Z-discs or sarcomeres.
Smooth muscle responds to stretch by relaxing, thus allowing a hollow organ to fill with a substance, such as in the stomach, urinary bladder or uterus.

72

Did

Check