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Flashcards in For exam 2 Lecture 2 Deck (63):
1

Muscular System

The driving force, the power behind movement, is muscle tissue

2

What are the three kinds of muscle tissue?

Skeletal, Cardiac, and Smooth

3

How do the three kinds of muscle tissue differ?

Differ form one another in their microscopic anatomy, location, and control by the nervous and endocrine system.

4

Skeletal muscle MUST be stimulated and what stimulates it?

The Central Nervous System
Somatic to be specific

5

What CNS controls Cardiac and Smooth muscle?

Autonomic

6

Muscular system properties?

Contractility
Excitability (or Irritability)
Extensibility
Elasticity

7

Which of the four muscle properties are involved in movement?

ALL four of them

8

The ability to contract or shorten is?

Contractility

9

What is excitability?

The capacity to receive and respond to stimulus.

10

The ability to be stretched.

Extensibility

11

Elasticity is?

The ability to return to original shape after being stretched or contracted.

12

Why is the skeletal muscle so named?

It is attached primarily to bones and it moves parts of the skeleton

13

Skeletal muscle is called striated because?

Altering light and dark bands are visible when the tissue is examined under a microscope.

14

How are the striations produced in skeletal muscle?

By characteristic arrangement of contractile proteins, myosin and actin

15

T:F Skeletal muscle is a voluntary muscle.

True
It can be made to contract and relax by conscious control?

16

The sheath of connective tissue surrounding the muscle is?

Epimsium

17

Fascicle are?

A bundle or cluster of muscle fibers.

18

A sheath of connective tissue surrounding each fascicle is?

Perimysium

19

Another name for muscle cell is?

Muscle Fiber

20

Sarcolemma is?

Plasma membrane of a muscle cell (fiber)

21

Myofibril is?

Threadlike structure, running longitudinally through a muscle fiber.

22

What are myofibrils made up of?

Thick filaments (myosin) and thin filaments (actin, troponin, tropomyosin). Myofilaments.

23

How are myofilaments arranged?

In sarcomeres

24

The basic contractile unit of striated muscle fibers are?

Sarcomere

25

Myosin, actin, troponin, tropomyosin are all?

Myofilaments

26

Smooth muscle is lacking which myofilament?

Troponin

27

Normally skeletal muscle is attached to bone at both ends by means of tendons, what are the exceptions to this?

External sphincter of the bladder
diaphragm

28

T:F Each muscle fiber has one nucleus.

False
Each muscle fiber has many nuclei, as well as mitochondria and other organelles.

29

Scattered satellite cells?

Lie between the endomysium and the muscle fibers. The function in repair of minor damage muscle tissue.

30

Cardiac muscle is only found in?

The heart

31

How does cardiac differ from skeletal muscle even though it is striated aswell?

The myocardial cells are shorter, branched, and intimately interconnected to form a continuous fabric

32

Intercalated discs which are characteristic of heart muscle are?

Special areas of contact between adjacent cell in heart muscle

33

T:F Gap junctions of intercalated discs couple myocardial cells together mechanically and electrically.

True
All cells in the myocardium are electrically joined by gap junctions, the myocardium behaves as a single unit.

34

T:F The heat can produce a graded contraction by varying the number of cells stimulated to contract.

False
Unlike skeletal muscle, the heart CANNOT produce a graded contraction by varying the number of cells stimulated to contract.

35

T:F The stimulation of one myocardial cell in the heart will result in the stimulation of all the cells in the mass and the whole hear will contract.

True
Myocardium are joined electronically by gap junctions of intercalated discs. Move one and they all move

36

What happens if heart cannot contract as a unit?

Arrhythmia

37

If heart cells are damaged do they grow back?

No they cannot repair themselves

38

If heart contractions are to its full extent for each contraction, how can the ability of myocardial cells to contract be increased?

Sympathetic system and stretching of the myocardial chambers.

39

What are the two very distinct myocardial chambers?

Atria and ventricles

40

What is the difference between cardiac and skeletal muscles in regards to action potential?

Skeletal muscle require external stimulation my somatic motor nerves before they can produce action potentials and contract
Cardiac is able to produce action potential automatically.

41

Cardiac action potential normally originates in a specialized group of cells called the?

Pacemaker

42

The rate of spontaneous depolarization and thus the rate of the heart beat are regulated by?

Autonomic innervation

43

In skeletal muscle there is a direct excitation-contraction coupling between?

The transverse tubules and the sarcoplasmic reticulum

44

What does stimulation of the heart muscle lead to?
(Also known as Ca2+ induced Ca2+ release)

Leads to Ca2+ entry into the cytoplasm through voltage-gated channel. This Ca2+ stimulates the opening of Ca2+ release channels of the sarcoplasmic reticulum

45

Transverse tubules are?

Small cylindrical invaginations of sarcolemma of striated muscle fiber that conduct muscle action potentials towards the center of the muscle fiber.

46

Intercalated discs are?

Cell to cell attachment with gap junctions that aid in the conduction of muscle action potentials and desmosomes that hold the cardiac muscle fibers together

47

Mechanism of contraction for cardiac and skeletal muscle?

Sliding filament theory

48

Describe smooth muscles?

Cells also called fibers. Each fiber is short, spindle shaped and slender which contain only one nucleus near the center of the fiber, at its widest point.

49

Why does smooth muscle lack striations?

The actin and myosin myofilaments are very thin and are arranged more randomly than in skeleton muscle fibers.

50

What are the actin filaments attached to in the smooth muscle?

Dense bodies

51

In smooth muscle where are the dense bodies?

They are distributed throughout the sarcoplasm in a network of intermediate filaments. Some are firmly attached to the sarcolemma

52

T:F In smooth muscle the sarcoplasmic reticulum is poorly developed and the T tubules and Z lines are present.

False
In smooth muscle the sarcoplasmic reticulum is poorly developed and the T tubules and Z lines are NOT present.

53

In smooth muscle the slowest contraction is thought to be due to?

A limited amount of ATPase activity at the crass bridges

54

Two types of smooth muscle are?

Single unit and multiunit

55

Where are the single units of smooth muscles found?

Found in the walls of tubes and hollow organs.

56

Which is more common smooth muscle types

Single unit

57

Smooth muscle multiunit

Consists of individual fibers, each with its own motor neuron terminals

58

What is the difference between single unit and multiunit smooth muscles?

stimulation of a single unit muscle fiber causes contraction of many adjacent fibers.
Stimulation of one one multiunit fiber causes contraction of only that muscle fiber

59

Where are smooth muscle multiunits found?

Found in the walls of large arteries, bronchioles, arrector pili muscles attached to hair follicles, radial and circular muscles of the iris that adjust pupil diameter, and in the ciliary bodies that adjust focus of the lens in the eye.

60

Smooth muscle single unit

Electrically linked by gap junctions, self excitable (myogenic activity)

61

Smooth muscle multiunit

Innervated by the autonomic nervous system (neurogenic activity)

62

T:F Sarcomeres are not present in smooth muscle cells.

True

63

Describe smooth muscle contraction.

Dense bodies and intermediate filaments anchor the actin thin filaments so that when sliding occurs between myosin and actin, the cell shortens and bilges between the points where the dense bodies are attached to the sarcolemma.