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Anatomy > Chapter 6A Study Guide > Flashcards

Chapter 6A Study Guide Flashcards

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0
Q

What are two other ways skeletal muscles are known?

A

Striated muscles-fibers have obvious stripes

Voluntary muscles- subject to conscious control

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1
Q

Name the three types of muscles

A

Skeletal, cardiac, and smooth

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2
Q

Starting with a muscle fiber, describe how skeletal muscles are bundled.

A

The muscle fibers are bundled by the endomysium, several fibers are wrapped by a perimysium to form a bundle of fibers called a fascicle. Then many fascicles are bound together by an epimysium

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3
Q

Describe a smooth muscle

A

Has no striations
Is involuntary
Found in hollow walls of visceral organs
Propels substances along a pathway

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4
Q

Where are cardiac muscles found?

A

The heart

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5
Q

Describe cardiac muscle

A

Forms bulk of the heart walls
Striated
Involuntary

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6
Q

What is the main function of all muscles?

A

Produce movement

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7
Q

What functions do skeletal muscles perform that other muscles do not?

A

Maintains posture
Stabilizes joints
Generates heat

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8
Q

What is the cell plasma membrane of a skeletal muscle called?

A

The sacrolemma

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9
Q

What are Myofibrils?

A

Long, ribbonlike organelles which nearly fill the cytoplasm

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10
Q

What are I and A bands?

A

Alternating light (I) and dark (A) bands along the length of the perfectly aligned Myofibrils give the muscle cell as a whole it’s striped appearance

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11
Q

Describe the structure of I and A bands

A

I bands have a midline interruption, a darker area called the Z disc

A bands have a lighter central area called the H zone. The M line in the center of the H zone contains tiny protein rods that hold adjacent thick filaments together

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12
Q

What are sacromeres?

A

The smallest contractile unit of muscle; extends from one Z disc to the other

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13
Q

Describe the different myofilaments

A

The thick filaments, also myosin filaments, are made mostly of bundled molecules of the protein myosin, but they also contain ATPase enzymes, which split ATP to generate the power for muscle contraction. Extend the entire length of the A band. Contain Cross bridges
Thin filaments are composed of the contractile protein called actin, plus some regulatory proteins that play a role in allowing binding of myosin heads to actin. Are anchored to the Z disc.

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14
Q

What does the sacroplasmic reticulum do?

A

Stores calcium and releases it on demand when the muscle fiber is stimulated to contract

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15
Q

What is a motor unit?

A

One neuron and all the skeletal muscle cells it stimulates is a motor unit

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16
Q

The long nerve extension is called what?

A

Axon, or nerve fiber

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17
Q

Where is the neuromuscular junction found?

A

Where the nerves and the muscles come together

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18
Q

What is a neurotransmitter?

A

Chemical released by neurons that may, upon binding to receptors of neurons or effector cells, stimulate or inhibit them

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19
Q

What is a neurotransmitter that stimulates skeletal muscle?

A

Acetylcholine, ACh

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20
Q

Explain the process of a single muscle contraction in a skeletal muscle

A

????

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21
Q

What is an action potential?

A

Action potential is unstoppable. It travels over the entire surface of the sacrolemma, conducting an electrical impulse from one end of the cell to the other resulting in contraction of the muscle cell.

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22
Q

Explain the sliding filament theory.

A

The Calcium ions trigger myosin cross bridges to attach to actin, initiating filament sliding where the myofilaments slide past each other

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23
Q

How does a contraction of a muscle as a whole differ from a contraction of a single muscle?

A

Whole muscles react to stimuli with graded responses, or different degrees of shortening.

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24
What are muscle twitches?
Single, brief, jerky contractions
25
Explain the 6 different movements of muscles- Circumduction
A combination of flexion, extension, abduction, and adduction; commonly seen in ball-and-socket joints. Ex: rolling shoulders/swinging arms in circle
26
Explain the 6 different movements of muscles- adduction
The movement of a limb toward the body midline
27
Explain the 6 different movements of muscles- abduction
The moving of a limb away from the midline, or median plane, of the body
28
Explain the 6 different movements of muscles- rotation
Movement of a bone around its longitudinal axis | -common of ball-and-socket joints-
29
Explain the 6 different movements of muscles- extension
A movement that increases the angle, or the distance between two bones or parts of the body
30
Explain the 6 different movements of muscles- flexion
A movement that decreases the angle of the joint and brings two bones closer together
31
The most powerful muscles have more what on hand?
More muscle cells in the muscle
32
The fascicle arrangement of muscles determines what?
Its range of motion and power
33
Circular arrangement of fascicles-
-Arranged in concentric rings -found surrounding external body openings which they close by contracting -Sphincter muscles Ex: orbicularis muscles surrounding the eyes and mouth
34
Convergent arrangement of fascicles-
-the fascicles converge toward a single insertion tendon -triangular or fan shaped Ex: pectoralis major muscle of the anterior thorax
35
Parallel arrangement of fascicles-
- Length of fascicles run parallel to the long axis of the muscle - straplike modification of the parallel arrangement called fusiform, results in a spindle-shaped muscle with an expanded midsection
36
Pennate arrangement of fascicle-
- short fascicles attach obliquely to central tendon - in the leg, the fascicles insert into only one side of the tendon and the muscle is unipennate. 2 or several bipennate. Several multipennate
37
Be able to describe muscles based on their names- Direction of muscle fibers
Rectus- straight Ex: Rectus femoris. The straight muscle of the thigh Oblique- at a slant
38
Be able to describe muscles based on their names- relative size of the muscle
Maximus- largest Minimus- smallest Longus- long
39
Be able to describe muscles based on their names- location of the muscle
-some muscles are named for the bone they are associated with: Ex: temporalis- temporal bone Ex: frontalis- frontal bone
40
Be able to describe muscles based on their names- number of origins
Biceps- two origins Triceps- three origins Quadriceps- four origins
41
Be able to describe muscles based on their names- location of the muscle's origin and insertion
``` -occasionally, muscles are named for their attachment sites. Ex: sternocleidomastoid (Sterno) sternum (Cleido) clavicle (Mastoid) mastoid process ```
42
Be able to describe muscles based on their names- shape of the muscle
-Spme muscles have a distinctive shape that helps to identify them Ex: detoid-triangular
43
Be able to describe muscles based on their names- action of the muscle
When muscles are named for their actions | Ex: flexor, extensor, adductor
44
How are skeletal muscles named?
Muscles are named on the basis of several criteria, each of which focuses on a particular structural or functional characteristic
45
What is a Fixator?
A specialized Synergist. They hold a bone still or stabilize the origin of a prime mover so all the tension can be used to move the insertion bone
46
What muscles work against the prime mover?
Antagonists
47
What are muscles called that work with the prime mover?
Synergists
48
The muscle that is responsible for most of the muscle move to is called the what?
Prime mover
49
Explain the special movements- dorsiflexion and plantar flexion
Dorsiflexion- standing on your heels | Plantar flexion- pointing the toes
50
Explain the special movements- inversion and eversion
To invert the foot- turn sole medially | To evert the foot- turn the sole laterally
51
Explain the special movements- supination and pronation
Supination- radius and ulna are parallel | Pronation- radius rotates over ulna
52
Explain the special movements- opposition
Pinching together the index finger and thumb
53
What is the insertion of a muscle?
The movable attachment of a muscle as opposed to its origin
54
What is the origin of a muscle?
The attachment of a muscle that remains relatively fixed during muscular contraction
55
If you want to build up your endurance what kind of exercise should you do?
Aerobic
56
If you want bigger muscles, what kind of exercises should you do?
Resistance or isometric
57
What are the two types of exercises that can affect muscles?
Aerobic and isometric (resistance)
58
Describe a muscle as flaccid and undergoing atrophy
If nerve supply to a muscle is destroyed, the muscle is no longer stimulated and it loses tone and becomes paralyzed. -then it becomes flaccid, or soft and flabby and starts to waste away (atrophy)
59
What is muscle tone?
A state of continuous partial contractions. | -it is the result of different motor units, scattered through the muscle
60
Describe the two types of muscle contractions- isometric contractions
Contractions in which the muscles do not shorten. | -muscle is pitted against some immovable object
61
Describe the two types of muscle contractions- isotonic contractions
The muscle shortens and movement occurs
62
When does oxygen deficiency happen?
It occurs during prolonged muscle activity: a person is not able to take in oxygen fast enough to keep the muscles supplied with all the oxygen they need when working vigorously
63
What is muscle fatigue?
When a muscle is unable to contract even though it is still being stimulated
64
How do muscles get their energy for muscle contractions?
1. Direct phosphorylation of ADP by creatine phosphate 2. Aerobic respiration 3. Anaerobic glycolysis and lactic acid formation
65
How do muscles respond to stronger stimuli?
Muscle contractions can be slight or vigorous depending on what work has to be done
66
When a muscle contraction is completely smooth and sustained the muscle is said to be what?
The muscle is said to be in fused, or complete, tetanus, or in tetanic contraction

Anatomy (13 decks)

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