muscles

Question 1

skeletal muscle tissues

Answer 1

striations; long, cylindrical cells called muscle fibers;
multinucleate cells

Question 2

cardiac muscle tissues

Answer 2

striations; branching cells with intercalated discs;
uninucleate cells

Question 3

smooth muscle tissue

Answer 3

No striations; spindle-shaped cells.
uninucleate cells

Question 4

skeletal muscle as an organ consists of

Answer 4

-skeletal muscle tissue
- Connective tissue (CT) membrane
- blood vessels
-nerve endings

Question 5

Each skeletal muscle fiber ( = skeletal muscle cell) is wrapped in..

Answer 5

a delicate CT membrane called ENDOMYSIUM

Question 6

Fascicle

Answer 6

consists of a group of endomysium-covered muscle
fibers wrapped in a coarse CT membrane called PERIMYSIUM

Question 7

Skeletal muscle (the organ)

Answer 7

consists of a group of fascicles
wrapped in a tough CT membrane called EPIMYSIUM
Skeletal muscles are attached to bones in the skeletal system

Question 8

Patterns of arrangement of fascicles in skeletal muscles

Answer 8

Muscle fibers in a skeletal muscle form bundles called fascicles.
The muscle fibers in a single fascicle are parallel, but the
organization of fascicles in the skeletal muscle can vary, as can
the relationship between the fascicles and the associated tendon.
The different patterns of fascicle organization form parallel
muscles, convergent muscles, pennate muscles, circular muscles

Question 9

The muscle fibers in a single fascicle are

Answer 9

parallel

Question 10

parallel muscles

Answer 10

In a parallel muscle, the fascicles are parallel to the long axis of the muscle. Most of
the skeletal muscles in the body are parallel muscles. Example: Biceps brachii
muscle

Question 11

convergent muscles

Answer 11

in a convergent muscle, the muscle fibers are spread over a broad area, but all the
fibers converge at one common attachment site.
Example: Pectoralis major

Question 12

pennate muscles

Answer 12

In a pennate muscle, the fascicles form a common angle with the tendon.
Example: Deltoid

Question 13

circular muscles

Answer 13

the fascicles are arranged in concentric rings; they surround external body openings.
Example: Orbicularis oris

Question 14

direct attachments

Answer 14

the epimysium of the skeletal muscles is fused directly to the periosteum.
the CT fuses with the bone

Question 15

indirect attachments

Answer 15

the connective tissue wrappings of the skeletal muscles extend as a tendon or an aponeurosis to anchor the muscle to bone, cartilage or facia.
outer CT forms a tendon that connects to the bone.
most skeletal muscles in human bod are attached indirectly.

Question 16

the advantages of indirect attachment of skeletal muscles (1)

Answer 16

1.) tendons occupy smaller bone surface so that 650 SM can attach to 206 bones in the bod

Question 17

the advantages of indirect attachment of skeletal muscles (2)

Answer 17

2.) several skeletal muscles binding to the same bone allows for interrelationships in the functions of skeletal muscles such as synergistic muscles and antagonistic muscles

Question 18

the advantages of indirect attachment of skeletal muscles (3)

Answer 18

3.) protects skeletal muscles (flesh) from direct contact with the rough bone surface which can tear the skeletal muscles

Question 19

the advantages of indirect attachment of skeletal muscles (4)

Answer 19

4.) allows for on bones to act a lever for movement when skeletal muscles coursing over joints contract

Question 20

advantages of direct attachment of skeletal muscles

Answer 20

to provide physical protection to vital organs in the body cavities

Question 21

myoglobin

Answer 21

a red pigment that binds and stores oxygen

Question 22

myofibrils

Answer 22

rod-like structures that run the entire length of the muscle fiber;
80% of the volume of the muscle fiber is occupied by the myofibrils. Myofibrils
contain 2 myofilaments: thick filaments and thin filaments

Question 23

inclusions

Answer 23

glycosomes contain glycogen

Question 24

mitochondria

Answer 24

or aerobic respiration to produce energy

Question 25

sarcoplasm

Answer 25

cytoplasm of the muscle fiber

Question 26

sarcolemma

Answer 26

plasma membrane of muscle fiber

Question 27

Sarcoplasmic reticulum(SR)

Answer 27

specialized smooth endoplasmic reticulum that stores/releases calcium into the sarcoplasm; the expanded ends of SR are called TERMINAL CISTERNAE

Question 28

triad

Answer 28

- composed of a transverse tubule in between 2 terminals cisternae of two SR function is to release calcium ions into the sarcoplasm when the sarcolemma depolarizes.

Question 29

Myofilaments

Answer 29

each myofibril contains smaller structures called myofilaments, there are 2 types

Question 30

thick filaments

Answer 30

16nm in diameter; composed of the protein MYOSIN . Each thick filament consists of 300 myosin molecules . Thick filament is also known as an A band Each myosin consists of a tail and 2 globular heads. The myosin globular heads contain the enzyme ATPase; binding sites for actin; binding sites for ATP

Question 31

thin filaments

Answer 31

8nm in diameter; anchored by the Z lines; Thin filaments contain 3 different proteins: - Actin - Tropomyosin - Troponin

Question 32

actin (thin filaments)

Answer 32

several actin proteins for the structural framework of the thin filament. Actin molecules contain the binding sites for the myosin globular heads

Question 33

tropomyosin (thin filaments)

Answer 33

a rod-shaped regulatory protein that spirals around the actin and blocks myosin binding sites on actin in a relaxed skeletal muscle

Question 34

troponin (thin filaments)

Answer 34

a three-polypeptide complex namely (refer to slide #19) TnC – binds calcium ions (ca2+) TnT – binds to tropomyosin TnI - inhibitory subunit that binds to actin 300 myosin

Question 35

sarcomeres

Answer 35

Sarcomeres are the Structural and Functional units of skeletal muscles = sarcomeres are arranged end to end throughout a myofibril

Question 36

Length of a sarcomere

Answer 36

A sarcomere is the distance between 2 successive Z discs in a myofibril.

Question 37

Thick and thin filament

Answer 37

- Thick filament: A band -Thin filaments alternating with “A” bands; the alternating pattern of the thick and thin filaments results in the characteristic striated appearance of skeletal muscle

Question 38

Z discs (zlines)

Answer 38

anchor the thin filaments in myofibril.

Question 39

H zone

Answer 39

middle region of the A band not overlapping with the thin filament.

Question 40

M line

Answer 40

line that bisects the H zone and anchors the A band.

Question 41

Transverse tubules(T-tubules)

Answer 41

involutions of the sarcolemma into the sarcoplasm

Question 42

I bands

Answer 42

region of the thin filament not overlapping with the A band

Question 43

The sliding filament mechanism of muscle contraction

Answer 43

states that the sliding of the thin filaments in the sarcomeres into the H zone, toward the M results in muscle shortening= contraction. shorting of the sarcomere results in shortening of myofibrils which result in shorting of skeletal muscle fibers and thus, shortening (contraction) of the skeletal muscle.

Question 44

What happens to everybody when the muscles contract?

Answer 44

According to this mechanism when a muscle contracts there is more overlap between the thin filaments and the A bands: - H zone decreases or disappears - I bands decrease or disappear - Sarcomere length shortens = Skeletal muscle shortens ( contracts) *** However, the length of the A bands and the length of the thin filaments remain the same – they do not shorten

Question 45

Wat stimulates skeletal muscles to contract.

Answer 45

When motor neurons that innervate skeletal muscles are activated

Question 46

How do motor neurons make contact with skeletal muscles fibers

Answer 46

Axon terminals

Question 47

each axon terminal innervates one skeletal muscle fiber in the skeletal muscle to form..

Answer 47

The neuromuscular junction

Question 48

Motor Unit

Answer 48

A motor neuron and all the skeletal muscle fibers it innervates in a skeletal muscle via its axon terminals is called a MOTOR UNIT * Motor units come in different sizes based on the number of skeletal muscle fibers innervated by a motor neuron via its axon terminals: small motor units; medium-sized motor units; large motor units

Question 49

Motor unit size?

Answer 49

Motor units come in different sizes based on the number of skeletal muscle fibers innervated by a motor units via their axon terminals small motor units; medium-sized motor units; large motor units

Question 50

The neuromuscular junction

Answer 50

forms between an axon terminal of a motor neuron and the motor end plate at the sarcolemma of a skeletal muscle fiber. Each skeletal muscle fiber forms only one neuromuscular junction with an axon terminal; each skeletal muscle fiber is a member of a single motor unit

Question 51

motor end plate

Answer 51

The highly folded region of the sarcolemma of the muscle fiber at the neuromuscular junction is called the Motor End Plate – expresses acetylcholine receptors

Question 52

factors that affect the strength/force of skeletal muscles contraction

Answer 52

- size of motor units activated - number of motor units activated - frequency of skeletal muscles activation the length of the sarcomere prior to contraction

Question 53

size of motor units activated

Answer 53

larger motor units generate more force in a skeletal muscle than smaller motor units

Question 54

number of motor units activated

Answer 54

force by a contracting skeletal muscle increases as the number of motor units activated increases Recruitment refers the order in which motor units are activated in a skeletal muscle - smaller motor units are activated first followed by medium-sized motor units and then the large motor units

Question 55

frequency of skeletal muscles activation

Answer 55

force generatedbythe skeletal muscle increases as the rate of skeletal muscle stimulation increases

Question 56

the length of the sarcomeres prior to contraction

Answer 56

sarcomeres at the optimum length generate the maximum force; sarcomere length below the optimum length ( shortened sarcomeres) results in decreased force; sarcomere length greater than the optimum length ( stretched sarcomeres) results in decreased force of contraction

Question 57

Isometric contraction

Answer 57

force(tension) generated by the muscle is increasing at a constant muscle length ( “isometric” = same length); occurs when the weight exceeds the force generated by the muscle

Question 58

isotonic contraction

Answer 58

muscle length changes at a relatively constant force ( isotonic = same force)

Question 59

Resistance exercise or isometric exercises (weightlifting, isometric exercises where muscles are pitted against immovable objects)

Answer 59

changes that occur in the skeletal muscles: Increase in the size of skeletal muscles = hypertrophy of skeletal muscles occur due to increase in the number of myofibril within each muscle fiber Increase in glycogen content Overall, bulky muscles generate more force = increase in muscle strength

Question 60

Aerobic or endurance exercise (jogging, biking, swimming)

Answer 60

changes that occur in the skeletal muscles: increase in capillaries increase in mitochondria increase in myoglobin content Overall, endurance improved = increase in stamina

Question 61

2 types of smooth muscle

Answer 61

based on smooth muscle fiber arrangement, innervation and responsiveness to stimuli

Question 62

single unit smooth muscle

Answer 62

Composed of circular and longitudinal smooth muscle layers in the walls of organs – Innervated by autonomic nerve fibers – Electrically-coupled by gap junctions hence, single-unit smooth muscle all the cells contract at the same time– functional syncytium – Stimulated to contract by chemicals – ****Exhibit pacemaker activity

Question 63

multiunit smooth muscle

Answer 63

Composed of individual smooth muscle fibers – Lacks gap junctions – smooth muscle cells contract independently, not together as a unit – Innervated by the autonomic nerve fibers – Stimulated to contract by chemicals – No pacemaker activity

Question 64

concentric contraction

Answer 64

Force generated by skeletal muscle exceeds the weight so the skeletal muscle shortens, and work is done, such as lifting the weight.

Question 65

eccentric contraction

Answer 65

force/tension develops as the skeletal muscle lengthens

Question 66

3 major types of skeletal muscles fiber types based on 2 criteria

Answer 66

- speed of contraction - major pathway for ATP production

Question 67

speed of contraction

Answer 67

due to the speed at which Myosin ATPase hydrolyzes ATP to activate the myosin globular heads- 2 types: - slow ATPase in slow fibers - fast ATPase in fast fibers

Question 68

3 skeletal types

Answer 68

Slow Oxidative Fibers (also known as red fibers) ii) Fast Oxidative Fibers (also known as intermediate fibers) iii) Fast Glycolytic fibers (also known as white fibers)