muscular system 2-types and function of muscles as well as skeletal muscle anatomy

Question 1

what are the 3 types of muscle tissue?

Answer 1

◦ Skeletal
◦ Smooth
◦ Cardiac

Question 2

what are some of the functions and characteristics of skeletal muscle tissue?

Answer 2

 Responsible for locomotion, posture, respiratory movements, other types of body movement

 Voluntary

Question 3

what are some of the functions and characteristics of smooth muscle tissue?

Answer 3

 Walls of hollow organs, blood vessels, eye, glands, skin

 Some functions: propel urine, mix food in digestive tract, dilating/constricting pupils, regulating blood flow

 In some locations, autorhythmic

 Controlled involuntarily by endocrine and autonomic nervous systems

Question 4

what are some of the functions and characteristics of cardiac muscle tissue?

Answer 4

 Heart: major source of movement of blood

 Autorhythmic

 Controlled involuntarily by endocrine and autonomic nervous systems

Question 5

comparisons between the 3 types of muscle tissue: where are each type located?

Answer 5

skeletal: Attached to bones
smooth: walls of hollow organs, blood vessels, eyes, glands and skin
cardiac: heart

Question 6

comparisons between the 3 types of muscle tissue: cell shape

Answer 6

skeletal: very long and cylindrical
smooth: spindle-shaped
cardiac: cylindrical and branched

Question 7

comparisons between the 3 types of muscle tissue: nucleus

Answer 7

skeletal: multiple nuclei: peripherally located
smooth: single, centrally located
cardiac: single, centrally located

Question 8

comparisons between the 3 types of muscle tissue: special cell-to-cell attachments

Answer 8

skeletal: None
smooth: Gap junctions join some visceral smooth muscle cells together
cardiac: Intercalated disks join cells to one another

Question 9

comparisons between the 3 types of muscle tissue: striations

Answer 9

skeletal: yes
smooth: no
cardiac: yes

Question 10

comparisons between the 3 types of muscle tissue: control

Answer 10

skeletal: Voluntary and involuntary
smooth: involuntary
cardiac: involuntary

Question 11

comparisons between the 3 types of muscle tissue: capable of spontaneous contraction

Answer 11

skeletal: no
smooth: yes(some)
cardiac: yes

Question 12

what are the 4 general properties of muscle?

Answer 12

 Contractility: ability of a muscle to shorten with force

 Excitability: capacity of muscle to respond to a stimulus (from our nerves)

 Extensibility: muscle can be stretched to its normal resting length and beyond to a limited degree

 Elasticity: ability of muscle to recoil to original resting length after stretched

Question 13

what are skeletal muscles composed of?

Answer 13

Composed of muscle cells
(fibers), connective tissue,
blood vessels and nerves

Question 14

what develops skeletal muscles?

Answer 14

myoblasts; numbers remain constant

Question 15

Connective tissue covering: layers

Answer 15

◦ Epimysium. C.T. that surrounds a whole
muscle (many fascicles)

◦ Perimysium. Denser C.T. surrounding a group
of muscle fibers. Each group called a fasciculus

◦ Endomysium. Loose C.T. with reticular fibers.

Question 16

Connective tissue covering: muscular fascia

Answer 16

◦ connective tissue sheet

◦ External to epimysium

◦ Holds muscles together and separates them
into functional groups.

Question 17

what makes tendons?

Answer 17

Epimysium + Perimysium + Endomysium = Tendon

Question 18

skeletal muscle fiber anatomy-where are the several nuclei?

Answer 18

just inside sarcolemma (cell

membrane of muscle fiber)

Question 19

skeletal muscle fiber anatomy-what is sarcoplasm? and what are its characteristics

Answer 19

 Cell packed with myofibrils within
cytoplasm

◦ Threadlike

◦ Composed of protein threads called
myofilaments: thin (actin) and thick (myosin)

Question 20

skeletal muscle fiber anatomy-what are sarcomeres?

Answer 20

highly ordered repeating units of myofilaments

Question 21

what is Actin (thin) Myofilaments?

Answer 21

Two strands of actin form a double helix extending the length of the myofilament;
attached at either end at sarcomere.

Question 22

what are the two parts of Actin Myofilaments?

Answer 22

 Tropomyosin

 Troponin

The tropomyosin/troponin complex regulates
the interaction between active sites on actin and
myosin(superfamily of motor proteins best known for their roles in muscle contraction)

Question 23

what is Myosin (thick) Myofilament?

Answer 23

Many elongated myosin molecules shaped like golf clubs

Question 24

what does Myosin Myofilament consist of?

Answer 24

Molecule consists of myosin heavy chains wound together to form a rod portion lying parallel to the myosin myofilament and two heads that extend laterally.

Question 25

what is the myosin heads and what are its functions?

Answer 25

1.Can bind to active sites on the actin molecules to form
cross-bridges.

2.Attached to the rod portion by a hinge region that can bend
and straighten during contraction.

3.Are ATPase enzymes: activity that breaks down adenosine triphosphate (ATP), releasing energy. Part of the energy is used to bend the hinge region of the myosin molecule during contraction

Question 26

what is a sarcomere?

Answer 26

basic functional unit of muscle fiber

Question 27

what is a Z disk?

Answer 27

filamentous network of protein. Serves as

attachment for actin myofilaments

Question 28

what gives the sarcomere a striated appearance?

Answer 28

◦ I bands: from Z disks to ends of thick filaments

◦ A bands: length of thick filaments

◦ H zone: region in A band where actin and myosin do not overlap

◦ M line: middle of H zone; delicate filaments holding myosin in place

Question 29

In muscle fibers, A and I bands of parallel

myofibrils are what?

Answer 29

aligned

Question 30

Sliding filaments model-how is the sarcomeres shortened?

Answer 30

Actin myofilaments sliding over myosin to shorten sarcomeres

Question 31

what happens to the actin and myosin and what is responsible for skeletal muscle contraction?

Answer 31

◦ Actin and myosin do not change length

◦ Shortening sarcomeres responsible for
skeletal muscle contraction

Question 32

during relaxation, what happens to the sarcomeres?

Answer 32

During relaxation, sarcomeres lengthen because of some external force, like contraction of antagonistic muscles

◦ Muscles that produce the opposite effect

Question 33

sarcomere shortening-what happens to the actin and myosin myofilaments when the muscle is relaxed?

Answer 33

the actin and myosin myofilaments overlap slightly, and the H zone is visible

Question 34

sarcomere shortening-what happens to the actin and myosin myofilaments when the muscle is contracting?

Answer 34

actin myofilaments slide past the myosin myofilaments, the z disks are brought closer together, and the sarcomere begins to shorten

Question 35

sarcomere shortening-what happens to the H zone when the muscle is contracting?

Answer 35

the ends of the actin myofilaments are pulled to and overlap in the centre of the sarcomere, shortening it and the H zone disappears

Question 36

what are the 3 types of muscle contraction?

Answer 36

Isometric: no change in length but tension increases
◦ Postural muscles of body

Isotonic: change in length but tension constant

Isokinetic: constant speed throughout movement

Question 37

what are the 2 types of isotonic contractions?

Answer 37

◦ Concentric: overcomes opposing resistance and
muscle shortens

◦ Eccentric: tension maintained but muscle
lengthens

Question 38

what are the 2 types of muscle fibers?

Answer 38

Slow-twitch oxidative (Type I)

Fast-twitch (Type II)

Question 39

what are the characteristics of Slow-twitch oxidative (Type I)?

Answer 39

◦ Contract more slowly, smaller in diameter,
better blood supply, more mitochondria, more
fatigue-resistant than fast-twitch, large amount of myoglobin.

◦ Postural muscles, more in lower than upper
limbs.

Question 40

what are the characteristics of Fast-twitch (Type II)?

Answer 40

◦ Respond rapidly to nervous stimulation,
contain myosin that can break down ATP more
rapidly than that in Type I, less blood supply, fewer and smaller mitochondria than slow-twitch

◦ Lower limbs in sprinter, upper limbs of most
people.

◦ Comes in oxidative and glycolytic forms