Muscles & M Tissue Slides

Question 1

Skeletal muscle tissue is

Answer 1

Attached to bones
Striated
Voluntary
Powerful
Cylinder shape
Multi- nucleited

Question 2

Cardiac muscle tissue

Answer 2

Only in the heart
Intercalated discs
Striated
Involuntary
1 nucleus

Question 3

Smooth muscle tissue

Answer 3

Not striated
In walls of hollow ograns; stomach bladder, airways
Involuntary
Spindleshaped

Question 4

Excitability

Answer 4

Receive/respond to stimuli

Electrical current

Question 5

Extensibility

Answer 5

Normal to larger size

Question 6

Contractility

Answer 6

Normal to 1/3 of size

Question 7

Elasticity

Answer 7

Back to normal size

Question 8

Muscle functions

Answer 8

Generate heat
Stabilize joints
Movement of bones/fluids
Posture/position

Question 9

Skeletal muscle

Answer 9

Each muscle is served by one nerve, one artery, 1+ veins

Question 10

Epimysium

Answer 10

Surrounds entire muscle; belly CT

Question 11

Perimysium

Answer 11

surrounds fascicles Ct

Question 12

Endomysium

Answer 12

surrounds each muscle fiber/ areolar ct

Question 13

Anatomy of skeletal muscle fiber

Answer 13

Cylindrical, up to 30 cm
Multiple peripheral nuclei
Many mitchondria
Glycosomes
Myioglobin- takes O2 to cells
Myofibrils, SR, T-tubules

Question 14

Myofibrils

Answer 14

Dense, 80% of cell volume

Question 15

Sarcomere features

Answer 15

Thick filaments: Myosin (A Band)
Thin filaments: Actin (I band and partially to A band)
Zdisc: Anchors thin filaments
Hzone: Lighter midregion where there is no overlap
Mline: Holds adjacent thick filaments together

Question 16

Myosin Tails

Answer 16

Two interwomen polypeptide chains

Question 17

Myosin Heads

Answer 17

2 smaller polypeptide chains; crossbridges
Binding sites for actin filaments
Binding sites for ATP
ATPase enzymes

Question 18

Sarcoplasmic Reticulum

Answer 18

Stores Calcium Ions

Question 19

T-tubules

Answer 19

Continuous with the sarcolemma

Pentrates cell’s interior at each A/I band junction

Question 20

During contraction…

Answer 20

myosin heads bind to actin, detach, and bind again to propel thin myofilaments toward the M-line. Zlines move together.. A band doesn’t move.

Question 21

Requirements for skeletal muscle contraction

Answer 21

Activation: neural stimulation at neuromuscular junction
Excitation: Generation and propagation of an action potential along the sarcolemma
Trigger; rise of intracellular Ca levels

Question 22

Events at neuromuscular junction

Answer 22

Axons of motor neurons go from CNS—> skeletal muscles via nerves. Each axon ending forms neuromuscular junction with a single muscle fiber

Question 23

Neuromuscular junction

Answer 23

Midway along length of a muscle fiber.
Axon terminal and muscle fiber separated by synaptic cleft. Synaptic vessicles contain neurotransmitter Ach.
Sarcolemma contain Ach receptors

Question 24

Events

Answer 24

Nerve impulse arrives at axon terminal.
ACh is released and binds with receptors on the motorr end plate of the sarcolemma. Electrical events lead to a generation of an action potential.

Question 25

Depolarization

Answer 25

ACh opens chemically ligand gated ion channels. There’s diffusion of Na in and K out. More Na is diffused so the sarcolemmma’s interior becomes less negative.

Question 26

Generation and Propagation of an action potential

Answer 26

End plate potential spreads to adjacent membrane areas. Voltage gated Na+ channels open. Na influx decreases membrane voltage towards a critical threshold. If the threshold is reached, an action potential is generated.

Question 27

Repolarization

Answer 27

Na channels close and voltage gated K channels open. K efflux rapidly restores the resting polarity.
Ionic conditions of resting state restored by calcium potassium pump.

Question 28

What happens at the peak of an action potential?

Answer 28

Na gates will close and K gates will open.

Question 29

E-C Coupling (excitation-contraction)

Answer 29

Sequence of events of an action potential leading to sliding of the myofilaments

Question 30

Latent period

Answer 30

lag time; time between initiation and contraction

Question 31

Events of EC

Answer 31

Action potential is propagted along sarcomere to t-tubules

Voltage sensitive proteins stimulate release of Calcium ions from SR.

Question 32

Role of calcium in contraction

Answer 32

Calcium binds to troponin, troponin moves tropomyiosin away from active sites on actin. Cross bridge occurs, when Nervous stimulation ceases, ca pumped back into SR and end of contraction.

Question 33

Cross bridge detachment

Answer 33

ATP attaches to myosin head and the cross bridge detaches.

Question 34

Cocking of myosin head

Answer 34

Energy from hydrolysis of ATP cocks myosin head into high energy state.