gainz histo

Question 1

What are characteristics of skeletal muscle?

Answer 1

voluntary control
strong, quick contractions
striated (actin and myosin)
large, elongated, multinucleated cells

Question 2

What are characteristics of cardiac muscle?

Answer 2

involuntary control
strong, quick contractions
striated
uninucleated cells
centrally located nucleus
elongated/branched cells joined by intercalated discs

Question 3

What are characteristics of smooth muscle?

Answer 3

involuntary control
weak, slow contractions
non striated
uninucleated, fusiform cells
centrally located nucleus

Question 4

What are the three types of fibers in skeletal muscle?

Answer 4

type I: slow, red oxidative fibers
type IIa: fast, intermediate oxidative-glycolytic fibers
type IIb: fast, white glycolytic fibers

Question 5

What are characteristics of type I fibers?

Answer 5

slow, red oxidative fibers

lots of mitochondria and myoglobin
energy from aerobic oxidative phosphorylation of fatty acids

slow, continous contractions (endurance)

Question 6

What are characteristics of type IIa fibers?

Answer 6

fast, intermediate oxidative-glycolytic fibers

many mitochondria, myoglobin and glycogen
use oxidative phosphorylation and anaerobic glycolysis
rapid contractions, short bursts of energy

Question 7

What are characteristics of type IIb fibers?

Answer 7

fast, white glycolytic fibers

few mitochondria and myoglobin, LOTS of glycogen
use anaerobic glycolysis
rapid contractions, but fatigue quickly

Question 8

What color are A bands?

Answer 8

dark

Question 9

What color are I bands?

Answer 9

light

Question 10

What runs through I bands?

Answer 10

Z disc

Question 11

What are the boundaries of a sarcomere?

Answer 11

Z disc to Z disc

Question 12

What is actin?

Answer 12

thin filament

Question 13

What is myosin?

Answer 13

thick filament

Question 14

What fibers are in an A band?

Answer 14

actin (thin) and myosin (thick)

Question 15

What fibers are in an I band?

Answer 15

only actin (thin)

Question 16

What is the M line?

Answer 16

in the center of an A band, thick filaments only, myosin fibers tie in with one another

Question 17

What is the H zone?

Answer 17

Area of an A band where there are only thick (myosin) fibers

Question 18

What happens during muscle contraction?

Answer 18

Z discs slide closer together

myosin ‘grabs’ actin and pulls Z discs closer together

A band remains same size
I band shrinks
H zone disappears, but M line stays

Question 19

What are characteristics of the globular heads of myosin?

Answer 19

acting binding
ATP binding
ATPase activity

Question 20

What blocks myosin binding to actin?

Answer 20

tropomyosin

Question 21

What are the important subunits of the troponin complex?

Answer 21

TnT: troponin and tropomyosin binding?
TnC: binds calcium

Question 22

What is the trigger for muscle contraction?

Answer 22

increased Ca2+ concentration in cytosol

Question 23

What is the role of the sarcoplasmic reticulum in muscle cells?

Answer 23

takes up and stores Ca, will release Ca upon contraction

Question 24

What is a T tubule and where is it located?

Answer 24

extension of plasma membrane that allows action potentials to reach deep into cells

located between A band/I band junction

Question 25

What is a terminal cisterna?

Answer 25

enlarged region of sarcoplasmic reticulum located near a T tubule

Question 26

What is a motor unit?

Answer 26

the motor neuron and all the muscle fibers it innervates | one axon innervates multiple muscle cells

Question 27

What is an important neurotransmitter in muscle contraction

Answer 27

acetylcholine (ACh)

Question 28

What are the steps of muscle contraction?

Answer 28

1. AP generated, sent down T tubules 2. AP triggers Ca release from SR 3. Ca ions bind to troponin, removing the blocking action of tropomysosin, actin binding sites exposed 4. myosin grabs actin and pulls fibers closer to center of sarcomere 5. Ca removed by active transport 6. tropomysoin blocks actin binding site again

Question 29

How do you change myosin heads from low to high energy conformations?

Answer 29

need ATP to change head myosin head conformation. need ATP to make the myosin head "let go" of actin need ATPase to get rid of ATP and put head into high energy conformation (look at pics this is confusing)

Question 30

What are the connective tissue sheaths associated with skeletal muscle?

Answer 30

endomysium (around individual fibers) perimysium (around fiber bundles called fasicles) epipysium (around entire muscle_

Question 31

What is the difference in T tubules between cardiac and skeletal muscle?

Answer 31

cardiac: one per sarcomere at Z disc (forms diads) skeletal: two per sarcomere at A-I junctions (forms triads)

Question 32

What are the components of intercalated discs?

Answer 32

Fascia adherens: links actin filaments desmosome: links intermediate filaments gap junctions: communicating junction