gainz histo Flashcards Preview

ANNNNNAAtomy > gainz histo > Flashcards

Flashcards in gainz histo Deck (32):
1

What are characteristics of skeletal muscle?

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

2

What are characteristics of cardiac muscle?

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

3

What are characteristics of smooth muscle?

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

4

What are the three types of fibers in skeletal muscle?

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

5

What are characteristics of type I fibers?

slow, red oxidative fibers

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

slow, continous contractions (endurance)

6

What are characteristics of type IIa fibers?

fast, intermediate oxidative-glycolytic fibers

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

7

What are characteristics of type IIb fibers?

fast, white glycolytic fibers

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

8

What color are A bands?

dark

9

What color are I bands?

light

10

What runs through I bands?

Z disc

11

What are the boundaries of a sarcomere?

Z disc to Z disc

12

What is actin?

thin filament

13

What is myosin?

thick filament

14

What fibers are in an A band?

actin (thin) and myosin (thick)

15

What fibers are in an I band?

only actin (thin)

16

What is the M line?

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

17

What is the H zone?

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

18

What happens during muscle contraction?

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

19

What are characteristics of the globular heads of myosin?

acting binding
ATP binding
ATPase activity

20

What blocks myosin binding to actin?

tropomyosin

21

What are the important subunits of the troponin complex?

TnT: troponin and tropomyosin binding?
TnC: binds calcium

22

What is the trigger for muscle contraction?

increased Ca2+ concentration in cytosol

23

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

takes up and stores Ca, will release Ca upon contraction

24

What is a T tubule and where is it located?

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

located between A band/I band junction

25

What is a terminal cisterna?

enlarged region of sarcoplasmic reticulum located near a T tubule

26

What is a motor unit?

the motor neuron and all the muscle fibers it innervates

(one axon innervates multiple muscle cells)

27

What is an important neurotransmitter in muscle contraction

acetylcholine (ACh)

28

What are the steps of muscle contraction?

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

29

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

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)

30

What are the connective tissue sheaths associated with skeletal muscle?

endomysium (around individual fibers)

perimysium (around fiber bundles called fasicles)

epipysium (around entire muscle_

31

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

cardiac: one per sarcomere at Z disc (forms diads)

skeletal: two per sarcomere at A-I junctions (forms triads)

32

What are the components of intercalated discs?

Fascia adherens: links actin filaments

desmosome: links intermediate filaments

gap junctions: communicating junction