muscle inside structures and sarcomeres

Question 1

functions of the skeletal muscle system

Answer 1

body movement
maintenance of posture
respiration
body heat production
communication

Question 2

what are the muscle properties

Answer 2

contractility = ability for muscle to contract

excitability = capacity of muscle to respond to a stimulus by producing action potentials

extensibility = muscle can be stretched beyond its resting length and still be able to contract

elasticity = ability of muscle to recoil to original resting length after its been stretched

Question 3

describe the structure of skeletal muscle.

Answer 3

• made up of muscle fibers, CT, blood vessels and nerves
• fibers are long, cylindrical and multinucleated
• striated appearance b/c of light and dark banding

Question 4

parts of the muscle

Answer 4

muscular fascia
- surroundings muscles and groups

epimysium
- surrounds muscles/ all of epimysiums

endomysium
- surrounds muscle fibers

periosteum
- irreg CT that surrounds bone

tendon

veins

arteries

neuromuscular junction
- connection synapses on muscle cells

Question 5

fascicle structure

Answer 5

sarcolemma = plasma membrane

sarcoplasm = cytoplasm of skeletal muscle

nuclei = pushed to the side

mitchondria = gives ATP

Transverse tubule (t tubules) = surrounding myofibrils

sarcoplasmic reticulum = on one side of tubule and hella organized smooth ER

Question 6

what does troponin bind to?

Answer 6

actin
calcium ions
tropomyosin

Question 7

what is the role of the sarcoplasmic reticulum in muscle contraction?

Answer 7

store calcium

Question 8

explain the triad grouping

Answer 8

theres one t tubule and 2 terminal cristerna on both sides of it

Question 9

what are is the terminal cisterna?

Answer 9

enlarged area of the sarcoplasmic reticulum near t tubules

Question 10

each muscle cell is a

Answer 10

fiber

Question 11

explain how muscle contraction occurs.

Answer 11

AP moves along sarcolemma –> into t tubules –> through the cell and makes a rapid signal –> sends signal to sarcoplasmic reticulum (SR) –> releases calcium into myofibrils => stimulates muscles to contract

Question 12

what would calcium deficiency lead to then?

Answer 12

irregular muscle contractions = muscle cramps

Question 13

what is the transverse tubule?

Answer 13

invagination of sarcolemma (plasma memebrane)

Question 14

what is myoglobin used for?

Answer 14

carrying oxygen from blood through muscle cell

Question 15

what is glycogen used for?

Answer 15

carbohydrate storage

Question 16

what are the parts of the sarcomere and explain their relevance.

Answer 16

z-disk = sarcomere spans from z-disk to z-disk. they help actin and myosin stay in place.

actin myofilament = thin filament

myosin myofilament = thick myofilament

titan = goes from z-disk to m-line (so theres 2 on each sarcomere). acts as a spring for when muscles are stretched

m-line = thin layer of protein that spans mid of protein, holds thick myofilament

Question 17

what is dystrophin?

Answer 17

connects to actin myofilaments and sarcolemma protein

When proteins contract - pulls on dystrophin - pulls on 2 bones

Question 18

what happens in resting condition?

Answer 18

actin and myosin arent connected to eachother

Question 19

what is the cross bridge?

Answer 19

during muscle contraction when actin and myosin bind to each other

• myosin doesnt EVER move the actin just moved till it meets the m-line

Question 20

describe the parts of actin myofilaments.

Answer 20

f actin molecules:
long stands of coiled helix pattern, made up of g proteins that have active sites that myosin binds to

tropomyosin:
twists around f actin to cover up active sites

troponin:
allows us to access active sites.
- binds to g protein, tropomyosin and calcium

Question 21

describe the parts of myosin myofilaments.

Answer 21

rod region:
2 protein chain

myosin heads:
are attached to light chains and myosin ATPase that breaks down ATP and gets energy to allow myosin heads to bind to actin

Question 22

why are some areas of the sarcomere lighter or darker than the other? what is light and what is dark?

Answer 22

theyre done based on the thickness of the myofilament.

darkest where myosin and actin overlap

lightest where theres only actin myofilaments

in between thickness where its just myosin

Question 23

what are the different parts of the sarcomere?

Answer 23

z disk:
attachment point for the actin myofilaments

I band:
from z disk to the ends of the thick filament

A band:
length of thick filaments (never changes during contraction)

H zone:
region in A band where actin and myosin DO NOT overlap - only have myosin

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

titan filaments:
elastic chains of amino acids that help make muscles elastic

Question 24

what is the basic contractile unit of muscle?

Answer 24

sarcomere