KIN 300 Test #2

muscle types

skeletal, cardiac, smooth

skeletal muscle attachment

-attaches bone to bone or bone to skin

skeletal muscle movement

movement at joints

skeletal muscle control

voluntary & involuntary

cardiac muscle control

involuntary

cardiac muscle

cardiac system (heart contractions)

smooth muscle

digestive tract

smooth muscle control

involuntary

muscle properties

electrical excitability, contractility, extensibility, elasticity

electrical excitability

conducts electrical impulses

contractility

contract and generates tension within muscle

extensibility

extends

extensibility property

passive

elasticity

stretches

elasticity properties

passive

specialized cell types

muscle, neurons, connective tissue , epithelial

organ (skeletal muscle)

muscle tissue, connective tissue, nervous tissue, endothelial

connective tissues

superficial fascia, deep fascia, deep connective tissue

superficial fascia location

in subcutaneous layer of skin

superficial fascia

holds everything in place

deep fascia location

beneath subcutaneous layer

deep fascia

protects muscle, conduit for nerves and muscles

deep connective tissue

tendons, aponeurosis

tendons

-attaches muscle to attachment

aponeurosis

type of tendon

what happens when a muscle contracts

generates tension and exerts force on skeleton to move body

what allows a movement

muscle attachment across a joint

microscopic anatomy of muscles

skeletal muscle → fascicle → muscle fibers (cells) → myofibrils

sarcolemma

muscle cell plasma membrane

sarcoplasm

muscle cell intracellular cytoplasm

myofibrils

muscle cell contractile organelle

sarcomere

functional unit of muscles

sarcomere contraction

simultaneously , whole muscle contraction

filament arrangement

thin filament within thick filament

contractile unit of skeletal muscle

striated appearance to muscle

thick filament made of

myosin proteins

thick filament structure

tail points towards center, globular head points outwards

thin filaments made of

acin, troponin, tropomyosin proteins

actin

binding site with myosin

troponin

keeps everything together

troponin binding sites

binds to calcium, binds actin and myosin together

when does troponin change structure

when calcium and troponin bind

tropomyosin at rest

blocks actin from binding to myosin

what happens when troponin changes structure

tropomyosin reveals actin’s binding site

tension produced is

how much force generating power muscle has

speed of contraction depends on

how long contraction can be maintained and how quickly myosin head can catalyze

muscle contraction →

generates tension → strength

more cross bridges means

more tension and more bonds between myosin and actin

where does calcium get released from

sarcoplasm reticulum

what needs to be present for a cross bridge to occur

ATP and calcium

muscle contraction cycle

1. calcium released into muscle cell from sarcoplasmic reticulum

2. calcium binds to troponin and changes troponin structure

3. troponin shape change moves tropomyosin out of way and actin binding site no longer blocked

4. myosin heads from thick filaments bind to actin in thin filaments

5. myosin pulls actin inward and makes muscle contract

6. second ATP attaches to myosin head

7. myosin is released from actin and binds to new actin if possible

what does myosin head contain

enzyme that breaks down ATP

what is the role of ATP in a muscle contraction

provides energy for powerstroke & allows cycle to continue

how muscle generates ATP to power contraction cycle

anaerobic glycolysis, anaerobic creatine phosphate, aerobic cellular respiration

creatine phosphate

short burst of energy, fast acting, anaerobic

creatine phosphate good for what activity

100 m dash, light lifting

glycolysis

breaking down glucose, anaerobic

cellular respiration

mitochondria produces ATP, aerobic

cellular respiration good for what activity

endurance activities, marathons, heavy weights

Muscle Fiber Types

Type I, Type IIa, Type IIx

type I

slow oxidative fibers

type I fiber aerobic or anaerobic

aerobic

type I fiber activity

long distance, endurance

type IIa fiber

fast oxidative glycolytic fibers

type IIa fiber aerobic or anaerobic

both

type IIa fiber activity

short distance activities, sprints

type IIx

fast glycolytic fibers

type IIx activity

intermediate

type IIx anaerobic or aerobic

anaerobic

muscle contraction types

tension, fatigability, speed of contraction

tension

opportunity to form cross bridges, proportional to number of cross bridges formed

tension size factor

large diameter = more filament proteins = more cross bridges

tension type I diameter

small diameter → less tension

tension type I

lots of myoglobin and mitochondria

tension type IIa diameter

large diameter → more tension

tension type IIa activity

short distances

tension type IIx

intermediate; force output greater than I less than IIa

fatigability

determined by supply of ATP

fatigability type I

fatigue resistant

fatigability type I aerobic or anaerobic

aerobic

fatigability type IIa

fatigable

fatigability type IIa aerobic or anaerobic

anaerobic

fatigability type IIx

not as fatigable as IIa but less endurance than I

fatigability type IIx aerobic or anaerobic

aerobic and anaerobic

speed of contraction

determined by speed of cross bridge cycle

speed of contraction type I

slow contraction speed

speed of contraction type IIa

fast contraction speed

speed of contraction type IIx

not as slow as I but not as fast as IIa

power athletes rely on

anaerobic systems (type IIa)

long endurance athletes rely on

aerobic systems (type I)

neutral wrist of finger flexor muscles

optimal length for muscle

flex wrist of finger flexor muscles → bend downwards

shortens muscles

extend wrist of finger flexor muscles → bend backwards

lengthens muscles

motor neurons location

spinal cord

motor neurons

transmits impulses from nervous system to muscle fibers

neural input

neural firing → neuromuscular junction → release of calcium into sarcoplasm → contraction cycle

neuromuscular junction

link between motor neuron & skeletal muscle fiber, cell to cell

motor unit connection

one motor unit has branches and connects to muscle fibers

small motor units

fine movements