giant

Sarcolemma

Cell membrane, similar to other cells membranes

Sarcolemma charge

-70 mV

Sodium Potassium Pump

Causes negative charge within the cells

K+ leak channels

Allows Potassium to leak out of cells to produce negative charge within cell

T-Tubules

Transverse tubules, deliver the sugnal for muscle contraction

Sarcoplasmic reticulum

similar to endoplasmic reticulim

Terminal cisternae

store calcium, on either side of the t tubules

80% of the muscle fiber volume

myofibrils

Shape of myofibril

cylindrical organelle

types of fibers in myofibril

thick actin, thin filament

Thick filaments

two strands, globular head, elongated tail

Binding sites on myosin

Atp and actin

Thin filaments

G-Actin

Tropomyosin

Ribbon around actin, regulatory protien

Troponin

Calcium binding site on tropomyosin

Unit of cell

sarcomere

I band

extends from both sides of z disk, only thin filaments

a band

central region containing the entirety of thick filaments

H band

contains only thick filaments

M line

protein disk in middle of h zone

Neuromuscular junction

where motor neuron innervates a cell, type of synapse

In the first step of muscle contraction, the arrival of a _____ signal triggers _____ to be released into the synaptic knob

nerve, calcium

in the second step of muscle contraction, calcium triggers _____ to be released into the _____ cleft

Ach, synaptic

ACh

diffuses across the cleft, binds with ACh receptors at the motor end plate

Excitation-Contraction coupling first step, at the motor ____ _____, ach opens ____ channels and a reversal of charges happen

end plate, ion

At the edge of the motor plate

altered mp triggers oppening of voltage gated channels

Inflow of sodium

Causes reversal of charges =action potential

Action potential causes

wave of Na+ channels oppening

Muscle impulse

Consecutive opening of voltage-gated channels

WHen action potential enters t tubules

voltage gated Ca+ channels located in terminal cisternae

First step of crossbridge cycling, calcium binds to _________, shifting __________, opening myosin binding sites

troponin, tropomyosin

Crossbridge

myosin binding to actin

Actin binding causes

Phosphate to be releases, conformation change

Thin filament towards the center of the A band

power stroke

At the end of the power stroke

ADP is released, ATP reattatches, myosin and actin reset

Contraction will continue as long as

Calcium is present

When the end plate potential stops

Calcium active transport pumps return Calcium to the sarcoplasmic reticium and contraction stops

Major energy molecule

ATP

Ultimate energy sources used to restore atp supply

Glucose, glycogen, triglyceride, protien

Most efficient form of respiration, but slow and needs oxygen

Aerobic respiration

Myoglobin

stores oxygen in muscle

Immediate ATP supply, uses kinase, no oxygen

Phosphagen system

Immediate ATP supply, merges 2 ADP

Myokinase system

Runs on glucose in blood, slower, lowers ph

Lactic acid fermentation

In long performance situation

body relies on aerobic respiration

Oxygen debt

additional oxygen needed after exercise

Type of contraction

twitch fibers

Fast-twitch fibers

greater power and speed

Slow twitch fibers

slower

Oxidative fibers

Fatigue resistant, use aerobic respiration, allow contractions for long periods of time

Oxidative fibers features

Increased cappilaries, mitochondria, and myoglobin

What makes oxidative fibers red?

Increased myoglobin

Glycolitic fibers

Use anerobic respiration, tire easily

Glycolitic fibers features

Have fever structures needed for aerobic respiration, but have large glycogen stores

Muscle tension

Muscle contracting

Threshold

Minimum stimulation needed to generate a contraction

Twitch

Single contraction/ reaction period

Latent period

time needed to inititate contraction

Contraction period

Begins as power strokes pull thin filaments

Relaxation period

Begins with the release of cross bridges

Muscle tones

Involuntary stimulation of random units

Graded response

Muscles exert varying levels of force, only use what they need

Treppe

stepwise increase in muscle strength

Incomplete tetany

Max tension with very short periods of relaxation, quivering contraction

Tetany

No relaxation

Fiber at resting length

Generates maximum contractile force

Fiber already contracted

Produce weaker contraction because filaments are limited in movement

Fiber overly stretched

Produce weaker contraction due to minimal overlap

Hypertrophy

Increased muscle fiber size due to exercise

Hyperplasia

Increase in number of muscle fibers due to exercise (limited)

Lack of exercise

Causes atrophy

Sarcopenia

Muscle loss begins in early 30s

What happens to number of myofibrils and myofilaments in sarcopenia?

Decrease

What happens to number of myoglobin in sarcopenia?

Decrease, store less oxygen

What happens to circulatory supply in sarcopenia?

Decrease

What happens to power of skeletal muscles in sarcopenia?

Decrease

What makes it harder to recover in sarcopenia

Less muscle cells

What replaces muscle mass

Regular connective tissue (fibrosis)

Features of cardiac muscle

1. cylindrical branching cells
2. single central nucleus (2 nucleoli)
3. cells are joined together by intercalated disks
4. almost 50% of the volume of the cell is mitochondria
5. abundant supply of myoglobin (huge oxygen requirement

Intercalated disks

form stairstep junctions between cardiac muscle cells

Desmosomes

anchoring junctions to reist pulling of cells as they contract (transverse)

Gap junctions

Membrane channel proteins, electrically couple all cardiac myocytes together in a functional syncytium (lateral portion

Smooth muscle charictaristics

Small, spindle like, can stretch

Cytoskeleton of smooth muscke

Formed bt intermediate filaments

Dense bodies

connect intermediate filaments

Dense plaques

anchor intermediate filaments to the inner sarcolemma

Contractile protiens

Thick and thin filaments between dense boddies

Contractile protiens lack

Sarcomeres

What globular protien does smooth muscle lack

Troponin

What replaces the sarcoplamic reticulum in smooth muscle

Caveolae

Calmodulin

Protien that binds Ca+

Myosin light-chain kinase

Adds a phosphate to mysoin head for activation

Myosin light chain phosphate

Removes a phospahte from the myosin head for innactivation

First step of smooth muscle contraction, stimulus triggers ______ to leave the ______

calcium, caveolae

second step of smooth muscle contraction, calcium binds to _____

calmodulin

Third step of smooth muscle contraction, _______ calcium complec activates _______ ______ ______ ______

calmodulin, Myosin light chain kinase

Fourth step of smooth muscle contraction, activated ______ _____ _____ ______ adds a phosphate to _____ head, activating it

myosin light chain kinase, myosin

The fifth step of smooth muscle contraction, activated myosin goes through _______ ________, the force generated pulls the ______ filaments, and the muscle compresses _____

crossbridge cylcing, anchoring, 3D

Relaxation of smooth muscle requires

Cessation of stimulation, removal of calcium, deactivation my myosin light-chain phosphate