Human Physiology Ch 11

triad

1 transverse tubule and 2 terminal cisternae on each side

aerobic respiration

Respiration that requires oxygen, produces ATP, CO2, H2O, heat

What 2 reactions does aerobic respiration include?

Krebs cycle, ETC

stress-relaxation response

Responds to stretch only briefly, then adapts to new length; Retains ability to contract on demand; Enables organs such as the stomach and bladder to temporarily store contents

unfused (incomplete) tetanus

Some relaxation occurs between contractions. The results are summed

sliding filament mechanism

The explanation of how thick and thin filaments slide relative to one another

calsequestrin

calcium binding protein

hyperplasia

increase in number of fibers

What proteins make up the M line?

myomesin

L-type voltage gated Ca channels

open for a long period of time, allow extra Ca to enter sarcoplasm serve as voltage sensors

neuromuscular junction (NMJ)

the synapse between a somatic motor neuron and a skeletal muscle fiber

smooth muscle components

thick and thin filaments, NO transvere tubules, small amount of SR

transverse (T) tubules

thousands of tiny invaginations of the sarcolemma filled with ECF due to being open to outside of fiber

resting membrane potential of skeletal muscle

-90mV

contraction cycle

1. ATP hydrolysis 2. Attachment of myosin to actin to form cross-bridges 3. Power stroke 4. Detachment of myosin from actin

4 functions of muscle

1. Produce movement 2. stabilize body positions 3. Store and move substances within body 4. Generate heat

3 ways oxygen debt used to restore metabolic conditions

1. convert lactic acid back into glycogen 2. resynthesize creatine phosphate and ATP 3. replace oxygen removed from myoglobin

4 special properties of muscle

1. electrical excitability 2. contractility 3. extensibility 4. elasticity

contraction phase of muscle twitch

10-100msec, Calcium binds to troponin, myosin cross bridges form, peak tension in muscle fiber

latent period of muscle twitch

2 msec, brief delay between application of stimulus and beginning of contraction

tension maximal at a sarcomere length of ____

2.2um

titin

3rd most plentiful protein in skeletal muscle (after actin and myosin) 50x larger than avg protein

inside a myosin molecule

6 polypeptide chains: 2 heavy large chains, 4 small light chains

inside sarcomeres

A band, I bands, H zone, M line

What does the sarcoplasmic reticulum store when relaxed?

Calcium ions

What is more plentiful than ATP in the sarcoplasm of a relaxed muscle fiber?

Creatine phosphate (3-6x more)

What cytoskeletal protein links thin filaments to integral membrane proteins of the sarcolemma?

Dystrophin

F actin

G actin molecules linked together, fibrous

M line

Middle of sarcomere, holds thick filament in place

How does muscle contraction occur?

Myosin heads pull thin filaments toward M line, causes thin filaments to slide inward and meet at center of sarcomere I band and H zone narrow, disappear once contracted width of A band unchanged

creatine

a small amino acid like molecule that is synthesized in the liver, kidneys, and pancreas and then transported to muscle fibers

What type of proteins make up Z discs?

a-actinin

contractility

ability of muscle to contract forcefully when adequately stimulated

Elasticity

ability of muscle to return to its original length and shape after contraction or extension

extensibility

ability of muscle to stretch without being damaged

electrical excitability

ability to respond to stimuli by producing action potentials neurons AND muscle cells

components of thin filament

actin, tropomyosin, troponin

Ca2+ -ATPase pumps

active transport proteins that transport Ca from sarcoplasm in SR

What happens when a somatic motor neuron is activated?

all of its muscle fibers in the motor unit contract in unison

muscular system

all skeletal muscles of the body

glycogen

also inside sarcoplasm, large polysaccharide consisting of thousands of glucose molecules covalently linked together stores glucose

myoglobin

also inside sarcoplasm, red-colored, oxygen-binding protein that is found only in muscle

striations in muscle

alternating light and dark bands (skeletal muscle)

where do tendons attach to bone?

at the origin and insertion

origin

attachment of a muscle's tendon to the more stationary bone

insertion

attachment of the muscle's tendon to the more movable bone

flexion

bending a joint

levers

bones, move around a fixed point

glycolysis

breaks down glucose into two molecules of pyruvate

twitch

brief contraction of a group of muscle fibers within a muscle in response to a single action potential

Autorhythmycity

built in rhythm the heart has to initiate each contraction (pacemaker)

fascicles

bundles of muscle fibers, 10-100

the concentration of ___ is 10,000x higher in SR than in sarcoplasm in a relaxed muscle fiber

calcium

What does sarcoplasmic reticulum release to trigger muscle contraction?

calcium ions are released

cardiac muscle comparison to skeletal muscle

cardiac and skeletal both striated, but cardiac is involuntary

effort (E)

causes movement

isotonic contraction

constant tension while muscle changes length used for moving objects

myofibrils

contractile elements of the skeletal muscle fiber, have filaments inside

actin and myosin

contractile proteins in muscle

3 proteins that make up myofibrils

contractile, regulatory, structural

graded contractions

contractions that vary in strength depending on how much force is needed

tendon

cord of connective tissue that attaches to muscle of bone

slow wave potentials

cycles of alternating depolarization and repolarization that do not necessarily reach threshold

sarcoplasm

cytoplasm of a muscle fiber, mitochondria, glycogen, and myoglobin are inside

A band of sarcomere

dark middle part, extends entire length of thick filaments

hypotonia

decreased or lost muscle tone

thin filaments inside smooth muscle

dense bodies, similar to Z discs in striated muscle fibers

2 phases of skeletal muscle contraction

depolarizing (rising) phase and a repolarizing (falling) phase

Terminal cisternae of sarcoplasmic reticulum

dilated end sacs that butt against a T tubule from both sides

Repeated ____ contractions produce muscle damage and soreness

eccentric isotonic

creatine phosphate

energy rich molecule found in muscle fiber

hypertrophy

enlargement of existing cells

multi unit smooth muscle

fibers that act independently of each other as multiple units

sarcoplasmic reticulum

fluid filled system of membranous sacs that encircle each myofibril

3 ways a skeletal muscle fiber can form ATP

from creatine phosphate by anaerobic glycolysis by aerobic respiration

When tremendous strength is needed, what type of tetanus is used>

fused tetanus

contractile proteins

generate force during contraction

What is used to generate ATP once creatine phosphate is depleted?

glucose

When oxygen is present, what happens?

glycolysis, Krebs cycle, ETC

smooth muscle contraction

happens once myosin head of thick filaments are phosphorylated

regulatory proteins

help switch contraction process on and off

voluntary manner

how skeletal muscle mainly works, activity consciously controlled by motor neurons (somatic motor system) some skeletal muscles controlled subconsciously too

when do skeletal muscles arise?

in embryonic development, from myoblasts # of muscle fibers you have is set before you are born

Ca release channels

in terminal cisternal membrane of SR aka ryanodine receptors

muscle fatigue

inability of a muscle to maintain force of contraction after prolonged activity

hypertonia

increased muscle tone

spasticity

increased muscle tone (stiffness) associated with an increase in tendon reflexes and pathological reflexes

rigidity

increased muscle tone where reflexes not affected

length-tension relationship

indicates how the forcefulness of muscle contraction depends on the length of the sarcomeres within a muscle before contraction begins

functional synctium of heart

interconnected cells that acts as single unit atria, and ventricles of heart two synctiums

load and velocity in concentric isotonic contraction

inversely related

fulcrums

joints, the fixed point

structural proteins

keep the thick and thin filaments in proper alignment and link the myofibrils to the sarcolemma and extracellular matrix

phases of a twitch

latent period, contraction phase, relaxation phase

I band

light area on each side of A band, contains rest of thin filaments

Dihydropyridine receptor (DHP)

links the T tubule and terminal cisternae L-type voltage gated Ca2+ channels

mechanical advantage

load closer to fulcrum than effort

mechanical disadvantage

load farther from fulcrum than the effort

smooth muscle

located in walls of hollow internal structures (blood vessels, airways, stomach, intestines, uterus)

actin

main component of thin filaments aka G actin (globular proteins)

myoblasts

mature skeletal muscle fiber that has multiple nuclei

satellite cells

matured myoblasts, fuse with one another to regenerate functional muscle fibers

What produces large amounts of ATP for muscle contraction?

mitochondria

single unit smooth muscle

most common, fibers contract together as a single unit aka visceral smooth muscle

myosin

motor protein and all types of muscle, push/ pull cell structures to achieve movement

the functional contractile unit of a skeletal muscle

motor unit

organization of skeletal muscle

muscle --> muscle fiber --> fascicles --> tendon

H zone

narrow zone in center of each A band, contains thick filaments

What nonelastic protein wraps around thin filaments?

nebulin

asynchronous recruitment

normally, some motor units are contracting while others are relaxed

load (resistance)

opposes movement

2 sources of oxygen for muscle tissue

oxygen diffused into muscle fibers oxygen released by myoglobin

Z disc (line)

passes through each I band, separates sarcomeres

refractory period of muscle fiber

period of lost excitability, time varies with each muscle (skeletal muscle period is short)

sarcolemma

plasma membrane of a muscle fiber

motor unit recruitment

process of increasing the number of active motor units

troponin

protein that consists of 3 globular subunits, one binds to tropomyosin, one binds to actin, one binds to calcium ions

anaerobic glycolysis

pyruvic acid generated during glycolysis is converted to lactic acid 2 lactic acid, 2 ATP

myogram

record of muscle contraction

sarcomeres

repeating units of myofibrils, filled with thin and thick filaments (not entire length)

recruitment of motor units

responsible for producing smooth movements instead of jerks

tropomyosin

rod-shaped protein that joins with other tropomyosin molecules to form 2 long strands that wrap around F actin double helix

excitation-contraction

sequence of events that links muscle action potential to muscle contraction happens at triads of skeletal muscle fiber

muscle tone

small amount of tautness or tension in muscle due to weak, involuntary contractions of motor units

contraction in smooth muscle vs striated muscle

smooth muscle contraction--triggered by calcium induced changes in thick filaments striated muscle contraction--triggered by calcium induced changes in thin filaments

fused (complete) tetanus

smooth, sustained contraction individual twitches cannot be detected

motor unit

somatic motor neuron plus all the muscle fibers it innervates

pacemaker potential

spontaneous depolarization that always reaches threshold, triggers making of action potential

wave summation

stimuli arriving at different times causes contractions with greater tension

extension

straightening a limb at a joint

component of NMJ (3)

synaptic end bulbs, motor end plate, synaptic cleft

eccentric isotonic contraction

tension exerted by myosin crossbridges resists movement of load, slows lengthening process walking downhill

concentric isotonic contraction

tension generated great enough to exceed load, muscle shortens picking book up off table

isometric contraction

tension generated is not enough to exceed load, muscle does not change length lifting objects too heavy to move

oxygen debt

the added oxygen, over and above the resting oxygen consumption, that is taken into the body after exercise used to pay back or restore metabolic conditions

key structural proteins

titin, α-actinin, myomesin, nebulin, and dystrophin

voltage gated channels and calcium release channels

trigger contraction of smooth muscle

When does wave summation and both kinds of tetanus happen?

when more Calcium is coming from SR by more stimuli whiles levels of calcium in the sarcoplasm are still elevated from first stimulus

myosin binding site

where a myosin head can attach

load-velocity relationship

The principle that the velocity of shortening of a muscle during isotonic contraction decreases as load increases.

What triggers a muscle action potential at the NMJ?

Acetylcholine