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360 Cards in this Set

  • Front
  • Back

muscle physiology

bone.

what happens when a muscle contracts?.

it shortens.

when is tension placed on tendons connecting to bones

 when muscles contracts

the bone that moves is attached at the ____________

muscle insertion

the bone that does not move is attached at the __________

muscle origin

movement is toward the _______

insertion

flexor muscles _____the angle between two bones at a joint

decrease

extensor muscles _______ the angle between two bones at a joint

increase

define agnoist or prime mover

the main muscle responsible for movement in a given direction

define antagonists

flexors and extensors that act on the same joint to produce opposite actions

Define the action of the Extensor

increases the angle at a joint

Define the action of the flexor

decreases the angle at a joint

Define the action of the abductor

moves limd away form the midline of the body.

define the action of adductor

moves limb toward the midline of the body

define the action of the levator 

moves insertion upward

define the action of the depressor

moves insertion downward

define the action of the rotator

rotates a bone along its axis

define sphincter

constricts an opening

structure of skeletal muscles are so that they are surrounded by a__________

fibrous epimysium

define fibrous epimysium

The external sheath of connective tissue surrounding a muscle

define perimysium

connective tissue that subdivides the muscle into fascicles

define fascicles

a small bundle or cluster, especially of nerve, tendon, or muscle fibers

each fascicle is subdivided into muscle fibers (myofibers) surrounded by what?

endomysium

define endomysium

the sheath of delicate reticular fibrils surrounding each muscle fiber.

define sarcolemma

plasma membranes in muscle fiber structures

muscle fiber structure are multinucleated; form a syncytium


 


TRUE or FALSE

TRUE

muscle fibers are striated name the 3 bands or lines

-I bands


-A bands


-Z lines


 

describe I bands

light bands

describe A bands

dark bands

describe Z-lines (disks)

dark lines in the middle of the I bands

Define motro units

a single motor neuron and all the muscle fibers it innervates


-all muscle fibers in a motor unit contact at once

define graded contractions

varied contractions strength due to different numbers of motor units beings stimulated

what is neuromuscular junction

site where a motor neuron stimulates a muscle fiber

define motor end plate

area of the muscle fiber sarcolemma where a motor neuron stimulates it using the neurotransmitter, acetylcholine

neuromuscular junction =

ach

when ach bind Na+ goes in what channel?

K , potassium

contraction comes from where?

 motor unit recruitment

finer muscle control requires _______ motor units 

smaller, (fewer muscle fibers)

the eye muscles may have _______muscle fibers/motor units

23

how many muscle fibers do larger, stronger muscles have?

thousands

control and strength are not tradeoffs


 


TRUE or FALSE

FALSE, they are tradeoffs

what are striations produced by ?

produced by thick and thin filaments

what kind of filaments do I bands contain? and primarily made up of what?

I bands contain only thin filaments, primarily of the protein, actin 

what kind of filaments do A bands contain? what are they made up of?

-A bands contain all of the thick filament with some thing filament overlap


-the thick filament is the protein, myosin

where are H bands located? how much thin filament overlap?

H bands are the center of the A band with no thin filament overlap

where are Z discs (lines) found?

Z discs are found in the center of each I band

define sarcomere

the basic subunt of striated muscle contraction

The sarcomere is the area from one ___disc to the next

Define Titin

protein that runs from the Z disc to the M line and allows elastic recoil

Where are M lines found?

M lines are found in the center of each A band and help hold down thick filaments

what 3-D pattern does a sarcomere form?

hexagonal pattern

define silding filament theory

when a muscle contracts shorten

A bands do not ______, but move ______together

shorten, closer

I bands do ________, but_______ filaments do not

shorten, thin

Thin filaments slide toward the _______bond

H

H bands ________ or disappears

shorten

how does a myofiber with all its myofibrils shorten?

by movement of the insertion toward the origin of the muscle

what causes the shortening of the myofibrils? 

caused by the shortening of the sarcomeres 


-the distance between Z lines (or discs) is reduced

how is shortening of the sarcomeres accomplished? 

by sliding of the myofilaments


-the length of each remains the same during contraction


 

sliding of the filaments is produced by what?

by asynchronous power strokes of myosin cross bridges, which pull the thin filaments (actin over the thick filaments (myosin)

What bands remain the same length during contraction? but are pulled toward the origin of the  muscle

the A bands

what bands are pulled closer together as the I bands between them shorten?

 Adjacent A bands

which bands shorten during contraction as the thin filaments on the sides of the sarcomeres are pulled toward the middle?

The H bands

define thick myofilaments

composed of the protein myosin

define thin myofilaments

 composoed of the protein actin

which myofilament has two protein globular heads with actin-binding sites and ATP-binding sites?

thick myofilament

which myofilament has proteins called tropomyosin and troponin that prevent myosin binding at rest?

thin myofilaments

what do tropomyosin and troponin prevent?

prevent myosin binding at rest

when sliding is produced by several cross bridges what is formed between them?

myosin and actin

what does the myosin head serve as during the action of sliding?

the myosin head serves as a myosin ATPase enzyme, splitting ATP into ADP+P

define ATP

energy

define ATPase

are a class of enzymes that catalyze the decomposition of ATP into ADP and a free phosphate ion.

what allows the head to bind to actin when the muscle is stimulated?

ATPase breaking down ATO into AD+P

define the power stroke



-pulls the thin filament toward the center

what causes the power stroke

release of P upon binding, cocks the myosin head which produced the power stroke

what happens after the power stroke

ADP is released and a new ATP binds

what  is released by myosin after ADP is released and a new ATP is binded

myosin releases actin

after myosin is released what happens to ATP?

ATP is split

What happens after ATP is split?

the myosin head straightens out and rebinds to actin farther back


this continues until the sarcomere has shortened

what are the steps of the cross bridges

1. resting fiber; cross bridge is not attached to actin


2. cross bridge binds to actin


3. P is released from myosin head, causing conformational change in myosin


4. power stroke causes filaments to slide; ADp is released


5. A new ATp binds to myosin, allowing it to release from actin


6. ATP is hydrolyzed and phosphate binds to myosin, causing cross bridge to return to its original orientation


 

F-actin is made up of how many G-actin subunits?

300-400 G-actin subunits

how is F-actin arranged?

in a double row and twisted to form a helix

what physically blocks cross bridges?

Tropomyosin

Define Troponin complex:

1. Troponin I inhibits binding of myosin


2. Troponin T binds to tropomyosin


3. Troponin C binds to calcium

When is Ca^2+ released inside the muscle fiber?

when muscle cells are stimulated

what causes a conformational change in troponin and tropomyosin?

when Troponin C attaches

______is allowed access to form cross bridges with______

Mysoin, actin

Define SR( sarcoplasmic reticulum)

modified endoplasmic reticulum that stores Ca^2+ when muscle is at rest

where is the most Ca^2+ found in the SR?

in the terminal cisternae

What happens when a muscle fiber is stimulated?

Ca^2+ diffuses out of calcium release channels (ryanodine receptors)

define ryanodine receptors 

-form a class of intracellular calcium channels in various forms of excitable animal tissue like muscles and neurons.


-It is the major cellular mediator of calcium-induced calcium release(CICR) in animal cells.

what happens at the end of a contraction?

Ca^2+ is actively pumped bak into the SR

define transverese tubules

narrow membranous tunnels formed from the sarcolemma

what opens to the extracellular enironment

transverse tubules

Transverse Tubules are not able to conduct action potentials


 


TRUE or FALSE

FALSE, they are able to conduct action potentials

where is Acetylcholine released from?

 a motor neuron

end plate potentials are _______

produced

All-or-none event 

action potentials are generated

what channels change shape is transverse tubules and causes calcium channels in SR to open?

voltage gated calcium channels

when clacium is released what does it bind to?

 troponin C

steps of skeletal muscle contraction and relaxation

1. a nerve impulse traels down and axon and causes the release of acetylcholine.


2. ACH caues the impulse to spread across the surface of the sarcolemma


3. the nerve impulse enters the T tubules and sarcoplasmic Reitculum, stimulating the release of calcium ions


4. calcium ions combine with troponin, shifting troponin and exposing the myosin bindinf sites on the actin


5. ATP breaks down ADP+P. the released energy activates the myosin cross bridges and results in the sliding of thing actin myofilaments.


6. the sliding of the myofilamens draws the Z lines towards each other, the sarcomere shortens, the muscle fibers contract and therefore muscle contracts


7. ACh is inactivated by Acrytcholinesterase, inhibiting the nerve impulse conduction across the sarcolemma


8.nerve impulse is inhibited calcium ions are acitvely transportes back  into the ST, using the energy from the earlier ATp breakdown


9.the low Calcium concentration causes the myosin cross brdiges to seperate from the thin myolifalments and the actin myofilaments return to their releaxed position.


10.sarcomeres return to heir resting lengths, muscle fibers relax and the muscle relaxes

excitation contraction coupling summary

1. somatic neuron releases ACh


 


                   SARCOLEMA


2. binds to nicotinic ACh receptors, open ligand (chemically)- gated channels


3.Na+ diffuses in, producing depolarizing stiumuls


4. Action potentials produced


 


        TRANSVERESE TUBULES


1. Action potentials conducted along transverse tubules


2. action potentials open voltage-gated Ca^2+ channels


        


                              SR


1.Ca^2+ release channels in SR open


2. Ca^2+ diffuses out into sacroplasm


 


                       MYOFIBRILS


1.Ca^2+ binds to troponin, stimulating contraction


 

define troponin

a complex of three regulatory proteins (troponin C, troponin I, and troponin T) that is integral to muscle contraction in skeletal muscle and cardiac muscle, but not smooth muscle.

describe muscle relaxation

-action potentials cease


-calcium release channels close


-Ca^2+-ATPase pumps move Ca^2+ back into SR (ATP)


-No more Ca^2+ is available to bind to troponin C


-Tropomyosin moves to block the myosin heads from binding to actin

Where do you see Ca2+ involved in muscle contractions?

1. in the Pre-Synaptic


2. Excitation Coupling


3.(relaxtion) ATPase pumps

define a twitch

when a muscle quickly contracts and relaxes after a single electrical shock of sufficient voltage

how do you increase the strength of a twitch?

you increase the voltage

define summation

when a second shock is applied immediately after the first, the second twitch will partially piggyback the first

define latent perio of a twitch

time between stimulusand the contraction (excitatio-contraction coupling to the attachement of myosin cross bridges to actin)

Define graded contraction

stronger contractions result in recruitment of more fibers, until all fibers are contracting

Define tetanus

 is a medical condition characterized by a prolonged contraction of skeletal muscle fibers

define incomplete tetanus

increasing the frequency of electrical shocks decreases the relaxtion time between twitches

Define complete tetanus

at a certain frequency there will be no relaxation, just a smooth sustained contraction.

Define Treppe

the graduated series of increasingly vigorous contractions that results when a corresponding series of identical stimuli is applied to a rested muscle

list the Treppe steps

1. as the voltage is increased, the number of muscle fibers used in vitro increases


2. this will reach a maximum value when all muscle fibers are stimulated


3.if a fresh muscle is stimulated with several shocks at maximum voltage, each will be progressively stronger.


4. when recorded, this will produce a staircase effect 

describe Force Velocity curve

for muscle contract they must generate force that is greater than opposing forces


 

the greater the froce, the _____ the contraction

slower

define isotonic contractions

muscle fibers shorten when the tension produced is just greater than the load

define concentric contraction

a muscle fiber shortens when force is greater than load

define eccentric contraction

a muscle may actually lengthen, despite contraction, if the load is too great

what does eccentric contraction allow after a full concentric contraction

allows you to lower a weight gently

define isometric contraction

muscles can't be shorten becuase the load is oo great

can isometric contraction be voluntary?

yes

what has to happen to concontractile parts of the muscle when it contracts?

it must be pulled tight

describe a tendon

-elastic, resist distension, snap back to resting length


-absorb some of the tension as muscles contracts


 

what is muscle strength determined by?

-number of fibers recruited to contract 


-freq of stimulation


-thickness of each muscle fiber (thick is stronger)


-initial length of the fiber at rest

when the tension is maximal, what are the sarcomeres?

at normal resting length

increasing sarcomere length, increases muscle tension


 


TRUE or FALSE

FALSE, increasing sarcomere length, decreases muscle tension

are there fewer or more interactions between myosin and actin, with an increasing sarcomere length, and decreasing muscle tension

fewer

What happens to muscle tension when the sarcomere length decreases? why does it happen

decreases muscle tension


-because the fiber gets shorter and thicker

when the sarcomere length decreases and the muscle tension decreases.


 


what happens to fluid pressure and what happens to the distance between the actin and the myosin? 

-the fluid pressure is increased


-the distance between the actin and myosin is increased

how is energy distributed? between Myosin ATPase and Ca2+

Myosin ATPase 70%


Ca2+ 30%


 

what is the role of the calcium pump 

to actively return calcium to the SR at a 30% clip

where do muscles get thier energy at rest and mild exercise

from the aerobic respiration of fatty acids

where do muscles get their energy for moderate exercise:

from glycogen stores

where do muscles get their energy fro heavy exercise

from blood glucose

as exercise intesnsity and duration increase, ______channels are inserted into the sarcolemma to allow glucose into cells

GLUT4

where are GLUT4 found?

only found in muscle cells and adipose tissues

what is the time for anaerobic of moderate to heavy exercise

45-90 seconds 

anaerobic allows time to increase what?

oxygen supply

what is another name for maximal oxygen uptake

aerobic capacity, or V02 max

what determines whether a given execise is light, moderate, or heavy for a given person

-a persons age, sex, size, and atheltic training

what age group and sex does aerobi capacity the highest?

for males and younger people

what is another name for lactate threshold

anaerobic threshold

what is lactate threshold

another way to determine exercise intensity for a given person

what % of maximal oxygen uptake rises as blood lactate levels occurs

occurs at about 50-70% V02max

need for ____ increases during exercise

glucose

more GLUT4 receptors in __________membrane

plasma

when blood glucose drops, where does the body get more glucose from? and how ?

from the liver, through hydrolysis og glycogen and through gluconeogenesis

define oxygen debt

when a person exercises, oxygen is withdrawn from reserves in hemoglobin and myoglobin

phosphocreatine

molecule that serves as a rapidly mobilizable reserve of high-energy phosphates in skeletal muscle and the brain

when are phosphocreatine stores replenished?

when at rest

how is creatine produced?

by the liver and the kidneys or obtained throught the diet

when is creatine supplements bad for the liver?

whens its used for long periods of time bad 

define slow twitch (type 1)

slower contraction speed; can sustain contraction for long periods witout fatigue


-rich capillary supply


-more mitochondria


-more respiratory enzymes


-more myoglobin

slow twitch muscles have _____oxidative capacity, so are called ______ oxidative fibers

high, slow

due to high myoglobin content found in slow twitch fibers are also called ____ fibers

red

where are slow twitch fibers found?

in postural muscles

define fast twitch fibers (type IIX)

-faster contraction speed


-fatigue fast


-fewer capillaries


-mitochondira


-respiratory enzymes


-less myoglobin

what is another name for fast twitch fibers? 

white fibers

fast twitch fibers have more glycogen stores and are called fast glycolytic fibers


 


TRUE or FALSE

TRUE

where are fast twitch muscles found?

stronger muscles

what are fast oxidative fibers intermediate (type IIA) ?

fast-twitch but with high oxidative capacity; 

why do people vary greatly in the percentage of fast-or slow-twitch fibers in thier muscles

result of genetics and training

what are the Z line thickness characteristics for slow oxydative, fast oxidative, and fast Glycolytic types?

-wide


-intermediate


-narrow

Glycogen content characteristics for slow oxydative, fast oxidative, and fast Glycolytic types?

-low


-intermediate


-high


 

Resistants to fatigue characteristics for slow oxydative, fast oxidative, and fast Glycolytic types?

-high


-intermmediate


-low


 

capillaries characteristics for slow oxydative, fast oxidative, and fast Glycolytic types?

-many


-many


-few

myoglobin content characteristics for slow oxydative, fast oxidative, and fast Glycolytic types?

-high


-high


-low


 

respiration characteristics for slow oxydative, fast oxidative, and fast Glycolytic types?

-aerobic


-aerobic


-anaerobic


 

oxidative capacity characteristics for slow oxydative, fast oxidative, and fast Glycolytic types?

-high


-high


-high


 

twitch rate characteristics for slow oxydative, fast oxidative, and fast Glycolytic types?

-slow


-faster


-fastest


 

diameter characteristics for slow oxydative, fast oxidative, and fast Glycolytic types?

-small


-intermediate


-large

muscle fatigue

reduced ability to generate force

what is muscle fatigue due to?

-accumulation of extracellular K+, reducing membrane potential


-short duration


-depletion of stored glycogen


-reduced SR calcium release


-lactic acid accumulation and lower pH


-increased concentration of PO4 due to phosphocreatine breakdown


-lack of ATP


-buildup of ADP


-fatigue of upper motor neurons (in the CNS), called central fatigue

what are some factors that can lead to adaptation to endurance exercise training?

-increased ability to use fatty acids as fuel and increased intracellular triglyceride storage


-increased lactate threshold


-decreased in type IIX and increase in type IIA muscle fibers


-decreased insulin sensitivity


-increase in number of mitochondria

what are the effects of endurance training on skeletal muscles

-improved ability to obtain ATP from oxidative phosphorylation


-increased size and number of mitochondria


-less lactic acid produced per given amount of exercise


-increased myoglobin content


-increased intramuscular triglyceride content


-increased lipoprotein lipase (enzyme needed to utilize lipids form blood)


-increased proportion of energy derived from fat; less from carbs


-lower rate of glycogen depletion during exercise


-improved efficiency in extracting oxygen from blood


-decreased number of type IIX (fast glycolytic) fibers; increased number of type IIA (fast oxidative) fibers 

what are some characteristics of muscle decline with aging

-reduced muscle mass (type II fibers)


-reduction in capillary blood supply


-fewer satellite cells

how can muscle decline with age be prevented or slowed down

- can be helped with strength training


-can be helped with endurance training


- increased myostatin production

define myostatin

inhibits muscle differentiation  and growth production 


- protein family that inhibits muscle differentiation and growth in the process known as myogenesis. 

define satellite cells

-cells that can fuse to damaged muscle cells and repiar them or fuse to each other to form new muscle fibers

where are satellite cells found

in skeletal muscles, near muscle fibers

define myostatin 

a paracrine regulator that inhibits satellite cells

what 3 proteins does myostatin require to serve as muscle fiber scaffolding

-titin


-nebulin


-obscurin

define titin 

giant protein that functions as a molecular spring which is responsible for the passive elasticity of muscle. 

define nebulin

an actin-binding protein which is localized to the thin filament of the sarcomeres in skeletal muscle.

define obscurin

may have a role in the organization of myofibrils during assembly and may mediate interactions between the sarcoplasmic reticulum and myofibrils. 

define hypertrophy

type II muscle fibers become thicker due to increased amount of actin and myosin (more sarcomeres)

what is the advantage of thicker fibers due to adaptation to strength training

thick fibers can split into two fibers, which can also increase in size

what proteins are required to maintain thicker fibers that split into two fibers that can also increase in size

-titin


-nebulin


-obscurin

describe  lower motoneurons (motor neurons)

neurons whose axons innervate skeletal muscles- also called the "final common pathway" in the control of skeletal muscles

describe higher (motor neurons)motoneurons

 neurons in the brain that are involved in the control of skeletal movements and that act by facilitating or inhibiting (usually by way of interneurons) the activity of the lower motoneurons

describe alpha neurons

lower motoneurons whose fibers innervate ordinary (extrafusal) muscle fibers

descirbe gamma motoneurons

lower motoneurons whose fibers innervate the muscle spindel fibers (intrafusal fibers)

describe agoinst/antagoinst

a pair of muscles or muscle groups that insert on the same bone, the agonist being the muscle of reference

describe synergist

a muscle whose action facilitates the action of the agonist

describe ipsilateral/contralateral

Ipsilateral- located on the same side or the side of reference


contralateral- located on the opposite side

describe afferent/efferent

afferent- sensory neurons


efferent -motor neurons

in skeletal muscle striated ______ and ______ arranged in sarcomeres

actin, myosin

in skeletal muscles well-developed _____ and tranverse tubules

(SR) Sarcoplasmic Reticulum

Skeletal Muscle contains troponin in the _____ filaments

thin

in skeletal muscle what is released into the cytoplasm form SR

Ca2+

skeletal muscle cannot _________ without nerve stimulation; denervation resultsin muscle _______

contract,atrophy

in skeletal muscles fibers are stimulated _______ and have no ___junctions

independently,gap

cardiac muscle are striated and have _____ and ______ arranged in sarcromeres

actin, myosin

cardiac muscle have moderately developed SR and ______

transverse tubules

cardiac muscle contains _____ in thin filaments

troponin

in cardiac muscle _____ enters cytoplasm from SR and extracellular fluid

Ca2+

cardiac muscle can contract without nerve stimulation; action potentials originate in _________cells of heart

pacemaker

in cardiac muscle ________junctions present as intercalated discs

gap 

smooth muscle is not striated; more ____ than ____; ________inserts into dense bodies and cell membranes

actin, myosin, actin

smooth muscle poorly developed _________ and no _________

SR, tranverse tubules

smooth muscle contains calmodulin, a protein that, when bound to Ca2+, activates the enzyme myosin light-chain______________

kinase.

in smooth muscle Ca2+ enters cytoplasm from extracellular fluid, sacroplamsmic reticulum, and perhaps_____________

mitochondria

smooth muscle maintains tone in absence of nerve stimulation; visceral smooth muscle produces pacemaker potentials; denervation results in ______to stimulation

hypersensitivity

smooths muscles's _______junctions present in most smooth muscles

gap

what happens to calcium when smooth muscle relax?

calcium is pumped out to SR using ATPase active transport pumps.

in smooth muscle relaxation calmodulin dissociates from ______light chain kinase

myosin

in smooth muscle relaxation phosphate groups are stripped away from the myosin by __________

myosin phosphatase

list excitation-contraction coupling in smooth muscle

1. begins with rise in intracellular calcium conconcentrations


2. calcium binds to calmodulin (no troponin in smooth muscle)


3. myosin light chain kinase phosphorylates myosin light chains 


4.stimulation is graded. more stimulation allows in more calcium, which allows stronger contractions


5. contractions are slow and sustained

in the beginning of the excitation-contraction coupling in smooth muscle where does the calcium come from?

-only some come from SR


-most come through plasma membrane after voltage-gated calcium channels are opened

when myosin light chain kinase phosphorylates myosin light chains, how does contraction happen?

myosin forms cross bridges with actin to initiate contraction

what is "latch state"?

Allows smooth muscle to keep tone under low ATP hydrolysis conditions, bc it surrounds many hollow organs that need constant tone bc cross bridges are still formed.
 

cardiac and smooth muscles are voluntary or involuntary

involuntary

what are cardiac and smooth muscles regulated by?

ANS (autonomic nervous system)

like skeletal muscle, contraction in smooth muscles are due to _________ cross bridges stimulates by _________

myosin/actin, calcium

cardiac muscle are not striated


 


TRUE or FALSE

FALSE, cardiac muscle are striated

_____ and actin filaments form sarcomeres

myosin

_______ occurs by means of sliding thin filaments

contraction

unlike skeletal muscles fibers, cardiac muscle fibers are ________, ________, and ___________ via gap junctions called intracalated discs

short, branched, connected

define myocardium

is a mass of cardiac muscle cells connected to each other via gap junctions

action potentials that occur at any cell in a myocardium can ___________ all the cells in the myocardium 

stimulate

myocardium behaves a  multi functional unit


 


TRUE OR FALSE 

FALSE, myocardium behaves a single functional unit

where are the myocardium located in the heart?

the atria of the heart compose one myocardium, and the ventricles of the heart compose another myocardium 

how can cardiac muscle produce action potentials automatically? (without innervation)

begin in a region called the pacemaker

heart rate is influenced by what?

autonomic innervation and hormones

unlike skeletal muscle, the voltage-gated calcium channels are not directly connected to ________channels in the SR

Calcium

in cardiac and smooth muscles calcium acts as a _______messenger to open SR channels

second

what is another name for when calcium acts as a second messanger

calcium-induced calcium release

what is slower then calcium-induced calcium release?

excitation-contraction coupling 

where is smooth muscle found

in blood vessel walls, bronchioles, digestive organs, urniary and reproductive tracts

how does smooth muscle propel content of its organs? 

usings peristaltic waves

smooth muscle contains no what?

sarcomeres

smooth muscle contain large amounts of what two proteins?

actin and myosin

smooth muscles have what length of actin filaments? what are they attached to ?

long actin filaments, dense bodies

how are myofilaments arranged? and what can they form with actin ?

myosin filaments are stacked vertically and can form cross bridges

what does the arrangment of myosin filaments in smooth muscle allow?

allows contractions, even when greatly stretched

single unit  smooth muscles

multiple gap junctions that make neighboring cells behave as a unit.

most smooth muscle are a multiunit


 


TRUE or FALSE

FALSE, most smooth muscles are single unit

single unit smooth muscles display pacemaker acitivity moderated by _____ or _______ innervatoin

stretch, autonomic

in single unit smooth muscles Muscarinic ACh receptors respond by closing _____channels

K+, potassium

multi-unit smooth muscles

require individual nerve innervation (no pacemaker activity)

multi-unit smooth muscles have few or no gap junctions


 


TRUE or FALSE

TRUE

smooth muscles arrector pili in skin and ciliary uslces in _____ are mulit -unit

eyes

autonomic innervation

neuroransmitter is released along the length of an autonomic neuron from varicosities

where are the receptors proteins located on the smooth muscles?

on the entire surface of smooth muscles

autonomic innervation forms synapses en passant


 


TRUE or FALSE

TRUE

lower motor neurons(motoneurons)

cell bodies in ventral horn of spinal cord or in the brain stem

how do  skeletal muscles travel to the spinal nerves?

by way of the ventral root

Skeletal muscles are influenced by sensroy feedback from _____ and _______

muscles, tendons

name the skeletal muscle sensory organs

-intrafusal fibers


-extrafusal fibers


-golgi tendon organs


-muscle spindle apparatus

muscles that are made of thin muscle cell are called

intrafusal fibers

regular muscle fibers are called

extrafusal fibers

golgi tendon organs

respond to tension a muscle puts on a tendon

muscle spindle apparatus

respond to muscle length

in a muscle spindle apparatus a muscle that reuquires more control have ______ spindles

more

in a muscle spindle stretching a muscle causes spindles to ______

stretch

muscle spindle apparatus contains ______ muscle cells called intrafusal fibers

thin

name two types of intrafusal fibers

nuclear bag fibers-


nuclear chain fibers


 

define nuclear bag fibers

nuclei in loose central aggregates

define nuclear chain fibers

nuclei in rows

alpha or gamma are going to innervate intrafusal

gabba

two types of sensroy cell wrap around fibers

primary (annulospiral)


secondary (flower-spray)

define primary (annulosprial)

most stimulated at the beginning of the stretch

define secondary  (flower spray)

respond more during sustained stretch

what is an alpha motorneuron?

innervate extrafusal (contracting) muscle fibers

what is a gamma motoneurons?

innervate intrafusal (active stretch) muscle fibers

alpha and gamma are both stimulated by which motoro neurons?

upper motor neurons at the same timecoacti

coactivation

both types of motor neurons alpha nad gamma are stimulated by upper motor neurons at the same time

skeletal muscle are usually referred to as _____ and are controlled by descending motor pathways under ______Control

voluntary, conscious

define a reflex

a skeletal muscle contracting unconsciously in response to a certain stimuli

monosynaptic stretch reflex?

simplest reflex

in monosynaptic strecth reflex it only involves a sensroy neuron synapsing on a motor neuron in the ________cord

spinal

one synapse equals

monosynaptic

muscle stretch reflex

maintains optimal length of skeletal muscles

whats the name of a stimiulation by stiking the patellar ligament

knee jerk reflex

golgi tendon organs

constantly monitor tension in tendons

_____ inhibits motor neuron

interneuron

disynaptic reflex involves how many synapses?

two

golgi tendon organs steps

1. tension on tendon activates sensroy neuron


2. sensroy neuron stimulates interneruon


3. interneuron inhibits motoneuron


4. tension on tendon is reduced

what is a reciprocal innervation in knee-jerk-reflex

when interneurons are stimulated in the spinal cord to inhibit antagonisttic musles on that limb

define double reciprocal innervation

a more complex reflex that requires contorl of muscles on the contralateral limb

reciprocal innervation

1. muscle stretch activates spindle apparatus


2. agonist muscle contracts in stretch reflex


3. antagoinst muscle relaxes

define crossed extensor reflex

type of double reciprocal innervation seen when you step on a tack

steps for crossed extensor reflex

1. flexor contracts and extensor relaxes to withdraw foot


2. extensor contracts and flexor relaxes in contralateral leg to support weight

upper motor neuron control pecentral gyrus

sends neurons through pyramidal tracts (contralateral) by the lateral and ventral cotricospinal tracts

neurons through extrapyamidal tracts

reticulospinal tracts

define reiculopspinal tract

inhibition of lower motorneurons

define cerebellum

receives information from muscle spindles and Golgi tandon organs as well as other senses

what inhibits regions of the basal nuclei, red nucei, and vestibular nuclei?

cerebellum

define basal nuclei

also act to inhibt motor activivty through the rubrospinal tract

define Babinski's reflex

extension of the great tow when the sole of the foot is storked along the lateral border

Spastic paralysis

high muscle tone and hyperactive stretch reflexes; flexion of arms and extension of legs

Hemiplegia

paralysis of upper and lower limbs on one side- commonly produced by damage to motor tracts as they pass through internal capsule (such as cerbrovascular accident-stoke)

paraplegia

paralysis of the lower limbs on both sides as a result of lower spinal cord damage

quadriplegia

paralysis of upper and lower limbs on both sides as a result of damage to upper region of the spinal cord or brain

chorea

random uncontrolled contractions of different muscle groups( as in Saint Vitus dance) as a result of damage of basal nuclei

resting tremor

shaking of limbs at rest; disappears during voluntary movements; produced by damage to basal nuclei

intention tremor

oscilltions of the arm following voluntary reaching movements; produced by damage to cerebellum

1. The stretch reflex is a ____________ reflex because the sensory neuron synapses directly with the motor neuron and does not use an interneuron involving spinal cord interneurons.

monosynaptic


 


The stretch reflex is a monosynaptic reflex because it involves only one synapse within the CNS. Striking the patellar ligament with a mallet is an example of a monosynaptic stretch reflex. You may review the monosynaptic stretch reflex in detail in Section 12.5:  Neural Control of Skeletal Muscles of the text.

As opposed to the upper motor neurons, the lower motor neurons have their cell bodies located in the ________________.

spinal cord as opposed to the brain

the maximum rate of oxygen consumption in the body

aeriobic capacity

the percentage of the ocygen uptake at which a signaificant rise in blood level occurs

lactate thresholdre

reversible, exercise induced reduced ability in the muscle to generate force

muscel fatigue

Muscle contraction is caused by

actin filaments sliding past myosin filaments.


 

Which of the following statements about H zones and I bands is TRUE?

the H zones contain only myosin, while the I bands contain only actin


 

During muscle contraction

the A band remains the same and the I band narrows.


 

1. Each somatic motor neuron, together with all of the muscle fibers it innervates, is called a ____________.

motor unit

An action potential enters a muscle cell ______________________.

by the T-tubules.


 

What structures do the calcium ions bind to when muscle contraction is initiated?

the troponin molecule.

Cross bridges form between _________________.

the actin filaments and the myosin heads.

A person who sprints for 45 seconds obtains most of their energy from

muscle glycogen.


 

What happens to the amount of muscle glycogen used for energy as exercise continues?

it decreases


 

After 3 hours of exercise what are the main sources of energy?

blood glucose and plasma free fatty acids


 

Where are most plasma free fatty acids obtained from?

hydrolysis of stored fat


 

What happens to the amount of plasma free fatty acids used for energy as exercise continues?

they increase


 

The inhibition of motor neurons of antagonist muscles during stretch reflexes is called ______________________.

reciprocal inhibition

1. Skeletal muscles are able to generate their greatest force during a contraction when their length is ____________ of their normal resting length.

100-120%


 

1. Cells adapt to endurance training by increasing their numbers of mitochondria


 


true or false

true

 Endurance training is improved when muscles reduce the amount of muscle glycogen they use for energy


 


true or falset

true

Resistance training results primarily in an increase in Type I fibers


 


true or false

false

 An increase in muscle size (hypertrophy) is the result of an increase in the number of muscle fibers


 


true or false

false

If a muscle is already at about 80% of its resting length, it cannot be stimulated to contract any more because __________________.

the Z lines abut against the thick filaments and cannot go any further

During contraction of a muscle, calcium ions bind to...

the troponin molecule.


 

The bond between the actin and myosin head is broken when...

an ATP molecule binds to the myosin head.


 

Energy is released when...

ATP is broken down into ADP and phosphate.

Which of the following shortens in length during during skeletal muscle contraction?

I bands

intermediate glycogen content has what type of fiber

type IIA

few capillaries has what type of muscle fiber?

type IIX

wide Z line thickness has what type of muscle fiber?

Type I

. Smooth muscles cells have a striated appearance


 


true or false

false

The ratio of thin to thick filaments in smooth muscle is about 16:1


 


true or false

true

Thin filaments in smooth muscles attach to Z discs


 


true or false

false

 Smooth muscle cells are capable of producing graded depolarizations and contractions


 


true or false

true

Smooth muscle contractions are fast and operate on the all-or-none principle


 


true or false

false

muscle tenison causes shortening

concentric contraction

Muscle tension does not cause shortening of the muscle

isometric contracction

Lengthening contraction

eccentric contraction

Each actin filament is composed of _________________________.

two strands of actin molecules wrapped together.


 

As actin and myosin filaments slide past each other during muscle contraction,

neither actin nor myosin filaments shorten.


 

Which of the following statements about the "heads" of the myosin molecules is TRUE?


they can attach to different sites on the actin filament


 

the nervous system regulates skeletal muscle contraction by receiving constant _______feddback

sensory

the tension a muscle exerts on its tendons is deetermined by _____ tendon organsgol

golgi

the muscel spindle _______ provides input on muscle length

apparatus

the thin muscle cell within the connective tissue sheath are called __________

intrafusual fibers

the muscle fibers which inset into the tendons of the muscle are called____ fibers

extrafusal

The sequence for skeletal muscle contraction is...

increased cytosolic calcium, which binds to troponin, which moves tropomyosin from blocking active sites on actin filament, which binds with myosin cross-bridges, resulting in contraction.


 

Which of the following statements is true concerning calcium ions?

in smooth muscle it binds with calmodulin.


 

Smooth muscle and skeletal muscle fibers both have their contractions triggered by calcium ions.


 


true or false

true

The structures responsible for monitoring muscle tension in the tendons during muscle contraction are:

Golgi tendon organs