Muscle tissue WUQ 3

axolemma

( sheath or husk )

Muscle tissue property: Extensibility

Ability of a muscular tissue to stretch without being damage Allows the muscle to contract forcefully even if it is already stretched (smooth muscle)

Muscle tissue property: Contractility

Ability of muscular tissue to contract forcefully and stimulated by an action potential

Muscle tissue property: Elasticity

Ability of muscular tissue to return to its original length and shape after contraction or extension

Conective Tissue Components

-Connective tissue surrounds + protects muscular tissue

somites appears on

20th day of embryonic development

H zone

A narrow region in the center of each A band that contains thick filaments but no thin filaments

acetylcholinesterase ( AChE )

ACh is rapidly broken down by enzyme

visceral layer (Attached to surface of tendon )

-Inner layer of tendon sheath

M line

A region in the center of the H zone that contains proteins that hold the thick filaments together at the center of the sarcomere

FOG fibers can generate considerable

ATP by aerobic cellular respiration , which gives them moderately high resistance to fatigue

contraction cycle consists of four steps

ATP hydrolysis, Attachment of myosin to actin to form crossbridges, Power stroke, Detachment of mysin from actin

Faster reactions use

ATP more rapidly , and more oxygen is needed to produce ATP

Stimulates meaning

Action of various agents on muscles, nerves, or sensory end organ

If another nerve impulse releases more acetylcholine ,

Activation of ACh receptors and Production of muscle action potential repeat

tendon ( synovial ) Sheaths

ArTendons enclosed by tubes of fibrous CT

Sensory Nervous system or Afferent division

Are synonymous, bring "input" info into the CNS from receptors

Autonomic nervous system

Automatic reflexes they happen if we think about it or not, control our involuntary tissues

Slow oxidative ( SO ) fibers appear SO fibers generate ATP mainly by

Because they have many large mitochondria , SO fibers generate ATP mainly by aerobic cellular respiration

nerve impulse elicits muscle action potential in following way Activation of ACh receptors

Binding two molecules of ACh to receptor on motor end plate opens ion channel in ACh receptor . Once channel is open , small cations , Na + , can flow across membrane

Responding to information (effectors)

CNS may promote change by directing effectors ( effect or change)

Processing and evaluating information

CNS processes and evaluates info from receptors

Functional of CNS - Collecting Information (receptors)

CNS: Collect information about internal stimuli in our environment at receptors

Skeletal muscle contains

CT Surrounding muscle fibers and muscles , blood vessels , and nerves

All 3 CT continous w

CT that attaches skeletal muscle to other structures -bone to another muscle -May extend beyond muscle fibers to form tendons

When Ca² + release channels opens

Ca2 + flows out of the SR into the cytosol around the thick thin filaments

Motor Nervous system or Efferent division

Carries info/commands from CNS to effectors , "output" Cause change

sarcoplasmic reticulum membrane contains

Ca² + active transport pumps that use ATP to move Ca² + constantly from cytosol into SR

As muscle action potential propagates along the sarcolemma and into the tubules , it causes

Ca² + release channels in the SR membrane to open

ganglia (nervous system)

Collection of neuron cell bodies outside the CNS and within PNS nerves

Skeletal muscle contains

Connective tissue surrounding muscle fibers and muscles, blood vessels, nerves

Skeletal muscle fibers also _________ and _________ at different speeds , and vary in which metabolic reactions they use to generate ATP and in how quickly they fatigue fiber.

Contract; relax

_________ cycle does not always result in shortening of the muscle fibers and the whole muscle

Contraction

How is skeletal muscle controlled

Controlled by neurons (nerve cells) and part of somatic voluntary

Muscle tissue has 4 special properties that enable function and contribute to homeostasis:

Extensibility, elasticity, Electrical excitability, Contractility

if maximal force is required , motor units of ___________ are also called into action

FG fibers

muscles have a high proportion of

FG fibers

myosin light chain kinase

After binding Ca² + calmodulin activates enzyme uses ATP to add a phosphate group to portion of myosin head Once phos phate group is attached , myosin head can bind to actin , and contraction can occur

contraction cycle - Detachment of myosin from actin

At end of power stroke , crossbridge remains firmly attached to actin until it binds another molecule of ATP . As ATP binds to the ATP binding site on myosin head myosin head detaches from actin

Contraction cycle - Detachment of myosin from actin

At end of the power stroke , the crossbridge remains firmly attached to actin until binds another molecule of ATP . As ATP binds to ATP binding site on myosin head , the myosin head detachest from actin

Cardiac muscle tissue has an

Cardiac muscle tissue has an endomysium and perimysium

Nucleus

Control center of the cell

neurogenesis

Creation of new neurons

Special receptors

Eyes, ears, nose senses

The hypodermis does

It separates muscles from skin

Afferent is

Means to carry towards or to something (to CNS)

2 types of tissues within nervous system

Neurons (nerve cells) and neural glial cell

cytoplasm contains

Nissl bodies , mitochondria , other organelles

Visceral sensory

Organ senses; (not rlly aware), outside of conscious awareness

Hypo dermis areolar CT and adipose CT provide

Pathway for nerves, blood vessels, lymphatic vessels to enter and exit muscles

CT element extends as

Per kende broad , flat layer tendon known as aponeurosis

2 actions of efferent/motor division

Somatic NS and Autonomic NS

3 receptors in body

Special sensory, somatic sensory, visceral sensory

ATP

adenosine triphosphate

intercalated discs ( to insert between )

are unique to cardiac muscle fibers

axon and its collaterals end by dividing into many fine processes called

axon terminals ( telodendria )

sarcoplasmic reticulum releases _______ into the cytosol

calcium ions ( Ca2 + )

central nervous system ( CNS )

consists of the brain and spinal cord

intercalated discs contain

desmosomes

neurons ( nerve cells ) possess

electrical excitability

Sympathetic NS means

fight or flight response

-between layer is a cavity that contains

film of synovial fluid

Sarcoplasm includes

glycogen

Release of Ca² + from the terminal cisterns of the sarcoplasmic reticulum triggers

muscle contraction

increase in Ca² + concentration in the cytosol starts

muscle contraction

SR encircles each

myofibril

contraction cycle repeats as the

myosin ATPase hydrolyzes the newly bound molecule of ATP and continues as long as ATP is available

two contractile proteins in muscle are

myosin and actin

On each actin molecule is a

myosin binding site

myosin binding site

myosin head can attach

contraction cycle - ATP hydrolysis

myosin head includes an ATP binding site and an ATPase , enzyme that hydrolyzes ATP into ADP and a phosphate group

two projections of each myosin molecule are called

myosin heads

crossbridges

myosin heads attach to actin during contraction

somatic motor neurons

neurons that stimulate skeletal muscle fibers to contract

Somatic motor neurons

neurons that stimulate skeletal muscle to contract

anaxonic

neurons without an axon

neurons contain two or even three types of

neurotransmitters

smooth muscle tissue powers are still limited when compared with

other tissues , such as epithelium

cardiac muscle requires a constant supply of

oxygen

long contraction is due to

prolonged delivery of Ca2 + into sarcoplasm

Z discs main component

protein actin

myoglobin

protein found only in muscle , binds oxygen molecules that diffuse into muscle fibers from interstitial fluid

Motor proteins

push or pull various cellular structures to achieve movement by converting chemical energy in ATP to mechanical energy of motion or production of force

fibrosis

replacement of muscle fibers by fibrous scar tissue

If two stimuli are applied , one immediately after the other , the muscle will

respond to first stimulus but not to the second

Neuronal cell bodies contain free

ribosomes and prominent clusters of rough endoplasmic reticulum termed Nissl bodies

Contraction cycle - Power stroke

rotates and releases the ADP After crossbridges form , the power stroke occurs . During power stroke , the site on crossbridge where ADP is still bound opens . As result , the crossbridge

As smooth muscle fiber contracts , it

rotates as corkscrew turns . The fiber twists in helix as it contracts , and rotates in opposite direction as it relaxes

columns of mesoderm undergo

segmentation into series of cube shaped structures called somites

most of the unique functions of the nervous system , such as

sensing , thinking , remembering , controlling muscle activity , and regulating glandular secretions

3 types of functional classifications of neurons

sensory (afferent), motor (efferent), interneurons

nervous system grouped into three basic functions

sensory , integrative , and motor

synaptic cleft

separates the two cells (somatic motor neuron and muscle fiber)

Slow oxidative ( SO ) fibers are

smallest in diameter and thus are the least powerful type muscle fibers

stimulus is any change in the environment that is

strong enough to initiate an action potential

neuromuscular junction ( NMJ )

synapse between somatic motor neuron and skeletal muscle fiber

Release of acetylcholine , ACh then diffuses across

synaptic cleft between motor neuron and motor end plate

tips of some axon terminals swell into bulb shaped structures called

synaptic end bulbs

When neurotransmitter molecules are released from

synaptic vesicles , they excite or inhibit other neurons , muscle fibers , or gland cells .

During exocytosis

synaptic vesicles fuse with motor neuron's plasma membrane , liberating ACh into synaptic cleft

Ca² + concentration in the cytosol rises

tenfold or more

extra oxygen is used to

" pay back " or restore metabolic conditions to the resting level in three ways

neurons have three parts

( 1 ) a cell body , ( 2 ) dendrites , and ( 3 ) an axon

cells of somite differentiate into three regions

( 1 ) a myotome , ( 2 ) a dermatome , ( 3 ) a sclerotome

Muscle fibers have three ways produce ATP

( 1 ) from creatine phosphate , ( 2 ) by anaerobic cellular respiration , and ( 3 ) by aerobic cellular respiration

Muscle tissue has two sources of oxygen

( 1 ) oxygen that diffuses into muscle fibers from the blood and ( 2 ) oxygen released by myoglobin within muscle fibers

skeletal muscle fibers are classified into three main types

( 1 ) slow oxidative fibers ( 2 ) fast oxidative glycolytic fibers and ( 3 ) fast glycolytic fibers

restore metabolic conditions to the resting level in three ways

( 1 ) to convert lactic acid back into glycogen stores in liver , ( 2 ) to resynthesize creatine phosphate and ATP in muscle fibers , and ( 3 ) replace oxygen removed from myoglobin

steps that connect excitation

( a muscle action potential propagating along the sar colemma and into the T tubules ) to contraction ( sliding of the filaments ) .

Titin

( gigantic ) is the third most plentiful protein in skeletal muscle ( after actin and myosin )

Dendrites

( little trees ) are receiving or input portions of neuron . usually short , tapering , and highly branched

effectors

( muscles and glands )

What cardiac muscle does

Form most of heart walls

Interneurons

Found only in CNS ... Sometimes may link sensory to motor (right in between)

When muscle contracts

Generates tension (force of contraction) while pulling on its attachment point

Liver cells can convert some of lactic acid back to

Glucose

Unipolar

Have dendrites and one axon that are fused together to form continuous process that emerges from the cell body.

Bipolar

Have one main dendrite and one axon

Oxygen use after exercise also

Is boosted by ongoing changes

Adipose connective tissue of hypo dermis layer does

It stores Body's triglycerides, serves as insulting layer that reduces heat loss and protects muscles from physical trauma

What is the hypodermis composed of

It's composed of areolar CT and adipose CT

How is cardiac muscle controlled

It's not consciously controlled by the contracts and relaxation of the heart

Cardiac muscle fibers can also use ______ _______ produced by skeletal muscle fibers to make _______ a benefit during exercise

Lactic acid; ATP

neurons need a constant supply of

Lots of glucose (sugar/energy) released and oxygen (used for ATP) taken in to undergo aerobic respiration (need energy constantly)

FG fibers have _______ myoglobin content

Low

Molecules of the protein myomesin form

M line

Z discs

Narrow , plate - shaped regions of dense protein material

Z discs

Narrow , plate shaped regions of dense material that separate one sarcomere from the next

Example of extensibility

One stomach feels with food, muscle and wall is stretched... Cardiac muscle stretched each time heart is filled with blood

Each skeleton muscle separates

Organ composed of hundreds to thousands of cells called muscle fibers( elongated cells)

Muscle tissue property: Electrical excitability

Properties of both muscle and nerve cells ability to respond to certain stimuli by producing electrical signals (action potential)

hypodermis provides

Provides pathway for nerves , blood vessels , lymphatic vessels to enter and exit muscles

_________ is one factor responsible for producing smooth movements rather than a series of jerks

Recruitment

muscle action potential in 4 ways

Release of acetylcholine, Activation of ACh receptors, Production of muscle action potential, Termination of ACh activity

unfused ( incomplete ) tetanus

Result in sustained but wavering contraction

Perimysium

Surrounds groups of 10-100 or more muscle fibers and separates them into bundles of fascicles

2 divisions of autonomic NS

Sympathetic NS and Parasympathetic NS

A band

The darker middle part of the sarcomere which extends the the entire length of the thick filaments

nerve impulse elicits muscle action potential in following way Production of muscle action potential

The inflow of Nat makes inside of muscle fiber more positively charged . This change in membrane potential triggers muscle action potential . The muscle action potential then propagates along sarcolemma into T tubule system . This causes the sarcoplasmic reticulum to release stored Ca2 + into sarcoplasm and muscle fiber subsequently contracts

Muscle cell and muscle fibers have

The same structure

sensory (afferent) neurons function

They deliver sensory information from receptors CNS

Fascicles give

They give a cut of meat it's characteristic " grain " , if you tear a • piece of meat it rips apart along fascicles

motor (efferent) neuron function

They originate in CNS and make way out of CNS to some kind of effectors either somatic neuron or autonomic neuron that will help us determine it's effector it's stimulating

What do neurons do

They receive, conduct and transmit action potential

Neural glial cells (glia)

They support, protect and nourish the neurons

somatic nervous system

Thing you can control and aware of, can control one thing only

Somatic motor neurons are

Threadlike axon that extends from brain or spinal cord to group of skeletal muscle fiberskum

3 sensory receptors are stimulated somatic sensory receptors and that information is sent

To afferent division in an input to CNS and tells brain information (someone is touching you, information goes to brain an input)

Efferent

To carry away (away from CNS)

Muscle tone keeps skeletal muscles firm , but it does not result in

a force strong enough to produce movement

skeletal muscle tissue can regenerate only to

a limited extent

muscle fatigue protective mechanism to stop

a person from exercising before muscles become damaged

In skeletal muscle about 300 molecules of myosin form

a single thick filament

electrical excitability

ability to respond to a stimulus and convert it into an action potential

metabolic changes that occur during exercise can

account for only some of extra oxygen used after exercise

skeletal muscle contracts only after it is activated by

acetylcholine released by nerve impulses in its motor neurons

Thin filaments contain

actin troponin and tropomyosin

dense material of the Z discs contains molecules of

actinin , which bind to actin molecules of the thin filament and to titin

smooth muscle tissue is usually

activated involuntarily

small groups of motor units are alternatively

active and inactive in constantly shifting pattern

Wave summation and both kinds of tetanus occur when

additional Ca² + is released from sarcoplasmic reticulum by subsequent stimuli while levels of Ca² + in sarcoplasm are still elevated from first stimulus

Muscular activity that lasts longer than half a minute depends increasingly on

aerobic cellular respiration

cardiac muscle depends largely on

aerobic cellular respiration to generate ATP

Lipofuscin is a product of neuronal lysosomes that accumulates as the neuron

ages but does not seem to harm the neuron

intercalated discs contain gap junctions which

allow muscle action potentials to spread from one cardiac muscle fiber to another

nervous system carries out complex array of tasks

allows us to sense various smells , produce speech , and remember past events , it provides signals that control body movements , regulates operation of internal organs

hyperplasia

an increase in number of fibers

tissue repair processes are occurring at

an increased pace

nervous system integrates ( processes ) sensory information by

analyzing and storing some of it and by making decisions for appropriate responses

Neurons (nerve cells)

and are structural and functional units of the nervous system

I band

and thin filaments side . The I band is a lighter , less dense area that contains the rest of the thin fila ments but no thick filaments

myoglobin and hemoglobin are

are oxygen binding proteins . They bind oxygen when it is plentiful and release oxygen when it scarce

hypodermis Composed of

areolar CT and adipose CT

The sarcoplasm of smooth muscle fibers are not

arranged in orderly sarcomeres as in stri ated muscle

slow oxidative fibers appears to increase due to

atrophy of other fiber types or conversion into slow oxidative fibers

visceral smooth muscle is

autorhythmic

Along length of axon , side branches called

axon collaterals

trigger zone , from which they travel along

axon to their destination

cytoplasm of an axon called

axoplasm

Muscle contraction occurs because

because myosin heads attach to and along the thin filaments at both ends of a sarcomere pulling thin filaments towards M line

nuclei of a skeletal muscle fiber are located

beneath the sarcolemma

calsequestrin

bind to Ca2 + , enabling even more Ca² + to be stored within the SR

excitation contraction coupling

binding sites are free , myosin heads bind to them to form crossbridges , and contraction cycle begins

calmodulin

binds Ca² + in cytosol

relaxed muscle myosin is

blocked from binding to actin because strands of tropomyosin cover the myosin binding sites on actin

Glucose easily passes from the

blood into contracting muscle fibers via facilitated diffusion and also produced by breakdown of gylcogen within muscle fibers

Isotonic contractions are used for

body movements and for moving objects

sensory infor mation is carried into

brain and spinal cord through cranial and spinal nerves

prolonged periods of muscle contraction increases in

breathing rate and blood flow enhance oxygen delivery to muscle tissue

twitch contraction

brief contraction of all muscle fibers in motor unit in response to single action potential in motor neuron

latent period

brief delay occurs between application of the stimulus ( time zero on the graph ) . The delay which lasts about two milliseconds

neurofibrils composed of

bundles of intermediate filaments that provide the cell shape and support

terminal cisterns

butt against the T tubule from both sides

sarcoplasmic reticulum stores

calcium ions ( Ca² + )

Neurons have extreme longevity meaning

can last years or lifetime and when produced can last or persist for years

rhythmic activity is a major physiological difference between

cardiac and skeletal muscle tissue

principal tissue in the heart wall is

cardiac muscle tissue

Involuntary tissues/muscles

cardiac, smooth muscle, Glands

Endurance exercises also result in what changes

cardiovascular and respiratory changes that cause skeletal muscles to receive better supplies of oxygen and nutrients but do not increase muscle mass

H zone in the

center of each A band contains thick but not thin filaments

nervous system consists of two main subdivisions

central nervous system ( CNS ) and peripheral ner vous system ( PNS )

released calcium ions combine with troponin , causing it to

change shape

central fatigue is caused by

changes in central nervous system ( brain and spinal cord )

Fatigue results mainly from

changes within muscle fibers

filaments are arranged in

compartments

Skeletal muscle fibers are not all alike in

composition and function

two types of isotonic contractions are

concentric and eccentric

axon hillock

cone shaped elevation ( small hill ) .

When smooth muscle fibers are stretched , they initially

contract , developing increased tension

Stimulation of the effectors causes muscles to ______ and glands to _______

contract and secrete

Most smooth muscle fibers _____ or ______ in response to action potentials from the autonomic nervous system

contract or relax

myofibrils (little fiber)

contractile organelles of skeletal muscle

Both thin and thick filaments are directly involved in the

contractile process

Myofibrils are built from three kinds of proteins

contractile proteins , regulatory proteins , structural proteins

increase in concentration of Ca² + in cytosol of smooth muscle fiber initiates

contraction

mechanisms regulate _____ and ______ of smooth muscle cells

contraction and relaxation

ATP is needed to power the

contraction cycle

structural proteins

contribute to the align ment , stability , elasticity , and extensibility of myofibrils

motor response by activating effectors through

cranial and spinal nerves

myosin heads are attached to actin , forming

crossbridges and generating force

sarcoplasm

cytoplasm of a muscle fiber

Dystrophin

cytoskele tal protein that links thin filaments of the sarcomere to integral membrane proteins of the sarcolemma

A band

dark middle part of the sarcomere that extends the entire length of the thick filaments and also includes parts of the thin filaments that overlap with the thick filaments

Slow oxidative ( SO ) fibers appear

dark red because they contain large amounts of myoglobin and many blood capillaries

loss of muscle mass is a

decrease in maximal strength , slowing of muscle reflexes , and a loss of flexibility

With aging decline is due to

decreased levels of physical activity

junctional folds

deep grooves in motor end plate that provide large surface area for ACh

Fascia

dense Sheet broad band of irregular CT that lines body wall + limbs + supports and surrounds muscles and organs of body

Bundles of intermediate filaments attach to

dense bodies and stretch from one dense body to another

As mesoderm develops part of it becomes arranged in

dense columns on either side of developing nervous system

Epimysium + perimysium = what kind of CT

dense irregular CT

Cell of somite 3/3 - Sclerotome

dermis which gives rise to the vertebrae

ratio of fast glycolytic ( FG ) and slow oxidative ( SO ) fibers in each muscle is genetically

determined and helps account for individual differences in physical performance

transformed muscle fibers show slight increases in

diameter , number of mitochondria , blood supply , strength .

glycogen is made much later from

dietary carbohydrates

called different motor units of entire muscle are not

different stimulated to contract in unison

muscle fibers of a motor unit are

dispersed throughout muscle rather than clustered together

certain smooth muscle fibers , retain their capacity for

division and thus can grow by hyperplasia

lengths of the individual thick and thin filaments

do not change

total number of skeletal muscle fibers usually

does not increase , the characteristics of those present can change to some extent

When skeletal muscle fiber is stimulated at higher rate of 80 to 100 times per second , it

does not relax at all

quickly breaks down

each glucose molecule into two molecules of pyruvic acid

When length of a muscle increases during a contraction , the contraction is an

eccentric isotonic contraction

Nerve impulse elicts muscle action potential in following way - Termination of ACh activity

effect of ACh binding lasts only briefly because ACh rapidly broken down by enzyme called acetylcholinesterase . This enzyme attached to collagen fibers in extracellular matrix of synaptic cleft . AChE breaks down ACh into acetyl and choline , products cannot activate ACh receptor

Once sensory information is integrated , the nervous system may elicit an appropriate motor response by activating

effectors ( muscles and glands )

position titin molecule that extends from the Z disc is very

elastic

action potential nerve impulse ) is an

electrical signal that propagates ( travels ) along the surface of membrane of a neuron

recovery oxygen uptake

elevated use of oxygen after exercise

Skeletal muscle fiber arises during

embryonic development from fusion

Outermost layer - Epimysium

encircling the entire muscle

muscle fibers

endomysium , perimysium epimysium

People with higher percentages of SO fibers are better at activities that require

endurance , such as long distance running

contraction cycle- Attachment of myosin to actin to form crossbridges

energized myosin head attaches to myosin binding site on actin and releases previously hydrolyzed phosphate group

creatine phosphate

energy rich molecule that is found only in muscle fibers

hypertrophy

enlargement of existing cells

hypertrophy ( above or excessive )

enlargement of existing muscle fibers

Cardiac muscle tissue lacks an

epimysium

Because various filaments have no regular pattern of overlap , smooth muscle fibers do not

exhibit striations causing a smooth appearance

filaments inside a myofibril do not

extend the entire length of a muscle fiber

3 layers of CT extend from

fascia ( protect + Strengthen) skeletal muscle

oxida tive fibers contain

fibers , large amounts of myoglobin and many blood capillaries also have a dark red appearance

Tendons

fibers that attach dense regular CT composed of parallel bundles of collagen fibers that attach a muscle to periosteum of a bone

skeletal muscle tissue undergoes muscle

fibrosis

With aging , humans undergo a slow progressive loss of skeletal muscle mass that is replaced largely by ______ connective tissue and _______ tissue

fibrous; adipose

Telodendria

fine terminal extensions at the end of the axon and its collaterals

After organ empties , the smooth muscle in the wall rebounds , and the wall retains its

firmness

neurotransmitter

first cell communicates with the second by releasing a chemical

When the motor neurons serving a skeletal muscle are damaged or cut , the muscle becomes

flaccid (flabby)

sarcoplasmic reticulum

fluid filled system of membranous sacs

crossbridge generates

force as it rotates toward the center of the sarcomere , sliding the thin filament past the thick filament toward the M line

combination of tautness of elastic com ponents and partially contracted state of the filaments enables the

force of another contraction to be greater than one before

Tendon Sheaths reduce

friction as tendons slide back n forth

dense bodies , which are

functionally similar to Z discs in striated muscle fibers

cells retain the capacity to

fuse with one another or with damaged muscle fibers to regenerate functional muscle fibers

contractile proteins

generate force during contraction

with Action potentials always have the same size in a

given neuron or muscle fiber

When muscle activity con tinues and the supply of creatine phosphate within the muscle fiber is depleted

glucose is catabolized to generate ATP

aerobic cellular respiration is slower than

glycolysis

Endurance type ( aerobic ) exercises , such as running or swimming , cause

gradual transformation of some FG fibers into fast oxidative glycolytic ( FOG ) fibers

heart and muscles used in breathing are still working

harder than they were at rest , and consume more ATP

After muscle contraction has stopped

heavy breathing continues for a while , and oxygen consumption remains above resting level

regulatory proteins

help switch the contraction process on and off

intercalated discs contain desmosomes which

hold the fibers together

M line

hold the thick filaments together at the center of the H zone form the M line

Fascia holds

holds muscles us similar functions toget ether

Because mature skeletal muscle fibers have lost the ability to undergo cell division , growth of skeletal muscle after birth is due mainly to

hypertrophy

Smooth muscle tissue like skeletal and cardiac muscle tissue can undergo

hypertrophy

cardiac muscle fibers can undergo

hypertrophy in response to increased workload

overall result is muscle enlargement due to

hypertrophy of the FG fibers

Motor Unit Recruitment is the process

in which number of active motor units increases

muscle fatigue

inability of muscle to maintain force of contraction after prolonged activity

With aging relative number of slow oxidative fibers appears to

increase

Sensory receptors detect internal stimuli such as an

increase in blood acidity , and external stimuli , such as raindrop landing on arm

hyperplasia ( molding )

increase in the number of fibers

FG fibers increase in size due to

increased synthesis of muscle proteins

increase in size of FG fibers is due to

increased synthesis of thick and thin filaments

length tension relationship

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

multiunit smooth muscle tissue consists of

individual fibers , each with own motor neuron terminals and with few gap junctions between neighboring fibers

part of the axon closest to axon hillock is the

initial segment

acetylcholine receptors

integral transmembrane proteins that bind specifically to ACh

fast twitch fibers are adapted for

intense anaerobic movements of short duration , such as weight lifting or throwing a ball but they fatigue quickly

Smooth muscle fibers also contain

intermediate filaments

Fast oxidative glycolytic ( FOG ) fibers are

intermediate in diameter between the other two types of fibers

T tubules filled with

interstitial fluid

At NMJ the axon terminal divides

into a cluster of synaptic end bulbs

Is smooth muscle voluntary or involuntary and striated or non striated?

involuntary + non striated (lacks skeletal+cardiac muscle tissue)

Is cardiac muscle voluntary or involuntary and striated or non striated?

involuntary and striated

intercalated discs- microscopic structures are

irregular transverse thickenings of sarcolemma that connect the ends of cardiac muscle fibers to one another

Muscle contractions are classified as either

isotonic or isometric

titin molecule elastic Because

it can stretch to at least four times its resting length and then spring back unharmed

What smooth muscle does

it's the walls of hollow internal structures like blood vessels, airway, organs in abdominal cavity, skin

cardiac muscle tissue contracts when stimulated by

its own autorhythmic muscle fibers

acetylcholine receptors are abundant in

junctional folds

structural proteins

keep the thick and thin fila ments in the proper alignment , give the myofibril elasticity and extensibility and link the myofibrils to the sarcolemma and extracellular matrix

glycogen resynthesis occurs from

lactic acid

anaerobic reactions convert most of pyruvic acid to

lactic acid in cytosol

glycogen is a

large molecule composed of many glucose molecules (synthesis of ATP)

large motor units are active where

large tension is needed and precision is less important

mitochondria in cardiac muscle fibers are

larger and more numerous than in skeletal muscle fibers

Fast glycolytic ( FG ) fibers are

largest in diameter and contain most myofibrils . they can generate most powerful contractions

relaxation period ( 3rd phase)

lasting 10-100 msec , Ca² + is actively transported back into the sarcoplasmic reticulum , myosin binding sites are covered by tropomyosin , myosin heads detach from actin , and tension in muscle fiber decreases

contraction period

lasts 10-100 msec . During time Ca2 + binds troponin , myosin binding sites on actin are exposed , and crossbridges form

I band

lighter , less dense area of the sarcomere that contains the rest of the thin filaments but no thick filaments AZ disc passes through the center of each I band

sarcoplasm appears stuffed with

little threads

Nebulin

long , nonelastic protein wrapped around the entire length of each thin filament

Smooth muscle tissue can thus sustain

long term tone which is important in gastrointestinal tract

fusion occurred

loses its ability to undergo cell division

slow twitch , fatigue resistant fibers are adapted for

maintaining posture and for aerobic , endurance - type activities such as running a marathon

contractions are important for

maintaining posture and for supporting objects in a fixed position

myoblasts

mature skeletal muscle fiber has a hundred or more nuclei

synaptic vesicles

membrane enclosed sacs

synaptic end bulbs and vari cosities contain many tiny

membrane enclosed sacs called synaptic vesicles

all muscles of body are derived from

mesoderm

Cardiac muscle develops from

mesodermal cells

Smooth muscle develops from (what cell)

mesodermal cells

Neurons have a high

metabolic rate meaning have lots of energy demand

M line is the

middle of the sarcomere

If sufficient oxygen is present , pyruvic acid enters

mitochon dria , where it completely oxidized reactions that generate ATP , carbon dioxide , water , and heat

An axon contains

mitochondria microtubules and neurofibrils

Red muscle fibers also contain more __________ and are supplied by more blood _________.

mitochondria; capillaries

protein actin

molecules join to form an actin filament that is twisted into a helix

muscle fibers are relaxed they produce

more ATP than they need for resting metabolism

repeated eccentric isotonic contractions produce

more muscle damage and more delayed onset muscle soreness that do concentric isotonic contractions

Myosin functions

motor protein in all three types of muscle tissue

Not only do calcium ions enter smooth muscle fibers slowly , they also

move slowly out of muscle fiber , which delays relaxation

What skeletal muscle tissue does

moves bones of skeleton

microtubules which assist in

moving materials between the cell body and axon

neurons have two kinds of processes

multiple dendrites and single axon

nerve impulse ( nerve action potential ) elicits

muscle action potential in 4 ways

During latent period

muscle action potential sweeps over sarcolemma and calcium ions are released from sarcoplasmic reticulum

myoglobin found only in

muscle cells

muscle -2 terms same Structure

muscle cells and muscle fibers

pattern of motor unit activity delays

muscle fatigue and allows contraction of a whole muscle to be sustained for long periods

capillaries during contraction

muscle fiber synthesizes and uses considerable ATP

Even at rest skeletal muscle exhibits

muscle tone

Fascia allows free movement of

muscles carries nerves blood vessels , lymphatic vessels and fills space between muscles

nerve impulse elicits muscle action potential in following way - Release of acetylcholine

nerve impulse at synaptic end bulbs causes synaptic vesicles to undergo exocytosis

single axon ( axis ) of neuron propagates

nerve impulses toward another neuron , a muscle fiber , or a gland cell .

cytokeleton includes both

neurofibrils and microtubules

somatic motor neuron branches out and forms

neuromuscular junctions with many different muscle fibers

nerve fiber is a term for

neuronal process ( extension ) that emerges from cell body of neuron

Nervous tissue consists of two types of cells

neurons and neuroglia

During wave summation , elastic components are

not given much time to spring back between contractions , and thus remain taut

cell body contains

nucleus surrounded by cyto plasm that includes typical cellular organelles such as lyso somes , mitochondria and Golgi complex

frequency of stimulation

num ber of impulses per second

motor unit recruitment

number of active motor units increases

total tension a whole muscle can produce depends on

number of muscle fibers that are contracting in unison

axoplasm

of surrounded by a plasma membrane known as axolemma

total force or tension that a single muscle fiber can produce depends

on rate at which nerve impulses arrive at neuromuscular junction

visceral smooth muscle fibers connect to

one another by gap junctions , forming network through which muscle action potentials can spread

plate Z discs separate

one sarcomere from the next

smooth , sustained voluntary muscle contractions are achieved mainly by

out of - synchrony unfused tetanus in different motor units

Brain processes information and

outputs response/ motor or efferent division (brain decides what to do and sends that information out)

thick and thin filaments overlap

overlap one another to a greater or lesser extent depending on whether the muscle contracted, relaxed or stretched

capillaries bring in

oxygen , nutrients and remove heat + remove waste products of muscle metabolism

Myoglobin releases

oxygen when it is needed by the mitochondria for ATP production

Outer layer is ( attached to bone )

parietal layer

Endomysium within

penetrating interior of each fascicle and separating individual muscle fibers from one another

important integrative function is

perception

new smooth muscle fibers can arise from cells called

pericytes

cell body also known as the

perikaryon or soma

refractory period

period of lost excitability , characteristic of all muscle and nerve cells

Everything outside the central nervous system is the

peripheral nervous system

wave summation

phenomenon in which stimuli arriving at different times cause larger contractions

smooth muscle tissue exhibits some important

physiological differences from cardiac and skeletal muscle tissue

lipofuscin

pigment that occurs as clumps of yellowish brown granules in cytoplasm

sarcolemma

plasma membrane of a muscle cell

crossbridges keep rotating back and forth with each

power stroke , pulling the thin filaments toward the M line

Aerobic cellular respiration supplies enough ATP for

pro longed activity provided sufficient oxygen and nutrients are avail able nutrients include pyruvic acid obtained from glycolysis of glucose , fatty acids from breakdown of triglycerides in adipose cells , and amino acids from breakdown of proteins .

aerobic cellular respiration

produce a large amount of ATP

nerve impulse travels

rapidly and at constant strength

all body cells make ATP by

reactions of anaerobic and aerobic cellular respiration

weakest motor units are

recruited first , with progressively stronger motor units added if task requires more force

found only in

red blood cells

What type of protein does glycogen contain

red colored protein called myoglobin

oxygen debt

refers to the added oxygen , over and above resting oxygen consumption

cardiac muscle has a longer

refractory period

under certain circumstances cardiac muscle tissue can

regenerate

skeletal muscle can

regenerate only to a limited extent

smooth muscle tissue has considerably greater powers of

regeneration

motor end plate

region of the sarcolemma opposite the synaptic end bulbs , is the muscle fiber part of the NMJ

synapse

region where communication occurs between two neurons , or between neuron and a target cell somatic motor neuron and muscle fiber)

Dystrophin and its associated proteins are thought to

reinforce the sarcolemma and help transmit the tension generated by the sarcomeres to the tendons

thick and thin filaments were the same in both

relaxed and contracted muscle

skeletal muscle fibers often switch between a low level of activity when they are

relaxed and using only a modest amount of ATP , and high level of activity , when they are contracting and using ATP at a rapid pace

hydrolysis reaction

reorients and energizes the myosin head

contraction cycle

repeating sequence of events that causes the filaments to slide (begins)

synthesized proteins produced by Nissl bodies are used to

replace cellular components as material for growth of neurons and regenerate damaged axons in PNS

Within particular motor unit , all of the skeletal muscle fibers are of the

same type

Muscle action potentials travel along the

sarcolemma and through the T tubules

sarcomere extends from

sarcomere from one Z disc to the next Z disc

Within the sarcolemma is the

sarcoplasm

Some dense bodies are dispersed throughout

sarcoplasm ; others are attached to sarcolemma

huge amount of Ca2 + is stored inside the

sarcoplasmic reticulum

In cardiac muscle fibers Ca² + enters the sarcoplasm both from the

sarcoplasmic reticulum and from interstitial fluid that bathes the fibers

Anaerobic cellular respiration

series of ATP producing reactions that do not require oxygen

aerobic cellular respiration

series of oxygen requiring reactions that produce ATP in mitochondria

Between the layers of cardiac muscle fibers , the contractile cells of the heart , are

sheets of connective tissue that contain blood vessels , nerves , and the conduction system of the heart .

neurons are tiny and propagate over

short distance

smooth muscle can both _____ ans _____ to a greater extent than the other muscle types

shorten and stretch

Shortening of the sarcomeres causes

shortening of the whole muscle fiber

Within relaxed smooth muscle fiber is

single , oval , centrally located nucleus

single nerve impulse in somatic motor neuron elicits

single muscle action potential in all skeletal muscle fibers with which it forms synapses

skeletal muscle fiber has only a

single neuromuscular junction

cardiac muscle contraction lasts much longer than

skeletal muscle twitch

The somatic NS stimulates

skeletal muscles (brain decides to slap hand away and solve that problem)

-each skeletal muscles

skeletal seperate organ composed of hundreds to thousands of cells called muscle fibers ( elongated shapes )

crossbridges rotate and generate tension but the thin filaments cannot

slide inward because the tension they generate is not large enough to move the load on the muscle

Slow oxidative fibers have a ________ speed of contraction

slow

aerobic activities and strength training programs are effective in older people and can

slow or even reverse age associated decline in muscular performance

Satellite cells divide

slowly and fuse with existing fibers to assist both in muscle growth and repair of damaged fibers

Creatine

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

muscle tone

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

Sarcoplasmic reticulum ( the reservoir for Ca² + in striated muscle ) is found in

small amounts in smooth muscle

movements are brought about by

small changes in muscle contraction

small muscles that produce precise movements are made up of

small motor units

caveolae

small pouchlike invaginations of plasma membrane that contain extracellular Ca2 + that can be used for muscular contraction

Calcium ions flow into

smooth muscle cytosol from both interstitial fluid and sarcoplasmic reticulum

there are no transverse tubules in

smooth muscle tissue

motor unit consists of

somatic motor neuron plus all skeletal muscle fibers it stimulates

smooth muscle tone

state of continued partial contraction

pericytes

stem cells found in association with blood capillaries and small veins

human growth hormone

stimulate an increase in the size of skeletal muscle fibers

skeletal muscle tissue contracts only when

stimulated by acetylcholine released by a nerve impulse in a motor neuron

Decrease in Ca² + concentration in the cytosol starts

stops it

synaptic vesicles

store a chemical neurotransmitter

Adipose CT of hypodermis layer does

stores body's triglycerides , serves as insulting layer that reduces heat loss and protects muscle from physical trauma

smooth muscle fibers can _______ considerably and still maintain their ______ function

stretch ; contractile

myofibrils prominent striations make the entire skeletal muscle fiber appear

striated

troponin takes role in

striated muscle fibers

In smooth muscle fibers the thin filaments attach to

struc tures called dense bodies

Besides contractile and regulatory proteins , muscle contains about a dozen

structural proteins

Neuroglia

support , nourish and protect neurons and maintain homeostasis in the interstitial fluid that bathes them

fused ( complete ) tetanus

sustained contraction in which individual twitches cannot be detected

site of communication between two neurons or between a neuron and an effector cell is called

synapse

stretch of elastic components such as

tendons and con nective tissues around muscle fibers also affects wave summation

concentric isotonic contraction

tension generated great enough to overcome resistance of object to be moved , muscle shortens and pulls on another structure , tendon , to produce movement and reduce angle at a joint

During eccentric contraction , the tension exerted by

tension the myosin cross bridges resists movement of a load and slows the lengthening process

mesodermal cells

that migrate to and envelop the developing gastrointestinal tract and viscera

mesodermal cells

that migrate to and envelop the developing heart while it is still in form of endocardial heart tubes

FOG fibers are " fast " because

the ATPase in their myosin heads hydrolyzes ATP three to five times faster than myosin ATPase in SO fibers , which makes speed of contraction faster

Z disc passes through

the center of each I band

Cell body

the central region of a neuron, which is the control center

perception

the conscious awareness of sensory stimuli . occurs in the brain

contraction cycle continues movement of cross bridges applies

the force that draws the Z discs toward each other , and sarcomere shortens

troponin change moves tropomyosin away from

the myosin binding sites on actin

molecules lie parallel to one another forming

the shaft of the thick filament

Axon

the singular extension of a neuron body , ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

During contraction of dense bodies

the sliding filament mechanism involving thick and thin filaments generates tension that is trans mitted to intermediate filaments

isotonic contraction

the tension ( force of contraction ) developed by the muscle remains almost constant while the muscle changes its length

isometric contraction

the tension generated is not enough to exceed resistance of the object to be moved , and muscle does not change its length

skeletal muscle shortens during contraction because

the thick and thin filaments slide past one another

Multiunit smooth muscle tissue is found in

the walls of large arteries in airways to lungs , in arrector pili muscles that attach hair follicles , in muscles of iris that adjust pupil diameter , and ciliary body that adjusts focus of lens in eye .

oxidative fibers

they SO fibers generate ATP mainly by aerobic cellular respiration

FOG Because their intracellular glycogen level is high ,

they also generate ATP by anaerobic glycolysis

Once you destroy neurons

they are gone and can't create new neurons

sliding filament mechanism

thick and thin filaments slide past one another during contraction

there are two thin filaments for every filaments

thick filament in the regions of filament overlap

The sarcoplasm of smooth muscle fibers contains both

thick filaments and thin filaments

sarcomere shortens when

thin filaments slide inward the Z discs come closer together

Nebulin helps anchor

thin filaments to the Z discs and regulates the length of thin filaments during development

Type of CT in Endomysium

thin sheath of areolar CT

synaptic vesicles acetylcholine (ACh)

thousands of molecules and released at NMJ

skeletal muscles are a mixture of all

three types of skeletal muscle fibers

structural proteins are

titin , actinin , myomesin , nebulin , and dystrophin

elastic components include

titin molecules , connective tissue around the muscle fibers

Fascicles

tittle bundles

M line proteins bind

to titin and connect adjacent thick filaments to one another

enzyme creatine kinase ( CK ) catalyzes the

transfer of one of the high energy phosphate groups from ATP to creatine forming creatine phos phate and ADP

action potential begins and travels due to the

travels movement of ions ( such as sodium and potassium ) between interstitial fluid and the inside neuron through specific ion channels in plasma membrane

A transverse tubule and two terminal cisterns on either side of it form a

triad ( three )

In most neurons , nerve impulses arise at the junction of axon hillock and the initial segment , an area called the

trigger zone

Smaller amounts of two regulatory proteins

tropomyosin and troponin

Troponin moves

tropomyosin away from the myosin binding sites on actin

when calcium ions ( Ca² + ) bind to

troponin it undergoes a change in shape

visceral ( single unit ) smooth muscle tissue found in

tubular arrangements that form part of walls of small arteries and veins and of hollow organs such as stomach intestines uterus and urinary bladder muscle

transverse ( T ) tubules

tunnel in from the surface toward the center of each muscle fiber

myogram

twitch produced by direct electrical stimulation of motor neuron or muscle fibers . The record of muscle contraction

Nonmitotic

unable to divide and produce new neurons

stress relaxation response , allows smooth muscle to

undergo great changes in length while retaining the ability to contract effectively

structural classification of neurons

unipolar, bipolar, multipolar

string of swollen bumps called

varicosities

two types of smooth muscle tissue

visceral ( single unit ) smooth muscle tissue and multiunit smooth muscle tissue

Is skeletal muscle voluntary or involuntary and striated or non striated?

voluntary + striated

arterioles

walls maintain steady pressure on contents of tract , and in walls of blood vessels , which maintain a steady pressure on blood

pyruvic acid formed by glycolysis in the cytosol enters mitochondria where it

where it undergoes a series of oxygen requiring reactions called aerobic cellular respiration that produce large amount of ATP

sarcomeres

which are the basic functional units of a myofibril

cells of a somite 2/3 -dermatome

which forms the connective tissue, including dermis of skin

cells of a somite 1/3 - myotome

which forms the skeletal muscles of the head , neck , and limbs

peripheral nervous system ( PNS )

which includes spinal nerves, cranial nerves, Ganglia

end of A band is a

zone of overlap

Dendrites

Branchlike parts of a neuron that are specialized to receive information.

autorhythmicity

Built in rhythm (in cardiac tissue and smooth tissue)

Multipolar

Usually have several dendrites and one axon. Most neurons in the brain and spinal cord are of this type.

filaments

Within myofibrils are smaller structures

titin molecule connects a

Z disc to the M line of the sarcomere , helping stabilize the position of the thick filament

Thin filaments are anchored to

Z discs

Two types of stimuli triggered action potential

1. Autorhythmic electrical signals arising muscular tissue itself (hearts pacemaker) 2. Chemical stimuli such as neurotransmitters released by neurons, hormones, distributed by blood, local change in pH

Somatic receptors

Body senses; touch, pain, temperature, body positions

Brain is highly

Metabolic

capillaries are

Microscopic blood vessels

Connective tissue surrounds and protects

Muscular tissue

Leg muscles , which not only support the body but are also used for walking and running , have large numbers of both

SO and FOG fibers

half the fibers in a typical skeletal muscle are

SO fibers

weak contractions suffice to perform a task , only

SO motor units are activated

2 functional divisions of nervous system

Sensory nervous system and Motors nervous system

Subcutaneous layer or hypodermis

Seperate muscle from skin

Muscle tone is important in

Smooth muscle tissues

parasympathetic NS means

Stop feeling, Rest and slow down