Chapter 10: Muscle Tissue and Muscle Organization

postural muscles contract continuously when a person is awake to prevent collapse

maintenance of posture

specialized region of the sarcolemma and increases the surface for connection of the synaptic knob

motor end plate

neurons that stimulate muscle contraction

motor neurons

composed of a single motor neuron and all of the muscle fibers it controls

motor unit

the total force exerted by the muscle depends on the number of activates ______ _____

motor units

multiple fascicles housing many muscle fibers, connect tissue coverings, blood vessels, nerve fibers

muscle

what muscle level does the epimysium cover?

muscle

elongated, multinucleated cylindrical fiber (cell); contains myofibrils, separated from other fibers by delicate layer of areolar connective tissue; exhibits striations, involved

muscle fiber (muscle cell)

what muscle level does the endomysium cover?

muscle fiber (muscle cell)

equated with responsiveness, very responsive to input from stimuli

Excitability

double-stranded contractile protein, binding site for myosin to shorten a sarcomere

actin

what are the three components of a thin filament?

actin, tropomyosin, and troponin

what is a sarcomere?

functional contractile unit of skeletal muscle and is the distance between two adjacent Z discs, and it shortens when the muscle contracts

ensheaths the three connective tissue layers, extensive sheet of dense irregular connective tissue what separates individual muscles, binds together muscles with similar functions, and forms sheaths to help distribute nerves, blood vessels, and lymphatic vessels, and to fill spaces between muscles

deep fascia

triangular muscle with common attachment site, direction of pull of muscle can be changed, does not pull as hard as equal-sized parallel muscle

convergent (ex: pectoralis major)

increase in muscle fiber size, (increased by exercising) develops more myofibrils and contains a larger amount of myofibrils, increased ability to produce ATP

hypertrophy

the length of the muscle does not change because the tension produced by this contracting muscle never exceeds the resistance (load)

isometric contraction

the tension produced equals or is greater than the resistance and then the muscle fibers shorten, resulting in movement

isotonic contraction

areolar connective tissue layer surrounding a muscle fiber

endomysium

fibrous connective tissue envelope surrounding a skeletal muscle

epimysium

blood vessels and nerve fibers extend through which two of the connective tissue components

epimysium and perimysium

what are the connective tissue coverings of skeletal muscle?

epimysium, perimysium, endomysium

has a fulcrum in the middle, between the effort and the resistance

first-class lever

synergist can also be considered ___________ by assisting the agonist by preventing movement at a joint thereby stabilizing the origin of the agonist

fixators

resting tension in a skeletal muscle

muscle tone

what are the levels of organization of skeletal muscles?

muscles, fascicle, muscle fiber (muscle cell), myofibril, myofilaments

long, cylindrical contractile element within muscle fiber; as long as the muscle fiber itself; composed of myofilaments; exhibits striations

myofibril

short contractile proteins of two types: thick (composed of myosin) and thin (composed of actin, tropomyosin, and tropnin)

myofilaments

slow fibers are also called red fibers because they contain the red pigment ____________

myoglobin

The motor neuron transmits the effect of a nerve impulse to the muscle fiber at a ______________

neuromuscular junction

the point where a motor neuron meets a skeletal muscle fiber

neuromuscular junction

a single motor neuron typically controls __________ muscle fibers in a muscle

numerous

the less mobile attachment of a muscle

origin

some motor units are always active, even when a muscle is at ______

rest

small in diameter and contract more slowly than fast fibers

slow fibers

what are the three types of skeletal muscle fibers?

slow, intermediate, fast

composed of short muscles cells that have a fusiform shape, single central nuclei, no visible striations/sarcomeres/z discs, involuntary control

smooth muscle

the voluntary muscles are controlled by what nervous system?

somatic nervous system

Skeletal muscle tissue formation is initiated during the fourth week of development from blocks of paraxial mesoderm that form structures called ______________

somites

store the material within an organ or to facilitate movement of materials

storage and movement of materials

protect organs and support their weight within the abdominopelvic cavity

support

a narrow space separating the synaptic knob and the motor end plate

synaptic cleft

expanded tip of an axon, nerve travels through the axon, exits at this tip to the sacrolemma

synaptic knob

these are within the synaptic knob and are filled with molecules of the neurotransmitter acetylcholine (ACh)

synaptic vesicles

muscle that assists the agonist in performing its actions by contributing to tension exerted close to the insertion of the muscle or stabilizes the point of origin

synergist

heat is always produced as a waste product of this energy usage, most of this heat maintains our normal body temperature

temperature regulation

attaches muscles to bone, skin or other muscle

tendon

expanded ends of the sarcoplasmic reticulum that contact the T-tubules, site of calcium ion release to promote muscle contraction

terminal cisternae

fine protein myofilament composed of bundles of myosin (11nm diameter), bind to thin filament and cause contraction

thick filament

what are the three types of myofilaments in myofibrils?

thick filament, thin filament, and titin

fine protein myofilament composed of actin, troponin, and tropomyosin (5-6nm diameter), thick filaments bind to it and cause contraction

thin filament

effort is applied between the resistance and the fulcrum, as when picking up a small object with a pair of forceps

third-class lever

filaments of an elastic protein, help return myofilaments to resting position after contraction; maintain positions of myofilaments in sarcomere

titin

narrow, tubular extensions of the sarcolemma into the sarcoplasm, contacting the terminal cisternae; wrapped around myofibrils, quickly transports a muscle impulse from the sarcolemma throughout the entire muscle fiber

transverse tubule (T-tubule)

double-stranded regulatory protein, covers the sites on actin, preventing myosin from binding to actin when muscle fiber is at rest

tropomyosin

regulatory protein that holds tropomyosin in place and anchors to actin, when calcium ions bind to one of its subunits, troponin changes shape, causing the tropomyosin to move off the actin active site, and this permits myosin binding to actin

troponin

are skeletal muscles voluntary or involuntary

voluntary

wasting of a tissue that results in a reduction in muscle size, tome, and power, losses tone and mass, becomes flaccid, fibers decrease in size and become weaker (happens when one wears a cast)

atrophy

cardia muscle cells are _________ meaning that the individual cells can generate impulse without nervous stimulation

autorhythmic

each motor neuron has a long extension called a

axon

transmits a nerve impulse to a muscle fiber, travels through the epimysium and perimysium, delivers the nerve impulse to an individual muscle fiber in the endomysium

axon

delievers nutrients and oxygen to muscle fibers needed for the production of ATP and removes wastes products produced by muscles fibers

blood vessels

move when muscles contract and pull on the tendons by which the muscles are attached to the bones

body movement

what are the five functions of skeletal muscle tissue?

body movement, maintenance of posture, temperature regulation, storage and movement of materials, and support

individual muscle cells arranged in thick bundles, striated, shorter and thick, only one or two nuclei, intercalated discs, involuntary control

cardiac muscle cells

fibers arranged concentrically, functions as a sphincter to close a passage way or opening

circular (ex: orbicularis oris)

what are the four shape of skeletal muscles?

circular, parallel, convergent, pennate

the resistance is between the fulcrum and the applied effort

second-class lever

how many muscles are in the skeletal system?

100

dark band in the middle of a sarcomere and doesn't shorten when the muscle contracts

A band

what are the five components of a sarcomere?

A band, H zone, M line, I band, Z disc

found in the motor end plate and are activated by ACh

ACh receptors

tension within cell that causes cells to shorten, shortening results in either a pull on bones of the skeleton or the movement of specific body parts

Contractility

ability to return to its original length when tension is released

Elasticity

What are the four common properties of muscle tissue?

Excitability, Contractility, Elasticity, Extensibility

capable of extending in length in response to the contraction of opposing muscle cells

Extensibility

lighter region in the middle of the A band and shortens when the muscle contracts

H zone

light bank containing thin filaments only and titin proteins, shortens when the muscle contracts

I band

a thin transverse protein meshwork that appears as a dark protein disc in center of H zone where thick filaments attach, doesn't shorten when muscle contracts

M line

dark proteins called connectins in the center of the I band where thin filaments attach, doesn't shorten when muscles contracts

Z disc

neurotransmitter found in the synaptic vesicles

acetylcholine (ACh)

resides in the synaptic cleft and rapidly breaks down molecules of ACh that are released into the synaptic cleft, very important to prevent ACh from continuously stimulating the muscle

acetylcholinesterase (AChE)

also called a prime mover, a muscle that contracts to produce a particular movement

agonist

each muscle fiber obeys this principle which states that a muscle fiber either contracts completely or does not contract at all, when a muscle unit is stimulated, all its fibers contract at the same time

all-or-none principle

a muscle whose actions oppose those of the agonist

antagonist

occurs when the tendon forms a thin, flattened sheet

aponeurosis

if a muscle extends between a broad aponeurosis and a narrow tendon, the __________ is considered the origin and the __________ is the insertion

aponeurosis, tendon

a bundle of muscle fibers separated from other bundles of fibers by a dense irregular connective tissue covering

fascicle

what muscle level does the perimysium cover?

fascicle

what fibers do the majority of skeletal muscle fibers consist of?

fast fibers

large in diameter and they contain large glycogen reserves, densely packed myofibrils, and relatively few mitochondria

fast fibers also called white fibers because of lack of myoglobin

more mobile attachment of the muscle

insertion

resemble fast fibers; however, they have a greater resistance to fatigue

intermediate fibers

fascicles are parallel to the long axis of the muscles, body muscles increases in diameter with contraction, high endurance, not ver strong

parallel (ex: rectus abdominis)

muscle body has one or more tendons, fascicles at oblique angle to tendon, pull harder than a parallel muscle of equal size, three types: uni-, bi-, multi-)

pennat (unipennate: extensor digitorum) (bipennate: Rectus femoris) (multipennate: deltoid)

fibrous sheath enveloping each of the fascicles of skeletal muscle fibers

perimysium

plamsa membrane of a muscle fiber, regulates entry and exit of materials

sarcolemma

what are the five structures of a muscle fiber?

sarcolemma, sarcoplasm, sarcoplasmic reticulum, terminal cisternae, transverse tubule

cytoplasm of a muscle fiber, site of metabolic processes for normal muscle fiber activities

sarcoplasm

smooth endoplasmic reticulum in a muscle fiber, stores calcium ions needed for muscle contraction

sarcoplasmic reticulum