A&P Muscle Unit

Thin filament has ___ chains of G actin

2

Incurable patients of DMD rarely live beyond age ____

30

Tropomyosin

A protein of muscle that forms a complex with troponin regulating the interaction of actin and myosin in muscular contraction

Botulism prevents release of _____ at synaptic knobs

ACh

What is the importance of regulating elimination of materials?

Allows our bodies to get rid of waste; circular sphincters control; passage of material at orifices

Dystrophin

Anchors some myofibrils to sarcolemma proteins

superficial fascia

Areolar and adipose CT superficial to deep fascia

Endomysium

Areolar connective tissue wrapping individual fiber; Delicate layer for electrical insulation, capillary support, binding of neighboring cells

terminal cisternae

Blind sacs of the sarcoplasmic reticulum

What are the five main functions of skeletal muscle?

Body movement, maintenance of posture, protection and support, regulating elimination of materials, heat production

Botulism

Caused by clostridium botulinum, commonly known as food poisoning

A bands make up _______ region of sarcomere

Central

Muscular Dystrophy

Collective term for hereditary diseases where skeletal muscles degenerate

Thin

Consists of bundles of many myosin protein molecules

Perimysium

Dense irregular connective tissue wrapping fascicle; houses many blood vessels and nerves

Abnormalities of _______ cause muscular dystrophy

Dystrophin protein

What are the three components of connective tissue?

Epimysium, Perimysium, and Endomysium

What are the five characteristics of Skeletal Muscle tissue?

Excitability, Conductivity, Contractility, Extensibility, Elasticity

Connectin

Extends from Z disc to M line

_________ is stored for when fuel is needed quickly

Glycogen

A bands contain __ zone and ___ line

H, M

Sarcolemma (plasma membrane)

Has T-tubules (transverse tubules) that extend deep into the cell;Sarcolemma and its T-tubules have voltage-gated ion channels that allow for conduction of electrical signals

Sarcoplasm (cytoplasm)

Has typical organelles plus contractile proteins and other specializations

What is the importance of heat production?

Helps maintain body temperature

Bisected by Z discs

I bands

Get smaller when muscle contracts (can disappear with maximal contraction)

I bands

The positions of thin and thick filaments give rise to alternating _____ and _______.

I-bands, A-bands

Incomplete tetany and tetany

If frequency is increased further, myogram exhibits incomplete tetany

Why is each skeletal muscle considered an organ?

It is multiple types of tissues working together: skeletal muscle fibers, connective tissue, blood vessels, and nerves

Protein meshwork structure

M Line

Example of direct (fleshy) attatchment

Margins of brachialis, lateral head of triceps brachii

Sarcomeres

Myofilaments arranged in repeating units

Each skeletal muscle is an ________.

Organ

What is the importance of protection and support?

Package internal organs and hold them into place

Specialized proteins are ________ to myofilaments

Perpendicular

What does the deep fascia do?

Separates individual muscles and binds muscles with similar functions

What does superficial fascia do?

Separates muscles from skin

What does maintenance of posture do?

Stabilize joints, maintain body position

indirect attatchment

Tendons bridge the gap between muscle ends and bony attachment

Twisted strands of F-actin; each F-actin composed of G-actin monomers

Thin filaments

Latent period

Time after stimulus but before contraction begins No change in tension

Relaxation period

Time when tension is decreasing to baseline Generally lasts a little longer than contraction period

Contraction period

Time when tension is increasing Begins as power strokes pull thin filaments

What is the one major purpose of muscle in the human body?

To convert chemical energy into mechanical energy

calcium release channels

Triggered by electrical signal traveling down T-tubule; calcium released into sarcoplasm

Skeletal is ______, has extensive blood vessels

Vascularized

What does DMD cause?

Walking difficulties, muscle atrophy, postural issues

Sarcomeres are delineated at both ends by

Z discs

Troponin

a smaller calcium-binding protein attached to the tropomyosin

Tetanus

a sustained muscular contraction resulting from a rapid series of nerve impulses

Extensibility

ability to be stretched

Excitability

ability to respond to a stimulus by changing electrical membrane potential

Elasticity

ability to return to original length following a lengthening or shortening

Muscle fibers have __________ mitochondria for ______ _____ production

abundant; aerobic ATP

Electrical excitation of a muscle fiber follows _______________ law

all-or-none

Myoglobin

allow for storage of oxygen used for aerobic ATP production within cells

Z discsZ disc are ______ for thin filaments

anchors

Where is skeletal muscle found?

attached to skeleton

Origin

bony attachment at stationary end of muscle

Insertion

bony attachment to mobile end of muscle

Myofibrils

bundles of myofilaments enclosed in sarcoplasmic reticulum

calmodulin

calcium binding protein

Calsequestrin

calcium-binding protein within the sarcoplasmic reticulum which aids in storage of intracellular Ca2+

Creatine Phosphate

can quickly give up its phosphate group to help replenish ATP supply

Although toxin ingestion can be life-threatening, how can we treat spasticity from botulism?

careful injections, can also be used for cosmetic purposes to diminish wrinkles

H Zone

central portion of A band

Dystrophin is a

clinically important protein

Elastic filaments

composed of titin

retinaculum

connective tissue band that tendons from separate muscles pass under

Thick filaments

consist of bundles of many myosin protein molecules, heads point towards ends of the filament

Myofiliments

contractile proteins within myofibrils; two types

Tendon

cordlike structure of dense regular connective tissue

Relaxation period begins with release of:

cross bridges

A band

dark area; contains thick filaments and overlapping thin filaments

deep fascia

dense irregular connective tissue superficial to epimysium

Epimysium

dense irregular connective tissue wrapping whole muscle

DMD causes problems that begin in _______________

early childhood

When sarcolemma is damaged during muscle contraction calcium...

enters the cells and damages proteins

Contractility

exhibited when filaments slide past each other; Enables muscle to cause movement

Muscle fibers bundled within a ______.

fascicle

A whole muscle contains many ________.

fascicles

Lower than normal pH of sarcoplasm weakens contraction and causes:

fatigue

vascularized

good blood supply

Muscles make up about _____ of body weight

half

Thick filament has ______ of myosin molecules

hundreds

How many myofibrils are in each cell?

hundreds to thousands

Multiple nuclei means:

individual cells are multinucleated

Tetanus blocks release of

inhibitory neurotransmitters in spinal cord, resulting in overstimulation of muscles

Skeletal muscle is ______ by somatic neurons

innervated

sarcoplasmic reticulum

internal membrane complex similar to smooth endoplasmic reticulum

Conductivity

involves sending an electrical change down the length of the cell membrane

I bands

light bands that only contain thin filaments

Direct (fleshy) attachment

little separation between muscle and bone;muscle seems to emerge directly from bone

M Line

middle of H zone

Duchenne muscular dystrophy (DMD)

most common form of muscular dystrophy

What does body movement allow us to do?

move bones, make facial expressions, speak, breathe, swallow

A muscle fiber is a ____________.

muscle cell

A fascicle consists of many _________.

muscle fibers

Synergist

muscle that aids a prime mover in a movement and helps prevent rotation

Antagonist

muscle that opposes or reverses a prime mover

Fixator

muscle that prevents movement of bone

Prime mover

muscle with the major responsibility for a certain movement

Do the muscle fiber twitches follow the all-or-none law?

no

Smooth muscle

non-striated, involuntary

fascicle arrangement

pennate are stronger than parallel, and parallel stronger than circular

multiple motor unit summation

recruitment of more motor units as voltage increases

In wave summation if stimulus frequency is set at about 20 per second:

relaxation is not completed between twitches and contractile forces add up to produce higher tensions

Muscle is stimulated ________

repeatedly

Voltage-sensitive calcium channels

responsive to the electrical signals (action potentials)

What do terminal cisternae do?

serve as reservoirs for calcium ions

What are the three kinds of muscle?

skeletal, smooth, cardiac

Recruitment order based on size of motor units:

small first, large last

Temporal summation

stimuli arriving closer together produce stronger twitches

Cardiac muscle

striated, branched, and involuntary

Skeletal muscle

striated, voluntary, multinucleated

innervated

supplied by nerve fibers

wave summation

temporal summation of twitches

Attachment of muscle to bone (or to skin or to another muscle) can be _______ or _______.

tendons, aponeuroses

Z discs are found in

the middle of I bands

Elastic filaments attach _____ filament to the Z disk, and prevent overstretching

thick

M line is an attachment site for _____ filaments

thick

Sarcomeres are composed of overlapping _____ and ______ filaments

thick, thin

Connectin _____ thick filaments and have ______ properties (passive tension)

thick; "springlike"

Belly

thicker, middle region of muscle between origin and insertion

Aponeurosis

thin, flattened sheet of dense irregular tissue

The minimum voltage that triggers a twitch is the:

threshold

Spastic paralysis is caused by:

toxins from clostridium tetani

Two cisternae with T-tubule in between

triad

T tubules

tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side

Incomplete tetany and tetany causes tension to increase and _________ to partially fuse

twitches

How can we prevent tetanus?

vaccination

Where is smooth muscle found?

walls of internal organs and blood vessels

Where is cardiac muscle found?

walls of the heart

Temperature of the muscles

warmed-up muscle contracts more strongly; enzymes work more quickly