Anatomy and Physiology Chapter 7 pt. 1

components of muscular system

muscles and tendons

what type of tissue are tendons

dense regular connective tissue

Muscle tissue consists of elongated muscle cells specialized for _____________--

contraction

Three types of muscle tissue

skeletal, cardiac, smooth

During embryonic development, What tissue layer are muscle tissues derived from?

mesoderm

Where is the mesoderm located?

between ectoderm and endoderm

skeletal muscles are ___________ composed of skeletal muscle tissue, connective tissues, nerves, and blood

organs

How are skeletal muscles attached to bones?

directly or indirectly via tendons

How many skeletal muscles are there?

~700(majority of our muscles are skeletal muscles)

five functions of skeletal muscle

Movement
Maintain posture and body position
Support soft tissues
Guard entrances and exits
Maintain body temperature

how do skeletal muscles move the skeleton

skeletal muscle pull on tendons that then move bones

Where do skeletal muscles support soft tissue

abdominal wall and pelvic cavity

How do skeletal muscles guard entrances and exit

by encircling openings of the digestive and urinary tracts, voluntarily controlling swallowing, defecation, and urination

skeletal muscles that encircle openings of digestive and urinary tracts are

sphincters

how do skeletal muscles maintain body temp

muscle contractions generate heat

skeletal muscle tissues are composed of skeletal muscles that encircle openings of digestive and urinary tracts are

muscle fiber

why are skeletal muscles called muscle fibers

long and slender

three CONNECTIVE tissue layers of skeletal muscles

epimysium, perimysium, endomysium

Epimysium

surrounds entire muscle

Perimysium

divides muscle into fascicles

What are fascicles?

bundles of muscle fibers

perimysium contains ______________ and ____________ supplying fascicles

blood vessels, nerves

Endomysium

Surrounds individual muscle fibers and ties them tog

endomysium contains _________ and ______________

capillaries and nerve fibers(axons); myosatellite cells

capillaries in endomysium deliver ___________ to skeletal muscle cells

blood

what do nerve fibers(axons) in endomysium do

allow muscles to move

myosatellite cells

stem cells that help repair damaged muscle tissue by fusing with damaged skeletal muscle cells

collagen fibers from all three skeletal muscle connective tissue layers come together to form 1____________ 2____________

tendon;
aponeurosis

what is a tendon

bundle of fibers that attaches muscle to bone

What is aponeurosis?

broad sheet of fibers (broad tendon) that connects muscles to EACH OTHER

skeletal muscles have ____________ that provide them w/ enough oxygen to make atp needed for them to contract

blood vessels

skeletal muscles require stimulation of central nervous system and are under__________control

voluntary

among the muscle cells, which is the largest in diameter and the longest

skeletal muscle fibers

skeletal muscle fibers are ___________(multi or uninucleate) and __________(striated or nonstriated)

multinucleate; striated

how are multinucleate skeletal muscle cells formed

during development, embryonic cells called myoblasts(containing ONE nucleus) fuse together to form multinucleate skeletal muscle cells

some myoblasts don't fuse and remain as____________ cells in adult skeletal muscle tissue

myosatellite

What is the name of muscle cell's membrane

sarcolemma

what does sarcolemma surround

sarcoplasm or cytoplasm

What does sarcoplasm have

cytosol + organelles

sarcolemma contains openings that lead into network of tubules called

transverse tubules or T tubules

Why are T-tubules important?

bc they allow electrical impulses or action potentials from sarcoplasm to reach cell's interior; allowing entire skeletal muscle cell to contract

what are the cylinder shaped structures inside the skeletal muscle fiber

myofibrils

what are myofibrils encircled by

T tubules

myofibrils are bundles of ______________- and _____________

thick and thin myofilaments

the sliding of thick and thin myofilaments causes muscle fibers to ________________

contract

during contraction, ____________________ shortens but ___________-- and ____________--stay the same

myofibril;
thick and thin

what is the terminal cisterna and what does it contain a high conc. of?

expanded portions on either side of T tubules;
calcium ions

conc of calcium ions is much higher in ____________than in the cytosol

sarcoplasmic reticulum

conc of calcium ions is much higher _________-- the cell than inside(intracellular fluid or cytosol)

outside(extracellular fluid)

Triad (sarcoplasmic reticulum)

area where 2 terminal cisternae and 1 t tubule come together

what is the smallest functional unit of skeletal muscle fiber

sarcomere

sarcomeres are repeating functional units of ________________

myofilaments

why do skeletal muscle fibers appear striated

the arrangement of thick and thin filaments in sarcomeres

thick filaments are found in the ________ of sarcomere while thin are found on ___________________of sarcomere

middle;; both sides

thin filaments are attached to the _____________--

z line

What mark the boundaries of sarcomeres?

z lines

thick filaments are attached to the z lines via strands of the protein_________________---

titin

M lines are located at the ______________ of each sarcomere

center

M line is made of proteins that connect central portions of the ________________-

thick filaments

What band (A,I,H) is the darker region containing thick filaments

A band

__________band includes zone of overlap containing BOTH thick and thin filaments

A

What band (A,I,H) is the lighter region containing thin filaments

I band

________band includes the Z line

I

What band (A,I,H) contains ONLY thick filaments when fiber is relaxed

H band

___________band includes the M line and light regions on either side

H

Thin twisted strand of actin molecules

thin(actin) filaments

active sites on actin interact with __________

myosin

At rest active sites are covered by strands of ___________

tropomyosin

how are tropomyosin strands held in position

by troponin

what is tropomyosin

a protein that prevents myosin-actin interaction

What is troponin?

a protein that consists of three globular subunits

first globular subunit of troponin interacts w/ ______________ forming troponin-tropomyosin complex

tropomyosin

Second globular subunit of troponin binds to one of the ___________molecules

actin

Third globular subunit of troponin has the ______which binds calcium ions

receptor

troponin and tropomyosin are proteins associated w _________ but NOT myosin

actin

THICK(myosin) filaments are composed of ____________ molecules

myosin

Each myosin molecule consists of

-Tail: binds to other myosin molecules
-Head: made of two globular protein subunits and projects toward nearest thin filament

the globular head of myosin molecule has ___________subunits

two

myosin tails point toward

M line(center of sarcomere)

myosin tails point ____________ heads project ___________

INWARD;
OUTWARD

During contraction, myosin heads interact with ____________on actin

active sites

In order for myosin heads to interact active sites on actin, the movement of what two proteins is required?

troponin and tropomyosin

what theory explains sarcomere contraction

sliding filament theory

sliding filament theory is based on observed ___________in sarcomere

changes

sliding filament theory

theory that actin(thin) filaments slide toward each other during muscle contraction, while the myosin(thick) filaments don't move

during contraction, the width of I and H bands

decreases

during contraction the width of A bands

stays the same
(bc thick filaments dont move)

during contraction the distance b/w z lines

decreases

during contraction the zone of overlap

increases

the binding of thick filaments to active sites produces

cross bridges

cross bridge formation is followed by the myosin head

pivoting

myosin head pivots toward

m line(center of sarcomere), pulling thin filament in that direction

what happens as a result of thin filament being pulled toward the center of sarcomere(m line)

sarcomere and myofibril shorten and skeletal muscle cell contracts

the neuromuscular junction is a specialized ________connection b/w a________________ and a skeletal muscle fiber

intercellular;
motor neuron

the neuromuscular junction consists of __________________ and _________

axon terminal; motor end plate

axon terminal of neuron contains _____________vesicles, which contain____________

synaptic; neurotransmitters(acetylcholine)

one of the most common neurotransmitters found in the body

acetylcholine

What is a neurotransmitter?

chemical signal that is produced mainly by the nerve cells

motor end plate is a portion of ____________

muscle sarcolemma

how is motor end plate separated from the axon terminal

by the synaptic cleft(or synaptic gap)