Chapter 10: Muscle Tissue Flashcards
Types of muscle tissue
- skeletal
- cardiac
- smooth
skeletal muscle tissue
how does it attach?
- attaches to bones by tendons + aponeuroses
- striated and voluntary
cardiac muscle tissue
what does it form?
- forms wall of heart
- striated + involuntary
smooth muscle tissue
where is it located?
- located in walls of hollow organs
- nonstriated + involuntary
functions of muscle tissue (4)
- produce body movements
- posture
- produce heat
- moves substances along passageways
properties of muscle tissue
- electrical excitability
- constractility
- extensibility
- elasticity
electrical excitability
- responds to electrical disturbance sacross its plasma membraane
- can produce electrical signals in form of APS
contractility
ability to shorten and generate force to do work
extensibility
ability to be stretched without damaging tissue
elasticity
ability to return to original shape after contraction
each skeletal muscle is composed of many individual cells called
fibers aka monocyte
fascia
description
function
tough sheet of fibrous CT that surrounds every organ, muscle, bone, blood vessel
- forms 3D web down to cellular level
superficial fascia
what does it contain?
function
contains white and yellow fibers embedded in ground substance
- seperates muscles from skin
- stores fat
- protects from trauma
deep fascia
function
covers, divides and protects muscles with similar function
- lines body walls + limbs
what are trigger points?
tight connective tissue adhesions within the deep fascia that can cause local and referred pain
tendon
ability to?
attaches
tough band of fibrous CT usually connects muscle to periosteum
- withstands great tension
Aponeurosis
description
layer of flat broad tendons that is shiny, white, not good blood/nerve supply
connective tissue membranes of the muscle
epimysium, perimysium, endomysium
epimysium
covers entire muscle mass
perimysium
individual muscle fibers are arranged in fascicles
- each fascicle surrounded by a CT membrane (perimysium)
endomysium
surrounds each fiber within the fascicle
what happens to mesenchymal cells during embryonic development?
- mesenchymal cells
- myoblasts
- myotubes
- mature muscle fibers; actin and myosin appears in myotubes
what are skeletal muscle fibers covered by?
sarcolemma
what is mitochondria in a muscle cell?
sarcosome
muscle fibers
descrption
what do they contain?
- multi-nucleated
- contain: t. tubules, sarcoplasm, myofibrils, sarcoplasmic reticulum
T-tubules
descrption
function
tiny invagination of the sarcolemma
- how AP reaches the interior of cell
sarcoplasm
description
has large amounts of what? why?
muscle cell cytoplasm that contains a large amount of glycogen for energy production and myoglobin for oxygen storage
myofibrils
what do they consist of?
thin/thick myofilaments
- contractile organelles of muscle cell
sarcoplasmic reticulum
where is it found?
what does it store?
encircles each myofibril and stores calcium ions
muscular atrophy
description
decrease in muscle mass
- can be partial or complete
- becomes weaker
- found in association with cancer, AIDS, heart disease, lung disease
muscular hypertrophy
description
increase in the diameter of muscle fibers due to increase in cell size
- not pathological
hyperplasia
pathological
increase in cell #
can muscle cells regenerate?
no
ways to grow muscle in size
sarcoplasmic increase in amount (not in strengh) or myofibrils increase in # (strength and size)
what are sacromeres?
the functional units of a myofibril
parts of sarcomeres (4)
- A bands: darker; consist of thick filaments. Length of myosin filaments
- I bands: lighter, consist of thin filaments only
- Z disc or line: passes through the center of the I band. Marks individual sacromeres
- H zone: center of each A band. Contains thick filaments
how do thick filaments attach to Z discs?
titin filaments
what generates force during contraction?
contractile proteins
myosin
function
main component of thick filaments
- functions as a motor protein
actin
function
main component of thin filaments
- binds to the myosin head for the sliding together of filaments
torpomyosin and toponin
function
part of thin filaments and occupy active sites on F actin helix
what keeps thick and thin filaments in alignment and give myofibrils elasticity + extensibility?
structural proteins
titin
function
anchors thick filaments to the Z disc
myomesin
function
anchors thick filaments to adjacent filaments at the M line
neublin
function
binds the thin filaments to the Z disc
what happens when a muscle contracts?
Sliding filament theory of muscle contraction
- thin filaments slide past the thick filaments bringing the Z lines together
- sarcomeres shorten
- filaments do not change in length
- causes shortening of the muscle fiber
what will happen to muscle contraction withoutu calcium ions?
after the original shortening, nothing will happen
how do calcium ions increase and decrease contraction?
increase: initiates muscle contraction
decrease: stops it
what does the SR do in response to depolarization of the sarcolemma?
releases stored calcium ions into the sarcoplasm
active transpo processes return _______ to the _____
calcium ions to the SR
rigor mortis
how does it occur?
state of muscular rigidity following death
- SR becomes extremely leaky to calcium ions and muscles lack ATP to split the myosin-actin cross bridges that will release them from contraction
neuromuscular junction
where interaction between a somatic neuron and skeletal muscle fiber take place
synapse
description
region (gap) of communication btwn 2 neurons or neuron + target cell
- dont allow direct contact btwn muscle cells and neurons
- neurotransmitters + enzymes required
acetylcholine ACh
neurotransmitter at a neuromuscular junction
