79 terms

muscular system review

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what are the 3 types of muscle tissue?
1. skeletal
2. cardiac
3. smooth
what type of muscle tissue is the muscular system comprised of?
ONLY skeletal muscle tissue
what is another name for cardiac muscle cells?
myofibers
5 cardiac muscle cell characteristics
1. striated
2. mono or multi-nucleate
3. branched/woven in appearance
4. joined by intercalated discs
5. autorhythmic
what are contained in intercalated discs?
gap junctions and desmosomes
what does it mean to be autorhythmic?
able to generate muscles impulses without stimulation from the nervous system
what is another term for autorhythmic?
myogenic conduction
if cardiac muscles are able to generate their own impulses, what regulates the rate of their contractions?
autonomic nervous system stimulation
where are smooth muscle fibers found?
walls of blood vessels, digestive tract organs, and ducts
smooth muscle fiber characteristics
1. cells are short and fusiform with one nucleus
2. no striations (sarcomeres)
3. dense bodies present within the cells
4. autonomic nervous system control
what is the purpose of the dense bodies found within smooth muscle fibers?
points of attachment for thick and thin protein filaments
what are the 4 properties of muscle tissue
1. excitability
2. contractility
3. elasticity
4. extensibility
excitability
ability to response to outside stimuli which initiate action potentials and lead to muscle contractions
contractility
stimulations leads to contraction of a muscle fiber
elasticity
the ability of a muscle fiber to return to its original length after contraction
extensibility
ability of a non-contracted muscle to be stretched past it relaxed length
what is type of tissue is found within each skeletal muscle?
epithelial, connective, muscular, and nervous (ALL TISSUE TYPES)
what are the functions of skeletal muscle tissue?
1. body movement
2. maintenance of posture
3. temperature regulation
4. storage and movement of materials
5. provide support for abdominal organs
skeletal muscle structural hierarchy
actin and myosin --> myofilaments --> myofibrils --> muscle fiber --> fascicles --> muscle
what does working out change in the skeletal muscle hierarchy?
can ONLY change the number of myofibrils NOT the number of muscle fibers!
term for cell membrane of a muscle
sarcolemma
term for cytoplasm of a muscle
sarcoplasm
term for smooth ER of a muscle
sarcoplasmic reticulum
what are the 3 main myofilaments (proteins)
1. actin
2. myosin
3. dystrophin
what is found within the sarcoplasm of a muscle fiber?
myofibrils
what is the function of myofibrils
to shorten, which contracts the entire muscle cell
what are myofibrils composed of?
myofilaments
what are the repeating groups found in myofilaments called?
sarcomeres
thin filament
actin and associated proteins (troponin and tropomyosin)
thick filament
myosin
two main types of myofilaments
actin and myosin
what is the functional contractile unit of a skeletal muscle fiber?
sarcomere
what causes skeletal muscle to appear striated?
the organization of thick and thin filaments (sarcomeres)
what is an A band?
the dark band (contains thick filaments and a portion of thin filaments)
what is an I band
the light band (contains thin filaments only)
what are the 4 layers of connective tissue?
1. endomysium
2. perimysium
3. epimysium
4. deep and superficial fascia
where is endomysium found
innermost layer that insulates each muscle fiber
where is perimysium found
surrounds fascicles
where is epimysium found
surrounds the entire muscle
where is the deep and superficial fascia found?
surround and separate muscles
what do tendons do?
connect muscle to bone
what is an enthesis?
point where a tendon connects to a bone
what is an aponeurosis?
a wide flat tendon
what moves when a muscle contracts?
the insertion
what are the 3 classes of levers in the human body?
1. first class
2. second class
3. third class
a _____ is an elongate, rigid object that moves at a point called a _______
lever, fulcrum
first class lever
fulcrum in the middle between resistance and effort
where is a first class lever in the human body?
the head sitting on the neck
second class lever
load in the middle between fulcrum and effort
where is a second class lever in the human body
ankle
third class lever
effort in the middle between resistance and fulcrum
where is a third class lever in the human body?
elbow, knee, and jaw
steps of muscle contraction
a motor neuron impulse (action potential) stimulating a muscle fiber and releasing a neurotransmitter onto its surface
what is a neuromuscular junction?
location where a motor neuron and muscle fiber come close together
what are the 4 components of a neuromuscular junction?
1. synaptic knob
2. synaptic vesicles
3. motor end plate
4. synaptic cleft
synaptic knob
expanded end of an axon terminal
synaptic vesicles
tiny sacs filled with a nuerotransmitter
motor end plate
part of the sarcolemma which meets the synaptic knob
synaptic cleft
the space between the synaptic knob and motor end plate
what is a motor unit
one motor neuron and the collection of muscle cells it controls
muscle hypertrophy
increase in the muscle fiber size from exercise (increase in myofibrils and myofilaments)
muscle atrophy
reduction in muscle mass due to lack of exercise
what are the 3 types of skeletal muscle fibers?
1. slow
2. intermediate
3. fast
slow muscle fiber characteristics
type 1
slow oxidative
red
intermediate muscle fiber characteristics
type 2a
fast aerobic
light red
fast muscle fiber characteristics
type 2b
fast anaerobic
white
what type of muscle fibers are found in majority of skeletal muscles?
trick question! majority of skeletal muscles contain all 3 types of muscle fibers
what type of muscle fibers are controlled by a single motor unit
only fibers of the same type
where can slow muscle fibers be found?
postural muscles of the back and the calf
where can fast muscle fibers be found?
eyes and hand muscles
what are the 4 fascicle patterns of muscles?
1. circular
2. parallel
3. convergent
4. pennate
what are the subtypes of pennate muscle pattern
1. unipennate
2. bipennate
3. multipennate
circular muscle pattern examples
sphincters and obicularis oris
parallel muscle pattern examples
rectus femoris, rhomboid major, and rectus abdominus
convergent muscle pattern examples
latissimus dorsi ad pectoralis major
unipennate muscle pattern example
extensor digitorum
bipennate muscle pattern example
rectus femoris
multipennate muscle pattern example
deltoid, soleius, gastrocnemius
what are the 6 things muscles are named upon?
1. appearance
2. location
3. function
4. origin/insertion
5. orientation
6. unusual features