Muscular System Flashcards
what is a muscle
type of tissue designed for contraction
muscle cells are also called…
muscle fibers
what are muscle fibers composed of?
actin and myosin (arranged into microfilaments)
3 types of muscle
skeletal, cardiac, smooth
skeletal muscle
moves the bones and eyes with help of the nervous system
cardiac muscle
-only found in the heart
-responsible for besting of the heart which pumps blood through the vessels
Smooth muscle
movement of internal organs with the help of the nervous system
characteristics of skeletal muscle
-numerous large cells
-may contain hundreds of nuclei and mitochondria in each cell
-nuclei are located along cell membrane
-VOLUNTARY
-STRIATED
-attached to bones by TENDONS
characteristics of cardiac muscles
-can contract without nervous system help
-specialized pacemaker cells within the heart muscle to signal heart
-INVOLUNTARY
-cell branch and are STRIATED
-cells are connected at the intercalated disc
characteristics of smooth muscles
-small, spindle shaped cells
-no striations
-contractions stimulated by nerves
-INVOLUNTARY
-blood vessels, uterus, bladder, intestines
muscle cell characteristics (4)
-excitability
-contractability
-extensibility
-elasticity
functions of muscle
-allow motion to occur
-maintain posture
-generate heat
muscle fiber
structures that make up a muscle
endomysium
connective tissues that covers each muscle fiber
fascicle
group of muscle fibers
perimysium
connective tissue that surrounds a fascicle
blood vessels and nerves
transport blood to muscle, nerve brings electrical impulses to muscle
epimysium
fibrous tissue covering around the entire muscle
tendon
fibrous tissue connecting muscle to bone
sarcoplasm
cytoplasm of a muscle fiber
sarcolemma
cell membrane of a muscle fiber
myofibrils
-made of 2 protein filaments (actin and myosin)
-each muscle fiber is made of 100’s of myofibrils
T-tubules
-passageways from the sacrolemma to the interior of the muscle fiber
-carry nerve impulses to the sarcoplasmic reticulum
sarcoplasmic reticulum
-like endoplasmic reticulum of other cell types
-calcium ions stored here
sarcomere
basic contacting unit of skeletal muscle (made of actin and myosin)
what is needed for a muscle to contract?
a nerve impulse
where is the muscle contraction started?
at the neuromuscular junction
synaptic cleft
space between nerve fiber and muscle fiber
synaptic vesicles
sacs within end of nerve fiber which contain acetylcholine (a neurotransmitter)
