Muscle Histology Flashcards
function of muscle
- motion and stability
- internal organ function
- maintains body temperature
motion and stability muscle function
- moves skeleton
- maintains posture
internal organ muscle function
- digestive (peristalsis)
- cardiac (heartbeat)
maintaining body temperature function
-muscle contraction (normal body temperature)
characteristics of muscle
- irritability
- contractility
- extensibility
- elasticity
irritability muscle characteristic
-receive and respond to stimulus from a neuron
contractility muscle characteristic
-respond by contracting (shortening)
extensibility muscle characteristic
-following contraction
define contraction
-a muscle will extend to its original length
elasticity muscle characteristic
-muscle will assume its desired shape after stretching
structure of muscle tissue
- composed of fibers
- fibers contain “contractile proteins”
muscle tissue fiber composition
-long, thing cells of muscle tissue
muscle tissue contractile proteins
- actin and myosin
- cells can shorten and produce movement
classifications of muscle
- skeletal
- smooth
- cardiac
skeletal muscle classification
- long multinucleated and striated
- attached to skeleton
- voluntary (under conscious control)
smooth muscle classification
- composed of long cells containing one nucleus
- found in GI tract and blood vessel walls
- involuntary (not under conscious control)
cardiac muscle classification
- composed of uni-nucleated branching cells; end-to-end
- found only in heart
- involuntary
skeletal muscle components
- associated connective tissue
- microscopic structure
- muscle contraction
skeletal muscle associated CT components
- attachments
- coverings
skeletal muscle attachments components
- tendons
- aponeurosis
skeletal muscle tendon attachments
- dense regular connective tissue
- muscle to bone
skeletal muscle aponeurosis
- dense regular connective tissue
- thin, tendinous sheet
skeletal muscle coverings components
- endomysium
- perimysium
- epimysium
- fascia
skeletal muscle covering composition
- organization of muscle
- tubes within tubes within tubes
define fascicle
-made of muscle cells (fibers)
skeletal muscle endomysium covering
-loose CT covering individual muscle fibers (muscle cells)
skeletal muscle perimysium covering
-surrounds bundles of muscle fibers (fascicles)
skeletal muscle epimysium covering
-covers entire muscle belly
skeletal muscle fascia covering
-CT which binds several muscle groups together
define a muscle fiber
-a single skeletal muscle cell
skeletal muscle microscopic characteristics
- multinucleated
- contain numerous specialized cellular organelles
skeletal muscle microscopic structure components
- sarcoplasm
- sarcolemma
- t-tubule
- sarcoplasmic reticulum
- mitochondria
- myofibril
- myofilament
- myoglobin
- sarcomere
skeletal muscle sarcoplasm
-cytoplasm within muscle cells
skeletal muscle sarcolemma
- plasmalemma (cell membrane)
- just deep to endomysium
skeletal muscle t-tubule
- tube-like extension of sarcolemma
- transmits nerve impulse to sarcoplasmic reticulum
skeletal muscle sarcoplasmic reticulum
- basically smooth ER of muscle
- stores a large amounts of calcium
- when releases calcium triggers contraction
skeletal muscle mitochondria
- provide energy (ATP) via aerobic respiration
- ATP provides the energy to allow myosin to form crossbridges with the actin
skeletal muscle myofibril
-“contractile organelles”
skeletal muscle myofilament
- in myofibrils
- contain contractile proteins
skeletal muscle myoglobin
-red protein: contains iron, stores oxygen
skeletal muscle sarcomere
- many sarcomeres within myofibrils
- smallest contractile unit
- extends from Z band to Z band
define contractile organelles
-cylindrical units run entire length of muscle
components of myofilaments
- actin filaments
- myosin filaments
skeletal muscle actin filaments
- thin filaments
- closer to each end of sarcomere (near each Z line)
skeletal muscle myosin filaments
- thick filaments
- center of the sarcomere
- pulls actin inward (Z lines contracts)
skeletal muscle muscle contraction I band
- light band
- contains actin
- Z band located in the middle of the I band
skeletal muscle contraction A band
- dark band
- contains both actin and myosin
skeletal muscle sliding filament mechanism
- initiated by the release of the neurotransmitter acetylcholine from a nerve fiber**
- results in the release of calcium within the muscle fiber which binds to the thin actin filaments
innervations of skeletal muscle
- neuromuscular junction
- motor unit
skeletal muscle neuromuscular junction
-point of contact between muscle fiber and axon of neuron which stimulates it
skeletal muscle motor unit “all or nothing” principle
-when a nerve impulse travels through a motor unit all of the fibers served by it contracts simultaneously to their maximum
first step in muscle excitation
-motor neuron releases neurotransmitter acetylcholine (ACh)
second step in muscle excitation
-ACh triggers action potential in sarcolemma (muscle cell membrane
third step in muscle excitation
-change in sarcolemma–> release of calcium ions from sarcoplasmic reticulum
fourth step in muscle excitation
-sarcomeres shorten–> myofibrils shorten–> muscle fibers shorten–> muscle contract
types of muscle fibers
- red slow twitch fibers
- white fast twitch fibers
- intermediate fast twitch fibers
myoglobin muscle fibers red slow twitch fibers
-high
myoglobin muscle fibers white fast twitch fibers
-little
myoglobin muscle fibers intermediate fast twitch fibers
-high
mitochondria muscle fibers red slow twitch fibers
-many
mitochondria muscle fibers white fast twitch fibers
-few
mitochondria muscle fibers intermediate fast twitch fibers
-many
capillaries muscle fibers red slow twitch fibers
-many
capillaries muscle fibers white fast twitch fibers
-few
capillaries muscle fibers intermediate fast twitch fibers
-nany
what is the function of capillaries?
-deliver blood and oxygen
energy production muscle fibers red slow twitch fibers
-aerobic metabolism for ATP production
energy production muscle fibers white fast twitch fibers
- anaerobic pathways for ATP production
- ->lactic acid is by-product
energy production muscle fibers intermediate fast twitch fibers
-aerobic
glycogen reserves muscle fibers red slow twitch fibers
-none
glycogen reserves muscle fibers white fast twitch fibers
-ranges
glycogen reserves muscle fibers intermediate fast twitch fibers
-N/A
power muscle fibers red slow twitch fibers
- high power
- sustained over a long period of time
power muscle fibers white fast twitch fibers
-generates powerful contraction
power muscle fibers intermediate fast twitch fibers
-powerful (less than white fast twitch)
fatigue muscle fibers red slow twitch fibers
-fatigue resistant
fatigue muscle fibers white fast twitch fibers
-quickly
fatigue muscle fibers intermediate fast twitch fibers
-fatigue resistant (between red and white)
contraction time muscle fibers red slow twitch fibers
-contrast slowly for long periods of time
contraction time muscle fibers white fast twitch fibers
-fast contraction time
contraction time muscle fibers intermediate fast twitch fibers
-between red and white
examples of red slow twitch fibers
-posture (steady, prolonged contraction)
examples of white fast twitch fibers
- eye movement
- lifting
- throwing
examples of intermediate fast twitch fibers
-muscles of lower limbs (support and movement)
synergistic
-two or more muscles working together
antagonistic
-two or more muscles working against one another
concentric contraction
- causes tension on your muscle
- as it shortens, it generates enough force to move an object
concentric contraction example
- bicep curl
- lifting a weight
eccentric contraction
-motion of an active muscle while it is lengthening under load
eccentric contraction example
-lowering a weight