anatomy lecture- exam 2 (ch. 9) Flashcards
- non-striated
- can replicate; hyperplasia
- reflex arcs or myogenic
smooth muscle characteristics
- myogenic
- branched
- scar tissue
- pumps blood
cardiac muscle characteristics
- multinucleated
- pulls on bones
- voluntary or reflex arcs
- hypertrophy
skeletal muscle characteristics
respond to stimuli; undergo action potentials
excitability
rebound towards its original length
elasticity
- produce movement
- maintain posture & body position
- support soft tissue
- regulate entering & exiting of material; found in some sphincters
- maintain body temp; shivering thermogenesis
skeletal muscle functions
skeletal muscle (organ)
muscle fiber (cell)
muscle fascicle (bundle of cells)
what’s labeled A
perimysium
what’s labeled B
muscle fiber
what’s labeled C
endomysium
- endomysium
- perimysium
- epimysium
cell membranes in muscles
membrane of muscle fiber
endomysium
Letter C
membrane of muscle fascicle
perimysium
Letter D
membrane of skeletal muscle
epimysium
Letter A
Whats labeled B
muscle fascicle
smallest functional unit of muscle
sarcomere
thick filament in sarcomere
myosin
thin filament in sarcomere
actin
myofilaments
sarcomere
myofibril
muscle fiber
fascicle
Muscle (as an organ)
discs form endplates for each sarcomere
Z discs/ line
Z-discs contract towards __line
M line/ disc
- “lock”
- reacts to Ca2+
troponin
- “chain”
- covers myosin binding sites
tropomyosin
when ____ is present, cross-bridge cycle can begin
Ca2+
Whats labeled A
Endomysium
What’s labeled B
myosatellite
What’s labeled C
sarcolemma
whats labeled D
myofibril
Whats labeled A
mitochondria
Whats labeled B
sarcolemma
Whats labeled C
myofibril
Whats labeled D
thin filament
Whats labeled E
thick filament
Whats labeled F
triad
Whats labeled G
sarcoplasmic reticulum
Whats labeled H
T-tubules
Whats labeled I
terminal cisterna
Whats labeled J
sarcolemma
Whats labeled K
sarcoplasm
Whats labeled L
myofibrils
automatic pathway that mediates a response to a stimulus
Reflex arc
Somatic reflex
skeletal muscle
motor neuron & muscle fiber it innervates
Motor unit
sequence of events from motor neuron signaling to a skeletal muscle fiber to contraction of the fiber’s sarcomeres
Excitation-Contraction Coupling
muscle surface that ACH binds to
motor end plate
degrades ACh in synaptic cleft
acetylcholinesterase (AChE)
- ACh released, binding to receptors
- AP reaches T tubule
- Sarcoplasmic reticulum releases Ca2+
- active site exposure and cross-bridge formation
- contraction begins
steps that initiate a muscle contraction
- ACh removed by AChE
- sarcoplasmic reticulum recaptures Ca2+
- active sites covered, no cross-bridge interaction
- contraction ends
- relaxation occurs, passive return to resting length
steps that end a muscle contraction
what time of muscle fiber & where is it located
slow fibers (smaller diameter, darker color due to myoglobin; fatigue resistant)
located in the calf & back (prolong contraction)
what time of muscle fiber & where is it located
fast fibers (larger diameter, paler color; easily fatigued)
located in the hands & eyes
increase in cell size & increase # of myofibrils
Hypertrophy
reduction in muscle size, tone, and power; due to disuse, age, or disease
Atrophy
theory that actin filaments slide toward each other during muscle contraction, while the myosin filaments are still
sliding filament theory
when contracting, they increase in diameter
Parallel muscles
not as strong as parallel muscles; direction of tension can vary
Convergent muscles
- shortest contraction distance
- produce more force than parallel muscles due to higher fiber concentration
Pennate muscles
- regulate opening and closing of an orifice
- can be found at sphincters
- some are active until relaxed
Circular muscles