Muscle physiology Flashcards
what are 3 types of muscles?
- skeletal muscle
- cardia muscle
- smooth muscle
skeletal muscle functions
- Producing body movements
- Walking and running - Generating heat
- Contracting muscle produces heat
- Shivering increases heat production - Stabilizing body positions
- Posture
cardia muscle functions
- Involuntary movement of the heart
- Heart muscle-pumping blood
smooth muscle function
- Involuntary movement of organs, blood vessels
- Control of blood vessels, airways, digestive tract,
urinary tract
give 4 types of properties in muscle
Properties that enable muscle function and contribute to homeostasis
- Excitability: Ability to respond to stimuli
- Contractibility: Ability to contract to forcefully when
stimulated - Extensibility: Ability to stretch without being damaged
- Elasticity: Ability to return to an original length
where does skeletal muscle attach to?
- inserted onto bone via connective tissue; tendons and ligaments
- Long cylindrical cells
- Many nuclei per cell
- Striated
- Voluntary
- Rapid contractions
- flexors and extensors
connective tissue components
- Facia
- Epimysium
- Perimysium
- Endosyium
- Tendon
- Aponeurosis
what neurons stimulate the skeletal muscle to contract?
somatic motor neurons
how does muscle growth occur?
hypertrophy: the organ’s increase in size of its cell
*testosterone and human growth hormone stimulate hypertrophy
what is each muscle fiber made of?
myofibrils
what are myofibrils made of?
myofilaments
what is the functional unit for muscle contraction? and what are they made of?
must know the structure from large to small scale
- sarcomeres
- made up of actin and myosin myofilaments
what are the 3 types proteins that make up muscle proteins?
- contractile proteins
- regulatory proteins
- structural proteins
contractile proteins
- actin and myosin
- generate force during contraction
regulatory proteins
switch the contraction process on and off
structural proteins
titin:
- stabilize the position of myosin
- accounts for much of the elasticity and extensibility of myofibrils
dystrophin:
- links thin filaments to the sacrolemma
events leading to muscle fiber contraction
- a motor neuron releases (ACH)
- ACH binds to receptors on the sarcolemma
- the action potential triggers the release of Ca2
- the Ca2 binds to troponin on the actin filament, and the troponin pulls tropomyosin off the active sites, allowing the myosin head to attach to the actin filament
when does onset contraction begin?
SR releasing calcium ions into the muscle cell
sarcolemma
plasma membrane of a muscle cell
transverse (T tubules)
- tunnel in from the plasma membrane
- muscle action potentials travel through the T tubules
sacroplasm
- the cytoplasm of a muscle fiber
- includes glycogen for synthesis of ATP and myoglobin which binds O2 molecules
- myoglobin releases O2 when it is needed for ATP production
myofibrils
thread-like structures which have a contractile function
sarcoplasmic reticulum (SR)
- membranous sacs which encircle myofibril
- stores calcium ions (Ca++)
- release of Ca++ triggers muscle contraction
filaments
- function in the contractile process
- 2 types of filaments (thick and thin)
- there are 2 thin filaments for every thick filament
sarcomeres
- compartments of arranged filaments
- basic functional unit of a myofibril
cardiac muscle
(heart muscle) involuntary
- found in the walls of the heart; myocardium
- medium-speed contractions
- striated
smooth muscle
- non-striated muscle, that lines hollow organs
- slow-speed contraction
- involuntary
what are muscles 2 categories?
- striated (striped)
- non-striated (no stripes)
actin
- thin filaments
- provide site where myosin head can attach
- tropomyosin and troponin are also part of the thin filament
myosin
- thick filaments
- functions as a motor protein that can achieve motion
- convert ATP to energy motion
- projections of each myosin head protrude outward
how does voluntary muscle occur?
- action potentials arrive from the motor neuron
- stimulates the release of neurotransmitters (most cases of skeletal muscle it is acetylcholine ACH)
- ACH diffuses across the synaptic cleft, binds to nicotinic receptors on the post-synaptic muscle cell
- muscle is then stimulated to contract
excitation-contraction coupling process
match the correct word starting from muscle belly to the muscle unit:
a. muscle bellies go down to the individual______.
b. each muscle fiber is made up of ______.
c. each myofibril is made up of ______.
d. myofilaments make up a repeating section of ______ is the functional unit of contraction
e. each sarcomere are made up of _____ and _____myofilaments.
a. muscle fiber
b. myofibrils
c. myofilaments
d. sarcomeres
e. actin and myosin
troponin and tropomyosin are components of which one of the following structures?
a. myosin (thick) filament
b. sarcolemma
c. T tubule
d. actin (thin) filament
e. sarcoplasmic reticulum
actin (thin) filament
a gross skeletal muscle belly can be instructed (by the central nervous system) to contract more forcefully by:
a. causing more of its motor units to contract simultaneously
b. increasing the amount of acetylcholine released during each neuromuscular synaptic transmission
c. increasing the frequency of action in the alpha motor neuron axon
d. both A and C
e. both B and C
both A and C
