Muscle Physiology Flashcards
Skeletal Muscle:
- Appearance
- What part of nervous system
- Function
- Appearance: Long and striated due to presence of actin + myosin bands
- What part of nervous system: Somatic
- Function: Provide motor to body via sliding filament mechanism
What is required for muscle contractoin?
ATP (energy) + calcium
What/where is the skeletal neurotransmitter? What effect does it have on the muscles
Acetylcholine (Ach), at ends of motor neurons, ceases muscle activity
What is the difference between origin and insertion of muscles?
- Origin: less moveable end of muscle/tendon attached to bone
- Insertion: more moveable end of muscle, usually attached to bone via tendons
- Skeletal muscles have both
What are skeletal muscles attached to?
Skeletal system (bone) by tendons (connective tissue)
Smooth muscle is AKA…
Visceral muscle
Where is smooth muscle found?
In the walls of all hollow organs
How are electrical impulses transmitted in smooth muscles? What are the neuro transmitters + their functions?
Through interstitial fluid as there are NO neuromuscular junctions
Neurotransmitter:
1. Acetylcholine (Ach): causes contractions
2. Norepinephrine: inhibits contractions
When does muscle relaxation occur in smooth muscle?
When calcium is moved OUT
What is the appearance of smooth muscle fibers?
Spindle shaped with a single nucleus
What muscle(s) are involuntary?
- Smooth muscle
- Cardiac muscle
What muscle(s) are voluntary?
- Skeletal muscle
What are the 3 types of muscles
- Skeletal Muscle
- Smooth/Visceral Muscle
- Cardiac Muscle
What is the function of the cardiac muscles
To pump blood in the circulatory system
What is the appearance + location of cardiac muscles?
Branching and striated, located in wall of heart
Define: Sarcomere
Contractile unit of muscle fiber
Define: Myofibril
Muscle fiber
Define: Sarcoplasmic reticulum
Endoplasmic reticulum that is needed for muscle contraction
Define: Z-line
Protein bands where actin filaments attach in a striated muscle fiber and mark the boundaries of adjoining contractile units
Define: Sarcolemma
Thin plasma cell membrane of a muscle cell
What is the process of muscle contraction? (5 steps)
- Action potentials (nerve impulses) trigger calcium release
- Calicum is stored in the sarcoplasmic reticulum when the muscle is at rest
- The calcium then binds to troponin on the thin filaments, which turns on actin and myosin interaction.
- This results in contraction of the sarcomere. After the contraction, calcium is pumped back into the sarcoplasmic reticulum via Calcium ATPase
- When the action potential reaches an axon terminal, acetylcholine is released from the vesicles,
which opens transmembrane channels and allows sodium to diffuse in. - After the action potential, the latent period occurs when acetylcholinesterase breaks down the acetylcholine at the neuromuscular junction.
- The sodium channels then close, and resting potential is restored by outflow of potassium.
How is action potential created?
When sodium ions rush in, the action
potential is created in the muscle fiber
An influx of sodium ions, decreases the resting potential at the end plate
What is the neuromuscular junction
The junction between the motor neuron terminal and the muscle fiber (a kind of synapse)
