Muscles and body position Flashcards
3 types of muscle
Skeletal (attached to bones)
Smooth (walls of organs, blood vessels)
Cardiac (forms bulk of heart)
How many types of skeletal muscle?
600
Flexor vs extensor
Flexor - bend
Extensor - straighten
Muscle fibers
Constitute muscle. Each is a living cell containing several nuclei
Muscle fibers
Constitute muscle. Each is a living cell containing several nuclei (in skeletal muscle)
Outer membrane of muscle is called?
Sarcolemma
Myofibrils
Long cylindrical structures found within muscle.
What are myofibrils made of?
Sarcomeres.
What are Sarcomeres made of?
Actin (thin filaments) and Myosin (thick filaments)
Sarcomere’s two darkened ends are called
Z lines, actin
Sarcomere’s lighter middle
H zone, myosin attached to fine M line
Sarcomere’s lighter middle
H zone, myosin attached to fine M line
EPP - End Plate Potential
Depolarises muscle membrane producing an action potential in the muscle membrane
Another term for Proprioception
Kinesthetic Sense
What system deals with movement of the head
The Vestibular System
Second set of muscles in centre of muscles
The Muscle Spindle System
What system possesses both Afference and Efference? How so?
The muscle spindle system
Afference - very fast - 1a sensory fibres
Efference - Gamma motor neurons
Two sources of information regarding limb position
Proprioception - Muscle spindles
Efference copy theory - the brain compares the muscle signal with the actual effect
Two sources of information regarding limb position
Proprioception - Muscle spindles
Efference copy theory - the brain compares the muscle signal with the actual effect
Alpha motor neurons
Among the largest in the body. Each muscle is served by at least one motor neuron, which branches to hundreds of axonal endings.
Neuromuscular junctions are between…
The axon endings of the motor neuron and the muscle fibre
What is involved in an endplate potential?
- Motor neuron’s endings (synaptic knobs) fit into ‘pits’ located in the motor endplate
- Release acetylcholine.
- This binds to ‘nicotinic acetylcholine receptors’
- Increases permeability of the muscle fibre membrane to sodium and potassium ions
Sarcoplasmic Reticulum
network of tubes and sacs found in the cytoplasm of each muscle fibre. As the action potential moves through the muscle fibre, it releases large numbers of Calcium ions. These are what cause actin and myosin to slide over one another.
Two sources of information regarding limb position
Proprioception - Muscle spindles
Efference copy theory - the brain compares the muscle signal with the actual effect
Alpha motor neurons
Among the largest in the body. Each muscle is served by at least one motor neuron, which branches to hundreds of axonal endings.
Neuromuscular junctions are between…
The axon endings of the motor neuron and the muscle fibre
What is involved in an endplate potential?
- Motor neuron’s endings (synaptic knobs) fit into ‘pits’ located in the motor endplate
- Release acetylcholine.
- This binds to ‘nicotinic acetylcholine receptors’
- Increases permeability of the muscle fibre membrane to sodium and potassium ions
Sarcoplasmic Reticulum
network of tubes and sacs found in the cytoplasm of each muscle fibre. As the action potential moves through the muscle fibre, it releases large numbers of Calcium ions. These are what cause actin and myosin to slide over one another.
Ia sensory fibres
Fibres wrapped around the middle of muscle spindles which project into spinal cord (
Ia sensory fibres
Fibres wrapped around the middle of muscle spindles which project into spinal cord
2 functions of a muscle spindle
Send information to CNS on the state and position of muscles and initiate reflex contraction of the muscle when stretched by a load
Best known example of a stretch reflex?
Patella tendon muscle reflex
Monosynaptic Reflexes
eg Patella tendon reflex - reflexes that only involve one synaptic gap
Golgi tendon organs
Lie at the point of attachment between muscle and tendon. Communicate with the spinal cord regarding the load on muscles by Ib sensory fibres
Reciprocal inhibition
simultaneous inhibition of one muscle while exciting another (for example, to withdraw from pain)
Two main components of vestibular system?
Semicircular canals and otolith organs
Utricle and saccule
two sac-like structures in the inner ear providing info about the position of the head relative to the body, gravity and accelleration
Why are the Utricle and Saccule sometimes called “otolith organs?”
because they contain little ‘stones’ that displace and cause sensory hairs to bend
Why are the Utricle and Saccule sometimes called “otolith organs?”
because they contain little ‘stones’ that displace and cause sensory hairs to bend
