The nervous system Flashcards
What is a synpase?
Junction between at least two neurons where electrical activity of one influences the electrical activity of another
What is an action potential?
The all-or-nothing electrical event that passes through neurons
What is the difference between inhibitory postsynaptic potentials (IPSP) and excitatory postsynaptic potentials (EPSP)?
Inhibitory promotes hyperpolarisation
Excitatory promotes depolarisation of postsynaptic
What is the difference between a muscle spindle and golgi tendon organ?
MS - detects change in length/stretch
GTO - detects change in force
Function of muscle spindles?
Regulate movement and maintain posture
Function of GTO?
Reduce muscle tension - by inhibition of motor neurones
Define motor unit
A motor neurone and all the muscle fibres that innervate it
What is innervation ratio?
The number of fibres that innervate a motor unit?
Explain the size principle
The body recruits the smallest motor units upW
What is spinal tuning
Refined voluntary movement that is translated into appropriate muscle movement by the spinal cord
What initiates movement - name the structures
- Subcortical
- Association cortex
- Basal nuclei or cerebellum
- Thalamus
- Motor cortex
- Motor units
What is the basal ganglia and cerebellum needed for in terms of movement?
BG - drives slow and deliberate movement
C - drives fast movement
Withdrawal reflex
A stimulus causes contraction of a muscle without higher brain inputs
Also results in a cross-extensor reflex
What neurotransmitter is released by the PNS
Acetylcholine
What neurotransmitter SNS
Norepinephrine
What nerve connects the PNS and heart
Vagus
What allows HR to increase during exercise - 2 parts
Parasympathetic withdrawal, up to 100 bpm
Sympathetic stimulation
What factors contribute to SV
- Frank Starling mechanism - greater EDV, the greater force of contraction
- Venous return
What contributes to venous return?
- Valves
- Muscle pump
- Respiratory pump
- Vasoconstriction of vessels via SNS
What is systolic pressure
Pressure generated during ventricular contraction
What is diastolic pressure
Pressure in arteries during cardiac relaxation
What is mean arterial pressure
Pressure in arteries during one cardiac cycle
MAP equation
MAP = DBP + 0.33 (SBP+DBP)
What determines MAP? Provide an equation
Q x total vascular resistance
