Week 3 Flashcards
What is a neuron?
Receives and sends messages (impulses) throughout the nervous system
What are the classifications of neutrons?
Afferent (sensory)
- From senses towards the CNS
Efferent (motor)
-From CNS to effectors (muscles etc)
Interneurons
- Forms connections between neurons
What is a synapse?
Junction between 2 neurons
What are the 4 steps of a synaptic transition?
- Action potential reaches axon terminal
2 Synaptic vessels release chemical transmitter (acetylcholine) - Chemical crosses a synaptic space
- Chemical enters receptor sites on dendrite
- What is the resting membrane potential or polarisation of a neuron?
- What is the depolarisation or action potential of a neuron?
Both in mV
- -70mV
2. 30mV
What are refractory periods?
Absolute refractory period
- Impossible to evoke another action potential
Relative refractory period
- Need stronger than normal stimulus to evoke AP
Name 2 facts about the neuron
- Action potential lasts approx. 1msec
- There is a minimum threshold for an action potential
What determines the speed of a synaptic transmission?
- Cross section diameter
- Larger=faster - Myelinated vs non myelinated
- Myelinated=faster
Note: Size and myelination developed in relation to urgency of info
What is a neuromuscular junction?
Connection between nerve and skeletal muscle
What are the 2 types of motor neurons?
- Alpha (skeletomotor)
- Innervates large musculoskeletal fibres - Gamma (fusiform)
- Innervates small specialised muscle fibres (muscle spindle)
What is a motor unit?
A motor neuron and the muscle fibres it Innervates
What is the peripheral nervous system?
Nerve fibres that enter or leave the brain stem and spinal cord and Innervate the sensory receptors, muscles and glands
What are the 2 divisions of the PNS and what do they do?
- Somatic PNS
- Controls skeletal muscles - Autonomic PNS
- Control heart, smooth muscles and glands.
What is the central nervous system?
The brain and the spinal cord.
What is the brain stem responsible for?
Many involuntary, autonomic and metabolic function (eg HR), orienting reflex, novel responses to stimuli that involves head turning, eye movements and postural adjustments.
What is the medulla oblongata responsible for?
- Transmits sensory and motor information to and from the brain to muscles and glands
- Provides regulation of vital processes (autonomic NS)
What is the Pons responsible for?
- Central and dorsal parts of pons contain several nerve tracts that allow for coordinated and involuntary influences on automatic movement and posture
- Integration centre for sensory information from muscles and joints
- Relay info form motor cortex to cerebellum
- Controls several automatic functions necessary for life
What is the role of the midbrain?
- Connects thalamus to the hypothalamus
- Visual and auditory reflex centres
What is the role of the reticular formation?
- Sets of nuclei and neurons distributed throughout the brain stem
- receives input from all sensory systems and nerve fibres from higher brain centres.
- involved in control of waking and sleeping.
- Important in attention and activation of individual for cognitive and motor ability
- Filters out unnecessary information
What are the three major parts of the cerebrum?
- Cerebral cortex
- Basal ganglia
- Cerebellum
What is the role of the cerebral cortex?
- The highest level of the motor control hierarchy
- Packed with cell bodies and neurons
What is the Basal Ganglia responsible for?
- Recieves information from motor areas of the cortex, then sends output to motor cortex via thalamus
- Responsible for organising complex motor activities, scaling and modifying parameters for movement (eg velocity, direction, amplitude)
- Role in thought control
What is the cerebellum responsible for?
- Connects spinal system, cerebral cortex and other brain structures
- Important role in coordinating and monitoring complex patterns of skilled movement.
- Functions to coordinate motor activities initiated by primary motor cortex
- Recieves info from proprioceptors
- Cognitive function of word association and puzzle solving
