Nervous System LO Flashcards
Describe the sections of the neurone
Cell body - contains nucleus
Axon - carry action potential away from cell body
Dendrites - extension of the cell body
Myelin sheath - allows electrical impulses to transit quickly and efficiently along the nerve cells
Nodes of ranvier - allows the generation of fast electrical impulses along the axon
Oligodendrocytes - enables fast saltatory impulse propagation
Axon terminal - releases the neurotransmitters of the presynaptic cell
Describe how an action potential is formed
1) stimulus received
2) stimulus changes voltage such that the threshold is met
3) opening of voltage gated sodium channels
4) sodium moves into the cell
5) inside of the cell becomes more positive (depolarised)
6) change in voltage triggers opening of voltage gated potassium channels
7) potassium leaves the cell
8) inside the cell becomes more negative (repolarised)
9) return to resting membrane potential
Describe the process of synaptic transmission
1) arrival of action potential
2) opens up the voltage gated Ca2+ channels
3) triggers vesicles to move and fuse with the nerve membrane
4) neurotransmitters diffuse across the synaptic cleft
5) act on specific receptors on post synaptic neurone (on its dendrites)
Describe what happens when an impulse reaches a neuromuscular junction
1) nerve impulse arrives at terminal axon
2) triggers opening of voltage gated Ca2+ channels
3) vesicles fuse with axon membrane
4) acetylcholine is released into the synapse
5) acetylcholine acts on acetylcholine receptors - they open
6) sodium enters - if threshold is reached an action potential is generated in the muscle, acetylcholine is broken down by acetylcholinerase
Identify the structures of the spinal cord
- white matter
- grey matter
- central canal
- dorsal and ventral horns and roots
- spinal meninges
Identify major components of the nervous system
Central nervous system made of brain and spinal cord
Peripheral nervous system made of nerves that branch from the spinal cord
Outline the functions of the brain stem
Midbrain - controls eye movements, regulates reflexes, orientate towards sounds of interest
Pons - responsible for chewing and sleep
Medulla - includes cardiovascular and respiratory centres
List the meninges of the brain and spinal cord
Brain and spinal cord are completely surrounded by three layers of tissue called the meninges
Named from the outside inwards they are the: dura mater, arachnoid mater, pia mater
Dura mater
- two layers of dense fibrous tissue
- outer layer lines inner surface of skull bones
- provides protective covering for the brain
Arachnoid mater
- layer of fibrous tissue between dura and pia maters
- separated from dura mater by subdural space and a small amount of serous fluid
- separated from pia mater by subarachnoid space which contains CSF
Pia mater
- delicate layer of connective tissue
- contains many tiny blood vessels
Identify the origin of CSF and its functions
CSF circulates constantly from the ventricles through the subarachnoid space, around the brain and spinal cord
CSF is a clear alkaline fluid consisting of: water, mineral salts, glucose, plasma proteins, leukocytes, creating and urea.
CSF is secreted into each ventricle of the brain by choroid plexuses (vascular areas, rich in blood vessels)
CSF passes back into the blood through tiny finger-like projections of arachnoid mater called arachnoid villi
CSF movement from subarachnoid space to venous sinuses depends on difference in pressure on each side of arachnoid villi, which act as one-way valves
CSF is secreted continuously at 0.5 ml per minute
Function - supports and protects the brain and spinal cord by maintaining a uniform pressure and acting as a cushion between the brain and the skull
Identify how sensory information is conveyed to the central nervous system through activation of sensory receptors
Stimulation of the sensory receptor activates the associated afferent neurone, which carries information about the stimulus to the central nervous system
Compare functions of the sympathetic and parasympathetic divisions of the autonomic nervous system
Sympathetic
- predominates in stressful situations
- equips the body to respond when exertion and exercise is required
Parasympathetic
- calm, non-stressful situations
Identify and state the functions of the: medulla, pons, midbrain, cerebellum, hypothalamus, thalamus, cerebrum
MEDULLA - helps control vital processes like your heartbeat, breathing and blood pressure
PONS - relays and regulates the signals that give you the sensation of pain from anywhere in your body below your neck
MIDBRAIN - associate with vision, motor control, sleep/wake, arousal and temperature regulation
CEREBELLUM - helps coordinate and regulate a wide range of functions and processes in both your brain and body
HYPOTHALAMUS - keep your body in a stable state called homeostasis
THALAMUS - your body’s information relay station
CEREBRUM - initiates and coordinates movement and regulates temperature
