Nervous System Flashcards
What are the structural classifications of the nervous system?
Central NS = brain and spinal cord
Peripheral NS = cranial nerves (12 pairs) and spinal nerves (31 pairs)
What are the functional classifications of the nervous system?
Peripheral NS = Sensory (afferent) and Motor (efferent) neurones
Sensory = senses and sensory receptors
Motor = Somatic and autonomic
Somatic (voluntary) = skeletal muscles
Autonomic (involuntary) = smooth muscle, glands, cardiac muscle
Autonomic = Parasympathetic and Sympathetic
Ganglion
A group of cell bodies in the PNS
Nuclei
A group of cell bodies in the CNS
How many efferent neurones does the neuron pathway, controlled by the divisions of the autonomic motor NS have?
2 efferent neurones
What are the 2 efferent neurones of the parasympathetic and sympathetic NS called?
1) Pre-ganglionic neurone = cell body will be in the CNS (anywhere apart from the cerebellum)
2) Post-ganglionic neurone = will be attached to the effector (smooth muscle, gland or cardiac muscle)
Describe the pre-ganglionic neuron of the sympathetic NS:
Cell body: In the CNS (anywhere but the cerebrum)
Axon: Extends down the anterior grey column of the spinal cord and terminates at the spinal cord between T1 and L2
Synapses with the cell body of the post-ganglionic neurone: Either in the lateral chain of sympathetic ganglia or the prevertal chain of sympathetic ganglia)
What is the neurotransmitter at the synapse between the pre-ganglionic neurone and the post-ganglionic neurone of the sympathetic NS?
ACETYLCHOLINE
Does the pre-ganglionic sympathetic neurone always synapse with the post-ganglionic neurone at the same level is terminated the spinal cord?
No it can either be on the same level or not
How does the pre-ganglionic axon of the sympathetic NS reach the prevertal chain of ganlia?
It must pass the lateral chain of ganglia before reaching the prevertal chain
Describe the post-ganglionic neurone of the sympathetic NS?
Cell body: In the lateral chain or prevertal chain of sympathetic ganglia
Axon: Attached to the effector
What is the neurotransmitter at the post-ganglionic neurone of the sympathetic NS?
Noradrenalin (however, can sometimes be acetylcholine)
Why does the post-ganglionic neurone of the sympathetic NS sometimes release acetylcholine at the synapse?
This will occur at effectors that are only supplied by the sympathic post-ganglionic neurones (Skin, sweat glands and skeletal muscles) and so ‘parasympathic’ effects can not occur.
These effectors contain NICATINE-ACETYLCHOLINE RECEPTORS - that bind to the acetylcholine from the post-ganglionic sympathetic neurones (in order for parasympathetic effects to occur)
Describe the pre-ganglionic neurones of the parasympathetic NS?
Cell body: In the CNS (anywhere but the cerebrum) or in the spinal cord
Axon: Extend down in the grey anterior column of the spinal cord and terminates the spinal cord at 2,3 or 4 sacral region.
Synapses: With the post-ganglionic neurone either in the ganglion or the effector wall
What neurotransmitter is at the synapse of the parasympathetic pre-ganglionic neurone and the post-ganglionic neurone?
ACETYLCHOLINE
Describe the post-ganglionic neurones of the parasympathetic NS?
Cell body: Ganglion or inside effector
Axon: Terminate with the effector
What neurotransmitter is at the synapse of the parasympathetic post-ganglionic neurone and the effector?
ACETYLCHOLINE
What receptors do the effectors (that are supplied by post-ganglionic parasympathetic neurones) have?
Either:
1) Nicotine-acetylcholine receptors (parsympathetic and can be sympathtic - skin, sweat glands and smooth muscles)
2) Muscarine-acetylcholine receptors (only parasympathetic)
Differences between the pre-ganglionic and post-ganglionic axons of the sympathetic and parasympathic neurones:
Sympathetic:
Pre-G: long
Post-G: short
Parasympathic
Pre-G: short
Post-G: long
What are the functions and type of reactions of the sympathetic NS?
Fight and flight
Catabolic (releases energy) reactions
What are the functions and type of reactions of the para-sympathetic NS?
Rest and Digest
Anabolic (stores energy) reactions
What are the 3 major anatomical regions of the brain?
1) Cerebrum (and lobes of the cerebral hemisphere)
2) Brain Stem (Midbrain, Pons and Medulla Oblongata)
3) Cerebellum
Cerebrum is divided into?
2 cerebral hemispheres
What joins together the 2 cerebral hemispheres?
CORPUS CALLOSUM
What are the 2 cerebral hemispheres divided into?
Lobes of the cerebral hemisphere
Why are the lobes of the cerebral hemisphere called what they are called?
The names will be associated with the bones of the cranium under which they live.
Where are the cell bodies and nerve fibres found in the brain?
Cell bodies = surface (grey matter)
Nerve fibres = inside (white matter)
What are the 4 main cerebral lobes?
1) Frontal lobe
2) Parietal lobe
3) Temporal lobe
4) Occupital lobe
What 3 sulcus’ separate the cerebral lobes?
1) Central sulcus (between the frontal and parietal lobe)
2) Lateral sulcus (between the frontal and the temporal)
3) Parietal - occupital sulcus (between the parietal and occupital lobe)
What areas are contained within each other 4 main cerebral lobes?
1) Frontal lobe: Motor speech area, pre-motor area and motor area
2) Parietal lobe: Sensory area, taste area and sensory speech area
3) Temporal lobe: Auditory area and olfactory area (deep within)
4) Occupital lobe: Visual area
Describe the higher motor neurones of the motor area?
Cell bodies: In the cerebral cortex (grey matter)
Axons: Pass through the internal capsule, cross over to the other side in the medulla oblongata and synapse at the appropriate level of spinal cord.
Why do the upper motor neurones cross over at the medulla oblongata?
Because the cells bodies of the upper motor neurones in the motor area control movements of the opposite side of the body to the hemisphere they are positioned in.
So left control right side of the body movements (visa versa)
Cell bodies of the upper motor neurones, positioned at the upper areas of the motor area control:
The lower parts of the body - feet
Cell bodies of the upper motor neurones, positioned at the lower areas of the motor area control:
The upper parts of the body - face, arms, hands
Describe the lower motor neurones of the motor area?
Axons are attached to skeletal muscle and the cell bodies of lower motor neurones will initiate voluntary actions
If a voluntary action is more complex how does this affect the amount of cell bodies in the cerebral motor area?
The more complex the voluntary action - the more cell bodies in the motor area control this action
What is the function of the pre-motor area?
The cell bodies in the premotor area of the cerebral cortex will exert a controlling force on the cell bodies in the motor area of the cerebral cortex.
So, the skeletal muscle movements that they control occur in an orderly fashion