The Central Nervous System Flashcards
Structures that protect the brain
- Cranium
- Meninges
- CSF
Cranium
The outermost bones which house the brain.
Meninges
Connective tissue coverings of the CNS. The three meninges are
1. Dura mater
2. Arachnoid mater
3. Pia mater
Dura mater
The outermost, tough, fibrous vascular layer that adheres to the cranium and vertebrae.
Arachnoid mater
Filmy, web like membrane between the other two. The space is filled with CSF.
Pia mater
The innermost, thin delicate membrane.
Function of meninges
1) Work with the CSF to protect the brain and spinal cord from shock (shock absorber)
2) Support the brain and spinal cord
3) Support blood vessels, supplying the brain and spinal cord
Cerebrospinal Fluid (CSF)
Found in between the meningeal layers and circulates through the CNS. Its a clear fluid formed from the blood. Contains some glucose, protein, … and salts
CSF function
Acts as a shock absorber when the CNS is hit, and carries nutrients to the CNS.
Spinal cord
- 31 pairs of spinal nerves
- Contains grey and white matter
- Controls some reflux actions (spinal reflex arcs)
Grey matter
Composed of unmyelinated nerve fibres
In spinal cord is at the centre
In brain at the surface
White matter
Composed of myelinated nerve fibres
In spinal cord surround grey matter
In brain in the centre
Corpus callosum (cerebrum)
A bundle transverse fibres that join the right and left hemispheres.
Parts of the brain
- The cerebrum
- The cerebellum
- The brain stem
Cerebral cortex (cerebrum)
2-4mm thick outer layer of grey matter.
Basal ganglia
Area of grey mater that is highly convoluted
a. Shallow down fold = sulcus - grooves (pl: sucli)
b. Deep downfold = fissure
c. Convolutions or gyrus - ridges (pl: gyri)
Tracts
Between the cerebral cortex and the basal ganglia there is white matter.
Cerebral cortex function
- Sensory areas (perception of sight, hearing, taste, smell, touch, etc
- Motor areas (movement/speech) send impulses to effectors - the voluntary muscles
- Association areas (awareness/memory) - areas of analysis and coordination of impulses.
Frontal lobe
Contains the primary motor and association responsible for voluntary control of muscle. Also responsible for thinking, problem solving, emotions.
Parietal lobe
Contains many sensory association areas. Responsible for temperature regulation, touch, taste.
Occipital lobe
The occipital lobe contains the visual areas (vision)
Temporal lobe
Contains the primary auditory (hearing) and auditory association areas. Also processes memories and links to senses.
Cerebellum structure
Found at posterior side of skull. 2nd largest part of the brain.
Hypothalamus
Regulates
- Heart rate
- Body temperature
- Sleeping patterns
- Release of hormones from pituitary gland
Brain stem structures
- Pons varolli (Pons)
- Medulla oblongata
- Spinal cord (start)
Medulla oblongata
- Under the influence of hypothalamus
- Contains nerve centres which control autonomic and reflex actions
1. Cardiac centre
2. Respiratory centre
3. Vasomotor centre
The cardiac centre
Regulates heart function
The respiratory centre
Controls breathing rate and depth
The vasomotor centre
Regulates blood vessel diameter
Spinal cord structure
- Central canal: A central space that is filled with cerebrospinal fluid
- Grey matter: The inner “H” mass made up of myelinated fibres which run up and nerve cell bodies
- White matter: The outer region made up of myelinated fibres which run up and down the spinal cord
Ascending tracts of the spinal cord
The sensory axons of nerve fibres taking impulses upwards towards the brain
Descending tracts of the spinal cord
The motor axons of nerve fibres taking impulses downwards away from the brain.
Spinal cord function
To carry sensory impulses to and motor impulses away from the brain.
