Central Nervous System (CNS) Flashcards
What does the CNS consist of
Consists of:
- Brain:
- Cerebrum
- Corpus Callosum
- Cerebellum
- Hypothalamus
- Medulla Oblongata
- Spinal cord
How is CNS protected by bone?
- Hardness of the cranium that encases brain.
- Spinal cord runs through vertebral canal in vertebrae.
How is the CNS protected by the meninges (3 layers)?
They are 3 layers of connective tissue (forming the meninges)
in between brain/spinal cord and these bones.
- Outer layer – tough and fibrous, sticks closely to cranium.
Its inflexibility prevents the brain from moving around.
- Middle layer – loose mesh of fibres
- Inner layer – more delicate, many blood vessels, sticks
close to brain / spinal cord. Creates a seal that protects
brain from infection.
What is cerebospinal fluid?
Cerebrospinal Fluid (CSF):
- Clear watery fluid
- made up of a few cells and some glucose, protein, urea and salts
- Fills space in between middle and inner layer of meninges
- Circulates through cavities in brain and spinal cord
What are the functions of the cerebospinal fluid?
- Protection – shock absorber (cushions blows)
- Support – brain is suspended in cranium and floats in CSF
- Transport – Takes nutrients to cells and wastes away
(CSF eventually re-enters blood capillaries)
Cerebrum (cerebral cortex)
- largest part of the brain
- cerebral cortex ( also called cerebrum) - outer surface of grey matter, 2-3 mm thick
- Many convolutions to increase surface area
- separated by shallow folds called sulci or deep folds called fissures
- cerebrum is divided into 2 hemispheres by the longitudinal fissure ( deepest fissure)
- Fissures are used to subdivide each hemisphere into 5 lobes
- large number of lobes = more surface area for neurons
Lobes of brain
Frontal
Temporal
Occipital
Parietal
3 functional areas of the cerebrum
SENSORY AREAS – receive and process nerve impulses from receptors/senses
MOTOR AREAS – send impulses to muscles, especially for voluntary movement
- control muscular movement
ASSOCIATION AREAS – interpret information from the senses and make it useful
- concerned with intellectual and emotional processes
Corpus callosum
- A wide band of nerve fibres that lie underneath the cerebrum.
- The nerve fibres cross from one hemisphere to the other and allow the two sides to communicate
Location and structure of cerebellum
- Located under the back of the cerebrum
- Folded into a series of parallel ridges
- Outer folds are grey matter, inner folds are white matter
that branch out like a tree
Roles of cerebellum
Roles:
- Receives constant input from senses and make adjustments to muscles if necessary
- Smooths contraction of muscles, maintains muscle tone and posture, coordinates movement of joints (walking,jumping,throwing)
Hypothalamus
located at the middle-base of the brain
- Controls mostly homeostasis
Also regulates - body temp
- food and water intake
- Sleeping patterns
- Contractions of urinary bladder
- Emotional response
- Secretion of hormones
Medulla oblongata structure and functions
Medulla Oblongata
- A continuation of spinal cord, about 3 cm long
- Passage for nerves to pass through going to or from other
parts of the brain
3 important roles for vital bodily functioning:
- Cardiac centre – regulates rate and force of heartbeat
- Respiratory centre – control of rate and depth of breathing
- Vasomotor centre – regulates diameter of blood vessels
Functions of spinal cord
- Carry sensory neuron and motor neuron impulses
- Integrate certain reflexes ( Fast automatic responses)
Structure of spinal cord
- Contains grey and white matter
- Unlike brain, in spinal cord, grey matter is at the centre and white matter is on the outside
- In the middle is the CENTRAL CANAL, which runs the entire
length of spinal cord and contains CSF - Surrounded by 3 meningeal layers and vertebrae.
