Centeral nervous system Flashcards
Protection of the CNS: Bone
- Hardness of cranium that encases brain.
- Spinal cord runs through vertebral canal in vertebrae.
Protection of the CNS: Meninges
3 layers of connective tissue in between brain/spinal cord.
Outer layer: Tough and fibrous, sticks closely to cranium. Inflexibility prevents brain from moving around.
Middle layer: Loose mesh of fibres. I
Inner layer: Delicate, many blood vessels, sticks close to brain/S.C. Creates a seal that protects brain from infection.
Protection of the CNS: Cerebrospinal fluid
- Clear watery fluid between middle and inner layer of meninges.
- Few cells with some glucose, protein, urea and salts.
- Circulates through cavities in brain and spinal cord.
Functions:
- Protection (shock absorber).
- Support (brain is suspended in cranium and floats in CSF).
- Transport (carries nutrients/waste to and from brain).
Cerebral cortex
- Largest part of brain.
- Outer surface of grey matter (2-3mm thick).
- Separated by shallow folds, sucli and deep folds, fissures.
- Longitudinal deep fissure separate cerebrum into left and right hemispheres.
- Main fissures subdivide each hemisphere into
- Frontal, Temporal, Occipital, Parietal lobes.
Tracts
Large bundle of transverse myelinated fibres under cerebral cortex.
- Connect various areas in same hemisphere.
- Carry impulses between hemispheres.
- Connect cortex to other parts of brain or spinal cord.
Basal ganglia
Grey matter tracts, deep in cerebral cortex.
Types of functional areas
Sensory: Interpret impulses from receptors.
Motor: Control muscular movements.
Association: Intellectual and emotional processes.
Primary motor cortex
Part of cerebrum that generates motor messages to body. If damaged paralysis to voluntary muscles.
Corpus collosum
- Wide band of nerve fibres that lie underneath cerebrum.
- Nerve fibres cross from one hemisphere to other, allowing two sides to communicate.
Cerebellum
Located under cerebrum. Folded into a series of parallel ridges (outer folds grey inner folds white).
Control of posture, balance and fine coordination (non – conscience).
Role
- Receives input from senses and make adjustments to muscles if necessary.
- Smooth’s contraction of muscles, maintains muscles tone and posture, coordinates movements of joints.
Hypothalamus
Located in middle of brain. Mostly controls homeostasis.
Role (Andy Bites Fred, Sometimes Controls Emotional Sam).
- Autonomic NS.
- Body temperature.
- Food and Water intake.
- Sleeping patterns.
- Contraction of urinary bladder.
- Emotional responses.
- Secretion of hormones.
Medulla Oblongata
- A continuation of spinal cord (3cm long).
- Passage for nerves going to or from other parts of brain.
- Upper motor neurons cross medulla, they become lower motor neurons when they exit S.C.
Role: Swallowing, coughing, sneezing, vomiting.
- Cardiac centre: Regulates rate and force of heartbeat.
- Respiratory centre: Control of rate and depth of breathing.
- Vasomotor centre: Regulates diameter of blood vessels.
Spinal cord
- Surrounded by 3 meningeal layers and vertebrae.
- Foramen magnum is hole in base of cranium.
- Central canal runs entire length of spinal cord and contains CSF.
Label a picture of the brain
Hypothalamus and Pituitary
