Nervous system is highly organised

Question 1

Protection of the CNS (Bone)

Answer 1

Cranium and vertebrae
Strong and rigid for protection

Question 2

Protection of the CNS (Meninges)

Answer 2

3 layers of connective tissue that form membranes around the CNS

Question 3

Protection of the CNS (Cerebrospinal Fluid CSF)

Answer 3

• In the space between the two inner layers of meninges, in brain cavities and through a central canal in the spinal cord
• 3 functions:
  
  1. Protection – a shock absorber
  2. Support – brain “floats” in CSF
  3. Transport – takes nutrients to brain and spinal cord and carries away wastes

Question 4

Cerebrum

Answer 4

• Grey matter (cell bodies) forms the outer section – the cerebral cortex)
• White matter (myelinated axons) form the inner section
• Folded to increase surface area – contains 70% of all neurons of the CNS:
  Folds are called convolutions
  Convolutions are separated by deep folds called fissures and shallow folds called sulci
• The longitudinal fissure (deepest fissure) separates cerebrum into two hemispheres
• There are 4 main lobes of the cerebrum – frontal, parietal, temporal and occipital

Question 5

Cerebral Cortex

Answer 5

• Involved in mental activities
  thinking memory
  reasoning intelligence
  learning sense of responsibility
  perception of senses
  initiation and control of voluntary muscle movements

Functional areas of the cortex are either:
1. sensory areas – interpret impulses from receptors
2. motor areas – control muscular movements
3. association areas – intellectual and emotional processes

Question 6

Corpus Callosum

Answer 6

• Lies underneath the cerebrum, at the base of the longitudinal fissure
• Nerve fibres cross across the hemispheres allowing them to communicate with each other

Question 7

Cerebellum

Answer 7

Lies posterior, underneath the cerebrum
Controls posture, balance and fine motor coordination (voluntary muscle)
- If damaged, movements become jerky, spasmodic and uncontrolled

Question 8

Medulla Oblongata

Answer 8

• Top bit of the spinal cord
• Important for sneezing, coughing, vomiting and swallowing reflexes
• Contains: (all under the control of Hypothalamus)
  1. cardiac centre – regulates force and rate of heartbeat
  2. respiratory centres – control rate and depth of breathing
  3. vasomotor centre – regulates the diameter of blood vessels

Question 9

Spinal Cord

Answer 9

• Enclosed in the vertebral canal of bone and three meningeal layers
  NOTE- the outermost meningeal layer is not attached to the vertebrae, instead there is a fatty connective tissue between them allowing the spinal cord to bend
• White matter on the outside and grey matter on the inside (opposite to the brain)
• CSF is in the central canal

FUNCTIONS:
1. Carry impulses from sensory receptors
to the brain (ascending tracts)
2. Carry impulses from brain to
effectors/muscles and glands (descending tracts)
3. Coordinate spinal reflexes

Answer 10

• Under normal circumstances the sympathetic and parasympathetic NS work together to maintain homeostasis
• Fight or flight responses occur when this balance is interrupted – in threatening situations the sympathetic NS takes over fear, anger, stress, danger, competition
• These responses prepare the body to act quickly
• Requires
  Greater supply oxygen
  Greater supply glucose = Needs greater blood supply to glands and muscles

Question 11

Typical effects of sympathetic NS

Answer 11

• Increased heart rate and force and therefore increased blood pressure
• Blood vessels dilate (vasodilation) in necessary organs – skeletal muscles, heart, liver
• Blood vessels constrict (vasoconstriction) in organs not involved - kidneys, stomach, intestines, skin
• Airways in lungs dilate and breathing rate and depth increases
• Blood glucose levels rise
• Sweating
• Adrenalin and noradrenalin are released