Overview Of The Nervous system

Question 1

CNS

Answer 1

Brain and spinal cord

• Ways a brain is sliced and orientations
o Coronal
o Sagittal – midline
o Transverse – top to bottom

• Three major brain regions
o Forebrain – cerebrum and diencephalon
o Brain stem - midbrain, pons and medulla oblongata
o Cerebellum

Question 2

Forebrain

Answer 2

Cerebrum - consists of cortex which has 4 lobes

1) Occipital lobe – visual processing
o Colour, orientation and motion
Case study:
o Hallucinations are a symptom of schizophrenia
o MRI scans – more activation of occipital regions in schizophrenia patient

2) Parietal Lobe – sensory processing and proprioception (being aware of yourself)
Case study:
o Some dyslexic people have abnormally less activation of parietal lobe

3) Frontal lobe – emotions, decision making, attention, consciousness, deliberate movement
Case Study:
o Prefrontal lobotomy - Used to treat a number of personality and cognitive disorders which often results in impaired voluntary behaviour

4) Temporal Lobe – auditory processing, speech and language
Case Study:
o Wernicke’s area - Stroke or damage to Wernicke’s area lets patient talk but don’t make sense (random words)

 Corpus callosum – Connects right and left hemispheres, allowing info to be passed between
Case study:
o Experiment on people who had corpus connection severed
o Testing hemispheres in isolation, left and right hemisphere have certain
o behaviours

 Hippocampus - memory formation and memory retrieval
Case study:
o Viral infection caused damage to hippocampus and so has no short-term memory
o Hippocampus not only part in memory formation as he still talks and has some long-term memories

 Basal Ganglia – movement, balance and posture
Case Study:
o Damage to region associated with Parkinson’s disease and Huntington’s chorea
o Parkinson – neurodegenerative diseases caused by selective death of particular part of basal ganglia which usually produces dopamine.
o Huntington chorea- generic disorder causes destruction of basal ganglia

Question 3

Diencephalon – posterior part of fore brain

Answer 3

 Thalamus – over 40 different nuclei, multi-modal functions
Case study:
o Deals with almost all function in the brain apart from smell
o track information passage through the thalamus
o Damage – ‘blending’ of information streams - leads to synasthesia (e.g. hear colour or feel sounds)

 Hypothalamus – many small nuclei to control many functions
o Temperature
o Hunger thirst
o Neuroendocrine control (nervous hormone)
o Circadian rhythms (sleep wake cycle)
o Blood pressure/heart rate
o Bodies response to stress- fight or flight response controlled by hypothalamus

Question 4

Brain stem

Answer 4

• Central part of brain consisting of midbrain, pons and medulla oblongata
• Control homeostasis and motor movements

 Homeostasis (breathing heart rate, blood pressure)
o Damage to part of homeostats – “brain-stem dead”
o Loss of blood circulation to all brainstem regions

 Motor movements – reflexes, fine motor movements of limbs and face in conjunction with cortex
o Locked-in syndrome – damage to pons area, sill had homeostatic function controlled, but very little voluntarily movement
o Loss of blood circulation to pons

 Brain-stem dead and locked-in syndrome can both be caused by stroke to the brainstem region

Question 5

Cerebellum

Answer 5

 Movement precision and coordination
Case study:
o Ronan sea lion - Finding beat in musical rhythm
o Many other mammals have fine motor control, have found the beat to rhythms because of their cerebellum

Question 6

Spinal cord

Answer 6

 Extends to 45cm
 Transmits signals to/for the brain/body
 Important function - Reflexive circuits
o Not all sensory information detected in our periphery is transmitted to our brain for appropriate response
o Only two neurones used
o If no immediate return synapse, may cause further tissue damage

Case study:
o Spinal cord injury - damage to certain area of spinal cord, which can lead to the lack of control and different levels of spinal cord injury
o Cervical, Thoracic, Lumbar, Sacral, Coccygeal regions
o L1 injury – loss of bottom half of body
o T6 above – loss of trunk as well
o C6 injury – limbs injury as well
o C4 - also loss of neck control

Question 7

PNS

Answer 7

• Autonomic Nervous system and Somatic Nervous system
• Autonomic – important in unconscious control of function
o Heart rate
o Blood Pressure
o Breathing Digestion
• Somatic - voluntary control of body movements using skeletal muscle
o Neurotransmitter release
o Neuromuscular junction
o Receptors
o Muscle contraction