THE NERVOUS SYSTEM Flashcards
Why do we have the nervous system?
- detects stimulus and brings about change via a receptor
-sends electrical messages
-maintains homeostasis
What does the nervous system contain?
Neurons, interneurons and neurglia (support system)
What happens during a response via SNS?
Increased heart rate, rate of digestion reduced, bronchodilation
What happens during a response via ANS?
decreased heart rate, better digestion, bronchoconstruction
What does a neurone consist of?
-Dendrites (branches making connections with other neurones
-cell body (contains nucleus)
-axon hillock (where a.p generated)
-axon
-myelin sheath (electrical insulation)
Axon terminal
What is myelin made from?
Protien
Where are oligodendrocytes found and what do they do?
CNS
grabs into different neurones
Forms and maintains myelin
Where are Schwann cells found?
Peripheral NS
Where is the cell body found in sensory neurons?
Middle
Meaning of pseudo unipolar?
One axon
What does bipolar mean?
2 axons
How is the resting membrane potential established?
High K+ conc inside the cell
Higher Na+ conc outside the cell
RMP= -70mv
What depolarises the cell?
When the stimulus received causes the voltage to exceed threshold
Voltage gated Na gates open allowing sodium to move into the cells
What causes repolarisation?
Change in voltage causes voltage gated K channels to open
K+ leaves the cell
Inside of the cell becomes more negative
What is saltatory conduction?
A.p can jump between nodes of ranvier
Quicker in myelinated neurons
What triggers vesicles containing neurotransmitter to move and fuse with the synaptic membrane?
A.p reach pre-synaptic membrane
Opens up voltage gated Ca2+ channels
Ca2+ enters
What happens after vesicles fuse to membrane?
Neurotransmitters diffuse across cleft
Neurotransmitters act on specific receptors on post synaptic neurones and cause an a.p
Why do neurotransmitters have to be inactivated or reabsorbed?
Will cause continuous depolarisation of post synaptic membrane
What reflexes involve skeletal muscle?
Somatic
What does autonomic reflexes involve?
Smooth muscles and glands
What happens to the volume of grey matter in the cerebral cortex during pregnancy?
-reduced
What does grey matter do?
-contains neurons to process electrical impulses
What is carpel tunnel syndrome?
Compression of median nerve in carpal tunnel causing numbness and tingling
What causes carpal tunnel?
-odema
-hameodilution causes soft tissue to become waterlogged and diluted blood has less plasma proteins in so fluid moves out of blood vessels and into interstitial space
-odema compresses the nerve
