Nervous System

Central Nervous System (CNS) - Brain and Spinal Cord
1. Peripheral Nervous System (PNS) - All other nerves from brain and spinal cord
Neurons- Specialized to carry messages around the body
1. 3 Types:
  1. 1) Sensory- Carry impulses towards CNS
  2. 2) Motor- Carry impulses away from CNS to an effector Eg; Muscle
  3. 3) Interneurons- Carry info between sensory and motor
Parts of the Neuron:
1. Cell Body- Contains Nucleus. Group of cell bodies called Ganglia
2. Dendrites- Picks up impulse
3. Axon- Transports Electrical Message away from cell body
4. Myelin Sheath- Fat rich cover. Insulates Electrical Impulse
5. Schwann Cell- Makes Myelin Sheath
6. Synapse- Gap between Neurotransmitter swelling of 1 Neuron and Dendrite of the next
7. Neurotransmitter Swellings- Contain chemicals called neurotransmitters
Features of Nerve Impulses:
1. Threshold- Min. stimulus required to cause an impulse to be carried in a neuron
2. All or Nothing Law- If threshold reached, impulse is carried. If it is not reached, impulse is not carried
3. Refractory Period- Short time span after impulse is carried, where a stimulus fails to cause a response
Synapse- Region where 2 neurons come into close contact
1. Synapse Cleft- Gap between 2 neurons bridged by chemicals (Neurotransmitters)
  1. Neurotransmitter: Chemical released across a Synaptic Cleft to carry a signal from 1 Neuron to another
*Impulses can be blocked by certain chemicals~ Drugs*
The Brain:
1. Composed of over 100 billion neurons, each receiving messages simultaneously from thousands of other neurons.
  1. Meninges- Membrane covering brain and spinal chord. Contains cerebrospinal fluid
  2. Cerebrum- Controls voluntary movements Eg; Thinking and Memory
  3. Cerebellum- Controls Muscular Co-ordination and learned movements Eg; Riding a bike
  4. Medulla Oblongata- Controls involuntary movements Eg; Breathing and Swallowing
  5. Hypothalamus- Monitors blood temp and Bp (Homeostasis)
Studied Disorder:
1. Parkinson's Disease:
  1. Cause - Failure to produce Dopamine
    1. Prevention- No way to prevent or cure it
      1. Treatment- Exercises and Drugs
Spinal Cord:
1. White Matter- Axons Only
2. Grey Matter- Cell Bodies and Dendrites
3. Cord is located in the Central Canal
4. Dorsal Root located towards front of body and contains Motor Neurons
Reflex Action- An automatic. unthinking response to a stimulus Eg; Burning your finger

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	Erstellt von Fionnuala Gillain vor mehr als 3 Jahre