Nervous System Flashcards
Two parts of the nervous system
CNS - Central Nervous System
PNS - Peripheral Nervous System
Neuron
A nerve cell
Types of Neurons
Sensory Neuron - to CNS
Motor Neuron - away to muscles and glands
Interneuron - within CNS
Dendrites
Receive information
Carry electrical impulse towards cell body
Axons
Carry electrical impulses AWAY from cell body
Cell body
Contains a nucleus
Forms dendrites and axons
Myelin sheath
Insulates electrical impulses
Schwann cells
Secretes myelin sheath
Neurotransmitter swellings
Produce neurotransmitter chemicals
Movement of an Impulse
Receives a stimulus of sufficient strength
Ions move in and out of dendrites and axons
Electrical impulse travels along a neuron
Threshold
Least possible stimulus needed to send an impulse
Features of a nerve impulse
All or nothing rule (threshold is reached or not)
Impulses travel at same speed
Delay between impulses (to allow message to pass between neurons)
Only travel from sensory to motor neurons
Synapse
A region where two neurons come in close contact
Synaptic cleft
Tiny gap between two neurons
Events at a Synapse
- Electrical impulse at synapse stimulates release of neurotransmitter chemicals
- Chemicals diffuse along synaptic cleft
- Chemicals Enter neuron and are broken down
- Electrical impulse is regenerated
Function of Synapse
Control the direction of impulses in the nervous system
What surrounds the brain and spinal cord
Meninges (3 membranes) and cerebro-spinal fluid
Color of cell bodies
Grey
Color of myelin sheath (near dendrites and axons)
White
Cerebrum
Conscious movement
Senses, intelligence, personality
Left hemisphere of brain
Language, maths, logic
Right side of brain
Music, art, emotions, shapes
Cerebellum
Balance
Muscular co-ordination
Medulla
Involuntary muscles
Thalamus
Sorting centre for the brain
Directs incoming impulses to correct part of brain
Hypothalamus
Homeostasis
Meninges
Surrounds and enclose entry of materials to brain and spinal cord
Spinal nerves
31 pairs
Carry impulses to and from spinal cord
Dorsal root
Carries impulses into spinal cord along sensory neurons
Ganglion
Swelling that contains the cell bodies of sensory neurons
White matter
Contains Axons
Grey Matter
Contains cell bodies
Central Canal
Contains cerebrospinal fluid
Ventral Root
Carries impulse OUT OF the spinal cord along motor neurons
Reflex Action
Automatic, involuntary or unconscious response to a stimulus
• Knee jerk, blinking for protection
• Protect the body from harm through faster responses
Reflex Arc
Path taken by electrical impulse
Events of a Reflex Action
- Receptors on finger detect reflex action
- Impulse travels along sensory neuron to spinal cord into spine through dorsal root
- Impulse splits: crosses Synapse onto an interneuron/crosses another Synapse to brain (brain becomes aware)
- Impulse crosses another synapse from interneuron and travels out of ventral root
- Motor neutron connects to a muscle that causes the response
PARKINSON’S DISEASE
CAUSE: Failure to produce dopamine
SYMPTOMS: Trembling of hands and legs, muscular stiffness, difficulty in waking
PREVENTION: Protective clothes from pesticides
TREATMENT: Levadopa (drugs)
