1. NERVOUS SYSTEM
FUNCTION

2. NEURON FUNCTION Transmit messages from one cell to the next
Dendrites carry impulse to the cell body
Axons carry impulse away from cell body
Neurilemma (myelin sheath)
Covering that speeds up nerve impulse along axon
Fatty substance that protects axon called myelin and white matter

3. Neuron function continued
Synapse
Space between neurons
Neurotransmitter
Chemicals that carry an impulse across the synapse
Nerve impulse
A stimulus creates an impulse. The impulse travels into the neuron on the dendrite(s) and out on the axon. At the end of the axon, a neurotransmitter is released that carries the impulse across the synapse, to the next dendrite.

4. NERVOUS TISSUE Sensory neurons (afferent) Motor neurons (efferent)
Carry impulses from skin and sense organs to spinal cord and brain
Motor neurons (efferent)
Carry messages from brain and spinal cord to muscles and glands
Associative neurons (interneurons)
Carry impulses from sensory neurons to motor neurons

5. brain Part of the Central Nervous System (CNS)
Brain tissue will die in 4-8 mins without oxygen
Meninges
Dura mater – outer brain covering; lines the inside of the skull
tough, dense fibrous connective tissue
Arachnoid – middle layer
Resembles a fine cobweb with fluid filled spaces
Pia mater – covers the brain itself
Consists of blood vessels held together by fine areolar connective tissue
Subdural space – between arachnoid and dura mater
Subarachnoid space – between arachnoid and pia mater, filled with cerebrospinal fluid, acts as liquid shock absorber and source of nutrients for brain.

6. brain continued Ventricles – 4 cavities Cerebral ventricles
2 largest located in cerebral hemisphere: right and left lateral ventricles
Third ventricle is behind and below the lateral ventricles
Fourth ventricle is below the third, in front of the cerebellum and behind the pons and medulla oblongata
1st two and 3rd connected via the interventricular foramen
3rd and 4th connected via cerebral aqueduct

7. Ventricles continued
Cerebrospinal fluid fills ventricles and acts as shock absorber
Blood-brain barrier – prevents substances (like drugs) from penetrating brain tissue, but also makes infections like meningitis difficult to cure
Choroid plexus – blood vessels that help make cerebrospinal fluid
Part of the pia mater
In contact with the cells lining the ventricles
Have selective permeability

8. Cerebrospinal fluid (CSF)
Forms inside the ventricles from the choroid plexus
Formed by filtration
Transports nutrients to and removes metabolic waste products from the brain cells
Flows from 2 lateral ventricles to 3rd ventricle to 4th and finally to spinal cord and subarachnoid spaces
Eventually it returns to the bloodstream via the venous structures in the brain called arachnoid villi

9. Cns – brain - cerebrum
Responsible for conscious thought, judgment, memory, reasoning, and will power
Largest part of the brain
Occupies the whole upper part of the skull
Weighs about 2 lbs.
Cerebral cortex: gray matter covering the upper and lower surfaces
Divided into 2 hemispheres by a deep groove – longitudinal fissure
Covered with furrows and ridges
Deep are fissures
Shallow are sulci

10. diencephalon Thalamus Hypothalamus Found in cerebral hemispheres
Relay station for incoming or outgoing nerve impulses
Receives nerve impulses from sense organs and brain
Damage may result in increased sensitivity to pain or total loss in consciousness
Hypothalamus
Lies below the thalamus
Considered the “brain” of the brain
Stimulates pituitary to release hormone

11. HYPOTHATLAMUS VITAL FUNCTIONS ARE: ANS control Cardiovascular control
Temperature control
Appetite control
Water balance
Manufacture of oxytocin
GI control
Emotional state
Sleep control
Mind-over body experiences

12. Brain continued Cerebellum (controls ALL functions w/skeletal muscles)
Maintenance of balance
Maintenance of muscle tone
Control of muscle movements
BRAIN STEM (made up of 3 parts):
Pons
Controls respiration
Midbrain
Vision and hearing
Medulla oblongata
Controls heart rate and blood pressure

13. Cns (which is what?) SPINAL CORD Surrounded by cerebrospinal fluid
Conducts nerve impulses to and from brain
Acts as reflex center

14. PERIPHERAL NERVOUS SYSTEM
Cranial nerves
How many pairs?
Spinal nerves
REMEMBER ANY OF THIS???

15. TO REFRESH YOUR MEMORY:
Cranial nerves
12 pairs beginning in the brain
Mainly deal with functions of the head and neck
Except vagus nerve (X) – responsible for ___ (pg. 175)
Designated by name and number
Name can give a clue to function
Spinal nerves
31 pairs originating at the spinal cord
Exit through openings in the vertebrae
Named according to region and level they exit
Largest is the sciatic nerve

16. AUTONOMIC NERVOUS SYSTEM
Regulates visceral organs, no subject to conscious control
Sympathetic system
Fight or flight – when the body perceives danger, SNS sends message to adrenal medulla to secrete adrenaline and heartbeat increases
Parasympathetic system
Counters SNS, decreases heart rate
Reflex – unconscious and voluntary
Stimulus
Example: tapping the patellar tendon
What are some other examples?