1. CENTRAL NERVOUS SYSTEM

2. CNS
The study of functions reveals that the body consists of millions of small structures that perform a multitude of different activities that are coordinated and integrated in one harmonious whole.

3. Divisions of the Nervous System
The nervous system can be divided into three divisions:
Central nervous system (brain and spinal cord)
Peripheral nervous system (12 pair cranial nerves extending out from brain and 31 pairs of spinal nerves from the spinal cord)
Autonomic nervous system (peripheral nerves and ganglia)

5. Central and Peripheral Nervous Systems
Where decision is called for and action must be taken, the central and peripheral nervous systems are involved.
They carry information to the brain where it is interpreted, organized, and stored. An appropriate message is sent to organs or muscles.

6. Autonomic Nervous System
This is part of the peripheral nervous system because it involves the peripheral nerves as well as ganglia, which are a group of cell bodies outside the central nervous system that carry impulses to involuntary muscles and glands.
Supplies the heart muscle, smooth muscle, and secretory glands with nervous impulses as needed.
It is usually involuntary.

7. Autonomic Nervous System

8. Central Nervous System
Brain and Spinal Cord

9. Function of CNS
It is the communication and coordination system in the body
It receives messages from stimuli all over the body
The brain interprets the message
The brain responds to the message and carries out an activity
The brain is also the seat of intellect and reasoning

10. CNS Most highly organized system of the body

11. Neuron Is another name for a nerve cell
Constructed to transmit a message from one cell to the next
It has a nucleus, cytoplasm, and cell membrane
From the cell body, the neuron has extensions of cytoplasm from the cell body called dendrites and axons

12. More on the Neuron…
A neuron may have many dendrites, but only one axon.
The axon has a specialized covering called the myelin sheath which speeds up nerve impulse as it travels along the axon.
The myelin sheath produces a fatty substance called myelin that protects the axon; it is also called white matter.
Axons carry impulses away from the body; dendrites carry messages to the cell body.

13. Nervous Tissue There are two major types of nerve cells: Neuroglia
Known as “nerve glue”
These cells insulate, support, and protect the neurons
Neurons
Have the characteristics of irritability and excitability
Dendrites receive the impulse and transmit it to the cell body, and then to the axon.

14. Three Types of Neurons Sensory neurons or afferent neurons
Emerge from the skin or sense organs and carry messages toward the spinal cord and brain
Motor neurons or efferent neurons
Carry messages from the brain and spinal cord to the muscles and glands
Associative neurons or interneurons
Carry sensory impulses from the sensory neuron to the motor neuron

15. Function of Nerve Cell
Nerves carry impulses by creating electric charges in a process known as membrane excitability.
Neurons have a membrane that separates the inside cytoplasm from the fluids outside the cell which creates two chemically different environments.
The inside cells are more negatively charged.
When a neuron is stimulated, ions move across the membrane creating a current.

16. Synapse A synapse is where messages of from one cell to the next.
Messages go from the axon of one cell to the dendrite of another…without actually touching.
The “space” is called the synaptic cleft and the conduction is done by neurotransmitters at the end of each axon.

17. Synapse

18. The Brain Weighs about 3 lbs consists of 100 billion neurons
The brain is white and gray matter (the outer or cerebral cortex is gray)

19. More Brain…
The outer part of the cerebral cortex is the highest center of reasoning and intellect, “you need to use your gray matter.”
The deeper part of the cerebral cortex is the white matter and has the myelinated nerve tracts.
Without oxygen, brain damage will occur within 4 to 8 minutes
The brain is divided into four major parts…cerebrum, diencephalon, cerebellum, and brain stem.

20. Protection for the Brain…
Protected by the cranium and three membranes called meninges and cerebrospinal fluid.
There are three layers of meninges…
Dura mater – outer covering of the brain and spinal cord
Arachnoid – middle layer
Pia mater – inner covering of the brain and spinal cord
The ventricles – four lined cavities within the brain that contain the choroid plexus, a rich network of blood vessels that help form the cerebrospinal fluid.
Cerebrospinal fluid – acts as a shock absorber and a source of nutrients for the bain and spianl cord.

21. Memory
The brain stores “old” information we have learned and packages and stores new information…memory!
To create a memory, it is thought that nerve cells make a new connection.
No one area of the brain stores all memories, because the storage site depends on the type of memory…swimming would be inn the motor area, visual would be stored in the visual area.
Can be long or short term depending on how much attention we pay to that memory, and how many times we repeat an activity.

22. Effects of Aging
As an individual ages, there is a general slowing of nerve conduction due to a decrease in the number of functioning neurons and a degeneration of the existing neurons.
Changes in the nervous system are primarily due to diminished blood supply to the brain and loss of neurons.
Slow progressive loss in brain size in the cerebral cortex leads to impairment in thinking, reasoning, and remembering.
There is a slowing in reaction time due to decrease in motor and sensory nerve conduction

23. More on Aging…
Sleep patterns change…they easily waken, take longer to fall asleep, and wake up more frequently during the night…napping is a normal pattern as people age.
There is evidence that continued physical and mental activity keeps minds sharp. Disrupting the ‘Normal” routine can stimulate nerve cells, enhance blood flow, and increase chemicals called nerotrophins.

24. Parts of the Brain
The cerebrum is the largest and highest part of the brain.
It is divided into two hemispheres
Each hemisphere is divided into:
Frontal
Parietal
Occipital
And temporal lobes

25. Cerebral Lobe Functions:
Frontal – motor area; controls voluntary muscles (lt controls rt – rt controls lt) speech is on the left
Parietal – sensory area pain, touch, heat, and cold and helps with distance, size, and shape.
Occipital – visual
Temporal – auditory and olfactory
Limbic – survival behaviors

26. Diencephalon
Located between the cerebrum and midbrain