THE NERVOUS SYSTEM

• Detects changes in the body• Make decisions• Stimulate muscles or glands

to respond

• Works by sending an electrical signal known as an action potential through the cells of the nervous system, which are called neurons

FUNCTIONS

THE DIVISIONS

• Abbreviated CNS• Consists of Brain and Spinal Cord

CENTRAL NERVOUS SYSTEM

• Abbreviated PNS• Consists of cranial and spinal nerves• Further divided into Sensory Division and

Motor Division

PERIPHERAL NERVOUS SYSTEM

• Signals sent to the CNS from PNS• Various senses – sight, hearing, touch

(temperature, pressure, etc.) , taste, smell

SENSORY DIVISION

• Signals sent from CNS to PNS• Carry out effectors- actions that result in an

effect happening• Skeletal, smooth, cardiac muscle movement

and glandular secretion• Further divided into Somatic Nervous System

and Autonomic Nervous System

MOTOR DIVISION

• Voluntary effectors, such as breathing and skeletal muscle contraction

SOMATIC NERVOUS SYSTEM

• Involuntary effectors, such as heartbeat, smooth muscle contraction, secretion of hormones and enzymes

AUTONOMIC NERVOUS SYSTEM

• Cell Body• Nucleus• Dendrites• Axon hillock• Axon• Myelin Sheath• Schwann Cells• Nodes of Ranvier• Axon Terminal• Synaptic Knob

NEURON

• Myelinated neurons appear white• Unmyelinated neurons appear gray• 3 purposes– Protects axon– Insulates axon– Speeds rate of transmission

• Schwann Cells enclose, but do not wrap around myelin sheath

MYELIN

• Multipolar – found mostly in the brain and spinal cord

• Bipolar – found in eyes, nose, and ears

• Unipolar – connect PNS with CNS

TYPES OF NEURONS

• Sensory Neurons – Sensory Divison• Interneurons – Relays info between neurons in

brainand spinal cord• Motor Neuron – Motor Division

OTHER TYPES OF NEURONS

• Cells of the nervous system that perform other functions apart from transmitting impulses

NEUROGLIA

• Astrocytes – structural support, mop up excess ions and neurotransmitters, induce synapse formation

• Oligodendrocytes – creates myelin• Microglia – structural support and phagocytosis• Ependyma – forms a membrane for which

substances can diffuse from the fluid of the brain to the cerebrospinal fluid

NEUROGLIA OF CNS

• Schwann Cells – protect axons, speed neurotransmition

• Satellite Cells – Support ganglia (clusters of neurons)

NEUROGLIA OF PNS

• Presynaptic neuron – the neuron carrying the message

• Postsynaptic neuron – the neuron receiving the message

• Synaptic Cleft – separates the 2 cells– Synaptic knob of presynaptic neuron connected

with dendrite or cell body of postsynaptic neuron

SYNAPSE