1. 19: The Nervous System Section Objectives:
Analyze how nerve impulses travel within the nervous system.
Interpret the functions of the major parts of the nervous system.
Compare voluntary responses and involuntary responses.

2. The Nervous System
Controls and coordinates the body’s responses to changes in the environment
HOW:
Stimulus: a change in the external or internal environment which initiates an impulse
Impulse~ an electro-chemical charge generated along a neuron
Receptors~ structures specialized to detect certain stimuli
Response~ a reaction to a stimulus
Effectors~ what responds to a stimulus such as muscles or glands

3. Neurons: Basic Units of the Nervous System
Neurons conduct impulses throughout the nervous system.
A neuron is a long cell that consists of three regions: a cell body, dendrites, and an axon.

4. Neurons: Basic Units of the Nervous System
Dendrites~ receive impulses and carry them toward the cell body
Axon~ carries impulses away from the cell body and toward other neurons, muscles, or glands.
Cell body~ contains the nucleus

5. Myelin coating Axon coated with insulation made of myelin cells
signal
direction
Axon coated with insulation made of myelin cells
speeds signal
signal hops from node to node
330 mph vs. 11 mph
myelin coating
Multiple Sclerosis
immune system (T cells) attacks myelin coating
loss of signal

6. Fun facts about neurons
Most specialized cell in animals
Longest cell
blue whale neuron
10-30 meters
giraffe axon
5 meters
human neuron
1-2 meters
Nervous system allows for 1 millisecond response time

7. Neurons: Basic Units of the Nervous System
3 Types of neurons.
1. Sensory neurons: carry impulses from the body to the spinal cord and brain (sense receptors)
2. Motor neurons carry the response impulses away from the brain and spinal cord to a muscle or gland. (effectors)
3.Interneurons: connect sensory &motor neurons within the brain and spinal cord

8. Types of neurons sensory neuron (from senses) interneuron
(brain & spinal chord)
motor neuron
(to muscle)

9. How an impulse is transmitted
1. Resting: no impulse, cell is polarized ( + on outside & - on inside)
Sodium/Potassium pump in axon using ATP maintains this polarity

10. How an impulse is transmitted
2.Impulse: stimulus excites neuron
Na+ gates open
Na+ goes inside, therefore inside becomes more +
Depolarization occurs ~ a nerve impulse
Impulse moves in one direction

11. Synapse ~ connection between neurons & effector cells
Junction between nerve cells
1st cell releases chemical (neurotransmitter) to trigger next cell
where drugs affect nervous system
synapse

12. Nervous System Central nervous system (CNS)
cerebrum
cerebellum
spinal cord
cervical
nerves
thoracic
lumbar
femoral
nerve
sciatic
tibial
Central nervous system (CNS)
brain & spinal cord
Peripheral nervous system (PNS)
nerves from senses
nerves to muscles
2 systems work together

13. Anatomy of the brain Cerebrum: Cerebellum: -Coordinates motor activity
Conscious activities
Intelligence
Memory
Language
Voluntary activity
Cerebellum:
-Coordinates motor activity
-balance
Medulla Oblongata:
involuntary activities such as breathing,&heart rate

14. Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Central Nervous System (CNS)
Somatic Nervous System (voluntary)
Relays information to and from skin and skeletal muscles.
Autonomic Nervous System (involuntary)
Relays information to internal organs.
Parasympathetic Nervous System
Controls organs when body is at rest
Sympathetic Nervous System
Controls organs in times of stress.