1. 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

2. The Nervous System
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 Neuron ≡ Basic Unit 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
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 sheath coating
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 and/or slowing of signal impulse

6. 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. Types of Neurons 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 (active transport);slower

10. How an impulse is transmitted
2.Impulse: stimulus excites neuron
Na+ channels open
Na+ goes inside, therefore inside becomes more +
Depolarization occurs = a nerve impulse
Impulse moves in one direction
Depolarization works with concentration gradient

11. Synapse: a connection Junction between nerve cells
Connection between neurons & effector cells
synapse

12. Synapse: a connection
1st cell releases chemical (neurotransmitter) to trigger next cell
where drugs affect nervous system
synapse

13. The Nervous Systems Central nervous system (CNS) brain & spinal cord
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/glands
Both systems work together

14. Anatomy of the brain Cerebrum: Conscious activities Intelligence
Memory
Language
Voluntary activity
Cerebellum:
Coordinates motor activity & balance

15. Anatomy of the brain Midbrain: reptilian brain (instincts, emotions)
Hindbrain/Brain stem:
Medulla Oblongata: involuntary activities such as breathing & heart rate

16. Central Nervous System (CNS)
The Nervous System
Nervous System
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.
Sympathetic Nervous System
Controls organs in times of stress.
Parasympathetic Nervous System
Controls organs when body is at rest