Nervous System Parts of the Nervous System Brain

Nervous System

Parts of the Nervous System • Brain • Spinal Cord • Nerves

Vocabulary to Know • Homeostasis –The regulation of steady, lifemaintaining conditions inside an organism, despite changes in its environment

Function • This system works to pass electrical messages from sensory nerves to the brain. • The brain interprets the message then sends a response to motor neurons.

The Neuron • Neurons –Basic functioning units of the nervous system

http: //ilearn. senecac. on. ca/aahs/health/IHP/ottawa/anatomy/neuron/map/neuron. html

Under the microscope… http: //35. 9. 122. 184/images/40 -Animal. Structure. And. Function/

Neurons • Made up of a (1)cell body and branches called (2)dendrites and (3)axons – Dendrites receive messages from other neurons and send them to the cell body – Axons carry messages away from the cell body

Draw the neuron in your notes. Be sure to label parts! Any message carried by a neuron is called an impulse

Neurons An electrical message carried by a neuron is called an impulse

Types of Neurons • Sensory • Motor • Interneuron

Sensory Neurons • Receive information • Send impulses to the brain or spinal cord

Interneurons • Send impulses from sensory neurons to motor neurons

Motor Neurons • Conduct impulses from the brain or spinal cord to muscles or glands throughout your body

Synapse • Small space across which an impulse moves from an axon to the dendrites or cell body of another neuron

Synapse • An impulse reaches the end of an axon • Axon releases a chemical • Flows across the synapse (space) • Stimulates the impulse in the dendrite of the next neuron • Impulse moves from neuron

http: //www. med. harvard. edu/publications/On_The_Brain/Volume 7/Number 1/images/Neuron. jpg

Two Parts • Central (CNS) • Peripheral (PNS)

http: //inside. salve. edu/walsh/cns_pns. jpg

Central Nervous System • Brain • Spinal cord

The Brain • Coordinates body activities • Made up of approximately 100 billion neurons

Cerebrum • • • Largest part of the brain Thinking Memory is stored Movements are controlled Impulses from the senses are interpreted.

Cerebellum • Interprets stimuli from eyes, ears, muscles • Controls voluntary muscle movements • Maintains muscle tone • Helps maintain balance

Brain Stem • Connects brain to spinal cord

http: //www. cbituk. org/GRAPHICS/brain. gif

The Spinal Cord • Extension of the brain stem • Bundles of neurons that carry impulses from all parts of the body to the brain and from the brain to all parts of your body

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Peripheral Nervous System • Connects body to brain & spinal cord • 12 pairs of nerves from your brain (cranial nerves) • 31 pairs from your spinal cord (spinal nerves) – Bundles of sensory and motor neurons held together by connective tissue

http: //www. christopherreeve. org/Research. cfm? ID=178&c=21

Peripheral Nervous System • Two divisions – Somatic – Autonomic

http: //abdellab. sunderland. ac. uk/lectures/Parmacology/Pics/anatomy/PNS. GIF

Somatic Nervous System • Controls voluntary actions • Made up of the cranial and spinal nerves that go from the central nervous system to your skeletal muscles

Autonomic Nervous System • Controls involuntary actions-those not under conscious control-such as your heart rate, breathing, digestion, and glandular functions

http: //users. rcn. com/jkimball. ma. ultranet/Biology. Pages/A/autonomic. gif

Reflexes • Involuntary, automatic response to a stimulus • Involves a simple nerve pathway called a reflex arc

FIGHT OR FLIGHT… • This theory states that animals react to threats with a general impulse of the nervous system, priming the animal for fighting or fleeing. • Physical Response: Increased heart rate, sweaty palms, nostrils open up and breathing speeding up, dilated pupils, constricted blood flow. • FYI Males are more likely to respond to an emergency situation with aggression (fight), while females are more likely to flee (flight), turn to others for help, or attempt to defuse the situation