nervous system central nervous system (cns) peripheral nervous system (pns)

Nervous System

CentralNervousSystem(CNS)

PeripheralNervousSystem(PNS)

Organization of the nervous system

Organization of the nervous system

The Nervous System

Nervous System: Consists of all the nerve cells. **It is the body’s speedy, electrochemical communication system.

Central Nervous System (CNS): the brain and spinal cord.

Peripheral Nervous System (PNS): the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

Organization of the nervous system

The central nervous system

BrainSpinal cordA collection of neurons and supportive tissue running from the base of the brain down the center of the back

Protected by spinal column

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Central Nervous System – The Spinal Cord and Reflexes

Organization of the nervous system

The Nerves

• Nerves consist of neural “cables” containing many axons.

• They are part of the peripheral nervous system and connect muscles, glands, and sense organs to the central nervous system.

Divisions of the Peripheral Nervous System

• There are two divisions of the peripheral nervous system: – the somatic, or voluntary portion– the autonomic, or involuntary portion

Somatic Nervous System: The division of the peripheral nervous system that controls the body’s skeletal muscles (voluntary).

Autonomic Nervous System: Part of the PNS that controls the glands and other muscles (involuntary).

Organization of the nervous system

• The autonomic portion of the peripheral nervous system governs involuntary, visceral functions…such as heart and breathing rate, blood pressure, etc.

• It is divided into two systems:– Sympathetic Nervous System: Division of

the ANS that arouses the body, mobilizing its energy in stressful situations.

– Parasympathetic Nervous System: Division of the ANS that calms the body, conserving its energy.

Autonomic Nervous System (ANS)

Organization of the nervous system

The Sympathetic Nervous System

• Mobilizes the body’s resources for emergencies and creates the fight-or-flight response.

• “Arouses”

Organization of the nervous system

The Parasympathetic Nervous System

• Activates processes that conserve bodily resources… slowing heart rate, reducing blood pressure, etc.

• “Calms”(rest and

digest)

Recap

See “Fight or Flight” in action in this short cartoon: http://cmhc.utexas.edu/stressrecess/Level_One/fof.html

Review

• In everyday situations the sympathetic and parasympathetic nervous system work together to keep you in a steady internal rate.

• What happens if these are out of wack?– .

Journal

• How does information flow through your nervous system as you pick up a fork? Summarize this process.