The Nervous System

Section 35-3: Divisions of the Nervous System

Do Now 3/1/13

1. What is the process that keeps internal conditions relatively constant despite changes in the external environment?

2. In a resting membrane of a neuron, what is the overall charge inside? What is the charge outside?

3. During an action potential, what happens to the charges?

4. What chemical is released in the synapse?

The Central Nervous System (CNS)

• The central nervous system relays messages, processes information, and analyzes information

• Control center of the body

• Consists of the brain and spinal cord

The Central Nervous System (CNS)

• Meninges = 3 layers wrapped around brain and spinal cord

• Cerebrospinal fluid (CSF) = bathes brain and spinal cord and protects the central nervous system

The Brain

• The Cerebrum– Largest part of the

human brain– Voluntary and conscious

activities– Site of intelligence,

learning, and judgment– Each half deals with the

opposite side of the body

The Brain

• The Cerebellum– 2nd largest region of the

brain, known as the “little brain.”

– Coordinates and balances the actions of the muscles

The Brain

• The Brain Stem– Connects the brain and

spinal cord– Consists of the Pons and

Medulla Oblongata– Controls blood pressure,

heart rate, breathing, swallowing, visceral organs (autonomic)

The Brain

• Thalamus– Receives messages and

relays messages to proper regions of the cerebrum for processing

• Hypothalamus– Control center for

recognition– Analysis of hunger, thirst,

fatigue, anger, and body temperature

– Coordinates nervous system with the endocrine system

The Spinal Cord

• Main communication link between the brain and the rest of the body

• 31 pairs of spinal nerves branch out to communicate information to different parts of the body

• Reflexes are processed directly to the spinal cord

• Reflex = quick automatic response to a stimulus

The Peripheral Nervous System (PNS)

• Outside of the Central Nervous System

• Divided into the sensory division and motor division

• Sensory Division of the PNS transmits impulses from sense organs to the CNS.

• Motor Division transmit impulses from the CNS to the muscles or glands.

The Peripheral Nervous System (PNS)

Somatic Nervous System• Regulates activities under conscious control• Some somatic nerves are also involved with

reflexes that can act with our without conscious control

The Peripheral Nervous System (PNS)

• Reflex arc = involves sensory neuron, motor neuron and effector (sometimes interneurons)

• Neurons in spinal cord automatically activates motor neurons before information relayed to brain

The Peripheral Nervous System (PNS)

• Autonomic Nervous System– Regulates activities that are automatic, or

involuntary (not under conscious control).– Subdivided into 2 parts:– Sympathetic nervous system (fight and flight)– Parasympathetic nervous system (rest)• Opposing effects of sympathetic and parasympathetic

help maintain homeostasis.– Ex. Heart rate increased by sympathetic but decreased by

parasympathetic

Due Today 3/1/13

• Do the Quick Lab on page 903. You will need safety goggles, a sheet of scrap paper, and another sheet of paper to answer the questions.

• Do 35-3 Section Assessment #1, 3-6 on page 905.

Do Now 3/5/131. Which part of the brain is involved in balance and

coordination?2. Which part of the brain is involved in controlling heart rate,

blood pressure, visceral organs, and body temperature?3. Which part of the brain is involved in learning?4. What is the CNS made of?5. What is the PNS made of?6. What does the Autonomic Nervous System control?7. What does the Somatic Nervous System control?8. What are the two parts of the Autonomic Nervous System?– Which one deals with fight or flight?– Which one deals with rest?