Regulation:Nervous System

A World Without Pain

Perry Goldberger, 15, can't distinguish between hot and cold and cannot feel pain

Four-year-old Roberto Salazar does not feel pain because of a rare genetic disorder.

NERVOUS SYSTEM

NERVE REGULATON

STIMULUS:Example – heat

From a stove

IMPULSE:Example – neurons Send a message to CNS to tell the hand

To move

RESPONSE:Example – removing

Hand off the stove

HUMANNERVOUSSYSTEM

Central Nervous System (CNS) –brain and spinal

cord

Peripheral Nervous System (PNS) –

nerves outside the CNS

Nerve Cells

• Nerve cells = neurons• Receive impulses and send the

messages to various parts of the body via Cellular Communication

• Nerve cells make up:– Nerves– Brain– Spinal cord – Receptors

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• You accidentally place your hand on a hot iron and quickly move it away.– What is the stimulus?– What is the impulse?– What is the response?

• What is the difference between the CNS and PNS?

• What is the function of a neuron?

Neuron Structure

• 1. Cyton- cell body• 2. Cell nucleus• 3. Dendrites –

receive impulses

Neuron Structure Cont…• 7. Axon – carries

impulses away from the dendrites

• 6. Myelin Sheath – fatty covering of the axon which speeds up impulses

• 5. Schwann Cells (make myelin)

Neuron Structure Cont…• 9. Terminal Branches• Synapse – gap where

impulses travel from the axon of one neuron to the dendrites of another neuron.

• Neurotransmitters – chemical messengers that cross the synapse

Types of Neurons

– Sensory: carry impulses to the CNS– Motor: carry impulses from the CNS to

other parts of the body such as muscles– Mixed: contain both

Receptors• Receive messages• Found on the cell membrane and are

VERY SPECIFIC!!!

CNS

The Brain• Cerebrum – thinking,

memory, voluntary actions, emotions

• Cerebellum – coordination and balance

• Medulla (brain stem) – involuntary actions like breathing and heartbeat

Spinal Cord

• Mass of nerve cells • Vertebrae – protect it• Function –

– relays impulses to and from the brain– center for some reflex actions

Autonomic Nervous System• Part of the peripheral nervous system• Controls involuntary behavior (automatic)• Examples:

– Breathing– Heart rate– Blinking, dilation of pupil– Production of saliva– Increases and decreases the rate of these

involuntary behaviors to help maintain homeostasis

Reflexes- Reflex arc• Involuntary behavior• Reflex:

– Receptor (nerve endings in the knee) receive a message

– Sensory neuron sends to message to the spinal cord (CNS)

– The interneuron connects the sensory neuron to the motor neurons

– The motor neuron sends the message to the muscle in the leg (EFFECTOR)

– Effector then reacts such as a knee jerk

Somatic Nervous System

• Part of the peripheral nervous system• voluntary behavior• Examples: movement of skeletal

muscles

Disorders of the Nervous System

Cerebral Palsy

• Birth disorder that affects motor function.

Polio

• a viral pathogen that weakens muscles and leads to paralysis

Stroke

• When a free-floating blood clot reaches the brain

• Blood vessel ruptures in the head/neck

Meningitis

• Inflammation of the meninges (membrane surrounding the brain and spinal cord)

• Can be viral (not severe) or bacterial (VERY severe)

• Symptoms come quickly– Fever and chills, nausea and vomiting,

sensitivity to light, severe headaches

The meningococcal vaccination is recommended for:

• Adolescents ages 11 - 12 and adolescents entering high school (about age 15) who have not already received the vaccination.

• All college freshmen who have not been vaccinated and are living in dorms.

• Those traveling to countries where diseases caused by meningococcus are very common