Chapter 20HumanNervous System

RegulationIs achieved by both the

nervous system and the endocrine system

in humans*Both systems secrete

chemicals and play a major role in homeostasis

NeuronsThe nervous system is made up of nerve cells called neuronsNeurons are used for the transmission of impulses (message)Three types of neurons:

Sensory neurons Interneuron Motor neuron

http://psych.hanover.edu/Krantz/neurotut.html

Sensory neuronTransmit impulses from the sense organs (receptors) to the spinal cordSense organs include eyes, ears, tongue, nose, and skin

InterneuronFound in the spinal cord and brainTransmit impulses from the sensory neuron to the motor neurons

Motor neuron

Transmit impulses from the brain and spinal cord to effectors (muscle or gland)

Reflex Arc

The difference between both:

Nervous SystemNerve responses are more rapid (neurons) than the endocrine system (blood)

Endocrine System

Endocrine responses are of

a longer duration than that of nerve

responses

(II) Central Nervous System

Consist of a brain and spinal cord

A) BrainThe most active organ in the bodyReceives 20% of the blood pumped by the heartIs a large mass of neurons located in the cranium (skull)Three major division:

Cerebrum Cerebellum Medulla Oblongata

The Human Brain

A) BrainNote that the brain is convoluted or folded.The convolutions of the brain allow for a greater surface area for gray matter.

CerebrumLargest part of the brainCenter of control for:

a) voluntary body movements b) 5 senses c) memory (learning +

thought)

CerebrumDivided into left and right hemispheres.Outer layer of the cerebrum is the cortex (cerebral cortex).Different areas are responsible for different functions.

Brain Scans

PET scan on the left shows two areas of the brain (red and yellow) that become particularly active when volunteers read words on a video screen: the primary visual cortex and an additional part of the visual system, both in the back of the left hemisphere.Other brain regions become especially active when subjects hear words through ear-phones, as seen in the PET scan on the right.

CerebellumCoordinates motor

activities (voluntary movement)

Aids in maintaining balance

MedullaInvoluntary

activities like breathing and

heartbeat

B) Spinal Cord

Extends from the brain and is protected by the vertebrae of the spinal column.

Is not the backbone or spine.

The spinal cord coordinates activities between the brain and other body structures

B) Spinal Cord

It is the center for reflex action a) a reflex is an involuntary,

automatic response to a given stimulus

b) reflex behavior involves a pathway known as the reflex arc over which impulses travel

                                                            

C) Peripheral Nervous System

Consist of nerves extending throughout the bodyIs separated into 2 parts:

Autonomic Nervous System Somatic Nervous System

Autonomic Nervous System

Consists of nerves that regulate

involuntary actions like heartbeat and gland secretions

Somatic Nervous System

Consist of nerves that regulate voluntary

muscles of the skeleton

http://www.illusionworks.com/html/breathing_square.html

http://www.illusionworks.com/html/color_aftereffect.html

http://www.illusionworks.com/html/motion_aftereffect.html

http://www.illusionworks.com/html/shadow.html

Olfactory senses

"The VNO appears to be a much more primitive structure that uses a different set of molecular machinery than the main olfactory system ,"

                                                                                                                                                                                                  

                                         

Disordersof the

Nervous System

Cerebral PalsyA group of diseases caused by damage to the parts of

the brain that control voluntary movement

This damage occurs during embryonic development

Meningitis

Inflammation of the membrane that

surrounds the brain and spinal cord

StrokeA disorder in which the brain is damaged as a

result of cerebral hemorrhage (a broken

vessel in the brain) or a blood clot in a blood

vessel located in the brain

PolioA viral disease of the

central nervous system which may result in paralysis

It is now prevented through immunization

What is Alzheimer's? Is a progressive and fatal brain disease. More than 5 million Americans now have Alzheimer’s disease. Alzheimer's destroys brain cells, causing problems with memory, thinking and behavior severe enough to affect work, lifelong hobbies or social life. Alzheimer’s gets worse over time, and it is fatal. Today it is the seventh-leading cause of death in the United States.

http://alz.org/alzheimers_disease_what_is_alzheimers.asp

What is Alzheimer's? Alzheimer’s disease leads to nerve cell death and tissue loss throughout the brain. Over time, the brain shrinks dramatically, affecting nearly all its functions.

http://alz.org/alzheimers_disease_what_is_alzheimers.asp

What is Alzheimer's? Alzheimer tissue has many fewer nerve cells and synapses than a healthy brain. Plaques, abnormal clusters of protein fragments, build up between nerve cells. Dead and dying nerve cells contain tangles, which are made up of twisted strands of another protein. Scientists are not absolutely sure what causes cell death and tissue loss in the Alzheimer brain, but plaques and tangles are prime suspects.

http://alz.org/alzheimers_disease_what_is_alzheimers.asp

What is Alzheimer's? Some change in memory is normal as we grow older, but the symptoms of Alzheimer’s disease are more than simple lapses in memory. People with Alzheimer’s experience difficulties communicating, learning, thinking and reasoning — problems severe enough to have an impact on an individual's work, social activities and family life.

What is Alzheimer's? AgeFamily history (genetics)

Scientists have so far identified one Alzheimer risk gene called apoliprotein E-e4 (APOE-e4).

Major head traumaContinuous head trauma

What is Parkinson disease?

Parkinson disease is a brain disorder.  It occurs when certain nerve cells (neurons) in a part of the brain called the substantia nigra die or become impaired. Normally, these cells produce a vital chemical known as dopamine. Dopamine allows smooth, coordinated function of the body's muscles and movement.  When approximately 80% of the dopamine-producing cells are damaged, the symptoms of Parkinson disease appear.

What is Parkinson disease?

What are the signs and symptoms of Parkinson

disease? The loss of dopamine production in the brain causes the primary symptoms of Parkinson disease.  The key signs of Parkinson disease are:

Tremor (shaking)

Slowness of movement

Rigidity (stiffness)

Difficulty with balance

Other signs of Parkinson disease may include:

Small, cramped handwriting Stiff facial expression Shuffling walk Muffled speech Depression