the nervous system how does it work? video:
TRANSCRIPT
THE NERVOUS THE NERVOUS SYSTEMSYSTEM
HOW DOES IT WORK?HOW DOES IT WORK?
Video: http://www.brainpop.com/health/bodysystems/nervoussystem/
Purpose: Purpose: •Controls and coordinates the body’s Controls and coordinates the body’s response to changes in the environmentresponse to changes in the environment
Why? Why? •Failure to respond may result in disease or Failure to respond may result in disease or deathdeath
How? How? •Uses neurons to send electrical messages (impulses)
A. Stimulus and Response
i. stimuli is a change in the internal or external environment of the body
– Receptors are used to detect stimuli (sensory organs) (ie. Ears, skin, nose, mouth)
ii. response is the way you react to a certain stimuli
•Effectors are organs that produce the response (ie. muscles or glands)
Stimuli Response
Bright light Blink, squint
hunger Salivate, stomach growls
Wasp or bee Swat, move away
Neurons: (nerve cells)
• nerve cells specialized for receiving and transmitting impulses/signals
• functioning units of the nervous system
http://www.brainpop.com/health/bodysystems/neurons/
Axon terminals
Myelin sheath
Nodes
Cell body
Axon
Nucleus
Dendrites
Section 35-2
A Neuron
1. Nerve cell (neuron) “DCATS” – order of impulse
1 = dendrite • Detects stimulus• Starts impulse
2 = cyton (cell body)
Has nucleus
3 = axon (covered by myelin sheath)
• Carries nerve impulses• sheath insulates axon
4 = endbrushes • Terminal branches• Release
neurotransmitters across synapse to another neuron
5 = synapse • The space between neurons where impulses “jump” from one neuron to the next
5
DD
CC
AA
TT
SS
Neurotransmitter
–Chemicals used Chemicals used to help transfer to help transfer the impulse the impulse across the across the synapsesynapse
–Found in tiny Found in tiny sacs (vesicles) sacs (vesicles) at the axon at the axon terminalsterminals
Sensory From sense organs (eyes, nose, skin, ears,
tongue) to brain/spinal cord Interneurons
Interconnect other two types Found in brain and spinal cord
Motor From brain/spinal cord to muscles/glands
http://www.brainpop.com/health/bodysystems/neurons/
3. Nerves – – bundle of neurons that transmits impulses
4. Types of neurons
http://www.dnatube.com/video/2116/Nervous-System-how-it-works
Reflex Arc (Loop)Reflex Arc (Loop)• Quick involuntary Quick involuntary
action that doesn’t action that doesn’t involve the braininvolve the brain
• Neurons may release chemicals to stimulate each other, or these chemicals may be released to stimulate a muscle or gland.
• An example of a muscle being stimulated by a neuron appears after the reflex path pictured in number four in the diagram.
Receptor
Effector
“RSIME”- order of stimulus
• R- RECEPTOR (DETECTS STIMULUS)- SENSORY ORGAN
• S- SENSORY• I- INTERNEURON
• M- MOTOR NEURON
• E- EFFECTOR (RESPONDS TO STIMULI)- MUSCLE OR GLAND
The Nervous SystemThe Nervous System
How is it made up?How is it made up?http://www.dnatube.com/video/2116/Nervous-System-how-it-works
Divisions of the Nervous SystemDivisions of the Nervous System
• The nervous The nervous system is divided system is divided into into 22 main parts: main parts:– The Central The Central
Nervous Nervous System (CNS)System (CNS)
– The Peripheral The Peripheral Nervous Nervous System (PNS)System (PNS)
http://www.morphonix.com/software/education/science/brain/game/specimens/nervous_system.html
CNSCNS• cerebrum: center for voluntary
activity interprets sensory impulses, initiates some motor activities, and responsible for memory, thinking and reasoning
• cerebellum: coordinates motor activities and aids in maintaining balance
• medulla: controls involuntary activities such as breathing, heartbeat, blood pressure and peristalsis (is part of the brain stem)
• Brain stemBrain stem– Connects brain to spinal Connects brain to spinal
cordcord– Consists ofConsists of
• Medulla oblongataMedulla oblongata (heart (heart rate, etc)rate, etc)
SPINAL CORD
1. Central Nervous System (CNS)
• Consists of the brain Consists of the brain
& spinal cord& spinal cord
2. Peripheral Nervous System (PNS)•Includes all the spinal nerves TWO FUNCTIONS
a) TRANSFER IMPULSES FROM SENSE ORGANS CNS
b) TRANSFER IMPULSES FROM CNS MUSCLES OR GLANDS
D. Nervous System Disorders
• Very serious: the nervous system Very serious: the nervous system CANNOT repair itselfCANNOT repair itself
1. Stroke – cerebral bleeding or clot
2. Parkinson’s disease – missing dopamine (neurotransmitter); movement related problems (ie. Shaky)
3. Alzheimer’s – interference w/ brain neurons causing cognitive problems (memory loss, recognition, etc)
4. Meningitis – bacterial or viral
Pons
Pituitary gland
Hypothalamus
Cerebrum
Medulla oblongata Spinal cord
Cerebellum
Pineal gland
Thalamus
Section 35-3
The Brain
Disorders Stroke
Results from a cerebral hemorrhage or blood clot in a cerebral BV blocking blood flow to brain
Parkinson’s Disease Loss of the functioning of a particular group of
nerve cells in brain May be due to a shortage of dopamine Scientific American Frontiers - Season 3 Prescription
poison
Parkinson’s Disease Symptoms
Shaking Poor balance Lack of coordination Stiffening of Muscles
Cause Triggered by by
environmental factors Genetic tendency
Disorders Alzheimer’s Progressive
degenerative disease that advances over time
Symptoms Memory loss Inability to think,
speak or care for oneself
Multiple Sclerosis Cells in the brain and
spinal cord do not function properly due to destruction of myelin sheath
Symptoms Shaking of hands Blurred vision Slurred speech Muscle weakness Loss of bladder control