the nervous system chapter 36. basic structure neurons composed of 3 parts cell body dendrites axon
TRANSCRIPT
The Nervous SystemChapter 36
Basic Structure
• Neurons• Composed of 3 parts
• Cell body
• Dendrites
• Axon
DENDRITES• Branchlike extensions that receive impulses
and carry them to the cell body
AXON
• Single extension of neuron that carries impulses away from the cell body and toward other neurons, muscles, and glands
CELL BODY
• Contains nucleus of nerve cell
How are neurons connected?
• SYNAPSES!• Junction between neurons
• Impulses must cross synaptic space to reach the brain and other destinations
What’s the Matter?White and Gray Matter
• Axons are covered with a white substance called the MYELIN SHEATH
• This white covering gives this part of the brain its “white” appearance.
• The MYELIN SHEATH is formed from SCHWANN cells
• SCHWANN cells insulate the axon and increase the speed of the impulse
WHITE MATTER
GRAY MATTER
• Absence of myelin sheaths in neurons accounts for gray matter in the brain.
MOVEMENT OF A SIGNALThe “Electric Slide” in the body!• Neurons send electrical signals/impulses in
the body!
• Where is the signal going?• Sensory organs
• Brain
• Muscles
3 Types of Neurons• Sensory neurons
• carry signals from outside and inside the body to the brain and spinal cord
• Interneuron• found in brain and spinal cord
• process sensory impulses and send the message on the motor neuron
• Motor neurons• carry impulses away from the brain and spinal
cord
How do neurons work?
1. Reception-stimulus from outside is detected
2. Transmission-message is sent to brain3. Interpretation-brain interprets message
and formulates response4. Transmission-message is sent to muscle5. Response-muscle responds to stimulus
LOOK AT PICTURE ON NOTES
ANATOMY OF THE BRAIN• CEREBRUM - 2 hemispheres
• controls conscious activities, intelligence, memory, language, skeletal muscle movements, and senses
• gray matter
• surface area increased by folds (more surface area = greater intelligence)
ANATOMY OF THE BRAIN• CEREBELLUM-located at back of brain
• controls balance, posture, and coordination
ANATOMY OF THE BRAIN
• MEDULLA OBLONGATA - brain stem• controls involuntary activities (ex: breathing
and heart rate)
CENTRAL VS PERIPHERAL
• Brain and spinal cord
• Control center
• Nerves
• Outside informers
• Somatic system
• Autonomic system
• Sympathetic system
• Parasympathetic system
PERIPHERALSOMATIC SYSTEM -Relays info to and from skin,
skeletal muscles, and CNS
-Voluntary
-Exceptions: reflexes are involuntary p. 981
AUTONOMIC SYSTEM
-Sympathetic
-Parasympathetic
-Relays info to and from internal organs and CNS
-Involuntary
SYMPATHETIC -controls in times of stress
PARASYMPATHETIC -controls when body is at rest
REFLEX ARC