Post on 17-Dec-2015
transcript
Nervous System
Parts of the Nervous System
• Brain• Spinal Cord• Nerves
Vocabulary to Know
• Homeostasis– The regulation of steady, life-maintaining
conditions inside an organism, despite changes in its environment
Nerve Cells
• Neurons– Basic functioning units of the nervous
system
http://ilearn.senecac.on.ca/aahs/health/IHP/ottawa/anatomy/neuron/map/neuron.html
http://35.9.122.184/images/40-AnimalStructureAndFunction/
Neurons
• Made up of a cell body and branches called dendrites and axons – Dendrites receive messages from other
neurons and send them to the cell body – Axons carry messages away from the
cell body
Any message carried by a neuron is called an impulse Any message carried by a neuron is called an impulse
Neurons
A message carried by a neuron is called an impulse
Types of Neurons
• Sensory• Motor• Interneuron
Sensory Neurons
• Receive information• Send impulses to the brain or spinal
cord
Interneurons
• Send impulses from sensory neurons to motor neurons
Motor Neurons
• Conduct impulses from the brain or spinal cord to muscles or glands throughout your body
Synapse
• Small space across which an impulse moves from an axon to the dendrites or cell body of another neuron
Synapse
• An impulse reaches the end of an axon
• Axon releases a chemical• Flows across the synapse• Stimulates the impulse in the dendrite
of the next neuron• Impulse moves from neuron to neuron
http://www.med.harvard.edu/publications/On_The_Brain/Volume7/Number1/images/Neuron.jpg
http://mhln.com
An impulse moves in only one direction across a synapse - from an axon to the dendrites or cell body of
another neuron.
Two Parts
• Central (CNS)• Peripheral (PNS)
Central Nervous System
• Brain• Spinal cord
The Brain
• Coordinates body activities • Made up of approximately 100 billion
neurons • Divided into three major parts-
– the cerebrum– the cerebellum– the brain stem.
Cerebrum
• Largest part of the brain• Thinking• Memory is stored• Movements are controlled• Impulses from the senses are
interpreted.
Cerebellum
• Interprets stimuli from eyes, ears, muscles
• Controls voluntary muscle movements• Maintains muscle tone• Helps maintain balance
Brain Stem
• Connects brain to spinal cord• Made up of the midbrain, the pons,
– Act as pathways connecting various parts of the brain with each other
• Medulla – controls involuntary actions
The Spinal Cord
• Extension of the brain stem• Bundles of neurons that carry
impulses from all parts of the body to the brain and from the brain to all parts of your body
extension of the brain stem. It is made up of bundles of neurons that carry impulses from all parts of the body to the brain and from the brain to all parts of your body
Research Visit the Glencoe Science Web site at tx.science.glencoe.com for more information about the nervous system. Make a brochure outlining recent medical advances.
The Peripheral Nervous System Your brain and spinal cord are connected to the rest of your body by the peripheral nervous system. The PNS is made up of 12 pairs of nerves from your brain called cranial nerves, and 31 pairs from your spinal cord called spinal nerves. Spinal nerves are made up of bundles of sensory and motor neurons bound together by connective tissue. For this reason, a single spinal nerve can have impulses going to and from the brain at the same time. Some nerves contain only sensory neurons, and some contain only motor neurons, but most nerves contain both types of neurons.
Somatic and Autonomic Systems The peripheral nervous system has two major divisions. The somatic system controls voluntary actions. It is made up of the cranial and spinal nerves that go from the central nervous system to your skeletal muscles. The autonomic system controls involuntary actions-those not under conscious control-such as your heart rate, breathing, digestion, and glandular functions. These two divisions, along with the central nervous system, make up your body's nervous system.
Peripheral Nervous System
• Connects body to brain & spinal cord• 12 pairs of nerves from your brain
(cranial nerves)• 31 pairs from your spinal cord (spinal
nerves)– Bundles of sensory and motor neurons
held together by connective tissue
http://www.christopherreeve.org/Research/Research.cfm?ID=178&c=21
Peripheral Nervous System
• Two divisions– Somatic– Autonomic
http://abdellab.sunderland.ac.uk/lectures/Parmacology/Pics/anatomy/PNS.GIF
Somatic Nervous System
• Controls voluntary actions• Made up of the cranial and spinal
nerves that go from the central nervous system to your skeletal muscles
Autonomic Nervous System
• Controls involuntary actions-those not under conscious control-such as your heart rate, breathing, digestion, and glandular functions
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/autonomic.gif
Reflexes
• Involuntary, automatic response to a stimulus
• Involves a simple nerve pathway called a reflex arc