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3 parts of the Nervous System
- 1. Central Nervous System (CNS): brain and spinal cord.
- 2. Peripheral Nervous System (PNS): nerves of the body
- 3. Autonomic Nervous System (ANS): has parts of the CNS and PNS.
What are the two parts of the CNS?
Brain and Spinal cord
What does the Autonomic Nervous System control and what are its 2 divisions?
- Controls autonomic function (blood pressure, digestion, etc).
- a. Sympathetic division
- b. Parasympathetic division
1) 1. What kinds of neurons enter the CNS? 2) What kind of neurons leave the CNS?
- 1) Sensory (afferent) signals picked up by sensor receptors
- - Carried by nerve fibers of PNS to the CNS
- 2) Motor (efferent) signals are carried away from the CNS
- - Innervate muscles and glands
What sheath covers the axon (not referring to myelin)? What sheath covers a fascicle (bundle of neurons)? What sheath covers a bunch of fascicles?
What three things do all neurons do?
- 1. Receive a signal. Can be any type of stimulus (change in environment, signal from another neuron, etc).
- 2. Transmit a signal to another location. E.g. finger touching something --> signal to spinal cord or brain.
- 3. Stimulate another cell
- a. Another neuron --> transmit signal
- b. Muscle --> contraction
- c. Gland --> secretion
What three characteristics do all neurons share?
- 1. Longevity- can live and function for a lifetime
- 2. Do not divide - fetal neurons lose their ability to undergo mitosis; neural stem cells are an exception
- 3. High metabolic rate- require abundant oxygen and glucose
Picture of Sensory vs Motor Neurons
What receives the signal and carries the nerve conduction toward the cell body?
Where are the nucleus, ribosomes, and most organelles are located?
The CELL BODY
What has the function of transmitting signals?
What part of a neuron stimulates another cell?
Describe the correct path an impulse takes across a synapse.
- Axon of presynaptic neuron -> SYNAPTIC CLEFT -> dendrite of post synaptic neuron
What are synaptic knobs filled with?
The synaptic knob has vesicles filled with a neurotransmitter that carries the signal.
What are 4 types of glia cells?
- Schwann Cel
What are the supporting cells of the nervous system?
Where do most tumors originate from?
Most tumors of the brain originate from glial cells.
Photo of two of the 4 types of glial cells
- Schwann Cell
Which cells provide myelin sheath for neurons in CNS?
Which cells provide myelin sheath for neurons in PNS?
What is the function of MYELIN SHEATHS?
to speed up the nerve conduction.
What are the BARE regions of axonal membranes found only in myelinated axons called?
NODES OF RANVIER
What conducts impulses faster - myelinated or unmyelinated axon?
What is an autoimmune disease where the oligodendrocytes (the myelin sheaths) are destroyed, interfering with the neuron functions in the CNS and brain?
What is the most common neurological disease of young adults?
What are the two differences between SCHWANN CELLS and OLIGODENDRICYTES?
- Schwann cells are in PNS & each cell only forms 1 myelin sheath.
- Oligodendricytes are in CNS and each cell can form more than one myelin sheaths.
What are the 3 functions of an ASTROCYTE?
- a. Physically supports the neurons
- b. Transmits materials from capillaries to neurons
- c. Forms blood-brain barrier (BBB)
What is the only function of the BBB?
The only function of the blood-brain barrier is to help protect the central nervous system.
Define MICROGLIA and their function
They are macrophages. They pick up bacteria and dead cell, etc
What is the portion of the CNS that is unmyelinated (cell bodies of neurons, glia, and dendrites)?
What is the portion of the CNS with myelin (axons)
What is a collection of axons in the PNS?
- No cell bodies, dendrites, or synapses; just axons.
What is a collection of axons in the CNS
Where is most information processed?
- Most synapses are in the CNS
What is a collection of cell bodies in the PNS?
What is a network of nerves called?
What are the neurons that leave the CNS to effect a muscle or gland?
What neurons go from body to CNS, carrying sensory information?
What is a small neuron found only in the CNS?
What is the function of interneuron?
it connects two other neurons in the spinal cord
What makes the CNS complex?
The large number of interneurons in the CNS
Where are the cell bodies of motor neurons and interneurons located?
In gray matter