Card Set Information
BYU Anatomy - Nervous System - Ch. 12
A nerve cell
Main body of neuron
- tree-like branches
- for input/sensory (not output)
Impulse generators and conductors that transmit nerve impulses away from their cell body.
Thin sheath around a nerve axon; external material
Fatty insulating sheath that surrounds all but the thinnest nerve fibers
Node of Ranvier
Gaps in the myelin sheath
Star-shaped glial cells of the CNS
Glial cells derived from mesoderm; function as macrophages (scavengers) in the CNS.
Form a simple epithelium that lines the central cavity of the spinal cord and brain.
"few branch cells"; line up in small groups and wrap their cell processes around the thicker axons in the CNS, producing insulating coverings called myelin sheaths.
Type of neuroglia in the PNS; surround neuron cell bodies within ganglia(clusters of cell bodies).
Type of neuroglia in the PNS; surround all axons in the PNS and form myelin sheaths around many of these axons.
Extreme Longevity (Neurons)
Neurons can live and function for a lifetime, over 100 years.
Do not divide; lose ability to undergo mitosis.
High Metabolic Rate (Neurons)
Continuous and abundant supplies of oxygen and glucose. Neurons cannot survive for more than a few minutes without oxygen.
Conducting Potential (Neurons)
The way neurons communicate; transmit information through chemical messengers. Some neurons in the CNS transmit signals electronically through gap junctions.
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
-Everything outside the CNS.
-Divide into several functional systems
-transmits impulses toward the CNS
: controls touch, temperature, propioception in skin, body wall, and limbs
-visceral sensory: controls stretch, pain, temperature, and chemical changes in viscera, nausea, and hunger.
-transmits impulses away from the CNS
: voluntary, innervates skeletal muscle
visceral motor (Autonomic Nervous System/ANS): involuntary, innervates involuntary muscle and glands
Sympathetic: most active when body is in excitement or emergency situations
Parasympathetic: most active when body is at rest
-more than two processes
-numerous dendrites and single axon
-small multipolar neurons have no axon and rely on dendrites for conducting signals
-99% of neurons belong to multipolar
-found in the CNS as interneurons
-exit CNS as motor neurons
-more than two processes
-occur in special sensory organs (inner ear, retina of the eye, epithelium of the nose)
-serve as sensory neurons
Unipolar (Pseudounipolar) Neurons
-found in PNS as sensory neurons
-short, single process
-emerges from cell body and divides like an inverted T into two long branches
-start out as bipolar first
-make up typical sensory neurons
-covers schwann cells
-delicate layer of loose connective tissue
Groups of axons bound into bundles
Wrapping of connective tissue
Whole nerve surrounded by a tough fibrous sheath.
Functional role of a Synapses
-determine the direction of information flow through the nervous system
Action Potential (Impulse)
-positive ions- sodium and potassium
-no interneuron between the sensory neuron and the motor neuron
-one or more interneurons are part of the reflex pathway between the sensory and motor neurons.
Multiple Sclerosis (MS)
-myelin is attacked by the body's own immune system
: blindness, weakness, clumsiness/balance, slurred speech, bladder inconsistence, fatigue, depression
-myelin sheaths in the CNS are destroyed, forming scleroses
View of the Brain Stem
View of Brain sectioned midsagittally
View of the Brain diencephalon