Chapter 7 Pt. 1 Flashcards
The ________ ________ integrates and coordinates all the body’s varied activities
nervous system
What are the 2 primary divisions of the nervous system?
1) Central Nervous System
2) Peripheral System
What is the difference between the central nervous system and the peripheral system?
Central Nervous System- consisting of the brain and spinal cord
Peripheral System- consisting of all the nervous tissue in the body outside the brain and spinal cord
What are Neurons?
excitable cells that generate and transmit messages
Neurons are also known as ______ _____
nerve cells
What are Neuroglia cells (glial cells)?
support and protect neurons
__________ cells (_____ cells) outnumber neurons
Neuroglia cells (glial cells)
What are nerve growth factors?
a steady supply of chemicals supplied by glial cells
What is a myelin sheath?
glial cells that form insulating sheaths around axons
What are the 3 categories of neurons?
1) sensory (or afferent) neurons
2) motor (or efferent) neurons
3) interneurons (or associate) neurons
What are the characteristics of sensory (or afferent) neurons?
- conduct information toward the brain and spinal cord
- generally extend from sensory receptors
What is a motor (or efferent) neuron?
carry information away from the brain and spinal cord to an effector
What is an effector?
either a muscle, which will contract, or a gland, which will secrete its product
What are the characteristics of interneurons (or associate) neurons?
are located between sensory and motor neurons
found only within the brain and spinal cord
What are the most numerous nerve cells in the body?
interneurons (or associate) neurons
What is amyotrophic lateral sclerosis (ALS)?
a progressive disease in which motor neurons die and stop sending messages to skeletal muscles
amyotrophic lateral sclerosis (ALS) causes the person to lose control over _____, ____, and _____
arms
legs
body
How does amyotrophic lateral sclerosis (ALS) cause death?
respiration failure
Amyotrophic lateral sclerosis (ALS) is also known as ____ _______ ________
Lou Gehrig’s disease
What are dendrites?
branching projections attached to a neuron
_________ provide a huge surface for receiving signals form other cells
dendrites
What is the cell body?
the enlarged central region; has all the normal organelles
What is an axon?
a single one extension of the neuron
What is a neurotransmitter?
alters the activity of the effector
_____________ are released by the many branches at the end of the axon
Neurotransmitters
Neurotransmitters are released by the many _________ at the end of the ______
branches
axons
The _____ is the sending portion of the neuron, whereas the _________ and ____ _____ are typically the receiving portions
axon
dendrites
cell body
What is a nerve?
a bundle of parallel axons, dendrites, or both arising from many neurons
The structure of a neuron:
1) ________, receive information form other neurons or from the environment
2) the ____ ______ controls the cell’s metabolic activities
3) the ____ ______ integrates input from other neurons
4) an _____ conducts the nerve impulse away form the cell body
5) _____ ________ release chemicals called neurotransmitters that affect the activity of nearby nears or an effector
dendrites cell body cell body axon axon endings
______ _______ increased the rate of conduction of a nerve impulse and helps repair it
Myelin sheath
Myelin sheath increased the rate of __________ of a nerve impulse and helps ______ it
conduction
repair
Myelin sheath plays a role in the ____________ of cut axons in the __________ nervous system
regeneration
peripheral
What are Schwann Cells?
glial cells, outside the brain and spinal cord, that form neurons’ myelin sheaths
The ______ _______ is kept alive by the Schwann cell’s nucleus and cytoplasm, which are squeezed to the _________ as the sheath forms
myelin sheath
periphery
The myelin sheath is kept alive by the Schwann cell’s ________ and _________, which are squeezed to the periphery as the sheath forms
nucleus
cytoplasm
What are nodes of Ranvier?
the gaps between adjacent Schwann cells, where the axon is exposed to the extracellular environment
What is saltatory conduction?
a transmission of a nerve impulse “jumps” successively form one node of Ranvier to the next
_______ means to jump
saltare
What is multiple sclerosis?
a disease in which the myelin sheaths in the brain and spinal cord are progressively destroyed
the damaged regions of myelin become hardened scared called _________
scleroses
_________, interfere with the transmission of nerve impulses
scleroses
