Chapter 11 A Flashcards
What is the nervous system?
Master controlling and communicating system of the body
How do cells communicate?
By electrical and chemical signals
How fast do cells respond to electrical and chemical signals?
Almost immediately
TF: Cell communication is slow and specific
False
Cell communication is fast and specific
What are the three functions of the nervous system?
Sensory input
Integration
Motor output
How is sensory input gathered?
By the sensory receptors that notice internal and external changes
What is integration?
Processing and interpretation of sensory input
What is motor output?
Activation of effector organs that produce a response
What are the effector organs of the nervous system?
Muscles and glands
What are the two main divisions of the Nervous system?
Central nervous system
Peripheral nervous system
What is held within the CNS?
The brain and the spinal cord
What does the CNS do?
It is the integration and control center so it dictates motor output
Where is the PNS?
outside CNS
What does the PNS hold?
Nerves that extend from the brain and spinal cord
What nerves are in the PNS?
Spinal nerves (spinal cord) Cranial nerves (brain)
What are the main divisions of the PNS?
Sensory (afferent)
Motor (efferent)
What are the two different fibers held in the sensory division of the PNS?
Somatic sensory fibers (from non internal organs to CNS)
Visceral sensory fibers (carries impulse from visceral organs to CNS)
What does the motor (efferent) division of the PNS do?
Transmits impulses from CNS to effector organ (muscles and glands)
What are the two divisions of the Motor division of the PNS?
Autonomic nervous system
Somatic nervous system
What does the autonomic nervous system house?
Visceral motor nerve fibers (smooth muscle, cardiac muscle, and glands)
What does the somatic nervous system house?
Somatic motor neurons
from CNS to skeletal muscle
TF: the somatic nervous system and autonomic nervous system are voluntary
False
The SNS is voluntary
The ANS is involuntary
What are the two divisions of the autonomic nervous system?
Sympathetic
Parasympathetic
What does the sympathetic nervous system do?
Mobilizes body systems when they are active
What does the parasympathetic nervous system do?
Conserves energy to maintain the body’s house keeping during rest
How is nervous tissue arranged?
They are highly cellular with little extracellular space so they are tightly packed
What are the two different cell types of nervous tissue?
Neuroglia and Neurons
What do neuroglia do?
They surround and wrap delicate neurons
What are the different types of Neuroglia in the CNS?
Astrocytes
Microglial cells
Ependymal cells
Oligodendrocytes
What is the function of astrocytes in the CNS?
They support/brace neurons Help with exchange between capillaries and neurons Guide young neurons Control chemical environment Respond to nerve impulses Influence neural functioning
(they are basically the mother cells of the CNS)
What is the most abundant type of neuroglia in the CNS?
Astrocytes
What type of cells are astrocytes?
Neuroglia but they are considered highly branched glial cells
Where are astrocytes in the CNS?
They are clung to the neurons, synaptic endings, and capillaries
What are the functions of microglial cells?
They can transform to phagocytize microorganisms and neuronal debris
(janitors of the CNS)
Important in immune functions in the CNS
What is the structural make up of microglial cells of the CNS?
They are small
Ovoid cells
Have thorny processes (extensions) that touch and monitor neurons
They move to injured cells to complete function
What kind of cells can ependymal cells be?
Squamous to columnar and can be ciliated
Why are ependymal cells of the CNS usually ciliated?
To move cerebrospinal fluid throughout the CNS
Where are ependymal cells of the CNS located?
They are in the lining of central cavities of brain and spinal column
What is the function of Ependymal cells in the CNS?
They form a PERMEABLE barrier between the CSF in cavities and tissue fluid bathing the CNS cells
What do Oligodendrocytes do in the CNS?
They wrap CNS nerve fibers to form insulating myelin sheaths for thicker nerve fibers
What are the two types of neuroglia in the PNS?
Schwann cells
Satellite cells
What do schwann cells of the PNS do?
They surround all peripheral nerve fibers to form myelin sheaths in the thicker nerve fibers (like oligodendrocytes in the CNS)
Vital to regeneration of damaged peripheral nerve fibers
What is another name for Schwann cells?
Neurolemmocytes
What do satellite cells in the PNS do?
Surround neuron cell bodies in the PNS
They are similar to astrocytes in the CNS
What do neurons do?
They are excitable nerve cells that transmit electrical signals
What is the structural unit of the nervous system?
Neurons
What are neurons?
Highly specialized cells that conduct impulses
How long do neurons last?
A 100 years or more but they are amitotic so they do not produce new cells when old ones are damaged
Why do neurons need a constant supply of oxygen and glucose?
They have a high metabolic rate
What do all neurons have?
a cell body and 1 or more processes
What are cell bodies of neurons?
The biosynthetic center of the neuron
What do cell bodies do?
Synthesize proteins, membranes, and other chemicals
What are the cell bodies in the CNS called?
Nuclei
clusters of neuronal cell bodies in CNS
Where are most of the cell bodies found?
In the CNS
What are cell bodies in the PNS called?
Ganglia
Where are the ganglia in the PNS?
They lie along nerves in the PNS
What are processes of neurons?
Armlike processes that extend from body
What are tracts?
bundle of neuronal processes in CNS
What are nerves?
Bundles of neuronal processes in the PNS
What are dendrites?
100s of short tapering diffusely branched processes in motor neurons
What do dendrites do?
Carries incoming messages to cell body as graded potentials
Where do axons arise from?
The axon hillock coming off of the cell body
How many axons are in each cell?
One
What are the branches coming off of axons called?
Axon collaterals
Where are axon collaterals found?
In the axon terminal
What do axons do?
They are the conducting region of the neuron and create nerve impulses that are transmitted along neuron cell membrane
What is the axolemma?
The neuron cell membrane where impulses travel in the axon
What happens at the axon terminal?
Neurotransmitters are released into the extracellular space
What can axon terminals do?
Excite or inhibit neurons near by
What is a good thing about the axon lacking a golgi and a rough ER? Bad thing?
Good-allows for efficient transport mechanism
Bad- quickly decay if they are damaged
Where are proteins regenerated within a neuron?
The cell body
What moves molecules and organelles along the axon?
Motor proteins and cytoskeletal elements
What does anterograde mean?
Movement away from the cell body
What does retrograde mean?
Movement to the cell body
When does retrograde happen in the neuron?
When organelles need to be degraded
When signal molecules need to go to the cell body
When viruses and bacterial toxins enter the neuron
What cell parts participate in anterograde?
Mitochondria, cytoskeletal elements, membrane components, and enzymes
What is the myelin sheath composed of?
Myelin
What is myelin?
Whitish, protein, lipoid substance
What does myelin do?
Protects and electrically insulates the axon
Increases the speed of nerve impulses
What forms the myelin sheath in the PNS?
Schwann cells
TF: there are channels and carriers in the plasma membrane of schwann cells to allow impulses and chemicals in the myelin?
False
The plasma membrane of the schwann cells have no proteins in them
Where are the channels and carriers found in the PNS?
In the nodes or gaps between each schwann cell
How is the myelin sheath formed in the CNS?
By multiple flat processes of oligodendrocytes
How many axons can 1 oligodendrocyte wrap around at once?
Up to 60
What is the white matter?
Regions of the brain and spinal cord (CNS) with dense collections of myelinated fibers (tracts)
What is gray matter?
Mostly neuronal cell bodies and non myelinated fibers in the CNS
How are neurons structurally grouped?
By the number of processes
What are the three structural groups of neurons?
Multipolar
Bipolar
Unipolar
What is multipolar neuron?
When the neuron has 3 or more processes (1 axon and other dendrites- mainly seen in the CNS)
What is a bipolar neuron?
Where the neuron has two processes
(1 axon and 1 dendrite)
Rare (retina and olfactory mucosa)
What is a unipolar neuron?
When a neuron has 1 short process that divides like a T into axon branches
(distal - sensory, proximal- enters CNS)
How are neurons functionally classified?
By the direction in which nerve impulses travel through relative to the CNS
What are the 3 functional groups of neurons?
Sensory (afferent)
Motor (efferent)
Interneurons (association neurons)
What do sensory neurons do?
They transmit impulses from sensory receptors to the CNS
usually all unipolar
Where are the cell bodies for sensory neurons?
In the ganglia of the PNS
What do motor neurons do?
They transmit impulses from the CNS to the effectors
Multipolar
Where are most of the cell bodies for motor neurons?
In the CNS
Where are interneurons?
Between motor and sensory neurons
What do interneurons do?
Shuttle signals through CNS pathways
Where are interneurons mainly located?
In the CNS
What are 99% of the body’s neurons?
Interneurons
