9.1 Flashcards
Nervous System is divided into what 2 categories?
- Central Nervous System: Brain & spinal cord
- Peripheral Nervous System: Cranial nerves
The spinal cord contains how many neurons?
100 million
The brain contains how many neurons?
100 billion
Cranial Nerves are located in the…
Peripheral Nervous System
Spinal nerves differ by their…
location
How many pairs of spinal nerves are there?
31 pairs
What are small masses of neurons inside the PNS?
Ganglia
Enteric Plexus are located where?
Inside the GI tract
Sensory neurons
(afferent)
bring information into CNS (brain and spinal cord)
Interneurons
(association neurons)
Located within the CNS
Transmit impulses between neurons, such as between sensory and motor neurons
Motor neuron
(efferent)
conveys information away from the CNS through the PNS to effectors
What are specialized cells that monitor change in the internal and external environment?
Sensory Receptors
What are small masses of nervous tissue consisting of neuronal cell bodies that are located outside the brain and spinal cord.
Ganglia
What are extensive network of nerves that are located in the walls of the gastrointestinal tract that help regulate the digestive system.
Enteric Plexus
How many pairs of cranial nerves?
12
The nervous system carries out what tasks?
- sensing smell
- touch
- temperature
- producing speech
- remembering past events
- provides signals that control body movement
- regulates the operation of the internal organs
What are the 3 basic functions of the Nervous System?
- Sensory
- Integrative
- Motor
What function detect internal and external stimuli and carry information into brain and spinal cord via cranial and spinal nerves.
Sensory function
What function does information processing through perception, analyzing and storing information to help lead to appropriate responses?
Integrative function
What function may elicit motor response to muscles or glands via cranial and spinal nerves?
Motor function
Nervous tissue consists of what 2 types of cells?
- Neuron
- Neuroglia
What type of cells provide most of the unique functions of the nervous system?
Neurons
What are the 4 basic parts of a neuron?
- Axon
- Cell body
- Dendrites
- Axon terminals
What part of a Neuron contains the nucleus, cytoplasm with typical organelles?
Cell body
What part of a neuron is highly branched structures that carry impulses to the cell body?
Dendrites
What part of neuron conducts away from cell body toward another neuron, muscle or gland
Axon
What part of a neuron contains synaptic vesicles that can release neurotransmitters?
Axon terminals
What possess electrical excitability, ability to respond to stimulus and convert it into action potential
Neurons
Multipolar
(Most common type in brain and spinal cord)
Several dendrites
1 axon
Bipolar
(specialized)
1 dendrite
1 axon
Example: In retina of eye and inner ear
Unipolar
fused dendrite and axon
Sensory neurons of spinal nerves
What are the 3 Structural Classes of Neurons?
Unipolar
Bipolar
Multipolar
What are the 3 functional classes of neurons?
Sensory
Motor
Interneurons
Sensory
(afferent)
Convey impulses into CNS
(brain or spinal cord)
Motor
(Efferent)
Convey impulses from brain or spinal cord out through the PNS to effectors
Muscles & glands
Interneurons
(association neurons)
Located within the CNS
Transmit impulses between sensory and motor neurons
Neuroglia
- Support, nourish and protect neurons
- Critical for homeostasis of interstitial fluid around neurons
- smaller but more numerous than neurons
- Make up half the volume of the CNS
What are the 6 types of Neuroglia?
S-chwann cells
O-ligodendrocytes
S-atellite cells
A-strocytes
M-icroglia
E-pendymal cells
What neuroglia form the blood brain barrier?
Astrocytes
What neuroglia produce myelin in CNS?
Oligodendrocytes
What type of neuroglia protect CNS cells from disease?
Microglia
What type of neuroglia form CSF in the brain?
Ependymal cells
What type of neuroglia produce myelin around PNS neurons?
Schwann cells
What type of neuroglia support neurons in PNS ganglia?
Satellite cells
Most axons are surrounded by what?
myelin sheath
What insulates the axon and speeds up the nerve impulse?
myelin
Gaps in the myelin along the axon are called?
Nodes of Ranvier
What 2 diseases destroy myelin sheaths?
- Multiple sclerosis
- Tay-Sachs
What is a cluster or collection of cell bodies in PNS
Ganglion
What is a clusters of cell bodies in the CNS?
Nucleus
What is a bundle of axons in PNS called?
Nerve
What is a bundle of axons in CNS called?
Tract
What is primarily myelinated axons?
White matter
What is made up of cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia?
Gray matter
White matter surrounds gray matter in the
Spinal cord
Gray matter surrounds white matter in the
Brain
Regeneration of PNS neurons
Can be repaired if: cell body is intact and Schwann cells are functional
Form a regeneration tube and grow axons or dendrites if scar tissue does not fill the tube
Regeneration of CNS neurons
Very limited even if cell body is intact
Inhibited by neuroglia and by lack of fetal growth-stimulator cues
What are nerve impulses that allow for communication between neurons
Action potentials
How many pairs of cranial nerves are there?
12
What type of cells function to provide support, nourishment, and protection?
Neuroglia
Action potential requires what 2 things?
- resting membrane potential
- ion channels
What kind of channel allows ions to leak through?
Leakage channel
What kind of channels open and close on command?
Gate channels
How many mv is a membrane at rest?
-70mv
How many mv causes a membrane to reach its threshold?
-55
During this Voltage gated Na+ channels open as more Na+ enters cell, membrane potential rises and becomes positive
+30mv
Depolarizing phase
During this phase Voltage gated K+ channels open as more K+ leave cell, membrane potential is returned to resting value
-70mv
Repolarizing phase
What are the 2 types of conduction?
- Continuous
- Saltatory
Conduction in unmyelinated axons, where currents flow across the plasma membrane
Continuous conduction
Conduction in myelinated axons, Nodes of Ranvier allow impulses to “leap” from one node to the next
Saltatory conduction
What allows neurons to communicate with other neurons or effectors?
Synapses
Presynaptic neurons are…
sending neurons
Synaptic cleft is known as…
Space between neurons
Postsynaptic neurons are
Receiving neurons
Action potential arrives at the…
presynaptic neuron’s end bulb
Neurotransmitters
- Acetylcholine
- Glutamate
- Aspartate
- GABA
- Glycine
- Norepinephrine
- Dopamine
- Serotonin
- Endorphins
- Nitric Oxide
Consists of the brain and spinal cord
Source of thoughts, emotions, and memories
Central Nervous System
Includes all the nervous tissue outside the central nervous system
Include the cranial nerves, spinal nerves, ganglia and sensory nerves
Peripheral Nervous System
PNS can be subdivided into what 3 categories?
1) Somatic nervous system (SNS)
2) Autonomic nervous system (ANS)
3) Enteric nervous system (ENS)
1) Sensory neurons: Convey info from head, body wall, and limbs
and from receptors for special senses (vision, hearing, taste smell)
to CNS
2) Motor neurons: Conduct impulses from CNS to skeletal muscles
(voluntary control)
Somatic Nervous System
1) Sensory neurons: Convey information from receptors in the
visceral organs (stomach and lungs) to CNS
2) Motor neurons: Conduct impulses from CNS to smooth muscles, cardiac muscles, and glands (involuntary control)
Autonomic nervous system
Motor neurons in the ANS can be divided into 2 subcategories:
- Sympathetic: fight or flight
- Parasympathetic: rest and digest
AKA “Brain of the gut”
a) Sensory neurons: Monitor chemical changes in GI tract, stretching of walls
b) Motor neurons: Regulate contractions, acid secretion, endocrine cell secretions
c) Involuntary control
Enteric Nervous System
Autonomic neurons originate in the…?
Lateral gray horn
