Nervous system Flashcards
What is the main function of the nervous system
communication
What 3 things does the communication of the nervous system involve
- Collecting information 2. Processing/evaluating information 3. Initiating responses to information
What are the 2 major structural divisions of the nervous system
- Central Nervous system 2. Peripheral Nervous system
What 2 things is the central nervous system composed of
- Brain 2. Spinal cord
What 2 things is the peripheral nervous system composed of
- Nerves 2. Ganglia
What 2 types of nerves are found in the peripheral nervous system
- Cranial 2. Spinal
How many cranial nerves are there
12 pairs
How many spinal nerves are there
31 pairs
What are the 2 major functional divisions of the nervous system
- Sensory 2. Motor
Sensory
input
Motor
output
What 2 divisions make up the sensory nervous system
- Visceral Sensory 2. Somatic Sensory
Visceral Sensory
Input not consciously aware of
Somatic Input
Input we are generally more aware of
What are the 2 division of the motor nervous system
- Somatic Motor 2. Autonomic Motor
Somatic Motor
Controls skeletal muscle
Autonomic motor
Controls glands, cardiac muscle, and smooth muscle
What are the 2 divisions of the autonomic motor system
- Sympathetic (fight or flight) 2. Parasympathetic (Rest and Digest)
What are the 2 major cell types of nervous tissue
- Neurons 2. Neuroglia
Neurons
Excitable amitotic cells that initiate and transmit signals
Do neurons divide
no
neuroglia
non-excitable mitotic cells that support/protect neurons
Neuroglia are also known as
aka glial cells
What 4 types of neuroglia are found in the CNS
- Astrocytes 2. Microglia 3. Ependymal cells 4. Oligodendrocytes
What 2 types of neuroglia are found in the PNS
- Schwann cells 2. Satellite cells
Astrocytes help to form the
Blood-Brain barrier
Astrocytes anchor
neurons to capillaries
Astrocytes regulate
interstitial fluid composition
Astrocytes assist
neuronal development
Ependymal cells line cavities of
brain and spinal cord
Ependymal cells produce and circulate
cerebrospinal fluid
Ependymal cells regulate
nutrient waste exchange
Microglia replicate in
response to infection
Microglia engulf
infectious agents and remove debris
Oligodendrocytes wrap around and insulate
axons within the CNS to form myelin
Satellite cells arrange themselves
around cell body
Satellite cells regulate
nutrient-waste exchange
Schwann cells wrap around and insulate
axons of PNS to form a myelin sheath
What is the process of wrapping an axon with myelin
Myelination
What is the substance produced by glial cells that contains mostly lipids
Myelin
What is the function of myelin
Increases impulse transmission speed
What is impulse speed based on
presence or absence of myelin and thickness of axon
Signals move fastest along
thick myelinated axon
What are the 3 structural classifications of
neurons
- Unipolar neurons 2. Bipolar neurons 3. Multipolar neurons
Unipolar neurons have ______ process extending from the cell body/soma
1
Most sensory neurons are
unipolar neurons
Bipolar neurons have _____ processes extending from cell body/soma
2
What type of neurons are found in special sense organs
bipolar neurons
Multipolar neurons have _____ processes extending from cell body/soma
3+
All motor neurons and most interneurons are
Multipolar neurons
What is the most common type of neuron
Multipolar neurons
What are the 3 functional classifications of neurons
- Sensory neurons 2. Motor neurons 3. Interneurons
What is the most abundant type of functional neuron
Interneurons
Sensory neurons transmit impulses
Toward CNS
Motor neurons transmit impulses
Away from CNS
Interneurons
Receive, process, and store information (decide how the body responds to stimuli)
Neuron
Individual cells
Nerve
bundle of axons
What are the 3 functional divisions of nerves
- Sensory 2. Motor 3. Mixed
What are the 2 structural divisions of nerves
- cranial nerves 2. spinal nerves
Sensory nerves contain only
sensory axons
Motor nerves contain only
motor axons
Mixed nerves contain
sensory and motor axons
Synapse
A functional connection between two cells
What are the 2 types of synapses in the nervous system
- Electrical synapse 2. Chemical synapse
What is the less common type of synapse
Electrical synapse
Electrical synapse the signal
“hops” from cell to cell
Chemical synapse involve the
release and binding of neurotransmitters
What are the 3 components of a chemical synapse
- Presynaptic neuron 2. Postsynaptic neuron 3. Synaptic cleft
Presynaptic neuron
Releases neurotransmitters
Postsynaptic neuron
binds neurotransmitters
Synaptic cleft
Narrow fluid-filled gap between presynaptic and postsynaptic cells
Where are sodium potassium pumps found on a neuron
everywhere
What do sodium potassium pumps do
help establish resting membrane potential
Where are leak channels found on a neuron
everywhere
What do lead channels do
allow passive movement of ions
Where are chemically-gated channels found on a neuron
Receptive segment
What do chemically gated channels do
open in response to neurotransmitter binding
Where are voltage-gated channels found
axon and axon hillock
What do voltage-gated channels do
open in response to changes in electrical charge across the PM
When a neuron is at rest the chemically-gated channels are
closed
When a neuron is at rest the voltage-gated channels are
closed
In resting neurons ions are _______ distributed across the PM due to actions of pumps
unevenly
When neurons are at rest the cytosol/ intracellular fluid has a higher concentration of ______
K+/potassium
When neurons are at rest the interstitial fluid (outside the cell) has a higher concentration of ______
Na+/sodium
When neurons are at rest their membrane is
polarized
When neurons are at rest the cytosol is relatively ______ compared to the IF
negative
The resting membrane potential of neurons at rest is
-70
What opens the chemically-gated channels on neurons at rest
The binding of neurotransmitters
After neurotransmitters bind to the chemically gated ion channels ions
diffuse across the membrane changing its voltage
The voltage change of a resting neurons membrane generates a
graded potential in the postsynaptic neuron (postsynaptic potential)
Graded potential are ______ distance potentials
short
What causes graded potentials
movement of a small number of ions across PM
What determine the direction of a potential
what type of ion channels open
If Na+ channels open Na+ moves
into the cell and the inside becomes more positive
It is more likely that an action potential will occur when ______ ion channels open
Na+
If Cl- or K+ channels open Cl- moves ____ K+ moves _____
Cl- moves in and K+ moves out which causes the inside to become more negative
If the inside of the cell is less negative than -70 mV the cell is
depolarized
If the inside of the cell is more negative than -70 mV the cell is
hyper-polarized
What is the threshold stimulus of a neuron
-55
All or none law
Only if there are enough excitatory graded postsynaptic potentials and the threshold stimulus is met will an action potential be created
Action potential
temporary reversal in polarity exhibited by a neuron
What are action potentials also known as
A nerve impulse or nerve signal
Action potentials include what 2 things
- Depolarization 2. Repolarization
Depolarization
opening of voltage-gated Na+ channels along axon
Depolarization causes Na+ to move
into the cell
Repolarization
return to resting state due to opening of voltage-gated K+ channels
Repolarization causes k+ to move _______ followed by the action of ______
K+ to move out followed by the action of Na+/K+ pumps
Neuroglia in the CNS are found in
Brain and spinal cord tissue
Neuroglia in the PNS are found within
cranial and spinal nerve tissue
