Ch.11 Flashcards
What is in the CNS?
brain and spinal cord
What is in the PNS?
cranial nerves and spinal nerves
What do nerves do?
connect CNS to the rest of the body
What type of neuron carries information toward the CNS?
afferent
What type of neuron carries motor output away from the CNS and towards the PNS?
efferent
Where does integration mostly occur?
CNS
What is the role of the somatic sensory division?
carries general sensory stimuli from muscles, bones, joints, and the skin, as well as special sensory stimuli
Example is proprioception- where you are in space
What is the role of the visceral sensory division?
comes from organs
examples: what the Ph of the blood is, bladder is too full
What is the role of the somatic motor division?
carries stimuli to skeletal muscles
What is the role of the ANS?
carries stimuli to smooth muscle, cardiac muscle, and glands
What is the role of neuroglial cells?
protection and support of neurons
Why can’t neurons divide?
they do not have centrioles
What facilitates communication between 2 cells?
neurotransmitter
What do neurotransmitters bind onto?
target cells
Where do neurons receive info?
dendrites
Where is the cell body located?
in receptive region (aka soma)
What does the cell body do?
receives info from dendrites and integrates it (adds it together)
What does the axon hillock do?
decides if there is an action potential or not
If there is an action potential, where does it conduct?
conducts down axon from cell body
What are axon terminals called?
secretory region
What is a multipolar neuron?
most common neuron in CNS
Known as motor neuron in the PNS
known as motor (efferent) neurons or interneurons
What is a bipolar neuron?
sensory (afferent) neuron class
nose, eyes, special senses in the PNS
What is pseudopolar neuron?
sensory (afferent) neuron class
no dendrites
sensory neurons in PNS associated with touch, pain, and vibration sensations
What are ganglia?
collection of neuron cell bodies in the PNS
What do interneurons do?
integrate
are multipolar
What are cell bodies in the CNS called?
nuclei
What are the functions of astrocytes?
-anchor neurons and blood vessels
-regulate the extracellular environment
-help form the blood-brain barrier
-repair damaged tissue
What are the functions of oligodendrocytes?
myelinate certain axons in the CNS
What does myelin do?
wraps around axons to allow them to conduct electricity more effectively
What are the functions of microglial cells?
act as phagocytes
What are the functions of ependymal cells?
-line cavities
-cilia circulate fluid around the brain and spinal cord
-some secrete this fluid
-line hollows of brain and spinal cord
Where does the PNS get oxygen from?
capillaries
How is the PNS different from the CNS?
does not have a blood-brain barrier
What do schwann cells do?
myelinate certain axons in the PNS
wraps entire cell body around axon
What do satellite cells do?
surround and support cell bodies
make sure environment is perfect since there is no blood-brain barrier
they do less
Where is the last place myelination happens in the brain?
prefrontal cortex
What are the differences between oligodendrocytes and Schwann cells?
-Oligodendrocytes are in the CNS, have multiple axons, and this type of myelination largely occurs after birth
-Schwann cells are in the PNS, have a single axon, and myelination occurs in the womb
What do both oligodendrocytes and Schwann cells do?
-myeline insulates myelinated axons
-increases speed of action potentials
-makes nerves appear white
How does myelination occur?
-in segments called internodes
What are axon internodes called?
nodes of Ranvier
What do oligodendrocytes have?
multiple internodes that separate cell bodies
What happens when an axon is not attached to a cell body?
it disintegrates
What does the CNS do because it cannot regenerate?
replaces neurons with scar tissue
retrain remaining neurons to do different tasks (plasticity)
What do Schwann cells do in nerve regeneration?
form path for new growth
wrap new axon in myelin
can grow back, but not as well sometimes
What happens in wallerian degeneration?
axon distal to injury disintegrates
What is transmembrane potential?
charge between ECF and intercellular fluid
What does the transmembrane potential do?
move charged particles to produce electrical charge
What is resting potential?
negative number of neurons
-65 to -70 mV
What is a graded potential?
local potential change
Where does a local potential occur?
only on dendrites and cell body
does not travel far
What happens when an action potential travels down the axon?
it causes a release of neurotransmitter that then bind onto the next neuron
When do mechanically gated ion channels open?
stretch/deformation
Where are leak channels located?
Entire neuron
help establish resting membrane potential
always open
When do ligand-gated channels open?
open in response to binding of neurotransmitter
responsible for local potential changes in local receptive areas
When do voltage-gated channels open?
open when threshold is reached and opening causes action potential
Found abundantly in the axolemma
Where does an action potential start?
axon hillock
What is the threshold for opening voltage-gated channels?
-55 to -60 at axon hillock
What happens when voltage-gated channels open?
sodium rushes in
Where do potential changes come from?
dendrites and cell body
Why does depolarization happen?
up to +30 because voltage-gated channels open
What happens at +30?
sodium channels close and are inactive
potassium channels open
potential becomes negative
What is repolarization?
return to resting membrane potential (-70 mV)
What is hyperpolarization?
potassium is still leaking through channels at -70 mV
What is the absolute refractory period?
time when another action potential can’t be generated
What is the relative refractory period?
membrane potential is almost normal
very large stimulus can trigger action potential
What is continuous propagation?
unmyelinated axons along the entire axon
all portions of axon plasma membrane participate
What is saltatory propagation?
-myelinated axons jumps from one node of Ranvier to another
-faster and uses less energy than continuous propagation
-depolarization only occurs at nodes
What happens when an axon is smaller in diameter?
the action potential moves slower
What are type A fibers?
-myelinated and large diameter so has high speed
- somato sensation (where you are in space and motor fibers)
-responsible for position, balance and motor impulses
What are type B fibers?
-sensory (fine touch, vision and special senses)
-also responsible for ANS
-causes fast pain
What are type C fibers?
-unmyelinated, small diameter
-slow speed
-responsible for temperature, ANS, and slow pain information
What does a presynaptic neuron do?
releases neurotransmitter at synapse
What does a postsynaptic neuron do?
has receptors at synapse
How does a neurotransmitter travel?
from high to no concentration by diffusion across cleft
What happens at a chemical synapse?
-action potential causes depolarization which opens voltage-gated calcium channels
-calcium rushes in and causes synaptic vesicles to release neurotransmitters which diffuse and bind onto receptors
-if channel opens and ions move in out (local potential) it may or may not causes an action potential in the post synaptic neuron
Where are calcium channels found?
only at axon terminal
What causes an action potential?
threshold is reached at axon hillock
What are local potential changes AKA?
post synaptic potential
What is depolarization AKA?
excitatory
brings closer to threshold
What is hyperpolarization AKA?
inhibitory
moves away from threshold
What is temporal summation?
multiple action potentials from a single neuron, one after the other
What is spatial summation?
many neurons all at the same time produce excitatory post synaptic potential
How does an action potential fire?
ADD EPSP to IPSP at threshold
What makes sure that neurotransmitters don’t move to another neuron?
astrocytes
What is dopamine’s role?
plays a role in motor control and reward neurotransmitter
What is seratonin’s role?
involved in mood
major neurotransmitter in gut (gastric motility)
What is GABA?
major inhibitory neurotransmitter in CNS
What is NE/E?
more common neurotransmitter
released by neurons and bind onto post-synapse (adrenergic)
What synapse uses Ach?
NMJ
What is glumamate?
major excitatory neurotransmitter in CNS
What is substance P?
pain neurotransmitter
What does cholinergic mean?
synapses that use Ach
Where are ligand-gated ion channels located?
Dendrites and cell body
