Unit 5: Neurophysiology Flashcards
Functions of the nervous system and example
Receive info (receptors)
Visual, taste, touch, etc. sensing
Process info (integrators)
Decision making (feel rain, decide to go back for umbrella)
Initiate response (effectors)
Act on decision (muscle contracts to walk, muscle squeezes saliva from gland)
Define CNS and what it contains
Central Nervous System
Brain and spinal cord
Define PNS and what it contains
Peripheral Nervous System
Nerves and Ganglion
Define nerve
Bundle of neuronal axons surrounded by connective tissue
Define cranial nerve
Nerve branching from brain
Define spinal nerve
Nerve branching from spinal cord
Define ganglion
Collection of cell bodies in nerve
What are the 2 divisions of the PNS
Sensory (afferent)
Motor (efferent)
Define afferent division and what it entails
Sensory division of PNS
Visceral sensory - from within
Somatic sensory - from surface
Define efferent division and what it entails
Motor division of PNS
-Autonomic nervous system AKA visceral motor
Effectors include cardiac and smooth muscles, glands
Sympathetic - “fight or flight”
Parasympathetic - “rest and digest”
-Somatic motor = skeletal muscle
Neuro
nervous system
affer
go in
effer
exit
somatic
surface
visceral
deep within
glia
support
dendr
branch
astro
star
myelin
fatty insulator
What are the main cells in the nervous system
Neurons
Glia
What is the function of a neuron
“do-er”
responds to stimuli w/ electrical activity and by releasing neurotransmitters
Name a few neurotransmitters
Acetylcholine
Amino acids (glutamate, glycine, GABA)
Monoamines (epinephrine, norepinephrine, dopamine, serotonin)
What is the function of a glial cell
Supports neurons
What are the glial cells in the CNS
Oligodendrocytes
Astrocytes
Ependymal
Microglia
What are the glial cells in the PNS
Schwann
Satellite
Describe an oligodendrocyte
Forms myelin sheaths to insulate action potentials to many neuronal axons
Describe an astrocyte
Provide BBB (blood brain barrier) which protects CNS from pathogens, toxins, etc.
Define BBB
Blood brain barrier
Describe an ependymal cell
Lines cavities, produces CSF (cerebrospinal fluid), and moves CSF with cilia thru CNS
Describe a microglia
Specialized phagocyte WBC which cleans away debris and pathogens, typically in damaged areas
Define phagocyte
WBC “eater”
Describe a schwann cell
Insulates actions potentials with myelin fibers in PNS
(Similar to oligodendrocyte)
Describe a satellite cell
Surrounds neuron cell bodies in PNS
(similar to astrocytes)
What are the types of neurons (by function)
Sensory (afferent)
Interneurons (association)
Motor (efferent)
What do sensory (afferent) neurons do
send messages to CNS
What do interneurons do
“think”
process information
What do motor (efferent) neurons do
carry message out of CNS to the effector
What are the types of neurons (structural)
Multipolar
Bipolar
Unipolar
Describe a multipolar neuron
Neuron with 1 axon and many dendrites
(typically motor and interneurons)
Describe a bipolar neuron
Neuron with 1 axon and 1 dendrite
(typically sensory)
Describe a unipolar neuron
Neuron with 1 axon and no dendrites
(sensory in the PNS)
Define cell body
AKA soma
body which contains typical cell contents (nucleus, cytoplasm, DNA, etc.)
Define dendrite
Branching extension which receive messages
Define axon and its features
Carries electrochemical message (AKA action potential)
Axon terminal - end of axon
Synaptic vesicles - contain neurotransmitters
Define myelin sheath
Fatty covering of an axon (oligodendrocytes and schwann cells)
Define Nodes of Ranvier
Gaps between myelin sheaths where axon is exposed
What are the 5 characteristics of a neuron
Excitability
Conductivity
Secretion
Amitotic
Longevity
How is a neuron excitable
Responds to stimuli
How is a neuron conductive
Spreads action potential
What do neurons secrete
Neurotransmitters from the axon terminal
Define amitotic
Cell cannot regenerate
How do neurons have longevity
Can function for 100+ years (in good health)
Where is the trigger zone
The axon hillock and the area before the first myelin sheath
Define voltage
Measure of potential energy generated by separate charges
A larger difference between charges at 2 points means
Higher voltage
Define current
Flow of charged particles (ions)
Define resistance
Substance that hinders flow of current
Myelin sheaths act as
Insulators
Electrical potential is
the difference in concentration of charged particles (ions)
Resting membrane potential is _____ mV
~ 70 mV
_____ are typically outside the cell and ______ and _____ are inside
Na (sodium), K (potassium) and anions (negative ions)
What causes a local potential
Neuron stimulated and depolarizes from Na gates opening
Local potentials on occur along ______ and for _____ distances
Dendrites
short
Local potentials get ______ as they travel
Weaker
_______ potentials are reversible
Local
Where do action potentials begin
Trigger zone
Action potentials are ________
Irreversible
Define absolute refractory period
VG-Na gates are open so no stimulus can trigger another AP
Define relative refractory period
K gates are open so only a very strong stimulus can trigger another AP
Which type of Action Potential propagation is fastest?
Myelinated
Which type of Action Potential propagation moves the longest distance?
Myelinated
Describe action potential propagation along an unmyelinated axon
1 segment depolarizes and opens a VG-gates Na channel in the next, causing it to depolarize and the AP travels
“Domino effect”
Describe action potential propagation along a myelinated axon
“Saltatory Conduction”
AP “jumps” from node to bode because each node has many VG Na gates so more Na diffuses
Define Saltatory Conduction
Myelinated AP propagation
Define synapse
The connection between a neuron and its target
Define synaptic cleft
Gap between terminal and dendrites
Define presynaptic cell
First neuron which releases neurotransmitters into the synaptic cleft
Define postsynaptic cell
2nd cell which receives neurotransmitters in receptors
Describe enzymatic degradation
Enzymes destroy neurotransmitters in synaptic cleft
Describe reuptake
Neurotransmitters are removed from synaptic cleft and move back into presynaptic cell
Describe Excitatory Postsynaptic potential
ESPS
Postsynaptic cell is likely to fire
Describe Inhibitory Postsynaptic potential
ISPS
Postsynaptic cell less likely to fire
Define temporal summation
1 synapse receives many signals in a short time from one cell
Define spatial summation
1 synapse receives signals from many different cells
Define convergence
Many presynaptic cells talk to one postsynaptic cell
Define divergence
One presynaptic cell talks to many postsynaptic cells
Describe Multiple Sclerosis, its risk groups, and symptoms
Autoimmune disorder which causes demyelination (neuron signals can no longer travel far)
Mostly affects women, diagnosed between 20s-40s
Deteriorating muscle coordination and vision, numbness, and memory loss
Describe Fibromyalgia, its risk groups, and symptoms
Poorly understood disease
Mostly affects middle age women
Tender points, headaches, loss of sleep and memory, and numbness in hands and feet
Describe Amyotrophic Lateral Sclerosis (ALS), its risk groups, and symptoms
Disease where increased levels of neurotransmitter glutamate causes rapid motor neuron death
Mostly affects men over 40s
Deteriorating muscle control (speaking, writing, walking, etc.)
Describe Cerebral Palsy (CP), its risk groups, and symptoms
Congenital condition in which part of brain which controls muscle movement is developed improperly in womb
Less muscle control, slower to meet developmental milestones (smiling, crawling, walking, etc.)
Describe Spina Bifida
Defect in fetus where spinal cord covering is not formed properly in 1st trimester
Higher risk if mother has diabetes or is obese
Bowel and bladder control issues, can cause leg paralysis
Difference between CNS and PNS
CNS receives sensory info and integrates it
PNS sends sensory info to CNS and sends messages from CNS to the effectors
