Ch48 Flashcards
What must multicellular organisms be able to do?
communicate between cells
What have neurons evolved to do?
Sense stimuli and move rapidly
How would you describe neuronal signaling?
long distance, electrical, specific
How would you describe hormonal signaling?
short distance, chemical, broad
Synaptic Cleft
communication point between cells
Presynaptic Cell
cell sending the message
Postsynaptic Cell
cell receiving the message
Dendrited
branched part off the soma that recieves the message from other neurons
Axon
cell extension that transmits the action potential
Soma
central part of the neuron that contains organelles
Axon Hillock
where axon and cell body meet, and where the action potential is genarated
Myelin Sheath
insulates axon and helps in signal conduction
Synaptic Terminal
end arms of the axon that transmits signal to dendrites of another neuron
how many neurons do we have in human body?
1 trillion
What are the three types of neurons?
Sensory, Inter, Motor
ALS
Amyotrophic Lateral Sclerosis; neurodegenerative disease that cause paralysis
Glial Cells
supportive cells of various types and functions, they outnumber neurons 10-50.
Astrocytes
provide structural support, regulate movement of ions and neurotransmitter concentrations, aids in nearby blood vessel dilation
Oligodendrocytes
few dendrites, but helps with myelin sheath (acts like a schwann)
What forms the sheath around the PNS axons?
Schwann Cells
What forms the sheath around the CNS axons?
Oligodendrocytes
Are cells more - or + inside?
negative
What contents are most abundant inside the cell?
potassium and proteins
what is the value of resting potential?
-70mV
what is the value of threshold?
-55mV
What 3 things helps to maintain resting potential?
K+ Leak Channel, Na+/K+ Pump, negatively charged inside of cel
What is happening during depolarization?
sodium channels are opening, and potassium channels are closed, leading to a more positive charge
If threshold is reached, what happens?
Rapid Depolarization; Na+ channels open rapidly, and K+ start to open
What happens at the top of the graph?
Na+ becomes inactivated, and K+ finish opening
Step 4?
potassium rushes out of the cell causing it to become more negative
Step 5?
so much potassium rushes out that the charge becomes more negative than -70mV
how does Na+ become inactive?
Inactivation Loop
What does the undershoot serve as?
Refractory period
How does the charge get back to resting potential?
Potassium channels close, and the NaK pump stabilizes concentration
What is being transported in the Na/K pump?
3 sodium out and 2 K in
In what conditions is conduction faster?
wider axons, myelinated axons
What are the little sausage links?
Schwann Cells making the Myeling Sheath or Oligodendrocytes in CNS
What is saltatory conduction?
“jumping” behavior of the action potential from node of ranvier to node of ranvier
Describe electrical synapses
electrical current flow, ion flow, good for a rapid response
Why is electrical synapse good for a rapid response?
because it is direct depolarization
describe chemical synapse
neurotransmitter is released, slower response (not that slow)
Why is chemical slower than electrical?
It is an indirect depolarization, because the neurotransmitter has to stimulate the ion channels to then depolarize (ie there is an extra step)
In chemical communication, what happens prior to depolarization?
Action potential arrives at synaptic terminal, calcium influx into the cell through voltatge gated channels, calcium causes the release of neurotransmitters form vesicles, neurotransmitters then bind to ligand gated ion channels,
What are some examples of neurotransmitter fate?
degraded by enzymes, taken up by surrounding cells, diffuses out of synaptic celft.
What are the two types of postsynaptic potentials?
Excitatory (EPSPs) and Inhibitory (IPSPs)
What do EPSPs do?
depolarize membrane
What do IPSPs do?
hyperpolarize membrane
What are the types of summation?
temporal, spatial, EPSP vs IPSP
Describe subthreshold, no summation
an excitatory signal is released, but then counteracted by an inhibitory, and repeat. Never reaches threshold
Describe temporal summation
Excitatory signal, then inhibited, then exicited to threshold and AP happens
Describe spatial summation
two excitatory singals at once, causing a dramatic change to AP
Describe spatial summation of EPSP and IPSP
Excitatory, the inhibited, the Excitatory and inhibitory hit at the same time
Role of Acetylcholine (ACH)
excitatory in vertebrate PNS
Role of Glutamate
excitatory in vertebrate CNS
Role of GABA
inhibitory in vertebrate CNS
Role of Glycine
inhibitory in vertebrate CNS
What are some modulatory neurotransmitters?
Dopamine, Serotonin, Norepinephrine
Characteristics of vertebrate nervous systems?
high degree of cephalization, distinct CNS and PNS
Area of brain responsible for automatic processes?
Hindbrain
Portion of brain that is responsible for processing vision, smell, and hearing, touch, and motor function.
forebrain
What are the spaces inbetween schwann cells?
Nodes of Ranvier
