Lecture 16 Flashcards
what are some neurons that send messages to the brain
Sensory or
afferent neurons
what are some neurons that send messages out of the brain
Motor neurons or
efferent neurons
What are the dendrites for
receiving signal, like a root
What is axon for
sending signal
what is terminal bulb of a neuron
releasing message to another cell
What is the potential different between the neuron and the external body
70 - 75 mv
What happens when the membrane potential is polarised
the intracellular will have negative potention (5+,10-)
where externally will be (15+, 10-)
What happens when the membrane potential is nerutral
intrecellular will be (10+, 10-), extracellular will be (10+, 10-)
What happens to the remainder of the fluid when membrane have serperate charges
electrically neutral
What is the extracellular Na+ concentration
150
What is the extracellular K+ concentration
5
What is the intracellular A- concentration
65
What is the intracellular K+ concentration
150
What is the intracellular Na+ concentration
15
What is the relative permeability of K+
25-30
What is the relative permeability of Na+
1
What is the relative permeability of A-
0
What happens at depolarization
the potential spikes up to +30mv
What happens at repolarization
Slowly drops back to -70mv or lower
What happens after hyperpolarization
recovering to the resting potential of -70mv
What happens when the voltage does not go above the threshold?
It will recover back to resting potential
What happens at slow depolarization
some Na+ channels open and allow Na+ to enter cell
What happens at neutral state
only K+ channels are open to transfer K+ in and out with different channels
What happens at depolarisation
all Na+ channels will open to allow Na+ to enter while K+ channels remain the same
What happens at repolarization
Na+ channel gate will close,, K+channels will constantly transfer K+ out and cell interior becomes negative
What happens after hyperpolarization
constant transfer f=of K+
What is refractory period
• Minimum time during which the neuron is
unresponsive to further stimulation
How many phases does refectory period have
2
What is phase 1 of refractory period
absolute refractory period
Voltage gated Na+ channels have become inactivated and
are incapable of being opened until resting membrane
potential is reached
What is phase 2 of refractory period
relative refractory period
Some but not all Na+ channels are responsive to further
stimulus and are capable of being partially opened
When does absolute refractory phase happen
depolarization and initial period of repolarization and after hyperpolarization
What does relative refractory period happen
all the time except for absolute period
can action potential propagation go both direction
no
Is the action potential propagation strength constant?
yes, Constant stimulus strength (self
perpetuating)
What is the difference between large and small axon
Larger axons propagate action
potentials at faster velocities
What is mylination
wrapping around a axon called a sheath
what does myelination do
increases the speed of action potential propagation
What is the unmyelinated part call
ranvier nodes
What does pacinian cause signal
signals change in pressure and vibration
What does pacinian send signal
the higher the magnitude of stimulus the more frequency the depolarization
How does intensity of stimulus relate to frequency of AP(action potential)
The intensity of stimulus is directly proportional to the frequency of AP. A stronger stimulus generates a greater receptor potential which is then transduced into more impulses of AP’s per second
What cell have action potential
a lot of cells
What is the electrochemical equilibrium on K+
-90mv
What is the electrochemical equilibrium on Na+
+60
What happen to K+ voltage gated channel during repolarisation
The voltage gated K+ channels close slowly causing hyperpolarisation of the membrane prior to returning to resting membrane potential by Na+ - K+ pump
How do Na+ go out of cell
Na+ K+ ATP pump
what is the amount Na+
- K+ pump exchange
3Na+ for 2K+
What is axon hillock for
it is the easier to trigger an action potential
Why does the the signal go only in one direction
due to the refractory period, all channels will already be opened
Why is larger axon faster
because there is less restriction
How is sensory information converted to a
language that the CNS can understand?
be accessory neurons. It will be converted to electrical signal which is then transferred
What is hair receptor for
hair movement and very gentle touch
What is Merkel’s disc:
light sustained touch
What is pacician corpuscle
vibrations and deep pressure
What is fuffini endings neurons
deep pressure
What is Meissner’s corpuscle
light, fluttering touch
What causes the sodium channels to open in pacinician recepter
the compression of the pressure pushes the sodium in
