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Human Physiology 1 > Lecture 10 & 11 Questions > Flashcards

Lecture 10 & 11 Questions Flashcards

1
Q

What is a synapse.

A

connection b/t 2 neurons or a neuron & another cell that is specialized for the transfer of information

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2
Q

Do synapses always occur between neurons

A

pre is telling postsynaptic to do something
- specialized for the transfer of info

1) Functional: electrical & chemical synapse
2) Location on post-synaptic cell: axodendritic, axosomatic, axoaxonic

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3
Q

define EPSP, IPSP, grand sum.

A
  • a DEpolarizing synaptic potential is called an excitatory postsynaptic potential (EPSP)
  • a HYPERpolarizing synaptic potential is called an inhibitory postsynaptic potential (IPSP)
  • the GRAND SUM of EPSP & IPSP at the axon hillock will determine if the threshold potential is exceeded & an action potential is stimulated
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4
Q

Under physiological conditions, what neurotransmitters cause EPSP and IPSP?
What receptors are they acting thru? (VERY IMPORTANT to know this.)

A
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5
Q

Differential between electrical synapses and chemical synapses using the
following phrases: gap junction, connexin, connexon, syncytium, bidirectional,
unidirectional, polarization, synaptic delay, small molecules, common, rare,
synaptic cleft.

A
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6
Q

Draw and label a simple synapse.

A

d

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7
Q

Describe how neurotransmitter is released from a prestnaptic terminal.

A
  1. AP travels down axon
    - DEpolarization opens VG Ca2+ channels
    - this allows Ca2+ to enter PREsynaptic terminal

2.Ca2+ entry causes some synaptic vesicles to FUSE with PREsynaptic membrane & release their neurotransmitter contents into the synaptic cleft

  1. Neurotransmitter BINDS to POSTsynaptic receptors.
    - some receptors are ion channels, some are GPCR
    - the POSTsynaptic response depends on the type of receptor
  • TIME taken to DIFFUSE across & cause POSTsynaptic response is SYNAPTIC DELAY (about 2 ms)
  1. Neurotransmitter is REMOVED from the cleft
    (with one of 4 ways)
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8
Q

describe the difference between the fast EPSP and the SLOW EPSP using Ach as
the neurotransmitter: use the following terms: nicotinic receptor, muscarinic
receptor, receptor channel, ionotropic receptor, metabatropic receptor, GPCR,
Na+ ions, K+ ions, open channels, close channels, fast, slow, short duration, long
duration,

A

The FAST EPSP:
BINDing of ACh to RECEPTOR CHANNEL (via the NICOTINIC receptor) causes:
- OPENING of channel
- ENTRY of Na+ (& EXIT of a small amount of K+)

Movement of + charge INTO cell causes DEpolarization

The POSTsynaptic DEpolarization is EXCITATORY: = EPSP

FAST!!! (happens after a delay of MILLISECONDS)

The SLOW EPSP:
BINDing of ACh to GPCR (via MUSCARINIC receptor) causes:
- GENERATION of 2nd messengers
- ACTIVATION fo kinases
- PHOSPHORYLATION of proteins in the POSTsynaptic membrane
- some of the proteins that get phosphorylated are PHOSPHORYLATION GATED ION CHANNELS
- phosphorylation gates K+ leakage channels CLOSED

SLOW (happens after a delay of SECONDS)

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9
Q

why does closure of K+ leakage cause depolarization?

A

more + charges inside

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10
Q

how many types of adrenergic exist? Are they receptor channels or GPCR?

A

s

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11
Q

how many types of glutamate receptors exist? Differentiate them according to
type of receptor (GPCR or receptor channel), ions passed. Do these channels
allow Cl- to pass?

A

2 main types of glutamate receptors:

  • receptor channels (ionotropic)
    1. NMDA receptor
    2. AMPA receptor
  • GPCR (metabotropic glutamate receptors)
  • several subtypes
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12
Q

Are glutamate receptors excitatory or inhibitory? Explain based on ionic
selectivity.

A

main EXCITATORY neurotransmitter used throughout the CNS

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13
Q

how many types of GABA receptor? What type of synapse is an ionotropic
(=receptor channel) GABAergic synapse: excitatory or inhibitory? Explain based on ionic selectivity. Are these synapses fast or slow?

A

2 kinds of receptors:

  1. receptor channel: IONOtropic GABAa receptor
  2. GPCR: METAbotropic GABAb receptor
    - effect is variable, depending on channels phosphorylated…
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14
Q

list two other small molecule neurotransmitters

A

s

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15
Q

can peptides be neurotransmitters? What kind of receptors do they activate?
Where are they synthesized? Where are small molecule transmitters synthesized?

A

s

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16
Q

Are the effects of peptide transmitters usually short or long lasting?

A

s

17
Q

differentiate between axoaxonic, axosomatic, or axodendritic synapses.

A

s

18
Q

why are axoaxonic synapses quite powerful compared to axodendritic synapses.

A

Axoaxonic synapses are happening right on the trigger zone itself

  • most powerful compared to the axodendritic b/c the EPSP doesn’t have to travel any distance across the cell membrane - it’s already there
  • so it has a huge powerful effect on whether or not this postsynaptic cell is going to fire an AP
19
Q

what is presynaptic facilitation? Presynaptic inhibition?

A

Presynaptic FACILITATION: the synapse is EXCITED, DEpolarizes & allows MORE Ca2+ INTO the membrane, MORE AP is fired, MORE neurotransmitter RELEASED

Presynaptic INHIBITION: HYPERpolarizes the membrane, PREVENTS RELEASE of neurotransmitters

20
Q

explain the difference between temporal summation and spatial summation.

A

TEMPORAL summation occurs when 2 GPS from one PREsynaptic neuron occur CLOSE together in TIME

SPATIAL summation occurs when the currents from NEARLY SIMULTANEOUS GPS combine

21
Q

using diagrams, explain the difference between divergence and convergence. See
fig 8-25.

A

In a DIVERGENT pathway, ONE PREsynaptic neuron branches to affect a LARGER # of POSTsynaptic neurons

In a CONVERGENT pathway, MANY PREsynaptic neurons provide input to influence a SMALLER # of POSTsynaptic neurons

22
Q

explain the difference between the two types of axoaxonic synapses. Which stops
axonal conduction of AP? Which influences selected synapses?

A

s

23
Q

Hypocalcemia is a condition where plasma and extracellular Ca++
concentrations are too low. What effect might this have on synaptic trans?

A

s

24
Q

Explain the process of LTP

A

s

25
Q

Why is it (LTP) important?

A

s

26
Q

Who is Brenda Milner? Who is patient HM? Who is eric kandel?

A

s

27
Q 
If the ECF K+ concentration falls, what happens to the resting membrane
potential of the
cells? (Circle all that are correct.)
a. It decreases. f. It depolarizes.
b. It increases. g. It hyperpolarizes.
c. It doesn’t change. h. It repolarizes.
d. It becomes more negative. i. All cells fire action potentials.
e. It becomes less negative.
A

d ?

28
Q

What causes the repolarization phase of the action potential? (Circle one
best answer.)
a. Na+ being pumped out of the cell by the Na+-K+-ATPase
b. K+ being pumped into the cell by the Na+-K+-ATPase
c. Na+ leaving the cell through leak channels, trying to reach its equilibrium
potential
d. K+ entering the cell through leak channels, trying to reach its equilibrium
potential
e. both a and b
f. both c and d

A

?

29
Q 
Put the letters of all identifying characteristics in the spaces after the
two terms. You may
use characteristics more than once.
action potential
graded potential
a. all-or-none
b. has a threshold
c. amplitude diminishes with distance
d. amplitude depends on strength of stimulus
e. results from opening of Na+ channels
f. exhibits a refractory period
g. can be summed
h. faster in myelinated neurons
A

action potential: a, b, d?, e?, f, h

graded potential: b, c, e?, g

30
Q

For the following questions, circle all the answers that are correct:
The action potential of a neuron
a. is initiated by efflux of Na+.
b. is terminated by efflux of K+.
c. declines in amplitude as it moves along the axon.
d. results in a transient reversal of the concentration gradient of Na+ across the cell membrane.
e. can be blocked immediately if the Na+-K+-ATPase is inhibited by ouabain.

A

b

c?

31
Q

During the rising phase of the action potential

a. voltage-gated sodium channels are open.
b. there is an increase in the potassium permeability.
c. sodium moves down both a concentration and electrical gradient.
d. the cell’s membrane potential moves away from the equilibrium potential for potassium.
e. sodium movement is part of a feedforward process.

A

a?

32
Q

In some tissues, such as skeletal muscle, there are ion channels that allow
both Na+ and
K+ to pass when the channel is open. When these channels open, normally the
result is
net Na+ into the cell. Use your understanding of ion movement in response to
electrochemical
gradients to explain why Na+ entry into the cell exceeds K+ exit through these
nonspecific cation channels.

A

More sodium ions enter the cell than potassium ions leave because Na+ has a greater
driving force, moving down both concentration and electrical gradients, while K+ is
pushed out down its concentration gradient but drawn back into the cell by the electrical
gradient–.

Human Physiology 1 (32 decks)

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