Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Mine > WEEK 4: Nervous System - PHYSIOLOGY > Flashcards

WEEK 4: Nervous System - PHYSIOLOGY Flashcards

1
Q

What is a membrane potential?

A

= Difference in electrical charge from the inside to the outside of a neuron. Measured in volts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a current?

A

= When ion channels in the membrane open and the ions move across membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The production of a nerve impulse depends on which two basic features of a plasma membrane?

A

a) The existence of a resting membrane potential (difference in electrical charge when at rest; inside is 70 millivolts more negative than outside at rest)

b) Presence of specific types of ion channels (ions move through channel to cause action potential or electrical current)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the different types of ion channels?

A
  • leak channels
  • ligand-gated channels
  • mechanically gated channels
  • voltage-gated channels
  • sodium-potassium pump (active)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Ion channels; leak channels

A
  • Randomly alternate from being open and close
  • When its open, ions can move with the concentration gradient
  • We have sodium and potassium leak channels.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Leak channels; ligand-gated

A
  • Opens in responds to binding of ligand or chemical stimulus.
  • Can be neurotransmitter, hormone, ion binding to the channel.
  • i.e., in plasma membrane of muscle and the Acyl
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Leak channels; mechanically gated

A
  • open with mechanical stimulus i.e., vibrations like sound waves in ear, touch, or pressure on skin, stretching of muscle/organ (gastrointestinal).
  • Distorts channel from resting position and it opens.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Leak channels; voltage-gated

A
  • Open in response to change in voltage or membrane potential.
  • Sodium and potassium channels.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Leak channels; sodium voltage gated

A

CLOSED = no sodium can move through, but when activated by an impulse they can.

OPEN = sodium ions can move down across concentration gradient.

INATIVATED = closed and incapable of opening. Important for conducting electrical impulse in one direction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Leak channel: sodium-potassium pump

A
  • Moves it against the concentration gradient in an attempt to restore the resting membrane potential.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

List the steps of the Sodium-Potassium Pump

A

1) Three sodium ions bind to intracellular sites on the sodium-potassium pump

2) A phosphate group is transferred to the pump via the hydrolysis of ATP

3) The pump undergoes a conformational change, translocating sodium across the membrane.

4) The conformational change exposes two potassium binding sites on the extracellular surface of the pump.

5) The phosphate group is released which causes the pump to return to its original conformation.

6) This translocates the potassium across the membrane, completing the ion exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is an action potential?

A

= rapid depolarisation and repolarisation of the membrane potential.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Stage of resting membrane potential?

A

= voltage-gated NA and K channels closed. Little movement of ions. The membrane potential is sitting at -70 mV.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Stage of depolarisation?

A

= Voltage-gated NA channels open. Na moves into the cell. Graded potentials inch the membrane potential closer to the threshold.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Stage of repolarisation?

A

= voltage-gated NA channel inactivated. Voltage-gated K channel opens. K moves out of the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Stage of hyperpolarisation?

A

= voltage-gated NA channel closed. Voltage-gated K channel open. K continues to exit the cell.

17
Q

What is the difference between an action and graded potential?

A

ACTION = rapid depolarisation and repolarisation of the membrane potential.

  • What transmits information.

GRADED = slight deviation in membrane potential.

  • Depolarising graded (changes bring it closer to threshold)
  • Hyperpolarising (changes bring it further from threshold)
  • A few can be summed together and these generally cause action potential
18
Q

What are refractory periods?

A

= time during which an organ or a cell is incapable of repeating a particular action

= in a neuron it is the period of time following an action potential, during which another action potential can’t be generated

TWO KINDS = absolute and relative refractory

19
Q

What is an absolute refractory period?

A
  • Another action potential can’t occur no matter the stimulus.

= because the sodium channels are already open (can’t open further) or they’re inactivated. We need sodium coming in to trigger the action potential.

20
Q

What is a relative refractory period?

A
  • An action potential can be generated, but only by a larger than normal stimulus.
  • We have this so neurons aren’t continually stimulated.
  • Important so that an action potential propagates in one direction only.
21
Q

What is propagation?

A

PROPAGATION: the way an action potential moves along an axon. Can only propagate in one direction.

  • only moves in one direction due to the refractory period (it closes the channel for a certain amount of time)

TWO TYPES: continuous and saltatory

22
Q

What is continuous propagation?

A
  • One part stimulated, membrane researches threshold, the voltage-gated sodium channels open, sodium moves into the neuron and the influx of sodium causes the membrane potential to change in the next segment of the axon.
  • Occurs in unmyelinated axons and muscle.
  • Is relatively slow as each part of the axon needs to be stimulated.
23
Q

What is saltatory propagation?

A

SALTAR = leaping

  • Much faster as it can leap entire sections of axons.
  • One part of axon stimulated, reaches threshold, opens sodium-gated channels and sodium moves or skips across the entire section until it reaches the nodes of Ranvier.
24
Q

What are synapses and what are the two types?

A

SYNAPSE = area of transmission of an action potential. Either between two neurons or a neuron and a gland or muscle.

TWO TYPES = electrical and chemical

25
Q

What are electrical synapses?

A
  • Conducted directly through the plasma membrane of adjacent neurons through gap junctions.
  • These gap junctions contain tubular connexon’s that connect the cytosol through cells directly.
26
Q

What are the advantages of electrical synapses?

A

1) Because the signal transmission is through the direct gaps, it can occur very quickly.

2) They can also coordinate the transmission of signals very precisely i.e., in the intestines.

27
Q

What are chemical synapses?

A
  • No gap junctions or connexons
  • Completely separated
  • There is a synaptic cleft
  • A signal moves from an electrical signal, to a chemical signal as it diffuses across the interstitial fluid and then back into an electrical signal
28
Q

Explain the processes at a chemical synapse

A
  1. Action potential arrives at the axon terminal.
  2. Voltage-gated CA channels open.
  3. CA enters the cell.
  4. CA signal to vesicles.
  5. Vesicles move to the membrane.
  6. It binds to the membrane and releases the neurotransmitter by exocytosis.
  7. Neurotransmitters diffuse across the synaptic cleft and binds to the receptors.
29
Q

What is summation?

A

= the additive effect of several electrical impulses on a neuromuscular junction, the junction between a nerve cell and a muscle cell.

2 types:
- excitatory postsynaptic potentials
- inhibitory postsynaptic potentials

Mine (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions