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A+P - Test 3 > Chapter 11 > Flashcards

Chapter 11 Flashcards

1
Q

Hyperpolarization

A

When the membrane potential becomes more negative and is the movement of the membrane potential further away from zero

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2
Q

Hypopolarization

A

in neurochemical transmission of nerve impulses this is decreased polarity of the postsynaptic membrane, e.g. that caused by excitation from receptor stimulation.

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3
Q

repolarization

A

is the return of the ions to their previous resting state, which corresponds with relaxation of the myocardial muscle

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4
Q

Explain the two functions of nervous tissue

A

Irritability Conductivity

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5
Q

What is irritability function of neurons?

A

This is the ability to respond to a stimulus and convert it into a nerve impulses

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6
Q

What is conductivity function of neurons?

A

This is the ability to transmit the impulse to other neurons, muscles, or glands

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7
Q

Describe the three different kinds of neurons, functionally and structurally.

A

Sensory Neurons

Motor Neurons

Interneurons

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8
Q

Describe the three components of a neuron.

A

Neuron Cell body

Dendrites

Axons

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9
Q

Sensory Neurons

A

Conduct action potentials toward the CNS

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10
Q

Motor Neurons

A

Conduct action potentials away from CNS toward muscles or glands

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11
Q

Interneurons

A

conduct actions potentials from one neuron to another within the CNS

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12
Q

Neuron Cell Body

A

Has the nucleus-source of information, and protein synthesis - done in the nissl bodies

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13
Q

Structure of a Typical neuron

A
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14
Q

Dendrites

A

These are neuron processes that convey incoming messages (electrical signals) toward the cell body

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15
Q

Axon

A

These are neuron processes that generate nerve impulses and typically conduct them away from the cell body

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16
Q

Axon Hillock

A

This is the conelike region of the cell body

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17
Q

What are axon terminals?

A

This is where axons end
These contain vesicles with neurotransmitters
They are also separated from the next neuron by a gap

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18
Q

What are neurotransmitters?

A

These are chemicals that is contained in the terminals’ tiny vesicles

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19
Q

What is the synaptic cleft?

A

This is the gap between adjacent neurons

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20
Q

What is a synapse?

A

Theses are the functioning junctions between the nerves

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21
Q

What is myelin?

A

This is the whitish, fatty material (which has a waxy appearance) covering most long nerve fibers. This protects and insulates the fibers and increases the transmission rate of nerve impulses.

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22
Q

What are schwann cells?

A

These produce myelin sheaths in jelly-roll like fashion

23
Q

What are myelin sheaths?

A

This is a tight coil of wrapped membranes enclosing the axon.

24
Q

Describe the various kinds of neuroglia.

A

Astrocytes

Ependymal Cells

Mycroglia

Oligodendrocytes

Schwann Cells

Satellite Cells

25
Q

Astrocytes

A

star shaped

cytoplasmic extensions end in foot processes

extensive cytoskeleton

help regulate ECF composition of brain fluid

the blood-brain barrier

They have other functions

26
Q

Ependymal Cells

A

line the ventricles of the brain and the central canal of the cord

their free surfaces have cilia

the choroid plexes (secrete the cerebrospinal fluid)

27
Q

Microglia

A

become mobile and phagocytic in response to inflammation

28
Q

Oligodendrocytes

A
29
Q

Schwann cells

A

form myelin on peripheral neurons

30
Q

Satellite cells

A

provide support, nutrition and protection of cell bodies

31
Q

The electrical properties of neurons are due to:

A

Ion concentration differences across the cell membrane

Permeability characteristics of the membrane

32
Q

Differences in the intra- and extra-cellular concentrations are due to:

A

Sodium-Potassium pump

Permeability characteristics of the membrane

33
Q

Two ion channels

A

leak ion (nongated) channels

gated ion channels:

a. ligand-gated ion channels
b. voltage-gated ion channels
c. other-gated ion channels

34
Q

Leak ion channels

A

always open

responsible for membrane permeabiity in resting states

each channel is specific for a particular ion

permeability is based upon the number of channels

35
Q

Gated ion channels

A

normally closed

opened by specific signals

36
Q

Ligand-gated

A

opens (or closes) when ligand binds to the receptor portion of the extracellular component of the channel

common in nerve and muscle and glands

exist for Na+, K+, C++, Cl-

37
Q

Voltage-gated

A

open (and close) in response to small voltage changes across the membrane

when a cell is stimulated, the permeability of the membrane is changed because gated ion channels open (or close)

the movement of ions across the membrane changes the charg difference across the membrane. This causes the voltage-gated channels to open (or close)

Those specific for Na+ and K+ are most numerous in electrically excited tissue

C++ channels are important in smooth and cardiac muscle

38
Q

Establishing the resting membrane potential

A

All fluids are electrically neutral because the concentration of positively charged particles is equal to the concentration of negatively charged particles

There is a difference in charge across the membrane because of the uneven distribution of ions on either side of the membrane

Potential difference = the electrical charge difference across the membrane

39
Q

Resting membrane potential

A

the potential difference across the membrane in an unstimulated (resting) state

40
Q

the resting membrane potential is due to

A

permeability characteristics of the membrane

differences in concentrations of various ions between the ECF and ICF

41
Q

Effect of K+

A

increasing [K+]ECF causes hyperpolarization

decreasing [K+]ECF causes hypopolarization

42
Q

Effect of Na+

A

increasing [Na+]ECF causes hyperpolarization

decreasing [Na+]ECF causes hypopolarization

43
Q

Effect of Ca++

A

increasing [Ca++]ECF closes voltage-gated Na+ channels

decreasing [Ca++]ECF opens Na+ channels

44
Q

Effect of Cl-

A

increasing [Cl-]ECF causes hyperpolarization

decreasing [Cl-]ECF causes hypopolarization

45
Q

Intercellular and Extracellular Potentials

A
46
Q

What are graded potentials?

A

these are local disturbances in the resting membrane potential

they can result from:

  • chemical signals binding with receptors
  • changes in voltage across the membrane
  • mechanical stimulation
  • temperature changes
  • spontaneous opening of the ion channels

they can be hypo- or hyperpolarizing events

A hypopolarizing event can lead to a depolarizing event

The magnitude of graded potentials is dependent upon the strength of the stimulus

they can summate

47
Q

Describe an action potential. What are the roles of of Na+ and K+ on the action potential,?

A

Depolarizing events

Reversal of polarity occurs

Action potentials rapidly repolarizes

The depolarizing phase of an action potential is caused by increasing permeability to Na+

The repolarizing phase of an action potential is caused by increasing permability to K+

An impulse is a wave of depolarization passing along a neuron followed by a wave of depolarization

Continuous conduction occurs along a non-myelinated neuron

Saltatory conduction occurs along a myelinated neuron

Frequency of action potential is dependent upon the magnitude of the stimulus

48
Q

Relate the strength of a stimulus to the strength of an action potential.

A
49
Q

Describe a synapse. An essay question could be to describe synaptic transmission across a myoneural junction.

A

When an action potential reaches the synaptic knob of a presynaptic neuron, it triggers the opening of calcium voltage gated channels. The influx of calcium ions (Ca2+) leads to the release of neurotransmitter that are stored in the synaptic vesicles. The neurotransmitter crosses the synaptic cleft to bind to ligand gated channels on the postsynaptic cell. This creates an end plate potential which may or may not trigger an action potential in the postsynaptic cell.

50
Q

Synapse (image)

A
51
Q

Myoneural Junction, simple terms

A

The synaptic connection of the axon of a motor neuron with a muscle fiber.

52
Q

What are EPSP and IPSP?

A

EPSP = excitatory post-synaptic potential

IPSP = inhibitory postsynaptic potential

53
Q

Relate a synaptic transmitter and a synaptic transmitter receptor to EPSP and IPSP.

A

An inhibitory postsynaptic potential (IPSP) is a kind of synaptic potential that makes a postsynaptic neuron less likely to generate an action potential. The opposite of an inhibitory postsynaptic potential is an excitatory postsynaptic potential (EPSP), which is a synaptic potential that makes a postsynaptic neuron more likely to generate an action potential.

54
Q
A

A+P - Test 3 (7 decks)

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