Chapter 48/49 Flashcards

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1
Q

Neurons

A

Nerve cells that transfer information within the body

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2
Q

Neurons have two types of signals to communicate:

A
  • Electrical signals (long-distance)

- Chemical signals (short-distance) AKA neurotransmitters

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3
Q

Most of a neuron’s organelles are in the _.

A

Cell body

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4
Q

Most neurons have _, highly branched extensions that receive signals from other neurons.

A

Dendrites

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5
Q

Axon

A

Typically a much longer extension that transmits signals to other cells

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6
Q

Synapse

A

A junction between the axon and another cell

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7
Q

Information is transmitted from a _ cell (a neuron) to a _ cell (a neuron, muscle, or gland cell).

A

Presynaptic; postsynaptic

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8
Q

Most neurons are nourished or insulated by cells called _ or _ cells.

A

Glia; glial

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9
Q

_ have numerous functions to nourish, support, and regulate neurons.

A

Glia (or glial cells)

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10
Q

Astrocytes

A

Form tight junctions in capillaries of the CNS, resulting in a blood-brain barrier which restricts the entry of most substances into the brain

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11
Q

Nervous systems process information in three steps:

A

1) Sensory input
2) Integration
3) Motor output

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12
Q

Sensors detect external stimuli and internal conditions and transmit information along _ neurons (step 1).

A

Sensory

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13
Q

Sensory information is sent to the brain or ganglia (in lower eukaryotes), where _ integrate the information (step 2).

A

Interneurons

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14
Q

Motor output leaves the brain or ganglia via _ neurons, which trigger muscle or gland activity (step 3).

A

Motor

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15
Q

Many animals have a complex nervous system that consists of:

A
  • A central nervous system (CNS)

- A peripheral nervous system (PNS)

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16
Q

Central nervous system (CNS)

A

Where integration takes place; this includes the brain and a nerve cord (spinal cord)

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17
Q

Peripheral nervous system (PNS)

A

Carries information into and out of the CNS

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18
Q

The neurons of the PNS, when bundles together, form _.

A

Nerves

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19
Q

Ion pumps and ion channels establish the _ of a neuron.

A

Resting potential

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20
Q

Every cell has a voltage (difference in electrical charge) across its plasma membrane called a _.

A

Membrane potential

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21
Q

The _ is the membrane potential of a neuron not sending signals.

A

Resting potential

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22
Q

Changes in membrane potential act as _, transmitting and processing information.

A

Signals

23
Q

In a mammalian neuron at resting potential, the concentration of K+ is highest _ the cell, while the concentration of Na+ is highest _ the cell.

A

Inside; outside

24
Q

_ pumps use the energy of ATP to maintain these K+ and Na+ gradients across the plasma membrane.

A

Sodium-potassium

25
Q

These concentration gradients represent chemical _ that gets converted to electrical potential when ion channels open.

A

Potential energy

26
Q

When gated K+ channels open, K+ diffuses out, making the inside of the cell more negative. This is _, an increase in magnitude of the membrane potential.

A

Hyperpolarization

27
Q

Opening other types of ion channels triggers a _, a reduction in the magnitude of the membrane potential.

A

Depolarization

28
Q

If a depolarization shifts the membrane potential sufficiently, it results in a massive change in membrane voltage called an _.

A

Action potential

29
Q

Action potential

A

Signal conducted by axons

30
Q

Action potentials have a _ magnitude, are all-or-none, and transmit signals over long distances.

A

Constant

31
Q

In vertebrates, axons are insulated by a _, which causes an action potential’s speed to increase.

A

Myelin sheath

32
Q

The speed of an action potential increases with the axon’s _.

A

Diameter

33
Q

Myelin sheaths are made by glia (oligodendrocytes in the CNS, and _ cells in the PNS).

A

Schwann

34
Q

Action potentials are formed only at _, gaps in the myelin sheath where voltage-gated Na+ channels are found.

A

Nodes of Ranvier

35
Q

Action potentials in myelinated axons _ between the nodes of Ranvier.

A

Jump

36
Q

At electrical synapses, the current flows from one neuron to another through _.

A

Gap junctions

37
Q

At _ synapses, a chemical neurotransmitter carries information between neurons.

A

Chemical

38
Q

Most synapses are _ synapses.

A

Chemical

39
Q

The synaptic terminal of one axon passes information across the synapse in the form of chemical messengers called _.

A

Neurotransmitters

40
Q

Acetylcholine (ACH)

A

A common neurotransmitter in animals

41
Q

Acetylcholine is involved in:

A
  • Muscle stimulation
  • Memory formation
  • Learning
42
Q

A number of _ disrupt acetylcholine neurotransmission (this leads to neurodegenerative diseases).

A

Toxins

43
Q

Acetylcholine is just one of more than _ known neurotransmitters.

A

100

44
Q

Neurotransmitters (other than acetylcholine) fall into four classes:

A
  • Amino acids
  • Biogenic amines
  • Neuropeptides
  • Gases
45
Q

The human brain contains about 100 billion neurons, organized into _ more complex than the most powerful supercomputers.

A

Circuits

46
Q

What do powerful imaging techniques allow researchers to do?

A

Monitor multiple areas of the brain while the subject performs various tasks

47
Q

Nervous systems consist of circuits of _ and supporting cells.

A

Neurons

48
Q

The simplest animals with nervous systems, the cnidarians, have neurons arranged in _.

A

Nerve nets

49
Q

Nerve net

A

A series of interconnected nerve cells

50
Q

More complex animals have _, in which the axons of multiple neurons are bundled together.

A

Nerves

51
Q

Nerves

A

Channel and organize information flow through the nervous system

52
Q

Bilaterally symmetrical animals exhibit _, the clustering of sensory organs at the front end of the body (head).

A

Cephalization

53
Q

The simplest cephalized animals, flatworms, have:

A
  • A central nervous system (CNS), with a brain and longitudinal nerve cords, and
  • A peripheral nervous system (PNS), with neurons carrying information into and out of the CNS