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Biology > Chapter 4: The Nervous System > Flashcards

Chapter 4: The Nervous System Flashcards

1
Q

Define neurons.

A

specialized cells capable of transmitting electrical impulses and then translating those electrical impulses to chemical signals

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2
Q

Synaptic bouton

A
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3
Q

Axon hillock

A
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4
Q

Synapse vs synaptic cleft

A
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5
Q

What are nerves?

A

bundles of neurons in the peripheral nervous system

can be classified as sensory, motor, or mixed (both sensory and motor)

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6
Q

What are tracts?

A

bundles of axons within the central nervous system

only carry one type of information

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7
Q

What is a nuclei?

A

a collection of cell bodies in the CNS

a grouping of the cell bodies of neurons in the same tract

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8
Q

What is a ganglion?

A

a collection of cell bodies in the PNS

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9
Q

What are glial cells (neuroglia)?

A

cells within the nervous system which are not neurons but support and myelinate neurons

play both structural and supportive roles

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10
Q

State and describe 5 types of glial cells.

A

astrocytes: nourish neurons and form the blood-brain barrier

ependymal cells: line the ventricles of the brain and produce cerebrospinal fluid which acts as a shock absorber for the brain

microglia: phagocytic cells that ingest and break down waste products and pathogens in the CNS

oligodenrocytes: produce myelin around axons within the CNS

Schwann cells: produce myelin around axons within the PNS

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11
Q

The equilibrium potential of potassium

A
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12
Q

What does the resting membrane potential result from and which value is it?

A

the net effect of both sodium equilibrium potential (+60mV) and potassium equilibrium potential (-90mV) as these ions flow through sodium and potassium leak channels in an attempt to reach their electrical/chemical equilibrium

approximately -70mV for the average neuron (inside of the neuron is more negative than the exterior)

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13
Q

What is the purpose of the sodium/potassium ATPase?

A
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14
Q

Describe inhibitory inputs.

A

cause hyperpolarization (raise the membrane potential)

make the neuron more likely to fire an action potentials

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15
Q

Inhibitory input causes ______.

A

causes hyperpolarization (lowers the membrane potential)

makes the neuron less likely to fire an action potential

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16
Q

What is the threshold voltage to trigger an action potential?

A

the axon hillock must receive enough excitatory input to be depolarized to -55 to -40 mV

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17
Q

Describe summation.

A

the additive effect of multiple signals received by a given neuron, both excitatory and inhibitory

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18
Q

What are the 2 types of summation.

A

temporal and spatial

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19
Q

Temporal summation

A

one presynaptic neuron delivers multiple signals during a relatively short time period

20
Q

Spatial summation.

A

multiple presynaptic neurons deliver signals at the same time

21
Q

Absolute vs relative refractory periods.

A
22
Q

Impulse propagation.

A
23
Q

Saltatory conduction.

A
24
Q

Describe the event of the action potential.

A
25
Q

What is an effector?

A

a post-synaptic cell which is a part of a gland or muscle rather than another neuron

26
Q

Describe the events at the synapse once the action potential reaches the terminus.

A
  • voltage gated calcium channels open and calcium enters the cell
  • the calcium influx triggers fusion of the membrane-bound vesicles with the cell membrane at the synapse
  • the neurotransmitters are released into the synaptic cleft via exocytosis
  • the neurotransmitters diffuse across the cleft and bind to receptors on the postsynaptic membrane
27
Q

The distinction between excitatory and inhibitor signals is ultimately determined by the ___________.

A

postsynaptic neurotransmitter receptors

28
Q

Neurotransmitter receptors tend to be either _______ or _______.

A

ligand-gated ion channels

G protein-coupled receptors

29
Q

Differentiate ligand-gated ion channels and G protein-coupled receptors.

A

ligand-gated ion channels: result in the postsynaptic cell being either depolarized or hyperpolarized

G protein-coupled receptors: results in changes in cAMP levels or a calcium influx within the postsynaptic cell

30
Q

Describe the 3 main mechanisms by which neurotransmitters are removed from the synaptic cleft.

A
  • neurotransmitters can be broken down by enzymes (acetylcholine)
  • neurotransmitters can be brought back into the presynaptic neuron via reuptake carriers (ex. serotonin, dopamine, norepinephrine)
  • neurotransmitters can diffuse out of the synaptic cleft (ex. nitric oxide)
31
Q

List and describe the 3 general kinds of nerve cells in the nervous system.

A

sensory neurons (afferent neurons): transit sensory information from receptors to the spinal cord an brain

motor neurons (efferent neurons): transmit motor information from the brain and spinal cord to the muscles and glands

interneurons: found between other neurons; most numerous; located predominantly in the brain and spinal cord and are often linked to reflexive behaviour

32
Q

Supraspinal circuits.

A
33
Q

Describe the major divisions of the human nervous system.

A
34
Q

Name and describe the 2 types of matter found in the brain.

A

white matter: consists of axons encased in myelin sheaths

grey matter: consists of unmyelinated cell bodies and dendrites

note: in the brain, white matter lies deeper than grey matter; in the spinal cord, grey matter lies deeper than white matter

35
Q

Differentiate somatic and autonomic nervous systems.

A

the 2 divisions of the PNS

somatic = voluntary

autonomic = automatic

36
Q

Describe the somatic nervous system.

A

consists of sensory an motor neurons

sensory neurons transmit information thought afferent fibres

motor neurons transmit information thought efferent fibres

37
Q

Describe the autonomic nervous system.

A

manages the involuntary muscles associated with many internal organs and glands (independent of conscious control)

ex. regulates heartbeat, respiration, digestion, glandular sections, temperature control

38
Q

What are the 2 divisions of the autonomic nervous system?

A

parasympathetic: rest and digest
sympathetic: fight or flight

39
Q

What are the 4 divisions of the spinal cord?

A

cervical

thoracic

lumbar

sacral

40
Q

Describe the structure of the spinal cord.

A

contains the axons of motor and sensory neurons

sensory neurons:

  • bring information in from the periphery
  • enter on the dorsal (back) side of the spinal cord
  • cell bodies are found in the dorsal root ganglia

motor neurons

  • exit the spinal cord ventrally (front side)
41
Q

What is a key difference between the somatic and autonomic nervous systems.

A

somatic nervous system: motor neuron goes directly from spinal cord to muscle (1 neuron)

autonomic nervous system: a preganglionic neuron with its soma in the CNS travels to a postganglionic neuron in the PNS which then affects the target tissue (2 neurons)

42
Q

Describe the parasympathetic nervous system.

A

main goal is to conserve energy (rest and digest)

associated with resting and sleeping states

reduces heart rate and constricts bronchi

controlled by acetylcholine

vagus nerve

43
Q

Describe the sympathetic nervous system

A
  • increases heart rate
  • redistributes blood to muscles of locomotion
  • increases blood glucose concentration
  • relaxes bronchi
  • decreases digestion and peristalsis
  • dilates the eyes to maximize light intake
  • releases epinephrine into the bloodstream
44
Q

What are reflex arcs? (2)

A
  • the nerve pathway involved in a reflex reaction
  • use the ability of interneurons in the spinal cord to relay information to the source of a stimulus while simultaneously routing it to the brain
45
Q

What are the 2 types of reflex arcs?

A

monosynaptic and polysynaptic

46
Q

Explain monosynaptic reflex arcs and provide an example.

A

explanation

  • there is a single synapse between the sensory neuron that receives the stimulus and the motor neuron that responds to it
    example: knee-jerk reflex
  • when the patellar tendon is stretched, information travels up the sensory neuron to the spinal cord where it interfaces with the motor neuron that contracts the quadricep muscles
47
Q

Explain polysynaptic reflex arcs.

A

explain:

  • the sensory neuron may fire directly onto a motor neuron as well as interneurons that fire onto other motor neurons
    example: the withdrawal reflex; stepping on a nail
  • stepping on a nail will send sensory signals to pul the foot away from the nail
  • however, the muscles in the other leg must be stimulated to account for the lifted food and maintain balance
  • interneurons in the spinal cord connect the incoming sensory information to the motor neurons in the supporting limb

Biology (11 decks)

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