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BIOL 186 > Animal Nervous System > Flashcards

Animal Nervous System Flashcards

1
Q

How do neurons transmit information across large distances?

A

Via electrical signals

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2
Q

What is membrane potential?

A

The difference in electrical charge (voltage) each cell has across the plasma membrane.

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3
Q

What is resting membrane potential?

A

The membrane potential of a neuron not sending signals.

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4
Q

What happens during resting membrane potential?

A

The K+ ion channel is the main channel (but not the only channel) that is open during rest. Neurons maintain a concentration gradient across membranes that is different for each ion. K+ diffuses out of the cell, down its concentration gradient thanks to chemical potential. Negative charges from I- builds along the inner membrane which creates an opposing electrical force.

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5
Q

What is equilibrium potential?

A

When the electrical and chemical forces are balanced.

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6
Q

What causes the membrane potential to change?

A

The flow of ions (the current).

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7
Q

What are the forces responsible for pushing and pulling K+ in/out of the cell?

A

Chemical potential pushes K+ out of the cell and electrical potential pulls K+ into the cell.

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8
Q

What is depolarization?

A

Changes to the membrane potential that cause the membrane to move above the neurons at resting potential, turning it more positve.

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9
Q

What is hyperpolarization?

A

Changes to the membrane potential that cause the membrane to move below the neurons at resting potential, turning it more negative.

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10
Q

What are graded potentials?

A

Changes in polarization where the magnitude of the change varies with the strength of stimulus (analogue signals). Graded signals cannot be propagated through great distances.

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11
Q

What is a hyperpolarized cell?

A

Positive ions move out of the cell (or negative ions move into the cell).

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12
Q

What is a depolarized cell?

A

Positive ions move into the cell, or negative ions move out of the cell.

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13
Q

What acts as the resistor in neurons?

A

Channels. Current through the channels depends on resistance.

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14
Q

What acts as the capacitor in neurons?

A

The phospholipid membrane.

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15
Q

What are dendrites and their function?

A

They are highly branched extensions that receive signals from other neurons. These signals are graded and funnels to the soma.

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16
Q

What is the soma?

A

The soma is the cell body of a neuron; location of neuron organelles and extends to the axon hillock.

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17
Q

What is the axon hillock and its function?

A

It is a cone-shaped structure that is the site of AP generation. Electrical current spreads and depolarizes neighboring regions of the axon membrane to repeat the AP cycle.

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18
Q

What is the axon and its function?

A

The axon is a long extension leading from the axon hillock that transmits APs.

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19
Q

What is the myelin sheathe?

A

The myelin sheathe insulates axons in vertebrates and causes AP speed to increase. They are made by glia: oligodendrocytes in the CNS and schwann cells the PNS.

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20
Q

What are nodes of Ranvier?

A

They are where APs are formed and located in gaps in the myelin sheathe where voltage-gated Na+ channels are found.

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21
Q

What are action potentials?

A

Created from a depolarization above a certain threshold that results in a massive change in the membrane voltage. They have a constant magnitude (all-or-none) and can transmit over a long distance. They come from voltage-gated ion (Na+/K+) channels that open/close when membrane potential passes distinct levels.

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22
Q

What are the five steps in the action potential-resting potential cycle?

A

1) Resting state. 2) Slow depolarization 3) Depolarization. 4) Repolarization. 5) Hyperpolarization & refractory period.

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23
Q

Describe the resting state.

A

At resting membrane potential (RMP) most gated channels are closed.

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24
Q

Describe the slow depolarization state.

A

Cell membrane potential slowly gets more positive and brings the cell to the threshold where voltage-gated Na+ channels are activated. The threshold phase.

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25
Describe the depolarization state.
A positive feedback loop makes a rapid increase in membrane potential to reach action potential. The rising phase.
26
Describe the repolarization state.
Voltage-gated Na+ channels turn off and slower voltage-gated K+ channels open, cause K+ to flow out of the cell and in the inside of the cell to become more negative. The falling phase.
27
Describe the hyperpolarization state.
The membrane potential wants to reach equilibrium and return to rest. Na+ channels are reset to recover from inactivation - the refractory period: K+ membrane permeability is higher at rest. Membrane potential undershoots RMD and cannot initiate a 2nd AP so the voltage-gated K+ channels close and RMP is restored (at equilibrium and rest).
28
What prevents APs from going backwards?
Inactivated Na+ channels behind the zone of depolarization.
29
What is the one direction APs travel towards (and what is the one exception?)
APs travel towards the synaptic terminals, but may back propagate to the soma/dendrites.
30
Speed of an AP increases with axon diameter. What helps with this? (In vertebrates)
The myelin sheathe.
31
What is saltatory conduction?
The process where APs in myelinated axons jump between nodes of Ranvier
32
What is the function of glia?
To nourish, support and regulate neurons.
33
What is the function of embryonic radial glia?
They form tracks for newly formed neurons to migrate upon.
34
What are astrocytes (type of glia) and their function?
They line capillaries in the CNS to form tight junctions, which act as a blood-brain barrier.
35
What is the function of the blood-brain barrier
Restrict the entrance of substances into the brain.
36
What is the nerve net, where is it found?
Series of nerve cells weakly connected by gap junctions in cnidarians.
37
What is encephalization and who exhibits it?
It is a clustering of sensory organs at the front of the body in bilaterally symmetrical animals.
38
What is the central nervous system made up of?
The brain and the longitudinal nerve cord (spinal cord in vertebrates).
39
What is the peripheral nervous system made of?
Neurons that carry information in and out of the CNS and ganglia in vertebrates.
40
What are the ganglia?
Segmentally arranged clusters of neurons.
41
What is the function of the spinal cord?
Conveys information to and from the brain and generates basic patterns of motion, produces reflexes independent of the brain.
42
What is a reflex?
The body's automatic response to stimulus.
43
Describe the hierarchy of the vertebrate NS.
1) PNS delivers into to the CNS by afferent neurons. 2) CNS by efferent neurons transfers information to the autonomic NS and the motor system. 3) Autonomic NS splits into sympathetic, parasympathetic and enteric.
44
What does the motor system control?
Voluntary movement and the control of skeletal muscle.
45
What does the autonomic nervous system control?
Generally involuntary action; control over smooth and cardiac muscles, glands.
46
Three systems of the autonomic nervous system?
Sympathetic, parasympathetic and enteric
47
What does the sympathetic NS control and what is it made up of?
'stern'. (quickens heart, stops bodily functions) Regulates arousal, energy generation, and fight-or-flight. Made of a paired chain of ganglia along the spinal column from the cervical to the coccygeal level.
48
What is the function of the parasympatheic NS?
'relax' (slows heart, relaxes body). Antagonistic effects on target organs and promotes calming and return to "rest and digest" functions.
49
What is the main function of the enteric NS?
It is incredible sophisticated and made up of 100 million neurons. It controls motility of the digestive tract, and secretion from the pancreases and gallbladder.
50
What are the three regionally specialized areas of the vertebrate brain?
The forebrain, midbrain and the hindbrain.
51
What is the main function of the forebrain?
The processing of olfactory information, regulating sleep and learning and all complex processes.
52
What is the main function of the midbrain?
It coordinates the routing of sensory input.
53
What is the main function of the hind brain?
It controls involuntary activities and coordinates motor activities.
54
What two regions make up the forebrain?
The Telencephalon and Diencephalon.
55
What region makes up the midbrain?
The Mesencephalon
56
What regions make up the hindbrain?
The Metencephalon and the Myelencephalon.
57
What is the Telencephalon made up of?
The cerebrum (cerebral cortex, white/grey matter, basal nuclei, cerebrospinal fluid).
58
What is the function of the corpus callosum?
The corpus callosum connects the right and left central hemispheres of the cerebrum.
59
What is the function of the cerebral cortex?
Perception and motion higher-order functions.
60
What is the function of basal nuclei and where are they located?
In white matter, they are clusters of nuclei used for motor planning.
61
What is grey matter made of?
Neuron cell bodies, dendrites and unmyelinated axons.
62
What is white matter made of?
Myelinated axon.
63
Where does the CNS develop from?
The hollow nerve cord from which the central canal of the spinal cord and the ventricles of the brain form.
64
Where is cerebrospinal fluid located and what is its function?
CSF is located in the canal and the four ventricles and it is filtered from blood to cushion the brain and spinal cord as well as give it nutrients and remove waste.
65
What are the four regions of the cerebrum?
Frontal, temporal, occipital, parietal
66
What is the function of the cerebrum?
It is the largest brain structure and is essential for awareness, language, cognition, memory and consciousness.
67
When is Broca's Area active?
During speech generation.
68
When is Wernickes Area active?
During speech hearing.
69
What is the Diencephalon made of?
The thalamus, pineal and pituitary gland and the hypothalamus.
70
What is the function of the Thalamus?
Relay centre for sensory information
71
What is the function of the hypothalamus?
Homeostasis and hormones, appetite and circadian rhythm.
72
What is circadian rhythm controlled by in the hypothalamus?
The suprachiasmatic nucleus (SCN) which functions as the pacemaker.
73
What is the function of the pineal gland?
Release melatonin; diurnal rhythm.
74
What is the function of the pituitary gland?
Regulates growth, metabolism, and reproduction through hormones.
75
What controls the pituitary gland?
The hypothalamus.
76
What makes up the Mesencephalon?
The midbrain (tectum and tegmentum)
77
What is the tectum made of and what is its function?
It is made up of the superior and inferior colliculi and is responsible for sensory motor integration.
78
What is the tegmentum made of?
The substantia nigra, the ventral tegmentum area (VTA), the periaqueductal gray (PAG), the red nucleus and the crus cerebi.
79
What is the function of the substantia nigra?
Initiating movement
80
What is the function of the Ventra Tegmentum Area (VTA)?
Reward (dopamine) and mesocortical projections
81
What is the function of the periaquiductal gray?
Gating pain signals
82
What is the function of the red nucleus?
Rhythmic movement and gait.
83
What is the function of the crus cerebri?
Descending motor efferents.
84
What makes up the metencephalon?
The pons and the cerebellum.
85
What makes up the pons?
The raphe nucleus and the iocus coerules
86
What is the function of the raphe nucleus in the pons?
Source of serotonin, controls respiration in the medulla, mood and sleep.
87
What is the function of the Iocus Coerules in the pons?
It is a source of norepinephrine, it is involved in arousal, alertness and attention.
88
What is the function of the cerebellum?
Motor coordination and learned motor tasks.
89
What makes up the mycencephalon?
The medulla oblongata
90
What is the function of the medula oblongata?
Respiration and heart rate.

BIOL 186 (17 decks)

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