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DAT BIOLOGY > ch 11.4- nervous system > Flashcards

ch 11.4- nervous system Flashcards

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1
Q

neuron

A

the most basic unit of the nervous
system. It has three parts: the soma (cell body),
dendrites (extensions that receive signals), and the
axon (sends signals out).

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2
Q

axon hillock

A

Area where the axon is connected
to the cell body. Responsible for the summation
of graded potentials.

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3
Q

myelin sheath

A

Fatty insulation of the axon that
speeds up action potential propagation by
stopping ion exchange. The myelin sheath is formed by

oligodendrocytes (in the central
nervous system) and

Schwann cells (in the
peripheral nervous system). Thicker myelinated neurons fire signals faster.

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4
Q

nodes of ranvier

A

Gaps between myelin sheaths
where ion exchange occurs. Propagation of the
action potential occurs here, jumping from gap to
gap (node to node) in a process called saltatory
conduction.

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5
Q

steps of action potential

A
  1. At resting potential, the membrane potential of
    the neuron is around -70mV and is maintained by Na+/K+ ATPases, which pump three Na+ ions out and two K+
    ions in, powered by hydrolysis of one ATP. K +leak channels are also present and help maintain resting potential through passive K+ leakage
  2. When a stimulus causes threshold potential to
    be reached (around -55mV in neurons),
    voltage-gated Na+ channels open up, letting Na+ in, resulting in depolarization of the neuron. K+ channels are closed.
  3. Next is repolarization of the neuron due to the opening of voltage-gated K+ channels, letting K+ out, and the closing of Na channels. This causes the membrane potential to become less positive
    since positive ions are leaving. This is the absolute refractory period: no stimulus can cause an action potential.
  4. When the membrane potential becomes even more negative than the normal resting potential, this is known as hyperpolarization. This results in a relative refractory period being established, during which another action potential can be fired, but it requires a much stronger stimulus.
  5. The membrane potential returns to normal resting potential through the pumping of Na+ /K+ATPases and K +leak channels.
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6
Q

absolute refractory period

A

refers to the period after the initiation of the action potential during which another action potential cannot be fired no matter how powerful the stimulus is. It is due to the inactivation of voltage-gated Na+ channels after they open.

the period of depolarization and repolarization

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7
Q

realative refractory period

A

refers to the period
after the action potential fires during which a stronger
than normal stimulus could cause another action
potential to be fired. (after repolarization)

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8
Q

steps of synaptic transmission

A
  1. Action potential reaches the end of the
    presynaptic axon, causing voltage-gated
    calcium channels to open and letting Ca2+
    ions into the neuron.
  2. The Ca2+ ions cause synaptic vesicles to fuse and undergo exocytosis, releasing neurotransmitters into the synapse.
  3. The neurotransmitters (described in the table on the next page) bind to ligand-gated ion channels on the postsynaptic neuron, producing graded potentials (depolarizations or hyperpolarizations
    of the membrane).
  4. These graded potentials summate at the axon hillock and an action potential will fire if the summation of graded potentials is higher than the threshold potential of neurons.
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9
Q

EPSP

A

An excitatory postsynaptic potential (EPSP) is a
graded potential that depolarizes the membrane.

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10
Q

IPSP

A

An inhibitory postsynaptic potential (IPSP) is a
graded potential that hyperpolarizes the membrane.

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11
Q

glutamate

A

Main ENT of the central nervous system

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12
Q

dopamine

A

Involved in reward motivated behavior

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13
Q

epinephrine

A

● Postsynaptic NT of the sympathetic nervous system
● Constricts blood vessels and dilates bronchioles
● Increases blood flow to skeletal muscles
● Decreases blood flow to smooth muscles

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14
Q

norepinepherine

A

Postsynaptic NT of the sympathetic nervous system

Aids epinephrine in the “fight or flight” response

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15
Q

acetylcholine

A

● Most common NT in the muscular system
● Released from presynaptic motor neurons to signal muscle fibers
● Signals muscle fibers by binding to ligand-gated sodium channels

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16
Q

GABA

A

Gamma-aminobutyric
acid (GABA)

● Main INT of the central nervous system

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17
Q

glycine

A

● INT of the central nervous system

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18
Q

seritonin

A

● INT of the brain

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19
Q

frontal lobe

A

Known for higher function
processes such as decision making, problem
solving, attention and concentration.

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20
Q

temporal lobe

A

Known for speech and hearing.

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21
Q

occipital lobe

A

vision

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22
Q

parietal lobe

A

Known for spatial perception and
sensation.

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23
Q

cerebellum

A

located underneath the occipital
lobe and is responsible for the coordination of
movement.

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24
Q

brainstem

A

midbrain
pons
medulla oblongata
reticular formation

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25
Q

midbrain

A

Relays senses to other parts of brain.

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26
Q

pons

A

Relays messages between the forebrain,
cerebellum, and medulla.

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27
Q

medulla oblongata

A

Heart and breathing rate,
blood pressure, toxin sensing. Connects the
cerebrum/cerebellum to the spinal cord.

28
Q

reticular formation

A

Neurons throughout the
brainstem that are involved in cortical arousal,
and consciousness.

29
Q

during embryonic development, the brain can be divided into what areas

A

forebrain

midbrain

hindbrain

30
Q

forebrain of embryo

A

Telencephalon

Diencephalon

31
Q

telencephalon

A

gives rise to the cerebellum

32
Q

Diencephalon

A

gives rise to the Thalamus,
hypothalamus, and
pineal gland

33
Q

midbrain of embryo

A

develops into the mesencephalon

34
Q

mesencephalon

A

gives rise to the midbrain

35
Q

hindbrain in embryo

A

develops into the metencephalon and myencephalon

36
Q

metencephalon

A

gives rise to pons and cerebellum

37
Q

myencephalon

A

gives rise to the medulla oblongata

38
Q

what is the limbic system composed of

A

thalamus,
hypothalamus, hippocampus, and amygdala.

39
Q

limbic system

A

It is
responsible for emotion, memory, learning, and
motivation.

40
Q

thalamus

A

The “relay center” of the brain and is
located between the cerebrum and the midbrain.
Relays sensory and motor signals from the body to
the brain.

41
Q

hypothalamus

A

Regulates hormone secretion in
the body.

42
Q

hippocampus

A

Responsible for memory
consolidation.

43
Q

amygdala

A

Responsible for the emotional reaction
to certain scents.

44
Q

peripheral nervous system

A

The peripheral nervous system is divided into the
somatic nervous system (voluntary motor action and
sensory input) and the autonomic nervous system
(involuntary).

45
Q

autonomic nervous system

A

The autonomic nervous system can be further
divided into the sympathetic nervous system (fight or
flight) and the parasympathetic nervous system (rest
and digest).

46
Q

sympathetic NS

A

● Release of sugar into blood for energy.
● Increase in heart rate for oxygen delivery to the
brain and muscles.
● Vasodilation of skeletal blood vessels, and
vasoconstriction of the digestive system.
● Dilation of bronchi and bronchioles to allow more
oxygen into lungs.
● Dilation of the pupil to give the brain more visual
information.

47
Q

parasympathetic NS

A

● Relaxation of muscles.
● Decrease in heart rate.
● Maintenance of homeostasis.
● Increase in gastrointestinal activity.

THROUGH THE VAGUS NERVE

48
Q

ganglion

A

cluster of nerve bodies in
the peripheral nervous system. The autonomic
nervous system’s neurons are either preganglionic or
postganglionic. The preganglionic neuron comes
from the central nervous system and synapses with
the postganglionic neuron at the ganglion.

49
Q

sympathetic NS preganglionic nerves

A

Acetylcholine

50
Q

sympathetic NS postganglionic nerves

A

norepinephrine/ epinephrine

also stimulates the adrenal medulla to release NE/E into blood

51
Q

parasympathetic NS preganglionic nerves

A

acetylcholine

52
Q

parasympathetic NS postganglionic nerves

A

acetylcholine

53
Q

acetylcholinesterase

A

is an enzyme that is
responsible for the breakdown of acetylcholine via
hydrolysis.

54
Q

outer ear

A

takes in sound waves, and the
tympanic membrane transfers the sound from
outer ear to middle ear.

55
Q

middle ear

A

composed of three bony
ossicles. The ossicles transfer vibrations through
the middle ear and amplify the signal. The
vibrations get transmitted from the middle to the
inner ear.

56
Q

cochlea

A

uses fluid and hairs to convert the
mechanical signal into a neuronal signal, known as
transduction.

57
Q

semicircular canal

A

has fluid and hairs just
like the cochlea but gives information about the
person’s movement. It is also the reason we get
dizzy.

58
Q

cornea

A

Transparent; focuses light and protects
the eye.

59
Q

iris

A

controls size of pupil

60
Q

pupil

A

controls how much light enters the eye

61
Q

lesn

A

focuses image on the retina

62
Q

retina

A

Back of the eye that has photoreceptors
(rods + cones).
○ Rods function at low levels of light and are
responsible for low-light perception.
○ Cones function at high levels of light and are
responsible for color perception.

63
Q

fovea

A

Highest concentration of photoreceptors in
the retina. Responsible for high acuity vision.

64
Q

optic nerve

A

Bundle of axons that transmits visual
information to the brain.

65
Q

optic disc

A

The blind spot of the eye, where the
optic nerve passes through to reach the brain.

66
Q

sclera

A

Protective layer of tissue; the “white part”
of the eye.

DAT BIOLOGY (32 decks)

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