Chapter 6: Nervous System Flashcards

1
Q

Neuronal structure from pathway of a neuronal impulse

A
  1. Dendrites
  2. Cell body (soma)
  3. Axon hillock: if number/strength of impulses arriving at axon hillock summate to a threshold stimulus an action potential is generated
  4. Axon
  5. Axon terminal
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2
Q

Mature neurons

A
  1. So specialized they dont divide
  2. When glucose is low, feed on ketone bodies and lactate
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3
Q

Na+/K+ and leak channels

A
  1. Na+/K+ channel: 3 Na+ out, 2 K+ in
  2. Leak channels: highly selective facilitated diffusion
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4
Q

The Nernst potential

A
  1. The direction of diffusion of any ion is determined by concentration gradient and electrical potential
  2. Is the potential that would exactly reverse dissuasion due to any ions concentration gradient
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5
Q

Action potential steps

A
  1. Membrane is at rest: voltage gated (VG) Na+/K+ channels closed
  2. Threshold stimulus causes VG Na+ channels to open: Na+ enter cell making it more positive=if it reaches threshold stimulus=local membrane depolarization=action potential
  3. Depolarization causes VG K+ channels to open when VG Na+ channels close
  4. K+ leave cell: repolarize… but VG K+ channels are slow to close so too many K+ leave=hyperpolarization
  5. Na+/K+ Channel reestablishes resting membrane once VG K+ channels close
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6
Q

Accommodation

A

action potential doesn’t occur due to threshold stimulus being surpassed very slowly

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7
Q

Refractory periods

A
  1. Absolute: no stimulus can create another AP
  2. Relative: after absolute….only abnormally large stimuli can cause AP
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8
Q

Electrical synapse

A
  1. Are the gap junctions between cells
  2. Less common than chemical, found in cardiac muscle and visceral smooth muscle
  3. Much faster due to no chemicals
  4. bidirectional
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9
Q

Chemical synapse

A
  1. When AP arrives at synapse, CA2+ VG channels open allowing Ca2+ into cell
  2. When Ca2+ enters presynaptic membrane, vesicles release neurotransmitter via exocytosis
  3. Neurotransmitters diffuse into synaptic cleft via Brownian motion
  4. Neurotransmitters attach to its receptors on postsynaptic cell which does its response
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10
Q

4 ways to lower concentration of neurotransmitter

A
  1. Simple diffusion
  2. Degradation by enzymes
  3. Reuptake via presynaptic cell via active transport
  4. Uptake by astrocytes
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11
Q

Summation

A
  1. Spatial: all at once
  2. Temporal: multiple right after another
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12
Q

EPSP vs IPSP

A
  1. EPSP: depolarizes & IPSP: hyperpolarization
  2. Both are ionotropic
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13
Q

Modulation

A
  1. Long term change in cell structure
  2. Accomplished through metabotropic
  3. Can be excitatory or inhibitory
    3a. Ach: excitatory
    3b. Dopamine: both
    3c. Histamine: excitatory
    3d. GABA: inhibit
    3e. Glutamate: excite
    3f. Norepinephrine/epinephrine: excite
    3g. Serotonin: inhibit
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14
Q

Neuroglia cells

A
  1. In CNS
    1a. Microglia: type of macrophage, clear waste
    1b. Astrocytes: give physical support to neurons and maintain minerals/nutrients
    1c. Oligodendrocytes: make myelin
    1d. Ependymal cells (nonglial): line cerebrospinal fluid
  2. In PNS
    2a. Satellite cells: support ganglia
    2b. Schwann cells: make myelin
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15
Q

Saltatory conduction

A
  1. Signal propagates from node of ranvier in saltatory conduction =speeds up signal
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16
Q

3 types of neurons

A
  1. Afferent (sensory): from environment to brain
    1a. Pseudounipolar (bipolar)
  2. Efferent (motor): brain to muscles/glands
  3. Interneurons: from neuron to neuron, is multipolar
17
Q

Nervous system overview

A
  1. Central: brain and spinal cord
  2. Peripheral
    2a. Somatic: sensory and motor
    2b. Autonomic: sensory and motor (parasympathetic and sympathetic)
18
Q

Somatic nervous system (SoNS)

A
  1. SoNS sensory neurons: located in dorsal root ganglia
  2. SoNS motor neurons: innervate only skeletal muscle, located in ventral hormones and use Ach
19
Q

Autonomic nervous system

A
  1. Sympathetic: fight/floght
  2. Parasympathetic: rest/digest
20
Q

Neurotransmitters of ANS

A
  1. Acetylcholine: receptors are cholinergic receptors
    1a. Nicotine receptors: excitatory
    1b. Muscarinic receptors: excitatory or inhibitory
  2. Epinephrine/norepinephine