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NURS 6413 Advanced Physiology and Pathophysiology > Neuro physiology > Flashcards

Neuro physiology Flashcards

1
Q

What does the ANS regulate

A

Visceral functions such as:

arterial pressure
Gastrointestinal activity
Urinary bladder control
Sweating
Body temperature

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2
Q

What is the brain stem reticular substance?

A

Control center of the ANS, located along the tractus solitarius in the medulla, pons, and mesencephalon.

Controls arterial pressure, HR, glandular secretion, gastrointestinal peristalsis, urinary bladder contraction

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3
Q

The hypothalamus, a control center of the ANS, controls what?

A

Influences brain stem centers and autonomic functions

Regulates body temperature, salivation, gastrointestinal activity, bladder emptying

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4
Q

Effects of brain stem transection above midpontine level

A

Basal control of arterial pressure remains, but higher modulation is lost

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5
Q

Effect of brain stem transection below medulla

A

Arterial pressure drops significantly

Dead?

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6
Q

ANS is activated by which areas of the brain?

A

Brain stem and hypothalamus

Cerebral cortex (especially limbic cortex) can influence autonomic control by sending signals to lower centers

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7
Q

ANS operates subconscious control of ________ _________

A

Visceral organs

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8
Q

Sensory signals from visceral organs can trigger ______ _________ in autonomic ganglia, brain stem, or hypothalamus

A

Reflex responses

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9
Q

Subdivisions of the Autonomic nervous system

A

Sympathetic nervous system
Parasympathetic nervous system

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10
Q

What does SNS do?

A

Prepares body for “fight or flight” responses

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11
Q

What does parasympathetic nervous system do?

A

Controls “rest and digest” functions, promoting relaxation and conservation of energy

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12
Q

Two pathways of the SNS

A

Paravertebral sympathetic chain: interconnected ganglia BESIDE the spinal column

Pre vertebral ganglia: celiac, superior mesenterio, aorticorenal, inferior mesenteric, and hypogastric ganglia.

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13
Q

Sympathetic nerve origin

A

Nerve fibers originate between T1-L2 segments of spinal cord.

Enter the sympathetic chain before traveling to target organs

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14
Q

Sympathetic neuron types (2)

A

Preganglionic neurons: originate in intermediolateral horn of spinal cord -> go to ganglion

Postganglionic neurons: synapse in ganglia and travel to target organ

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15
Q

Pathways of preganglionic fibers (3)

A

Synapse immediately in ganglion they enter

Travel up/down the chain to synapse in another ganglion

Pass through the chain to synapse in a peripheral ganglion

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16
Q

Distribution of sympathetic fibers: T1 fibers

A

To the head

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17
Q

Distribution of sympathetic fibers: T2

A

To the neck

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18
Q

Distribution of sympathetic fibers: T3-T6

A

To the thorax

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19
Q

Distribution of sympathetic fibers: T7-T11

A

To the abdomen

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20
Q

Distribution of sympathetic fibers: T12- L2

A

To the legs

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21
Q

SNS:
Some preganglionic fibers travel directly to the adrenal medullae and stimulate modified neurons to release _________ & _________ into the bloodstream

A

Norepinephrine and epinephrine

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22
Q

SNS vs PNS
Preganglionic axons in PNS are ________ than in the SNS

A

Longer

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23
Q

All preganglionic neurons are ____________ in both SNS and PNS

A

Cholinergic

Release acetylcholine

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24
Q

Cholinergic receptors:

A

Muscarinic: found on all effector cells targeted by postganglionic cholinergic neurons. USES G PROTEINS

Nicotinic: located in autonomic ganglia at synapses between preganglionic and postganglionic neurons. LIGAND-GATED ION CHANNELS

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25
Q

Adrenergic receptors

A

Alpha receptors:
Alpha 1 and alpha 2 - linked to different G proteins

Beta receptors: beta 1, beta 2, beta 3
(Norepinephrine excites primarily alpha receptors, epinephrine excites alpha and beta)

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26
Q

Cholinergic neurotransmitter

A

Acetylcholine

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27
Q

Adrenergic neurotransmitter

A

Norepinephrine

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28
Q

PNS postganglionic neurons

A

Almost all fibers are cholinergic

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29
Q

SNS postganglionic neurons

A

Most fibers and Adrenergic

EXCEPT, fibers to sweat glands and some blood vessels are cholinergic

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30
Q

SNS stimulation:

Stimulation of _________ ___________ lasts longer than direct sympathetic stimulation

A

Adrenal medulla

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31
Q

Acetylcholine synthesis and breakdown

A

Produced in terminal endings and varicosities

Rapid breakdown by acetylcholinesterase into acetate and choline after release

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32
Q

Norepinephrine synthesis and breakdown

A

Begins in axon terminal and finishes in secretory vesicles

Conversion: tyrosine -> dopa -> dopamine -> norepinephrine-> epinephrine

Breakdown: reuptake into nerve endings (50-80%)
Diffusion into surrounding fluids
Enzyme destruction (monoamine oxidase)

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33
Q

ANS receptors: acetylcholine, norepinephrine, epinephrine binding to effector cells causes __________ ____________ in receptor protein

A

Conformational changes

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34
Q

Conformational changes in receptor proteins can cause excitation or inhibition through which 2 mechanisms

A

Ion channel changes: alters membrane permeability

Enzyme activation: activates/inactivates enzymes inside the cell (adenylyl ciclase -> cAMP)

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35
Q

Neurons: A typical neuron receives signals through synapses on the _________ and soma and sends output signals via a single axon

A

dendrites

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36
Q

Neurons: Signals pass in a __________ across synapses, from theaxonof one neuron to thedendritesof the subsequent neuron

A

one-way direction (unidirectional)

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37
Q

Neurons: Information is carried asnerve impulses(action potentials) through sequential neurons and impulses can be:
1.
2.
3.

A
  • Blocked between neurons
  • Transformed into repetitive impulses
  • Integrated with other impulses for complex patterns
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38
Q

Synapses

A

Junction between neurons, allows signal transfer and controls direction of signal flow (Some synapses transmit signals readily, while others offer resistance)

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39
Q

Synapses: Facilitatory vs. Inhibitory

A

Facilitatory signalscan enhance transmission
Inhibitory signalscan reduce or block transmission

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40
Q

What is an axon?

A

Extends from soma to subsequent nerves, carrying output signals

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41
Q

What is the soma?

A

Cell body of a neuron

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42
Q

Synaptic transmission: Calcium Channels & Neurotransmitter Release:

A

Depolarization opens voltage-gated calcium channels
Calcium influx triggers neurotransmitter release from vesicles

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43
Q

What are dendrites?

A

: Branch out from the soma with up to 200,000 presynaptic terminals

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44
Q

Synaptic transmission: What are presynaptic terminals?

A

Form synapses with other neurons
Can beexcitatory(stimulating) orinhibitory(blocking)

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45
Q

What is the difference between inotropic receptors and metabotropic receptors?

A

Ionotropic Receptors: Directly open ion channels
Metabotropic Receptors: Activate second messengers to alter cell functions

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46
Q

Second Messanger Systems: (G-Proteins)

A

Activation Process: G protein binds GTP, and separates into active components

Functions:
Open ion channels for prolonged effects
Activate cAMP or cGMP to alter cell activity
Activate enzymes for specific cellular functions
Trigger gene transcription, leading to long-term changes

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47
Q

Types of ion channels:

A

Cation Channels: Allow sodium (Na+), sometimes potassium (K+) or calcium (Ca2+) influx;excitatory

Anion Channels: Primarily allow chloride (Cl-) ions influx;inhibitory

Channel Selectivity: Determined by size, shape, and charge of the channel

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48
Q

Mechanism of Excitation:

A
  1. Opening Sodium Channels: Allows positive ions to enter, increasing membrane potential toward threshold
  2. Reduced Chloride or Potassium Conductance:
    Chloride: Less negative ions enter
    Potassium: Fewer positive ions leave
    Both actions make the inside of the cell more positive
  3. Metabolic Changes:
    Increase excitatory receptors or decrease inhibitory receptors on the membrane
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49
Q

Chemical Synapses:
(Predominant in the brain and CNS)

A

Mechanism: Presynaptic neuron releases neurotransmitters to excite, inhibit, or modify the postsynaptic neuron
One-Way Conduction: unidirectional supporting actions like sensation and motor control
Ex: Acetylcholine, norepinephrine, GABA, serotonin, glutamate

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50
Q

Mechanisms of Inhibition:

A
  1. Opening Chloride Channels: Negative ions flow in, making the cell interior more negative
  2. Increased Potassium Conductance: Positive ions exit, further increasing negativity inside
  3. Enzyme Activation: Alters cellular functions to boost inhibition and reduce excitation
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51
Q

Electrical Synapses:
(Cytoplasms of adjacent cells connected bygap junctions)

A

Mechanism: Gap junctions allow free movement of ions and, therefore, electrical charge
Bidirectional Transmission: Allows coordinated activity across interconnected neuron groups
Common in cardiac and smooth muscle

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52
Q

Small-Molecule, Rapidly Acting Transmitters:

A

Trigger acute responses like sensory and motor signals
Synthesized in thecytosol of presynaptic terminalsand stored inrecycled vesicles
Example:Acetylcholine (synthesized from acetyl CoA and choline, broken down by cholinesterase in the synaptic cleft)

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53
Q

RMP: ___mV

A

-65

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54
Q

Neuropeptides, Slowly Acting Transmitters:

A

Induce prolonged effects(e.g., receptor number changes, long-term synapse modifications)
Synthesized in thecell bodyand transported to nerve terminals
Released vesicles arenot recycled; neuropeptides are more potent but released in smaller quantities

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55
Q

Co-Transmission:

A

Some neurons store both types in the same or separate vesicles, releasing them simultaneously or in sequence
(Small-molecule and neuropetides)

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56
Q

Ion Concentrations:
(Na, K, Cl)

A

HighNa+outside, low inside
HighK+inside, low outside
Cl-high outside, low inside due to the negative membrane potential

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57
Q

Does EPSP raise or decrease membrane potential?

A

Na+ Influxraises membrane potential (e.g., -65 mV to -45 mV)
Threshold for action potential ~ -45 mV

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58
Q

Neuronal Excitation: Spatial Summation

A

Multiple presynaptic terminals fire simultaneously

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59
Q

Neuronal Excitation: Temporal Summation

A

Repeated firing of one terminal over time

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60
Q

Neuronal Excitation: Dendritic Transmission

A

Primarily by electronic conduction; no action potentials
Closer synapses to soma have a greater effect

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61
Q

GABA opens ______ channels in the terminal, reducing the excitatory effect by counteracting Na+ influx

A

Cl-

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62
Q

What are two ways for IPSP to occur?

A
  1. Chloride Channels: Open to allow Cl- influx, making the interior more negative
  2. Potassium Channels: Open for K+ efflux, also increasing intracellular negativity
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63
Q

Summation of IPSP and EPSP:

A

IPSPs counteract EPSPs; they can partially or fully cancel each other
If excitatory potential nears but doesn’t reach threshold, the neuron is facilitated, making it more responsive to future excitatory inputs

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64
Q

What is hyperpolarization

A

moving membrane potential further from threshold (towards -70 mV)

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65
Q

What is post synaptic fatigue?

A

Repetitive stimulation of excitatory synapses leads to a decrease in postsynaptic neuron firing over time

Mechanism: Depletion of neurotransmitter stores, receptor inactivation, and abnormal ion concentrations

Prevents overexcitation, such as in epileptic seizures

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66
Q

What is synaptic delay and how many milliseconds is it?

A

Time taken for neurotransmitter release, diffusion, receptor binding, and initiation of an action potential

Approximately 0.5 milliseconds

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67
Q

What are the three factors affecting neuronal excitability?

A
  1. pH levels:
    Alkalosis (7.8-8.0) increases excitability (may trigger seizures)
    Acidosis (<7.0)- decreases excitability (induce coma)
  2. O2 supply: Lack of oxygen for a few seconds leads to neuron in-excitability, causing unconsciousness
  3. Drugs: Stimulants (e.g., caffeine) lower excitation thresholds, increasing excitability
    Anesthetics raise excitation thresholds, decreasing excitability
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68
Q

Sensation: Sensory Information Pathway:

A

Sensory data from receptors is transmitted through peripheral nerves to the CNS

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69
Q

Sensation: Initiation of Nervous System Activities:

A

Most activities are triggered by sensory experiences
Sensory input can lead to immediate responses or be stored as memories for future reactions

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70
Q

Sensation: what five areas is information relayed to?

A
  1. Spinal Cord: Initial processing and reflexes
  2. Reticular Substance: Located in the medulla, pons, and midbrain
  3. Cerebellum: Coordinates fine motor control
  4. Thalamus: Acts as a sensory relay station
  5. Cerebral Cortex: Integrates sensory information for perception and decision-making
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71
Q

Motor function: Primary role of the nervous system is to control bodily functions by regulating:

A

Skeletal Muscle Contraction: Enables movement
Smooth Muscle Contraction: Manages internal organ function
Secretion of Substances: Activates exocrine and endocrine glands

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72
Q

Motor function: What are the effectors in the nervous system?

A

Muscles and glands are the effectors, carrying out responses based on nerve signals

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73
Q

What are the five levels of control for skeletal muscles?

A
  1. Spinal Cord: Manages reflexive, automatic responses
  2. Reticular Substance: Controls arousal and involuntary motor functions
  3. Basal Ganglia: Facilitates smooth voluntary movements
  4. Cerebellum: Refines coordination and balance
  5. Motor Cortex: Plans and initiates complex voluntary movements
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74
Q

What are the three main divisions of the CNS?

A

Spinal cord, subcortical (lower brain level), cortical (higher brain level)

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75
Q

What is the spinal cord level responsible for?

A

Functions independently for many reflexes and movements
Ex:
Walking movements, withdrawal reflexes(from painful stimuli), postural reflexes(supporting body against gravity), autonomic reflexes(control of blood vessels, digestion, and excretion)

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76
Q

What is the subcortical level responsible for?

A

Manages subconscious and autonomic functions

Includes medulla, pons, mesencephalon, hypothalamus, thalamus, cerebellum, and basal ganglia

Controlsemotional responses(e.g., anger, pleasure) andbasic life functions

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77
Q

What is the higher brain responsible for?

A

Acts as a largememory storehouse

Essential forthought processesand precise control over lower brain functions

Works inassociationwith lower centers, which initiate wakefulness and access to memories

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78
Q

What percent of sensory information is discarded as irrelevant or unimportant?

A

99%

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79
Q

What is integrative function?

A

The process of filtering, channeling, and directing sensory information to evoke targeted responses

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80
Q

Where is most sensory information stored for future use?

A

Cerebral cortex

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81
Q

What do mechanoreceptors detect?

A

Detectmechanical compressionorstretchingin tissues

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82
Q

What is synaptic facilitation?

A

Repeated signal transmissionstrengthens synapses, making them more capable of transmitting similar signals in the future

It enables memories to be recalled even without sensory input

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83
Q

What are thermoreceptors?

A

Sensetemperature changes, with distinct receptors for cold and warmth

84
Q

What are nociceptors?

A

Pain receptors that detectphysical or chemical damagein tissues

85
Q

What are electromagnetic receptors?

A

Respond to light on the retina, enabling vision

86
Q

What are chemoreceptors?

A

Detect chemical changes:
1. Taste (mouth)
2. Smell (nose)
3. O2 and CO2 levels (blood)
4. Osmolality and other chemical factors in body fluids

87
Q

Normal SNS and PNS tone, both systems are continuously active.
What does normal SNS and PNS tone do?

A

SNS: keeps systemic arterioles constricted to about 1/2 their maximum diameter. Can increase constriction with heightened stimulation or dilate with decreased stimulation.

PNS: background tone in GI tract
Cutting vagus nerve can lead to serious and prolonged gastric and intestinal atony

88
Q

Denervation hypersensitivity

A

Loss of tone occurs immediately, but intrinsic compensation occurs over time, returning the function of the organ to almost normal level. Tissue may become hypersensitive to neurotransmitter.

89
Q

Mass discharge of SNS

A

Fight or flight reaction:

Increased arterial BP
Increased blood flow to active muscles (decreased flow to non-essential organs)
Increased cellular metabolism
Increased blood glucose concentration
Increased glycolysis
Increased muscle strength
Increased blood coagulation

90
Q

Autonomic reflexes

A

Baroreceptors: stretch receptors in large vessels -> inhibit SNS & excite PNS

GI reflexes: food stimuli initiates signals to vagus, glossopharyngeal, salivatory nuclei -> secretion of gastric juices before food even enters mouth

Urinary bladder functions: stretch of bladder sends impulse to sacral cord -> contraction of bladder -> promotes relaxation of urinary sphincters

91
Q

Adrenal medulla when stimulated by sympathetic nerves releases….

A

Epinephrine and norepinephrine into blood stream

92
Q

Physiologic effects of norepinephrine

A

Vasoconstriction
Increased Heart activity
Inhibit GI activity
Dilates pupils

93
Q

Physiologic effects of epinephrine

A

Similar to norepinephrine but,

Greater cardiac stimulation d/t beta receptor activation
Weak vasoconstriction
Increases metabolic rate 5-10 times more than norepinephrine

94
Q

Why is the adrenal medulla stimulated in addition to direct innervation?

A

Safety mechanism, one mechanism compensates for the other if needed. Also stimulates structures not DIRECTLY innervated by sympathetic fibers.

95
Q

Cerebral blood flow

A

4 large arteries: 2 carotid, 2 vertebral
Merge to form the circle of Willis.

96
Q

Map the branching of arteries in the cerebrum

A

Arteries from the circle of Willis travels along brain surface -> plial arteries -> penetrating arterioles-> capillaries

97
Q

Virchow-Robin space

A

Space that separates the brain tissues from the penetrating vessels, an extension of the subarachnoid space.

98
Q

Normal Cerebral blood flow

A

Avg. 50-65ml/100g of brain tissue

Total 750-900ml/min for entire brain

99
Q

Key metabolic factors influencing cerebral blood flow

A

CO2 concentration
Hydrogen ion concentration
O2 concentration
Substances released from astrocytes

100
Q

Increased CO2 causes __________ in the brain.

A

Vasodilation

70% increase in arterial CO2 = double cerebral blood flow

CO2 -> carbonic acid -> dissociating into H+ ions -> vasodilation

101
Q

O2 utilization in the brain

A

3.5ml O2/100g of brain tissue/min

Insufficient O2 supply -> vasodilation to restore blood flow

102
Q

Astrocyte influence on brain regarding blood flow

A

Releases vasoactive metabolites that mediate local vasodilation in response to neuronal activity

103
Q

Cerebral microcirculation:

Capillary density

A

Greatest density where highest metabolic needs are greatest

104
Q

Capillary structure in brain

A

Capillaries are much less ‘leaky’ compared to other tissues

Supported by glial feet, providing physical support & preventing overstretching

105
Q

Brain capillary response to high BP

A

Arterioles leading to capillaries thicken in response to high BP, maintaining constriction to protect capillaries from high BP.

Breakdown of this protective mechanisms can lead to brain edema -> coma -> death

106
Q

Normal Autoregulation of cerebral blood flow

A

Autoregulated between 60-150 mmHg

107
Q

Hypertension effect on cerebral blood flow

A

Chronic HTN —> hypertrophic remodeling of cerebral blood vessels —> shifts auto regulatory curve to right

Partially protects against high BP but increases vulnerability to ischemia if pressures drop too rapidly (think 20% rule)

108
Q

Impairment of autoregulation of cerebral blood flow makes blood flow more dependent on _________

A

Arterial pressure

109
Q

Conditions that can disrupt autoregulation of cerebral blood flow?

A

Preeclampsia: can cause pressure-dependent increases in cerebral blood flow —> edema —> seizures

Old age, atherosclerosis, varios brain disorders: autoregulation impairment increases risk of brain injury 2/2 blood pressure fluctuations

110
Q

Entire cerebral vault capacity

A

1600 -1700ml

111
Q

Normal Cerebrospinal fluid (CSF) capacity

A

150ml

112
Q

Location of CSF in brain

A

Present in:

Ventricles
Cisterns
Subarachnoid space surrounding brain and spinal cord

113
Q

Pressure of the CSF is maintained at a ________ ______

A

Constant level

All chambers containing CSF are interconnected

114
Q

Function of CSF

A

Cushions the brain
Allows brain to float in the fluid

115
Q

CSF is formed at a rate of ___________ /day

A

500ml

116
Q

2/3 of CSF originates from the ________ _______ in the ventricles

A

Choroid plexus

(Ependymal cells)

117
Q

What is the choroid plexus?

A

Cauliflower-like growth of blood vessels covered by epithelial cells. Responsible for CSF creation. Active transport of Na+ drives fluid secretion into ventricles

118
Q

Osmotic/ionic Characteristics of CSF

A

Osmotic pressure = to plasma

Na concentration similar to plasma

Cl concentration 15% > than plasma

K concentration 40% < than plasma

Glucose 30% < than plasma

119
Q

CSF flow pathway

A

Lateral ventricles —> 3rd ventricle —> aqueduct of Sylvius ->
4th ventricle —> exits 4th ventricle through cisterna magna —> subarachnoid space

120
Q

What are arachnoidal villi?

A

Microscopic projections that allow CSF to flow into venous sinuses

121
Q

Normal pressure of CSF

A

Average: 130 mm of H2O (10 mm Hg)

Ranges from 65 - 195 mm of H2O

122
Q

CSF pressure is regulated by

A

Arachnoidal villa: function as valves for CSF flow

(CSF pressure must be 1.5 mmHg greater than venous blood pressure for flow to occur)

123
Q

Blood brain barrier

A

Barrier between blood vessels and brain parenchyma

Facilitates transport of certain hormones into the hypothalamus

124
Q

Blood brain barrier is highly permeable to

A

Glucose, hormones, CO2, O2, most lipid-solvable substances (alcohol)

125
Q

BBB is mostly impermeable to

A

Plasma proteins and most non-lipid soluble large organic molecules

126
Q

Blood-CSF barrier

A

Tight junctions between endothelial cells limit permeability
Similar permeability as BBB

127
Q

Resting brain metabolism

A

15% of total body metabolism, but only 2% of total body mass

Metabolism per unit mass: 7.5 times than of non-nervous tissues

128
Q

Most brain metabolism occurs in the _______

A

Neurons

(Pumping ions across membranes)
High activity can increase metabolism 100-150%

129
Q

Brain relies on continuous O2 supply, therefore it cannot participate in

A

Anaerobic metabolism

130
Q

Cessation in cerebral blood flow can cause unconsciousness within __________

A

5-10 seconds

131
Q

Energy source of the brain

A

Glucose

132
Q

Glucose transport into neurons is insulin _________

A

Independent

Diabetic pt’s with low BG —> mental function impairment/possible coma

133
Q

Modalities of Sensation

A

Types of sensory experiences (sound, touch, pain, sight etc.)

134
Q

Sensory nerve fibers only transmit _______ regardless of sensation type

A

Sensory nerve fibers only transmit impulses regardless of sensation type

135
Q

Each sensory receptor type is highly sensitive to a specific ______

A

Each sensory receptor type is highly sensitive to a specific stimulus

136
Q

Labeled Line Principle

The type of sensation perceived depends on
the ________ of the nerve fibers in the CNS

A

The type of sensation perceived depends on
the destination of the nerve fibers in the CNS

137
Q

________ in neural pathways ensures each fiber
transmits only one modality of sensation

A

Specificity in neural pathways ensures each fiber
Specificity

138
Q

All sensory stimuli induce a
change in the membrane
_________ ________ of
receptors, called
a _______ _________

A

All sensory stimuli induce a
change in the membrane
electrical potential of
receptors, called
a receptor potential

139
Q

Receptor potentials trigger
action potentials when …..

A

Receptor potentials trigger
action potentials when they
rise above the threshold

140
Q

List 4 mechanisms of sensory receptor excitation:

A
  1. Mechanical Deformation:
  2. Chemical Application
  3. Temperature Change
  4. Electromagnetic
    Radiation
141
Q

Mechanical Deformation:

A

Stretches membrane causing opening of ion channels

142
Q

Chemical Application:

A

Opens ion channels via chemical signals

143
Q

Temperature Change:

A

Alters membrane permeability

144
Q

Electromagnetic
Radiation:

A

Changes
membrane characteristics
(e.g., light on retinal
receptors)

145
Q

Higher stimulus
strength increases…..

A

receptor potential amplitude

146
Q

Higher receptor potential
results in
increased….

A

frequency of
action potential

147
Q

Degree of Adaptation varies
among receptors:
* Pacinian Corpuscles:

A

Pacinian Corpuscles: Rapid
adaptation within milliseconds

148
Q

Degree of Adaptation varies
among receptors:
* Baroreceptors:

A
  • Baroreceptors: Slow
    adaptation, taking up to 2 days
149
Q

List the 2 mechanisms of adaptation:

A

Viscoelastic Properties: Fluid
redistribution in structures like
Pacinian corpuscles reduces
receptor potential
Accommodation: Gradual
inactivation of Na+ channels in
the nerve fiber

150
Q

Type of Adaptation?

Transmit impulses
continuously as long as the
stimulus is present
* Examples: Muscle spindles,
pain receptors, baroreceptors,
chemoreceptors

A

Tonic (slowly-adapting) receptors

151
Q

Respond only to changes in
stimulus strength; cease firing
when stimulus remains
constant
* Examples: Semicircular canals
for detecting movement and
rate of change

A

Phasic (Rapidly Adapting)
Receptors:

152
Q

Large to medium myelinated fibers with high
conduction velocity

A

Type A Fibers:
* Subtypes: Aα, Aβ, Aγ, Aδ

153
Q

Small, unmyelinated fibers with low conduction velocity
* Constitute most sensory fibers in peripheral nerves and all
postganglionic autonomic fiber

A

Type C Fibers:

154
Q

Function and Conduction Velocity of Type A Fibers:

A

Fast conduction for functions requiring quick response
(e.g., motor control)

155
Q

Function and Conduction Velocity of Type C Fibers:

A

Slower conduction, used for signals that can tolerate
delay (e.g., chronic pain)

156
Q

List the 2 Mechanisms for Transmitting
Intensity:

A
  1. Spatial Summation:
  2. Temporal Summation:
157
Q

Spatial Summation

A
  • Involves activating increasing numbers of
    parallel fibers
  • Stronger signals recruit additional fibers,
    broadening the response area
  • Example: Pain fibers covering a large area of
    skin, with each fiber branching into many nerve
    endings
158
Q

Temporal Summation:

A

Temporal Summation:
* Increases the frequency of action
potentials within a single fiber
* Higher stimulus intensity results in more frequent
impulses along the same fiber

159
Q

The area within a pool influenced by an incoming fiber, with
the strongest influence on nearby neuron

A

Stimulatory field

160
Q

Signal spreads to an increasing number of neurons in
successive orders (e.g., corticospinal pathway)

A

Amplifying Divergence

161
Q

Signal splits and travels to different areas
(e.g., dorsal columns to cerebellum and thalamus)

A

Divergence into multiple tracts

162
Q

Multiple terminals from a single input fiber unite
on one neuron, enabling spatial summation

A

Single source convergence

163
Q

Inputs from multiple sources (e.g., peripheral
nerves, corticospinal tract) combine on a single neuron, allowing summation of
diverse signals

A

Multiple source convergence

164
Q

A single excitatory input ____ causes an action potential

A

A single excitatory input rarely causes an action potential - Summation of inputs (either simultaneously or in rapid succession)
is needed to excite the neuron

165
Q

Neurons are strongly
stimulated and reach threshold for activation

A

Discharge Zone (Excited/Liminal Zone)

166
Q

Neurons are
influenced but do not reach threshold; they are more excitable for
future signals

A

Facilitated Zone (Subthreshold/Subliminal Zone):

167
Q

Inhibitory input dampens neuron activity, with the
strongest inhibition at the center of the field

A

Inhibitory Zone

168
Q

Reciprocal Inhibition Circuit:
* Enables coordination of _________ muscle pairs
* Input fiber excites one pathway and activates an inhibitory
interneuron to inhibit the opposing pathway

A

Reciprocal Inhibition Circuit:
* Enables coordination of antagonistic muscle pairs
* Input fiber excites one pathway and activates an inhibitory
interneuron to inhibit the opposing pathway

169
Q
  • A prolonged output discharge from a neuron that continues after the initial
    signal ends
  • Duration ranges from milliseconds to several minutes, depending on the
    mechanism
A

Afterdischarge:

170
Q
  • Mechanism of Afterdischarge:
  • Postsynaptic Potential: Excitatory synapses create an electrical potential
    that can persist for milliseconds, especially with _____-acting
    neurotransmitters
  • Sustained potential causes the neuron to continue firing a _______ of
    impulses, even after the initial input signal has ceased
A

Mechanism of Afterdischarge:
* Postsynaptic Potential: Excitatory synapses create an electrical potential
that can persist for milliseconds, especially with long-acting
neurotransmitters
* Sustained potential causes the neuron to continue firing a train of
impulses, even after the initial input signal has ceased

171
Q

Significance of Afterdischarge:
* Allows a single brief input to produce a _______ effect, enabling sustained
output without continuous input
* Important for processes requiring extended responses, such as maintaining
_______ ______ or continuous signal output

A

Significance of Afterdischarge:
* Allows a single brief input to produce a prolonged effect, enabling sustained
output without continuous input
* Important for processes requiring extended responses, such as maintaining
muscle tone or continuous signal output

172
Q

Continuous Output:
Intrinsic Neuronal Discharge:
* Some neurons have a high enough membrane potential to emit
impulses __________
* Common in neurons of the ________; output rate can be
adjusted by excitatory or inhibitory inputs

A

Continuous Output:
Intrinsic Neuronal Discharge:
* Some neurons have a high enough membrane potential to emit
impulses continuously
* Common in neurons of the cerebellum; output rate can be
adjusted by excitatory or inhibitory inputs

173
Q

Reverberatory Circuits:
* Self-sustaining reverberating circuits generate ________
impulses
* ______ signals can increase or decrease the output; inhibition can
___________ the signal

A

Reverberatory Circuits:
* Self-sustaining reverberating circuits generate continuous
impulses
* Input signals can increase or decrease the output; inhibition can
extinguish the signal

174
Q

Rhythmical Output:
* Rhythmical Signals: Produced by _________ circuits that create
________ patterns

A

Rhythmical Output:
* Rhythmical Signals: Produced by reverberating circuits that create
cyclical patterns
* Examples: Respiratory rhythm (medulla and pons), heart rate,
vascular tone, and digestive activity

175
Q

Give an example of a reverberating circuit and its location

A
  • Examples: Respiratory rhythm (medulla and pons), heart rate,
    vascular tone, and digestive activity
176
Q

Inhibitory Feedback Circuits:
* Feedback from pathway ______ inhibits excitatory neurons at the input or intermediate stages.
* Common in ________ pathways to prevent ________

A

Inhibitory Feedback Circuits:
* Feedback from pathway termini inhibits excitatory neurons at the input or intermediate stages.
* Common in sensory pathways to prevent overexcitation

177
Q

Inhibitory Neuronal Pools:
* Certain pools, like the _______ ________, exert broad inhibitory control, stabilizing functions such as
muscle control

A

Inhibitory Neuronal Pools:
* Certain pools, like the basal ganglia, exert broad inhibitory control, stabilizing functions such as
muscle control

178
Q

Synaptic Fatigue:
* Progressive Weakening: Synaptic transmission decreases with _________ excitation
* Moderates the sensitivity of ______ pathways (fatigue) and increases sensitivity in _______
pathways (recovery)

A

Synaptic Fatigue:
* Progressive Weakening: Synaptic transmission decreases with prolonged excitation
* Moderates the sensitivity of overused pathways (fatigue) and increases sensitivity in underused
pathways (recovery)

179
Q

Long-term Regulation:
* Downregulation of receptors with ________
* Upregulation of receptors with _________

A

Long-term Regulation:
* Downregulation of receptors with overactivity
* Upregulation of receptors with underactivity

180
Q

Physiological Types of Somatic Senses:
* Mechanoreceptive Senses: Includes ______ and _______ senses; Activated by ________ displacement in body tissues
* Thermoreceptive Senses: Detects ______ and _____
* Pain Sense: Triggered by factors that cause _____ _______

A

Physiological Types of Somatic Senses:
* Mechanoreceptive Senses: Includes tactile and position senses; Activated by mechanical displacement in body tissues
* Thermoreceptive Senses: Detects heat and cold
* Pain Sense: Triggered by factors that cause tissue damage

181
Q

Other Classifications of Senses:
* Exteroreceptive Sensations: From the body ______
* Proprioceptive Sensations: Related to body’s ______ state (e.g.,
position, muscle tension, balance)
* Visceral Sensations: Arising from _____ ________ (viscera)
* Deep Sensations: From ____ ______, including fasciae, muscles, and
bones; includes deep pressure, pain, and vibration

A

Other Classifications of Senses:
* Exteroreceptive Sensations: From the body surface
* Proprioceptive Sensations: Related to body’s physical state (e.g.,
position, muscle tension, balance)
* Visceral Sensations: Arising from _____ ________ (viscera)
* Deep Sensations: From deep tissues, including fasciae, muscles, and
bones; includes deep pressure, pain, and vibration

182
Q
  • Touch: Detected by _____ receptors near the ____ surface
  • Pressure: Result of ________ in deeper tissues
  • Vibration: Detected through rapidly ______ signals
A
  • Touch: Detected by tactile receptors near the **skin **surface
  • Pressure: Result of deformation in deeper tissues
  • Vibration: Detected through rapidly repetitive signals
183
Q

Types of Tactile Receptors:
* Free Nerve Endings: Found throughout skin; detect _____ and _______

  • Meissner’s Corpuscles: ______ sensitive, _____-adapting; abundant in fingertips and lips
  • Merkel’s Discs: _______-adapting, grouped in touch domes; localize _____ and _____
  • Hair End-Organs: Detect ______ and initial ______; adapt _____
  • Ruffini’s Endings: ____-adapting; detect _______ deformation, found in skin and joint
    capsules
  • Pacinian Corpuscles: _____-adapting; detect _____ and ______ changes in pressure
A

Types of Tactile Receptors:
* Free Nerve Endings: Found throughout skin; detect touch and pressure

  • Meissner’s Corpuscles: Highly sensitive, rapid-adapting; abundant in fingertips and lips
  • Merkel’s Discs: Slow-adapting, grouped in touch domes; localize touch and texture
  • Hair End-Organs: Detect movement and initial contact; adapt quickly
  • Ruffini’s Endings: Slow-adapting; detect continuous deformation, found in skin and joint
    capsules
  • Pacinian Corpuscles:** Rapid-adapting**; detect **vibration ** and quick changes in pressure
184
Q

Nerve Fiber Types:
* Type Aβ: _______ transmission (30-70 m/s), used by most ________ receptors
* Type Aδ and Type C: _______ transmission for _____ nerve endings; carry ____ critical signals

A

Nerve Fiber Types:
* Type Aβ: Rapid transmission (30-70 m/s), used by most specialized receptors
* Type Aδ and Type C: Slower transmission for free nerve endings; carry less critical signals

185
Q

T or F?
All tactile receptors can detect vibration

A

TRUE:
Each receptor type responds to different vibration frequencies based on its
adaptation rate and sensitivity

186
Q

Tickle and Itch sensation:
* Detected by ________ adapting ___________ ____ nerve endings in the
superficial skin layers
* Exclusively found in the ____ and respond primarily to light stimuli on the skin
surface

A

Tickle and Itch sensation:
* Detected by rapidly adapting mechanoreceptive free nerve endings in the
superficial skin layers
* Exclusively found in the skin and respond primarily to light stimuli on the skin
surface

187
Q

Itch and Tickle Transmission: Carried by _____, _________ type ____ fibers, similar to those
that transmit slow, aching pain

A

Itch and Tickle Transmission: Carried by small, unmyelinated type C fibers, similar to those
that transmit slow, aching pain

188
Q

Types of Position Senses:
* Static Position Sense:
* _________ perception of body orientation and position of body parts
relative to each other
* Dynamic Position Sense (Kinesthesia):
* Awareness of the ____ and _______ of movement

A

Types of Position Senses:
* Static Position Sense: Conscious perception of body orientation and position of body parts
relative to each other
Dynamic Position Sense (Kinesthesia): Awareness of the speed and direction of movement

189
Q

Mechanisms of Position Sensing:
* ______ Angulation: Determined by multiple receptors that provide
information on the angle and movement of joints

A

Joint

190
Q

Proprioceptive Receptor Types:
* Muscle Spindles: Key for sensing ______ joint angles and changes
in _______ ________
* Deep Receptors (e.g., Pacinian Corpuscles, Ruffini’s Endings):
Important at ______ joint angles, detect stretch in ligaments and deep
tissues
* Golgi Tendon-Like Receptors: Provide information on _______ ________
tension

A

Proprioceptive Receptor Types:
* Muscle Spindles: Key for sensing midrange joint angles and changes
in muscle stretch
* Deep Receptors (e.g., Pacinian Corpuscles, Ruffini’s Endings):
Important at extreme joint angles, detect stretch in ligaments and deep
tissues
* Golgi Tendon-Like Receptors: Provide information on muscle tendon
tension

191
Q

Cerebral Cortex Layers:
Six Layers of Neurons:
* Layer _____: Primary entry point for sensory signals
* Layers ___ & ____: Receive diffuse input for excitability control
* Layers ___ & ____: Send signals across hemispheres via the corpus callosum
* Layers ____ & ____: Project to deeper brain areas, controlling signal
transmission and influencing thalamic activity

A

Cerebral Cortex Layers:
Six Layers of Neurons:
* Layer IV: Primary entry point for sensory signals

  • Layers I & II: Receive diffuse input for excitability control
  • Layers II & III: Send signals across hemispheres via the corpus callosum
  • Layers V & VI: Project to deeper brain areas, controlling signal
    transmission and influencing thalamic activity
192
Q

Vertical Columns:
* Each column specializes in a _____ sensory modality (e.g., touch,
pressure)
* Located in ____________ _______ __ (postcentral gyrus), organized by ____
region

A
  • Vertical Columns:
  • Each column specializes in a single sensory modality (e.g., touch,
    pressure)
  • Located in somatosensory area I (postcentral gyrus), organized by body
    region
  • Somatosensory Areas:
  • Somatosensory Area I:
  • High degree of localization; different parts of the body are represented
    proportionally to receptor density (e.g., large areas for lips, fingertips)
  • Key for precise tactile information (located in Brodmann’s areas 3, 1, and 2)
  • Somatosensory Area II:
  • Less precise localization
193
Q
  • Somatosensory Area I: _______ degree of localization; different parts of the body are represented
    proportionally to receptor ______ (e.g., large areas for lips, fingertips); Key for precise tactile information (located in Brodmann’s areas ___, ___, and ___)
  • Somatosensory Area II: _____ precise localization
A
  • Somatosensory Area I:
  • High degree of localization; different parts of the body are represented
    proportionally to receptor density (e.g., large areas for lips, fingertips)
  • Key for precise tactile information (located in Brodmann’s areas 3, 1, and 2)
  • Somatosensory Area II: Less precise localization
194
Q

Somatosensory Association Areas:
Location:
* Brodmann’s Areas ___ and ____ in the parietal cortex, located behind
somatosensory area __
Function:
* Combines and interprets sensory information from _______ ______ _
* Effects of Damage: __________

A

Location:
* Brodmann’s Areas 5 and 7 in the parietal cortex, located behind
somatosensory area I
* Function: Combines and interprets sensory information from somatosensory
area I
* Effects of Damage: Amorphosynthesis:

195
Q

Amorphosynthesis:
* Loss of ability to recognize ______ objects or forms by touch on
the _______ side of the body
* Reduced ________ of the _______ side of the body and body
parts
* Leads to a lack of ____ and _____ perception on the affected side

A

Amorphosynthesis:
* Loss of ability to recognize complex objects or forms by touch on
the opposite side of the body
* Reduced awareness of the opposite side of the body and body
parts
* Leads to a lack of spatial and form perception on the affected side

196
Q

Sensory Information Entry:
* Sensory signals enter the spinal cord through the _____
roots of spinal nerves

A

Sensory Information Entry:
* Sensory signals enter the spinal cord through the dorsal
roots** of spinal nerves

197
Q

Two Main Sensory Pathways:
1. Dorsal Column-Medial Lemniscal System: ___ spatial orientation of nerve fibers; Transmits information ____ with high temporal and
spatial fidelity
*Ideal for _______, _______ sensations

  1. Anterolateral System:
    * ______ spatial orientation
    * Transmits information that does not require high speed or
    precision
    * Suitable for __________ sensations
A

Two Main Sensory Pathways:

  1. Dorsal Column-Medial Lemniscal System: **High spatial **orientation of nerve fibers
    * Transmits information rapidly with high temporal and
    spatial fidelity
    * Ideal for precise, localized sensations
  2. Anterolateral System:
    * **Less **spatial orientation
    * Transmits information that **does not **require high speed or
    precision
    * Suitable for generalized sensations
198
Q

Functional Differences:
* Dorsal Column: For sensory information that needs ______,
accurate transmission
* Anterolateral System: For sensory signals that can tolerate
_____, _____ precise transmission

A

Functional Differences:
* Dorsal Column: For sensory information that needs rapid,
accurate transmission
* Anterolateral System: For sensory signals that can tolerate
slower, less precise transmission

199
Q

Dorsal Medial Lemniscal Pathway:
Anatomy: Composed of ______ _________ fibers
* Fibers ascend in the _____ columns of the spinal cord
* Synapse in the _______ column nuclei (______ and
_______ nuclei) of the medulla
* Cross to the opposite side and ascend via the medial
lemniscus to the thalamus

A

Dorsal Medial Lemniscal Pathway:
Anatomy: Composed of large myelinated fibers
* Fibers ascend in the dorsal columns of the spinal cord
* Synapse in the dorsal column nuclei (cuneate and
gracile nuclei) of the medulla
* Cross to the opposite side and ascend via the medial
lemniscus to the thalamus

200
Q

Dorsal Medial Lemniscal Pathway:
Function:
* Transmits ______ touch, ________,
and _____________ information
* Provides high spatial resolution for tactile _______

A

Dorsal Medial Lemniscal Pathway:
Function:
* Transmits fine touch, vibration,
and proprioceptive information
* Provides high spatial resolution for tactile localization

201
Q

Dorsal Medial Lemniscal Pathway:
Key Characteristics
* ______ conduction velocities (____-_____ m/sec)
* Essential for discerning precise ____ and ____
position

A

Dorsal Medial Lemniscal Pathway:
Key Characteristics:
* Fast conduction velocities (30-110 m/sec)
* Essential for discerning precise touch and joint
position

202
Q

Initial Division of the Dorsal Medial Lemniscal Pathway:
* Large myelinated fibers divide into ______ and ______ branches upon
entering the spinal cord
* Medial Branch: Travels upward through the _______ columns to the
______

A

Initial Division of the Dorsal Medial Lemniscal Pathway:
* Large myelinated fibers divide into medial and lateral branches upon
entering the spinal cord
* Medial Branch: Travels upward through the dorsal columns to the
spinal cord
* Lateral Branch: Synapses locally in the dorsal horn and serves three
functions.

203
Q
  • Lateral Branch: serves three
    functions:
  • Sends fibers to the _____ columns for upward travel
  • Terminates locally to mediate ______ reflexes
  • Contributes to the ______________ tracts
A
  • Lateral Branch: serves three
    functions:
  • Sends fibers to the dorsal columns for upward travel
  • Terminates locally to mediate spinal reflexes
  • Contributes to the spinocerebellar tracts
204
Q

Dorsal Medial Lemniscal Path to the Brain:
* Fibers ascend through the dorsal columns to the dorsal medulla and
synapse in the ________ and ______ nuclei
* Second-order neurons cross to the opposite side in the ______ and ascend
via the _______ _________ to the ______
* Third-order neurons project to somatosensory area ___ in the postcentral
gyrus

A

Dorsal Medial Lemniscal Path to the Brain:
* Fibers ascend through the dorsal columns to the dorsal medulla and
synapse in the cuneate and gracile nuclei
* Second-order neurons cross to the opposite side in the medulla and ascend
via the medial lemnisci to the thalamus
* Thalamic Relay and Cerebral Cortex Projection:
* In the thalamus, fibers terminate in the ventrobasal complex
* Third-order neurons project to somatosensory area I in the postcentral
gyrus

205
Q

Dorsal Medial Lemniscal Pathway:
Thalamic Relay and Cerebral Cortex Projection:
* In the thalamus, fibers terminate in the ________ complex

A

Dorsal Medial Lemniscal Pathway:
Thalamic Relay and Cerebral Cortex Projection:
* In the thalamus, fibers terminate in the ventrobasal complex

206
Q

Spatial Orientation of the Dorsal Medial Lemniscal Pathway:
* Maintained throughout the pathway, with ______ body fibers central and _______
body fibers more lateral in the dorsal columns
* Medial lemniscal crossing results in _________ representation in the
________

A

Spatial Orientation of the Dorsal Medial Lemniscal Pathway:
* Maintained throughout the pathway, with lower body fibers central and higher
body fibers more lateral in the dorsal columns
* Medial lemniscal crossing results in contralateral representation in the
thalamus

NURS 6413 Advanced Physiology and Pathophysiology (6 decks)

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