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Spring 2014 > Physiology - Exam 2, Deck #2 - Nervous > Flashcards

Physiology - Exam 2, Deck #2 - Nervous Flashcards

1
Q

What is the Central Nervous System (CNS)?

A

Brain and Spinal Cord;

-Autonomic

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2
Q

What are Nuclei?

A

Groups of neuron cells bodies within the CNS

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3
Q

What are Tracts?

A
  • Group of nerve fibers (axons) that interconnect regions of the CNS;
  • Integrative function of the CNS
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4
Q

What is the Peripheral Nervous System (PNS)?

A

Nerves, ganglia, and nerves plexuses;

  • OUTSIDE the CNS;
  • Consists of cranial and spinal nerves and associated ganglia
  • *Cranial = 12 pair
  • *Spinal = 31 pair
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5
Q

What is an Association Neuron (interneuron)?

A

Multipolar neuron located ENTIRELY in the CNS

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6
Q

What is a Sensory Neuron (afferent - in)?

A

Neuron that transmits impulse from a sensory receptor INTO the CNS

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7
Q

What are Motor Neurons (efferent - out)?

A

Neuron that transmits impulses from the CNS to an effector organ (ex. muscle)

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8
Q

What is a Nerve?

A

A collection of axons, or nerve fibers, packaged within the same connective tissue sheath in the PNS

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9
Q

What is a Somatic Motor Nerve?

A
  • Voluntary effector organs;

- Nerve that stimulates the contraction of SKELETAL MUSCLES

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10
Q

What is an Autonomic Motor Nerve?

A
  • Involuntary effector organs;
  • Nerve that stimulates contraction (or inhibits) of SMOOTH and CARDIAC MUSCLES and that stimulates glandular secretion;
  • Both sympathetic and parasympathetic branches
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11
Q

What are Neuroglia cells?

A
  • Supporting cells of the nervous system;
  • Derived from the same embryonic tissue layer as the neurons = the ECTODERM;
  • Unlike neurons, neuroglial cells CAN DIVIDE throughout like;
  • Brain tumors are glial cells
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12
Q

What are the types of PNS Glial Cells?

A
  1. Schwann cells - Guillain-Barre syndrome

2. Satelite cells = ganglionic gliocytes

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13
Q

What are the types of CNS Glial Cells?

A
  1. Oligodendrocytes - Multiple Sclerosis
  2. Astrocytes
  3. Microglia
  4. Ependyma
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14
Q

What are Schwann Cells?

A
  • PNS;
  • Form myelin sheaths around peripheral axons;
  • Results in saltatory conduction
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15
Q

What are Satellite Cells?

A
  • PNS;
  • Support functions of PNS neurons within sensory and autonomic ganglia;
  • Also called ganglion gliocytes
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16
Q

What are Oliogodendrocytes?

A
  • CNS;

- Form myelin sheaths around CNS axons

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17
Q

What are Astrocytes?

A
  • CNS;

- Help regulates the passage of molecules from the blood to the brain, and contribute to the blood-brain barrier

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18
Q

What are Microglia?

A
  • CNS;

- Amoeboid cells within the CNS that are phagocytic

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19
Q

What are Ependyma?

A
  • CNS;
  • Form epithelial lining of the brain cavities (ventricles) and the central canal of the spinal cord;
  • Cover tufts of capillaries to form the choroid plexus;
  • Choroid plexus produces cerebrospinal fluid
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20
Q

What is Multiple Sclerosis (MS)?

A
  • Ages 20-40;
  • Chronic, degenerativem remitting, and relapsing disease that destroys myelin sheaths of neurons throughout the CNS;
  • Initially, lesion form on myelin sheaths and become hardened SCLEROSES;
  • Prohibits the normal conduction of impulses, resulting in loss of function
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21
Q

Why is MS commonly misdiagnosed?

A
  • Widespread myelin degeneration leads to a greater variety of symptoms than other neurological disease;
  • And common remissions
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22
Q

What is Guillian-Barre Syndrome?

A
  • Autoimmune disease of PNS;
  • Functially equivalent to MS of the CNS;
  • Can recover over time
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23
Q

What is the Autonomic Nervous System?

A
  • Provides autonomic control of INVOLUNTARY effectors;
  • Cardiac muscle, smooth muscle, and glands;
  • 2 neurons b/w CNS and effector =
    1. Impulses from CNS by an axon that synapses with a second autonomic neuron;
    2. Second neuron innervates the effector
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24
Q

What is a Preganglionic Neuron?

A

First neuron between the CNS and effector;

  • Axon is found in the gray matter of the brain or spinal cord;
  • Synapses with the second in an AUTONOMIC GANGLION;
  • Preganglionic neuron → acetylcholine
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25
Q

What is a Postganglionic Neuron?

A

Second neuron between CNS and effector;

  • Axon extends from the autonomic ganglion to the effector organ;
  • -Sympathetic → norepinephrine , +
  • -Parasympathetic → acetylcholine
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26
Q

What are the divisions of the Autonomic Nervous System?

A
  1. Sympathetic (Thoracolumbar) Division: T1 → L2;
  2. Parasympathetic (craniosacral) Division
  3. Adrenergic and cholinergic synaptic transmission
  4. Other autonomic neurotransmitters
  5. Organs with dual innervation
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27
Q

What is Mass Activation by the Sympathetic Division?

A

Occurs when almost all postganglionic neurons fire simultaneously due to the DIVERGENCE of preganglionic fibers and CONVERGENCE of post ganglionic nerve fibers

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28
Q

What is the Paravertebral Ganglia?

A

A double row of sympathetic ganglia where most sympathetic nerve fibers separate from somatic motor fibers and synapse with postganglionic neurons

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29
Q

Where do preganglionic fibers from the upper thoracic level go?

A

Preganglionic fibers that exit from the upper thoracic level go to the neck, where they innervate smooth muscles and glands of the head and neck

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30
Q

Where do preganglionic fibers from below the diaphragm go>

A

They pass through the sympathetic chain of the ganglia WITHOUT synapsing;
-Beyond the sympathetic chain they become SPLANCHNIC NERVES

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31
Q

What are the Collateral or Prevertebral Ganglia?

A
  • Preganglionic fibers in the SPLANCHNIC nerves synapse in the collateral ganglia;
  • Includes = celiac, superior mesenteric, and inferior mesenteric ganglia;
  • Postganglionic fibers then innervated the digestive, urinary, and reproductive systems
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32
Q

What is the Sympathoadrenal System?

A
  • Adrenal medulla is derived from the same embryonic tissue as the postganglionic sympathetic neurons;
  • Adrenal medulla secretes Epi and some NE under sympathetic stimulation;
  • Because the adrenal medulla is stimulated in part by the mass activation of the sympathetic system the two are group
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33
Q

What is the Parasympathetic (Craniosacral) Division of the Autonomic Nervous System?

A

Preganglionic fibers come from the brain and the 2-4th sacral levels of the spinal cord;

  • Preganglionic synapse in the ganglia next to or actually in the organs innervated — terminal ganglia;
  • Innervate the lower LI, rectum, urinary and reproductive systems
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34
Q

What are Terminal Ganglia?

A

Ganglia of the Parasympathetic division that are next to or actually in the organs innervated;
-Supply the postganglionic fibers that synapse with the effector cells

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35
Q

What is Cholinergic Synaptic Transmission?

A
  • Utilizes ACETYLCHOLINE =
  • Ach is the neurotransmitter of the PREganglionic fibers of the symp. and para. division;
  • Ach is also the transmitter most released by para. postganglionic fibers at synapses with effects
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36
Q

What is Adregenic Synaptic Transmission?

A
  • Utilizes NOREPINEPHRINE =
  • NE is the neurotransmitter released by most postganglionic sympathetic nerve fibers;
  • Exceptions = some innervate skeletal muscles and sweat glands and release Ach (cholinergic)
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37
Q

What are the Cathecholamines?

A

Epinephrine, Norepinephrine, and Dopamine;

-All derived from the amino acids TYROSINE

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38
Q

What is the transformation of Tyrosine to Epinephrine?

A
  1. Tyrosine (AA);
  2. DOPA;
  3. Dopamine;
  4. Norepinephrine (neurotransmitter/hormone);
  5. Epinephrine (major hormone of the adrenal medulla)
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39
Q

What are “synapses en passant”

A
  • Synapses in passing;
  • Found in smooth muscles;
  • Bulging synapses along the neurons of sympathetic and parasympathetic neurons;
  • Can exhibit antagonistic effects on each other
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40
Q

What are some other Autonomic Neurotransmitters?

A

-Some postganglionic autonomic axons don’t involve norepinephrine or Ach = “Nonadregenic, noncholergenic”
EX: ATP, vasoactive intestinal peptide (VIP), and nitric oxide (NO)

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41
Q

What is Dual Innervation?

A

Most visceral organs are innervated by sympathetic and parasympathetic fibers;
-Effects may be antagonistic, complementary, or cooperative

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42
Q

What is Action Potential?

A

Abrupt pulse-like changes in the membrane potential lasting a few ten thousandths to a few thousandths of a second;
-AP moves along the nerve fibers and yields a nerve signal

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43
Q

What can elicit an AP in a nerve fiber?

A
  • Any factor that suddenly increases the permeability to SODIUM IONS;
    1. Electrical stimulation;
    2. Mechanical compression of the fiber;
    3. Application of chemicals to the membrane
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44
Q

What are the Components of an Action Potential?

A
  1. Voltage regulated Na+ gates OPEN — Na+ diffuses INTO the cell;
  2. Membrane DEPOLARIZES from −70mV to +30mV;
    - 3. Voltage regulated K+ gates open — K+ diffuses OUT OF the cell = Less depolarization;
  3. Membrane potential depolarizes from +30mV to −70mV
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45
Q

What occurs when the depolarization stimulus hits the cell?

A
  1. Membrane at resting potential of −70mV;
  2. Depolarization stimulus acts on the cell — depolarizes to THRESHOLD at ~-50mV;
  3. Na+ diffuses IN causing abrupt depolarization to +30mV = ACTION POTENTIAL;
  4. Repolarization follows as K+ diffuses OUT of the cell — will depolarizes slightly below resting potential
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46
Q

What is the role of the Na-K Pump Diffusion Potentials in creating APs?

A
  • Na-K pump generates resting membrane potential;
  • At the start of the AP, Na+ permeability increases 5000x then returns to 73;
  • Followed by an increase in K+ permeability as the inside of the membrane REPOLARIZES;
  • Quick membrane change from (-) to (+) and back to (-) on the inside
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47
Q

What is the Plateau of APs?

A
  • Repolarization does not take place right after depolarization;
  • Remains on a plateau near the peak of the spike, before depolarization begins;
  • Mostly occurs in the HEART, lasting 200-300msec causing contraction for this entire period
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48
Q

How are the Refractory Periods (plateaus) elongated in Cardiac (heart) fibers?

A
  • Heart contracts as syncytium (all together) & thus can sustain force;
  • Its AP lasts about 250 msec ;
  • Has a REFRACTORY PERIOD almost as long as AP;
  • Cannot be stimulated to contract again until has relaxed
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49
Q

What causes the elongated plateau during depolarization-depolarization?

A
  1. Delay in the closure of Na+ channels = longer diffusion IN;
  2. Small influx of Ca2+ maintains inside + for longer;
  3. Permeability of K+ channels DECREASES 5x at the start of the AP in excitable membranes that have plateaus = DELAYS outflow of K+ and repolarization
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50
Q

What is Saltatory Conduction?

A

Propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials;
-Made possible by myelinated and unmyelinated fibers

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51
Q

What are the 2 types of nerve fibers in a nerve?

A
  1. Myelinated — rapid conduction velocity;

2. Unmyelinated — slower conduction velocity

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52
Q

What are Myelinated Nerve Fibers?

A
  • Surrounded by an insulator material called MYELIN;
  • Myelin greatly increases the velocity of impulse traveling on the fibers;
  • Functions =
    1. Control rapid body movements by skeletal muscles
    2. Transmit sensory signals from receptors to CNS
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53
Q

What are Unmyelinated Nerve Fibers?

A
  • About twice as many small fibers WITHOUT myelin sheaths;
  • Conduct APs SLOWLY — no rapid contractions;
  • Functions =
    1. Control subconscious activities via ANS
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54
Q

What are the subconscious actions controlled by unmyelinated nerves?

A
  1. Excitability of the heart
  2. Contaction of blood vessels
  3. GI movements
  4. Emptying of the urinary bladder
  5. Sensory impulses that DON’T require immediate attention (ex: aching type of pain, crude touch or pressure receptors)
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55
Q

What is Myelin?

A

A LIPID that will not conduct electrical current;

  • Acts as an INSULATOR around the fibers;
  • About every 1mm along the length of the fibers the myelin is broken by a NODE OF RANVIER
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56
Q

What happens at the Nodes of Ranvier?

A

At the Node of Ranvier typical membrane depolarization can occur but BENEATH the myelin sheath depolarization DOESN’T take place;
-Nerve impulses are transmitted along the myelinated nerve by SALTATORY CONDUCTION

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57
Q

What is the Mode of Action for Saltatory Conduction?

A
  1. Node of Ranvier becomes depolarized;
  2. Electrical current spreads along the outside of the myelin sheath to the next Node and it depolarizes;
  3. Process repeats from node to node
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58
Q

What makes Saltatory Conduction so valuable?

A
  • Jumping of impulse from node to node increases velocity of conduction;
  • Prevents depolarization of large areas of the nerve fiber and prevents leakage of large amounts of Na+ into the fibers and of K+ out of the fiber;
  • Conserves energy that would be required by the Na
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59
Q

What is the All-or-None Law?

A

Once stimulated a nerve fiber always responds at the same amplitude of response

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60
Q

What is a Refractory Period?

A

Period of time of axon membrane is producing an action potential it is INCAPABLE of responding to further stimulation;
Absolute + Relative Periods

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61
Q

What are the components of the Total Refractory Period?

A
  1. Absolute Refractory Period — due to inactivated Na+ channels;
  2. Relative Refractory Period — due to continued outward diffusion of K+
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62
Q

What is the Absolute Refractory Period?

A

Elapsed time following a depolarization stimulus when the axon CANNOT be deloparized again regardless of stimulus strength

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63
Q

What is Relative Refractory Period?

A

Follows the absolute refractory period;

-When only a stronger than normal stimulus will produce a second action potential

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64
Q

What does Summation effect?

A
  1. Neural physiology –the additive effects of graded nerve potentials
  2. Muscle physiology – The additive effects of contractions of different muscle fiber motor units
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65
Q

What is Spatial Summation?

A

If voltage of stimulation is increased from 0 to the maximum voltage there is an increase in the number of nerve fibers stimulated;
-recruitment of variable numbers of nerve fibers in a nerve

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66
Q

What is a Minimal Stimulus or Threshold Stimulus?

A

The least possible voltage that will cause the nerve to fiber;
-Voltage at which only ONE nerve fiber stimulated to fire

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67
Q

What is a Maximal Stimulus?

A

The least possible voltage at which ALL nerve fibers in a nerve are stimulated

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68
Q

What is Temporal Summation?

A
  • Frequency Modulation;
  • variation in number of action potentials sent along a nerve fiber per second;
  • Frequency is limited by the refractory period of the nerve fiber
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69
Q

What are Gap Junctions?

A

Adjacent cells that are electrically coupled are held together by GAP JUNCTIONS — electrical synapses;

  • Membranes of two cells are separated by only two nanometers;
  • Composed of 12 proteins know as CONNEXINS
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70
Q

Where are gap junctions found?

A

Between electrically coupled cells of CARDIAC and some SMOOTH muscles;

  • Allow excitation and rhythmic connotation of larges numbers of muscle cells;
  • Seen in some regions of the brain
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71
Q

What are Connexins?

A

12 proteins that make up gap junctions;

-Form a water-filled pore for molecules pass from one cell to the next

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72
Q

What is a Synapse?

A
  • Juncture between 2 neurons;
  • Has the capability of transmitting some signals and refusing others;
  • *Variable Transmission of Signals = makes synapses the most important determinant of the CNS
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73
Q

What is Excitatory Postsynaptic Potential (EPSP)?

A

Some presynaptic terminals release EXCITATORY TRANSMITTER SUBSTANCES — acetylcholine;

  • Elicits Excitatory Postsynpatic Potential by the opening of Na+ channels;
  • Summation of excitatory postsynaptic potential (EPSP) leads to discharge of the EFFERENT neuron
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74
Q

What is Inhibitory Postsynaptic Potential (IPSP)?

A
  • Some presynaptic terminals release INHIBITORY TRANSMITTER SUBSTANCES — GABA, serotonin or glutamine;
  • Opens K+ channels
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75
Q

What causes the effect of the per synaptic terminals?

A

LARGE numbers of presynaptic terminals must fire for the action potential to transmit to the efferent neuron

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76
Q

What initiates a synaptic transmission?

A
  • AP travels don the afferent nerve fiber to synaptic knob;

- AP causes cause Ach to be released from transmitter

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77
Q

What happens when the AP reaches the synaptic knob?

A
  • Ca2+ channels are OPENED — calcium diffused into the know and binds protein SYNAPTOTAGM N;
  • Occurs close to where synaptic vesicles are attached to the plasma membrane by SNARE
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78
Q

What is Synaptotagm N?

A

Protein that serves as a Ca2+ sensor, forming a Ca2+ complex in the cytoplasm of the cell being targeted by the nerve transmission

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79
Q

How many acetylcholine are in each vesicle?

A

10^4 acetylcholine molecules/vesicle

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80
Q

What is SNARE?

A

Complex of proteins that bind docked vesicles to the plasma membrane of the muscles cells

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81
Q

What allows the release of acetylcholine (neurotransmitter)?

A

The complete fusion of the vesicle and plasma membranes;

-A pore is formed that allows Ach release when the Ca2+ synaptotagm n complex displaces part of the SNARE

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82
Q

How quickly is Ach released?

A

In less than 100 microseconds after increased intracellular Ca2+

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83
Q

Where does the Ach go?

A

Ach diffuses across the synaptic cleft and attaches to receptor protein molecules on the postsynaptic neuron

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84
Q

How does Ach generate a EPSP?

A

Ach + receptor molecule alters the permeability of the plasma membrane Na+ channel;
Na+ enters the postsynaptic neuron generating an excitatory postsynaptic potential ;
-Enough Ach attached to receptors = large depolarization and AP goes over entire neuron

85
Q

What is the mechanism of a Synaptic Transmission?

A
  1. AP reaches axon terminals;
  2. Voltage-gated Ca2+ channels open;
  3. Ca2+ binds to sensor protein in cytoplasm;
  4. Ca2+-protein complex stimulates fusion and exocytosis of neurotransmitter
86
Q

What is Cholinesterase?

A

Enzymes that splits Ach into ACETIC ACID and CHOLINE in about 1/500 sec;
-Prevents continued stimulation of the postsynaptic cell unless more Ach is released

87
Q

What are special characteristics of Synaptic Transmission?

A
  1. One way conduction;
  2. Synapse fatigues easily while nerve fibers fatigue hardly at all — Important to stopping a though or movement;
  3. Memory function of the synapse
88
Q

What is Facilitation of synapses?

A

Need 25 presynaptic terminals to discharge neurotransmitters for an AP, but only 20 terminals to fire;
-Facilitated so that firing of 5 more presynaptic terminals in a short period of time will result in the AP being sent to the efferent neuron

89
Q

What happens when large numbers of impulses pass through a synapse?

A

Synapse becomes permanently facilitated so that impulses from the same origin can pass EASIER;
-How MEMORY occurs in CNS

90
Q

What is Memory?

A

Storage of info;

-Can be self initiated without sensory input

91
Q

How do Hypnotics, Anestethetics, and Acidosis affect neuronal circuits?

A

All DEPRESS transmission of impulses across the synapse

92
Q

How do Alkalosis and mental stimulants (caffeine, benzedrine, and strychnine) affect neuronal circuits?

A

All FACILITATE (enhance) synaptic transmission;

  • Strychnine causes spontaneous discharge;
  • Different neurons have different thresholds
93
Q

What is a Neuronal Pool?

A

Accumulations of neurons making up the numerous anatomical regions of the CNS

94
Q

What is an Area of Stimulation?

A

sphere of influence upon neurons with which the neuron synapses

95
Q

What is a Sphere of Influence?

A

Area of neurons that are acted by each incoming nerve fiber;
-Greater the number of presynaptic terminals that connect with a given efferent neuron, the greater the sphere of influence over it

96
Q

What is the Discharge Zone?

A

Presynaptic neuron causes the postsynaptic neuron to fire;
-Efferent neurons that have enough presynaptic terminals ending on them so that they will excite every time an incoming fiber is stimulated

97
Q

What is the Facilitated Zone?

A

Presynaptic neuron fires causes the postsynaptic neurons membrane potential to approach but not reach the threshold potential

98
Q

What are the types of circuits in a neuronal pools?

A
  1. One incoming — one out going neuron;
  2. Diverging or amplifying circuit;
  3. Converging circuit;
  4. Inhibitory circuit
99
Q

When does one incoming fiber stimulate one outgoing neuron?

A

NEVER exists in this form;

-Synapse simply acts as a SWITCH in this case

100
Q

What is a Diverging or Amplifying Circuit?

A

Single incoming fiber enters the neuronal pool and branching occurs to more and more neurons

101
Q

Where does an Amplifying Circuit occur?

A
  • CNS control of skeletal muscles;

- 50,000 amplification = ONE cell of motor cortex stimulates 50,000 neuromuscular junctions

102
Q

Where does a DIVERGING Circuit occur?

A

-Multiple tracts = one source neuron branches to different PARTS of the nervous system
EX: Sensory info from dorsal spine follows 2 paths to the brain = 1. Cerebellum; 2. Thalamus + cerebral cortex

103
Q

What is a Converging Circuit?

A
  • Simultaneous control of one neuron by two or more input neurons;
  • Mostly sensory branch of the nervous system;
  • 2 types:
    1. Single Source
    2. Multiple Sources
104
Q

What is a Single Source Converging Circuit?

A

An excitatory field comes from more than one neuron in a sensory receptor field to a single neuron synapsing with it

105
Q

What is a Multi-Source Converging Circuit?

A

Allows summation of info from several different sources

106
Q

What is an Inhibitory Circuit?

A

Shuts off one pathway while opening another;

  1. Respiratory center – inspiratory and expiratory oscillation
  2. Vasomotor center – Cardiac excitatory and inhibitory oscillations
107
Q

What is After Discharge of a neuronal pool?

A
  • A signal entering a pool causes a prolonged output discharge, called the AFTER-DISCHARGE, even after the incoming signal is over;
  • Usually stops due to fatigue
108
Q

What is the After Discharge of a Synaptic transmission?

A

15 mSEC before development of the postsynaptic potential

109
Q

What is the After Discharge of a REVERBERATING Circuit?

A
  • Basis of innumerable CNS activities;

- One input neuron elicits responses that last seconds, hours, or a lifetime

110
Q

What are some Reverberating Circuits?

A
  • Life long respiratory rhythm
  • Sleep- awake cycle
  • Rhythmic- walking movement
111
Q

What is a Parallel Circuit?

A
  • Repeats a DEFINITE number of times with a lag at each synapse of 0.5 mSEC;
  • Differ as to number of neurons in parallel
  • Can be combined with a diverging circuit to perform mathematical calculations
112
Q

What is a Neuromuscular Junction?

A

Connection between the end of a large myelinated nerve fiber and a skeletal muscle fiber;
-Each skeletal muscle fiber is supplied with at least one junction

113
Q

What is a Motor Unit?

A

Combo of nerve fiber + all muscle fibers it innervates

114
Q

What is different in the the action of Motor Units and muscles?

A

Motor units exhibit the ALL or NONE phenomenon;

Muscles DO NOT

115
Q

What events occur at a neuromuscular junction?

A

Action potential moves done the AFFERENT nerve fiber to the region of the SOLE PLATE and the action potential causes Ach to be released from the transmitter vesicle

116
Q

What is a Sole Plate?

A

The large and complex terminal formation by which the axon of a motor neuron establishes synaptic contact with a striated muscle fiber

117
Q

What is the Effect of Curare (drug) on the neuromuscular junction?

A

-Blocks transmission of the impulse at the neuromuscular junction by making the muscle membrane RESISTANT to Ach;
-Compete with Ach for the receptor sites on the motor end plate;
= No muscle stimulation

118
Q

What is the Effect of Neostigmine and Physostigmine like drugs on the neuromuscular junction?

A

Neostigmine and Physostigmine have the OPPOSITE effect of Curare;

  • ENHANCE transmission of the impulse at the junction;
  • INHIBIT cholinesterase that would breakdown Ach;
  • Leading to a buildup of Ach at the motor end plate
119
Q

What does the build of Ach at the motor end plate cause?

A
  • Every time the muscle depolarizes it immediately depolarizes;
  • Muscle fiber receives a succession of impulses and becomes spastic
120
Q

What is the Effect of Diisopropulfluorophosphate on the neuromuscular junction?

A

Nerves gas causes the breakdown of cholinesterase for several weeks;
-NO degradation of Ach

121
Q

How does Ca2+ effect the neuromuscular junction?

A

Number of vesicles releasing Ach increases directly with Ca2+ concentration

122
Q

How does Mg2+ effect the neuromuscular junction?

A

Number of vesicles releasing Ach decreases as the concentration of Mg2+ increases

123
Q

What are Sensory Receptors?

A
  • Relay environmental stimuli to the CNS;

- detect intensity gradients of such sensory stimuli as touch, sound, light, smell, taste, cold and warmth

124
Q

What are Receptor (Generator) Potentials?

A

-Produced by Sensory Receptors in proportion to the strength of the environmental stimulus and send pulse encoded information to the CNS for processing

125
Q

What determines the info sent from the sensory receptors to the CNS?

A

-Pulse encoded information is propagated to the CNS by variation in the FREQUENCY of the action potentials but NOT by variation in their AMPLITUDE

126
Q

What are Mechanoreceptors?

A

Detect mechanical deformation of the receptor or adjacent cells;
EX: hearing, equilibrium, and touch receptors

127
Q

What are Thermoreceptors?

A

Detect changes in temperature

128
Q

What are Nociceptors?

A

Detect PAIN, usually caused by physical damage or chemical damage to the tissue

129
Q

What are Electromagnetic Receptors?

A

Detect light on the retina of the eye

130
Q

what are Chemoreceptors?

A

Detect taste, smell, PO2, mOsM, PCO2 of body fluids

131
Q

What are Primary Receptors?

A
  • Free Nerve Endings;
  • Taste and pain receptors;
  • Touch;
  • Pressure
132
Q

What are Secondary Receptors?

A
  • ALL other human receptors;

- Have specialized EPITHELIAL cells which form synapses with transmitting neurons;

133
Q

What is Receptor Potential?

A

Local potential in the neighborhood of nerve endings caused by whatever type of stimulus excites the receptor

134
Q

What is Local Flow of Current?

A

Caused by the receptor potential that in turn excites action potentials in the sensory nerve fibers

135
Q

What are the ways in which receptor potentials can be elicited?

A
  1. Primary or

2. Secondary Receptors

136
Q

How do Primary Receptors elicit receptor potential?

A

Mechanically deform or chemically alter the terminal nerve ending ITSELF;
-Causes ions to diffuse through the nerve membrane, thereby setting up the receptor potential

137
Q

How do Secondary Receptor Cells elicit receptor potential?

A

Lie adjacent to the nerve ending and synapse with them;

  • Sound enters the cochlea of the ear — hair cells (receptor cells) like on the basilar membrane develop receptor potentials;
  • These RPs in turn stimulate nerve fibrils intertwining the hair cells
138
Q

What are the components of the eye that make it like a camera?

A
  1. Lens system
  2. Variable aperature system = Iris and pupil
  3. Film = retina
  4. Photochemistry = Chemicals of rods and cones
139
Q

What are the 4 surfaces or interfaces of the Lens of the Eye?

A
  1. Air — anterior surface of the cornea;
  2. Posterior surface of cornea — aqueous humor;
  3. Aqueos humor — anterior suface of lens;
  4. Posterior surface of lens — vitreous humor
140
Q

What is a Reduced Eye?

A

Schematic representation of the optics of the eye;

  • All refractive surfaces of the eye are algebraically summed and considered to be a single lens;
  • Useful for simple optical calculations
141
Q

Where are images focused in the eye?

A

Images are focused on the RETINA

142
Q

What is Accommodation of the eye?

A

Ability of the eye to change the refractive index of the lends and hence the focus of light on the retina

143
Q

What is the mechanism of Accommodation of the eye?

A

Altering the refractive power of the crystalline lends of the eye in young children;
-Occurs by contraction of the ciliary muscle against suspensory ligaments

144
Q

What is Presbyopia?

A
  • With age the lens loses the elastic nature and loses the power of accommodation;
  • Eye remains focused permanently at an almost constant distance depending on the the individual characteristics of the persons’ eye;
  • age 40-45 = bifocals
145
Q

What are the Errors of Refraction Lens Correction?

A
  1. Emmetropia
  2. Hypermetropia = Hyperopia = farsightedness
  3. Myopia = near-sightedness
  4. Astigmatism
  5. Cataracts
146
Q

What is Emmetropia?

A
  • Normal vision;

- When ciliary muscle is completely relaxed, parallel light rays from distant objects are i sharp focus on the retina

147
Q

What is Hypermetropia?

A

= Hyperopia = farsightedness;

  • Can’t focus CLOSE UP;
  • Eyeball is too short or lens is too weak when ciliary muscle is relaxed;
  • CONVEX lens would correct
148
Q

What is Myopia?

A

= Near-sightedness;

  • Can’t focus on DISTANCE;
  • When ciliary muscle is relaxed, lens is strong enough that light rays forming from distant objects are focused in front of the retina;
  • Eyeball is too long, or too much power in the lens;
  • No mechanism which can ever focus distant object sharply;
  • CONCAVE would correct
149
Q

What is Astigmatism?

A

A refractive error of the lens system of the eye usually due to an oblong cornea or lens

150
Q

What is Cataracts?

A

Common lens abnormality in older people;

  • Denaturation of the crystalline structure of the lens protein;
  • IMPLANTED LENES would correct
151
Q

What is the Variable Aperture System of the Eye?

A
  • Made of the PUPIL and IRIS;

- Iris controls the amount of light that is allowed to enter the eye = increase in darkness, reduce in brightness

152
Q

How does the Iris control light entering the eye?

A
  • Changes in the side of the iris changes the size of the pupil;
  • Diameter of the pupil - 1.5-8mm;
  • Light entering = diameter squared;
  • Amount of light can vary 30x
153
Q

What is the Retina?

A

“The Film of the eye”;

  • Light sensitive portion of the eye, containing the CONES and the RODS;
  • Retina is connected to the optic nerve which runs to the cerebral cortex
154
Q

What the Cones of the retina?

A

Mainly responsible for COLOR vision

155
Q

What are the Rods of the retina?

A

Mainly responsible for vision in the dark;

-Light intensity

156
Q

Where does light enter the retina?

A

Inner limiting membrane layer

157
Q

What is the Photochemistry of Vision?

A

Rods and Cones contains chemicals that breakdown when hit by light;
-Optic nerve is excited and sends the signal from the eye (retina) to the brain (cerebral cortex)

158
Q

What is the chemical breakdown in the eye?

A

Rhodopsin — Opsin (protein) + Retinene;

*All cones cell have retinene, but the protein varies

159
Q

What are the 3 types of cones?

A
  • Blue cones
  • Green cones
  • Red cones
160
Q

How does Rhodopsin change when exposed to light?

A

Splits into opsin and 11-cis-retinene;

  • Cis-retinene is converted to all-trans-retinene;
  • Converted back to cis-retinene and recombines with opsin = Rhodopsin is reformed
161
Q

What is Color Blindness?

A

Caused by a congenital lack of one or more types of cones, usually the absence of either red or green cones

162
Q

What are Dichromats?

A

People who only have 2 functioning cones within their eye

163
Q

What is Deuteranopia?

A

Absence of functioning GREEN cones (M cones);

-Most common form

164
Q

What is Protanopia?

A

Absence of functioning RED cones (L cones;

-Less common

165
Q

What is Tritanopia?

A

Absence of functioning BLUE cones (S cones);

-Least common

166
Q

When can’t someone distinguish red from green?

A

Having only one cone in the middle to long wavelength region (red or green cones);

  • Red and green pigments (photopsins) are cded on the X chromosome = much more common in MEN;
  • Men = 8%, Women = 0.5%
167
Q

What is Hearing?

A

A MECHANORECEPTOR Sense;

-The tympanic membrane and the ossicular system transmits sound through the middle ear to the inner ear

168
Q

What is the Tympanic Membrane?

A
  • Eardrum;

- Cone shaped with concavity facing downward towards the auditory canal

169
Q

What makes up the Ossicular System?

A
  1. Malleus
  2. Incus
  3. Stapes → Oval window to the Cochlea
170
Q

What is the Malleus of the Ear?

A

Handle is attached to the sneter of the tympanic membrane

171
Q

What is the Incus of the Ear?

A

Tightly bound to the other end of the malleus by ligaments so whenever the malleus moves so does the incus;
-Opposite end of the incus in turn articulates with the stamp of the STAPES

172
Q

What is the Stapes of the Ear?

A

The faceplate of the stapes lies against the membranous labyrinth in the opening of the OVAL WINDOW into the COCHLEA (inner ear)

173
Q

What is the Cochlea?

A
  • Inner ear;
  • A system of 3 tubes coiled side-by-side;
  • Sound waves are transmitted into the cochlea through the OVAL WINDOW
174
Q

What are the 3 tubes of the Cochlea?

A
  1. Scala vestibuli
  2. Scala media
  3. Scala tympani
175
Q

What is the Vestibular Membrane?

A

Separates the Scala Vestibuli from the the Scala Media;

-So thin and easily moved that it DOESN’T play a role in sound transmission

176
Q

What is the Basilar Membrane?

A

Separates the Scala Media and the Scala Tympani;

-On the surface of the Basilar Membrane lies the SPIRAL ORGAN OF CORTI

177
Q

What is the Spiral Organ of Corti?

A
  • Receptor organ that generates nerve impulses in response to vibration of the fibers of the Basilar Membrane;
  • Contains a serious of mechanically sensitive cells know as HAIR CELLS
178
Q

What are Hair Cells?

A

Mechanically sensitive cells;

-Receptive end-organs that generate nerve impulses in response to sound vibrations

179
Q

How are Hair Cells arranged?

A

-One inner row the length of the Basilar Membrane;
-Several outer rows in the cochlea =
— 3 rows in the basal turn;
— 4 rows in the middle turn;
— 5 rows in the apical turn

180
Q

How are sounds waves transmitted through the Cochlea?

A
  1. Sounds waves enter the Scala Vestibuli from the faceplate of the Stapes at the oval window;
  2. At the distal cochlea, Scala Vestibuli and Scala Tympani open directly to each other = HELICOTREMA;
181
Q

What is the Helicotrema?

A

The opening between the Scala Vestibuli and the Scala Tymapni;
-Where sound waves pass

182
Q

What determines PITCH?

A

The speed of the STAPES movement is directly related to the the frequency of the sound

183
Q

What occurs at a HIGH Frequency of sound?

A

Fluid moves through the basilar membrane, causing it to bulge back and forth with each sound vibration

184
Q

What occurs at LOW Frequency of sound?

A

Most of the fluid moves through the HELICOTREMA

185
Q

What determines Frequency Coding of Sound Waves?

A

The variation in fluid movement through the ear due to variation of in the vibration of basilar membrane fibers at high and low frequencies

186
Q

What is the function of Spiral Organ of Corti?

A
  • Membrane basilar fibers vibrate UPWARD;
  • In and out motion of the basilar membrane cause hair cells to go back and forth again the TECTORIAL MEMBRANE;
  • Movement of hair cells excites the cochlea nerve fibers upon vibration of the basilar membrane
187
Q

What determines Loudness?

A

Determined by the amplitude of variations of the basilar membrane and hair cells

188
Q

What determine Frequency Variation?

A

Due to hair cell movement in different places along the basilar membrane

189
Q

What happens at HIGH PITCH sounds?

A

Higher-pitched sounds produce a peak displacement close to the base of the basilar membrane

190
Q

What happens at LOWER-PITCH sounds?

A

Lower-pitch sounds produce a peak displacement further toward the apex

191
Q

What provides a neural code of Pitch Discriminaton?

A

The neurons that originate in hair cells that are where displacement is the greatest, will be stimulated more than those neurons in other regions

192
Q

What is Equilibrium?

A

Sense that provides orientation with respect to gravity;

-Due to the Vestibular Apparatus

193
Q

What are the parts of the Vestibular Apparatus?

A
  1. the Otolith organs
  2. Semicircular canals
    * *Sensory hair cells process the info from these about VELOCITY
194
Q

What is the function of the Otolith Organs?

A
  • Includes the UTRICLE and SACCULE;

- Provides info about linear acceleration

195
Q

What is the function of the Semicircular Canals?

A

Provide info about rotational or angular acceleration

196
Q

What is the sense of Taste?

A

Function of TRANSDUCTION of taste buds in the mouth

197
Q

What are the Primary Sensation of Taste?

A
  1. Sour=Acid – H+ channels
  2. Salty – Na+ channels
  3. Sweet and umami (savory = meaty flavor) – sugars and glutamate via G-protein coupled receptors
  4. Bitter – Quinine via G-protein coupled receptors
198
Q

How is the Taste Bud arranged?

A
  • On the papillae of the tongue;
  • Outer tips of taste cells are arranged around a minute TASTE PORE;
  • the tip of each cell, several microvilli a or TASTE HAIRS protrude through the taste pore into the mouth cavity
199
Q

What are the Microvilli or Taste Hairs?

A

Provide the receptor surface for taste

200
Q

How are taste cells of SALTY activated?

A

Depolarization by Na+ ions

201
Q

How are taste cells of SOUR activated?

A

Depolarization by H+;

-Acid

202
Q

How are taste cells of SWEET/UMAMI activated?

A
  • Sugars and glutamate via G-protein coupled receptors;

- Followed by second messengers

203
Q

How are taste cells of BITTER activated?

A
  • Quinine via G-protein coupled receptors;

- Followed by second messengers

204
Q

Where does the sense of SMELL come from?

A

OLFACTORY MEMBRANE which is high up in the nasal cavity

205
Q

What are Olfactory Cells?

A

Consists of receptor cells which are bipolar nerve cells derived originally from the CNS

206
Q

How many smell can humans experience?

A

up to 10,000 different odors

207
Q

How does the brain handle smells?

A

Brain integrates signals from several sensory neurons that have different olfactory receptor proteins and then interpret the patter as a “FINGERPRINT” for that odor

208
Q

What are the primary sensation of SMELL?

A
  1. Camphoraceous — moth ball
  2. Musky
  3. Floral
  4. Pepperminty
  5. Ethereal
  6. Pungent
  7. Putrid — dead animal flesh

Spring 2014 (22 decks)

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