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MCAT Miscellaneous > Review 12 > Flashcards

Review 12 Flashcards

1
Q

What are the mechanisms for a graded potential that cause it to reduce time and distance?

A
  1. Think Neurotransmitters, ligand-gated receptors, Electrical forces, and diffusion forces.
  2. Duration of NT transmitters and receptors: Depends on how long they are present, how quickly they decay, etc.

Na, Ca - Excitatory as they come in
Cl - Inhibitory as it comes in and K+ is inhibitory as it goes out.

Graph of depolarization and why a membrane potential does not keep increasing - Increase and the plateau is dependent on the ligand and the reduction is dependent on electrical and diffusion forces.

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2
Q

What are forces that drive ions in and out of the cell?

A

Diffusion - wants to go from area of higher to area of lower

Electrical - Wants to go to attractive force area.

K+, OA- - Abundant normally inside
Na+, Ca2+, and Cl- - Abundant normally outside

Note that the cell is overall negative

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3
Q

Important channels

A
  1. Leak channels
  2. Ca2+/Na+ antiporter
  3. Cl-/K+ symporter
  4. Na+/K+ antiporter
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4
Q

Saltatory Conduction

A

Differential jumping of action potential seen in myelinated and unmyelinated axons

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5
Q

Steps for action potential

A
  1. Trigger zone, sodium gated channels (rising phase, depolarization, maximal state and closing of gated channels), potassium gated channels (falling phase, leak channels), hyperpolarization (refractory period, relative period).

Note action potential does not travel backwards

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6
Q

Axon diameter and Myelin sheath

A

Large vs, small axon - more electrical pathway in axon given that there are other things here like filaments

Nodes of Ranvier and Myelination - Less capacitance in myelination, decreases permeability to ions, also action potential may dip a little at myelin sheaths because of lack of channels, and the node of Ranvier makes up for it. It increases efficiency of the neuron or axon

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7
Q

4 types of axon potential patterns

A
  1. Need input
  2. Firing regularly and stimuli can intensify it. It is related to leak channels.
  3. Like 2 it is firing regularly but a stimulus can inhibit the firing sometimes and stop it.
  4. No particular pattern. It could be going really fast then inhibited or stimulus can make it faster and reduce the time between firing, etc.

Adv. - Information can be fine-tuned due to the information. The patterns determine the type and amount of NT released.

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8
Q

Types of Synapse

A
  1. Chemical synapse:
    a. Has gap
    b. Release molecules at the synapse that cross from molecular terminal to the membrane of the target cell.
  2. Electrical synapse:
    a. Cells are physically connected to the membrane of cells.
    b. Physical channels - gap junctions that the inside of neuron communicates with the inside of the target cell.
    c. Ions can flow directly from one to the other.
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9
Q

Synapse Notes

A
  1. Information for neurons come in through dendrites.
  2. Some synapse come into soma
  3. Some synapse comes into the axon terminal.
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10
Q

Synapse Structure

A

Synaptic cleft, Pre-synaptic cleft, Post-synaptic cleft, neurotransmitters, synaptic vesicles, and NT receptors

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11
Q

Neurotransmitter Release

A

Ca2+-gated ion channel, the fusion of synaptic vesicles with the pre-synaptic membrane, action potential, Ca2+ importance.

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12
Q

Neurotransmitter Types

A
  1. Monoamines - Organic molecules with amino group linked by 2 Carbons to an aromatic group.
  2. Peptides
  3. Others
  4. Amino acids
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13
Q

Amino acid NTs

A

Necessary for nervous system function and flow of information.

  1. Glutamate - Excitatory
  2. GABA - Inhibitory in Brain
  3. Glycine - Inhibitory in Spinal cord
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14
Q

Peptide NTs

A

Perception of pain

a. Opioids like endorphin

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15
Q

Monoamines

A

Contain catecholamines - characterized by molecule with an aromatic group and two hydroxyls.

  1. Serotonin
  2. Dopamine
  3. Histamine
  4. Epinephrine
  5. Norepinephrine
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16
Q

Other NT

A

Acetylcholine:

a. ANS
b. Motor neurons of skeletal muscle

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17
Q

NT receptors note

A

There are a combination of synapses in contact with the neuron that contribute

  1. Ionotropic:
    a. Ligand-gated
    b. Cause graded potentials
    c. Na+, Ca2+ are excitatory and Cl- is inhibitory
    d. Usually faster
  2. Metabotropic:
    a. NT can activate 2nd messenger
    b. Can affect ion channels (Increase/Decrease)
    c. Can change protein activity
    d. Can change gene pattern.
    e. Activation of a target can be slow, larger than the other, widespread, and amplified.
    f. Can change even affect ionotropic channel
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18
Q

Neurotransmitter Removal

A
  1. Passive diffusion
  2. Enzyme breakdown
  3. Reuptake pumps
  4. Astrocyte endfeet for breakdown or transfer to neuron for recycling
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19
Q

Neuroplasticity Notes

A
  1. NS changes in response to inputs
  2. Changes in synapses or structures to take information
  3. Can happen in both directions
  4. Can be potentiation or depression
  5. Potentiation - the strength of information flowing increases and depression - the strength of information flow decreases.
  6. NP increases with young and decreases with old. It increases transiently with an injury.
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20
Q

Neuroplasticity moments

A
  1. Synaptic plasticity

2. Structural Plasticity

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21
Q

Synaptic Plasticity

A
  1. Potentiation response:
    a. Excess of NT release.
    b. Increased activity in post-synaptic receptors
    c. Increased types of receptors at post-synaptic receptor
  2. Depression Response:
    a. Amount of NT released decreases.
    b. NT receptors decrease in numbers
    c. Reduced activity of receptors and second messenger
22
Q

Structural Plasticity

A

Potentiation:

a. Sprouting
b. Terminals can be more branched along with dendrites.

Depression:

a. Pruning
b. Reduced terminals and simpler dendrites

Short term or long term potentiationand depression - Synaptic plasticity
Long-term potentiation and depression- Structural plasticity

23
Q

Visual cues for Perception

A

Depth, Form, Motion, and Constancy can be sone through binocular cues (depth) or monocular cues (others)

24
Q

Depth

A
  1. How far is away or close something?
  2. Binocular vision helps this:
    a. Gives retinal disparity through convergence (closer- muscles active and farther muscle relaxed)
    b. Brain uses convergence to form depth cues.
25
Q

Form

A
  1. Monocular cues:
    a. Relative size -gives form of object. E.g: 2 ants (big and small) where big one looks closer to us and can tell with one eye.

b. Interposition: Two things superimposed for example like circle and rectangle and we can tell which is in front that is the form.
c. Relative height: Objects that are higher are expected to be farther from us but infact sometimes they are the same height. It just depends on the elevation.
d. Shading in contours where the interaction of light and shade cabn show the form of an object. Think craters

26
Q

Motion Parallax (relative motion)

A
  1. Monocular cues.

2. Things close to us appear faster and those farther appear to move slower

27
Q

Constancy

A

Monocular cue

  1. Size constancy: Two women sit on a chair but one is closer than the other and might look bigger but we can tell or know they are the same size
  2. Shape constancy: Think of a door opening. As it opens, it changes shape but overall we know it is still the same shape.
  3. Color constancy: Think of a coffee mug that is red and light shines on it and the light part looks like a different color from the dark part but overall we know that it is the same color.
28
Q

Sensory Adaptation

A

Change in the sensitivity of the perception of a sensation.

  1. Hearing: Rock concert become accustomed to it because of the inner muscle of the ear that contracts and dampens vibration. It takes time to contract which is why the gun shot sound is less adaptable.
  2. Touch - Cold water first time and overtime. Muscles are saturated and desensitized.
  3. Smell - perfume, cells are desensitized.
  4. Proprioception - the sense of balance and self in space. Experiment with goggles and how even though upside down, one can adapt.
  5. Sight - bright and dark room where pupils contract and rod and cones are desensitized in bright light and vice-versa in dark rooms.
29
Q

Weber’s Law and Threshold

A

Threshold for just-noticeable difference.

  1. change in I = I*K where Change in I is incremental and I is the background intensity
  2. Weber’s fraction = Change in I/ I and law is Change in I/I = K
  3. Linear relationship and some people do a+ I in the denominator where a is the baseline level of activity.
  4. He noticed a constant with varying jobs in the mole fraction k value. It is affecting sensory-tactile tasks and auditory concert
30
Q

Absolute threshold of sensation

A

This is not equal to JND which is the smallest difference in stimulation you can detect the difference like light switch , volume of speaker turning, weights.

Absolute threshold is minimum intensity of a stimulus that is needed to detect a particular stimulus 50% of the time

Influences: Motivation, alertness, experiences, and expectations.

Think of the graph that shos absolute and subliminal

Sublimial is the stimuli that we cannot detect 50 % of the time.

50 % is important becasue it varies among individuals and within individuals.

31
Q

Types of Somatosensation

A
  1. Temperature - Thermoception
  2. Pressure - Mechanoception
  3. Pain - Nociception
  4. Position - Proprioception
32
Q

Vestibular System

A

Important for balance and spatial awareness

Cochlear, semi-circular canals, and otolithic organs

33
Q

Cochlear

A
  1. Full of specialized auditory reception

2. Process and transferr sounds to the brain

34
Q

Semi-circular canals

A
  1. Anterior, posterior, and lateral
  2. Orthogonal (90) to each other.
  3. Filled with fluid called ENDOLYMPH
  4. Rotation along a certain plane allows shifting within that particular canal.
  5. Because we can detect how much the head is moving, it can tell strength of rotation
35
Q

Otolithic organs

A
  1. Utricle and Saccule
  2. Helps with balance and spatial awareness
  3. Detects linear acceleration and head positioning.
  4. Structures have Ca2+ crystals attached to viscous gel substances.
    a. If accelerate, crystals move because they are heavier than the surrounding gels environment.
    b. They pull on hair cells in the process that carry information to the brain (Responds to gravity)
36
Q

What is the mechanism of dizziness?

A

Think about endolymphs

Scuba divers and astronauts can be affected where they have no sense of gravity.

37
Q

Signal Detection Notes

A

NOTE THE TABLE

d’ - strength of signal
c - strategy
a. Conservative - always say NO until 100 % (correct rejection and miss)
b. Liberal - Always say yes (lead to hit and false alarm)

38
Q

LOOK AT SIGNAL DETECTION THEORY PART 2 NOTES

A

C = Strategy:

a. 0 = Ideal observer
b. >1 = Conservative
c. <1 = Liberal

d’ - Strength = mean of the maximal height of noise and signal

B, D, C, and beta where in example:
B = 2, D = d’ - B, C =Ideal observer (B-d’/2), and beta = lnbeta = d’ * C

39
Q

Bottom-Up

A
  1. Begins with stimulus and it allows stimulus to influence perception
  2. No pre-conceived idea, training, background, etc on what is being stimulated.
  3. Data-driven
  4. What is being looked at directs cognitive awareness.
40
Q

Top-Down

A
  1. Uses background knowledge to influence perceptions.
  2. Theory-driven
  3. Used to shape cognitive understanding of what is being looked at.
  4. Perception influenced by our expectations e.g. find Waldo
41
Q

Gestalt Principles

A

One of the ways we can explain how watching a video works. A video is a continuum of images and we can make sense of it through:

  1. Similarity
  2. Pragnanz
  3. Proximity
  4. Continuity
  5. Closure
42
Q

Similarity

A

Items that are similar to one another are grouped together by the brain. Look at example in notebook alternating rectangles and circles

43
Q

Pragnanz

A

Reality is often reduced/organized to simplest form e.g Olympics symbol

44
Q

Proximity

A

Objects that are close to one another are grouped together. It takes account of distances. Look at example in book

45
Q

Continuity

A

Lines are seen as following the smoothest path that is the best slope and not steep slope

46
Q

Closure

A
  1. Objects grouped together are seen as whole
  2. Ignore gaps and contour lines
  3. Missing information to create familiar shapes and images.
47
Q

Sclera

A
  1. Thick fibrous tissue (white) forms
  2. Forms the substance of the eye
  3. Protects eye and attachment point for muscles
48
Q

Cornea

A
  1. Transparent
  2. Protects front of eye
  3. Bends eye a little bit
  4. Protected by thin layer of epithelial cells called conjuctiva (moisturizes it from dust and debris and friction).
49
Q

Aqueous humor

A
  1. Chamber of fluid
  2. After cornea
  3. Water + Salt
  4. Fills anterior chamber of eye
50
Q

Lens

A
  1. Biconvex lens (curved at both ends)

2. Changes shape (thicker or thinner)

51
Q

Ciliary Body

A
  1. Makes lens thinner or thicker

2. Made of suspensory ligaments connected to lens and ciliary muscles on both sides of lens

MCAT Miscellaneous (17 decks)

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