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physiology Flashcards

1
Q

If a mechanically-gate potassium channel opens and potassium moves down its concentration gradient, the cell becomes hyperpolarized

A

True

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2
Q

A graded potential is triggered at the axon hillock by opening the chemically-gated channels found there

A

False

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3
Q

Action potentials are all or none and should be the same aplitude for a given neuron

A

True

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4
Q

Action potentials differ in their size/amplitude, just like graded potentials

A

False

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5
Q

K+ Leaves the cell, carrying its positive charge out

A

True

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6
Q

Graded potentials happen at the dendrites or cell body. Action potentials are triggered at the axon hillock

A

True

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7
Q

A hormone is secreted and its receptor is found in the cytoplasm of the target cell

A

It is lipophilic

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8
Q

Thyroid Hormone

A

It is an amine, TSH is actually a protein hormone made by the anterior pituitary. Therefore it is hydrophilic, binds to plasma membrane receptors, and does nto need to be trasnported bound to plasma proteins. TSH is released in response to TRH once TRH binds to endocrine cells of he anterior pituitary.

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9
Q

Why are the receptive fields of Merkel’s disks and Meissner’s corpuscles smaller than those of Ruffini’s endings and Pacinian corpuscles

A

Merkel’s disks and Meissner’s corpuscles are located in the upper layers of the skin. Do not respond to mechanical perturbations farther away

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10
Q

What happens to restore the resting membrane potential after depolarization

A

Potassium voltage-gated channels open, allowing potassium ions to flow out of the neuron

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11
Q

In action potentials, what happens right after calcium ions enter

A

Synpatic vesicles fuse with the plasma membrane and release their contents

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12
Q

What is the difference between the anterior and posterior pituitary

A

The posterior releases hormones from the hypothalamus and the anterior creates its own hormones which then get released into the blood

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13
Q

A person is experiecing low blood pressure, weight gain, fatigue, and a sensitivty to cold temperatures. What is the likely cause of these symptoms?

A

The hypothalamus is not producing enough thryotropin relasing hormone

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14
Q

Endocytosis

A

Transport for very large molecules (proteins)
Molecules get invaginated andmove in like a balloon

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15
Q

Exocytosis

A

Transport for very large molecules
Secretory vesicle fuses with plasma membrane allowing to leave membrane

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16
Q

Homeostasis

A

Ability of the body to maintain a relatively constant internal environment
Dynamic & self regulatory process

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17
Q

Negative Feedback Control System

A

Maintains homeostasis
Local control (cell/tissue) -> Small area of the body
Long distance control (Nervous system)

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18
Q

Intracellular fluid

A

Fluid found within cells
Most of body fluids are within cells

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19
Q

Extracellular fluid

A

Fluid found outside of the cells
Plasma - Fluid in blood vessels outside of cells
Interstitial fluid- fluid directy surrounding cells, not in blood vessels

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20
Q

Plasma membrane

A

Separates inside of the cell from outside

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21
Q

Different Ion concentrations inside & outside

A

Na,Cl, Ca -> higher in the extracellular fluid
K -> higher in the intracellular fluid

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22
Q

Cell Membrane

A

Composition of interstitial fluid = plasma
Composition of intercellular fluid =/ extracellular fluid

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23
Q

Function of the cell membrane

A

Physical separation from the environment
Regulation of exchange with the environment
Communication of the cell with its environment

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24
Q

Cell Membrane separates interstitial and intracellular fluid

A

Selectively permeable
Contains transport mechanisms which favor the ion distribution

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25
Q

Cell Membrane Structure
Glycerol/phosphate heads

A

Hydrophilic

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26
Q

Cell Membrane Structure
Fatty acid tails

A

Hydrophobic

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27
Q

Cell Membrane Structure
Glycoprotein/Glycolipid

A

Self recognition (Transplats/blood type)

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28
Q

Cell Membrane Structure
Choleterol

A

Fluidity (How fluid the membrane is, how much movement)

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29
Q

Cell Membrane Structure
Trans-membrane protein

A

Exchange, communicate, adhere, enzymes ( mediations, adhering cells)

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30
Q

Cell Membrane Structure
Peripheral protein

A

Structure, enzyme (binding skeleton structure, for cell shape)

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31
Q

Transmembrane Protein

A

Spans the entirety of the cell membrane
Permit the transport of specific substances

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32
Q

Functions of membrane proteins

A

Ion channels
Enyzymes
Receptros
Membrane carriers

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33
Q

Types of membrane transport

A

Simple diffusion
Diffusion through protein channels
Facilitate transpor
Active transport
Endocytosis/ exoctosis

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34
Q

Diffusion

A

Movement of a molecule
Hight to low concentration
Until it reaches equilibrium

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35
Q

Simple diffusion

A

Substances like O2, CO2 OH
Substances cross the membrane unassisted molecules unassisted
Molecules: hydrophobic lipid substances

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36
Q

Simple Diffusion factors

A

Lipid solubility (organic compounds that are insoluble in water)
Size (Substances too large will not cross)
Membrane composition

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37
Q

Rate of diffusion

A

Surface area (more molecules across if larger membrane surface area)
Thickness (How much area does the substance have to cross)
concentration gradiet (higher gradient higher speed)

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38
Q

Ficks law of diffusion

A

Rate of diffusion = SA Concentration gradient/membrane thickness
Higher SA & higher concentration gradient = higher the rate of diffusion
Higher membrane thickness = slower the rate of diffusion

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39
Q

Channel mediated diffusion

A

Ions & water travel because they are hydrophilic

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40
Q

Ion channels

A

Tunnels in the membrane
Allowing charged molecules to move across membrane

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41
Q

Ion Channels
Factors

A

Higher Concentration Gradient
Results in a Higher speed
Sodium high one side & Low on the other

(2) # Channels Available ⇒ Faster Transport
Size
Sodium, Potassium, and Calcium are all cation channels
May not fit in the same channel due to size
Charge
Transmembrane protein have amino acids with charges
Different charge = attraction & same charge = repel

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42
Q

Water mediated diffusion

A

Water moves through channels called aquaporins
Rate of diffusion
concentration gradient & # of channels available
If a cell does not have aquaproins it is impermeable to water

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43
Q

Facilitate diffusion/facilitate transport

A

Requires a transmembrane protein to change confirmation
Move and flip confirmation, transporting molecule to the other side
Contains large hydrophilic substances (Glucose & amino acids)

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44
Q

Carrier Proteins

A

Selective will saturate, can be inhibited
Will saturate
Controlled by lengths of change confirmation
Similar shape & size substances (drugs) can bind, can stop transport or hijack the carrier

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45
Q

Active Transport

A

Substances move against the concentration gradient (Requires energy, ATP)
Moving from where a substance is low to where a substances is high
Uses membrane carriers, it is specifc, saturates, and can be inhibited.

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46
Q

Sodium Potassium ATPase Pump
Active Transport

A

Sodium out, where it is high
Potassium in , where it is low
Maintains concentration gradient across the membrane
ATPase enzyme breaks down ATP to allow conformational change

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47
Q

Local Communication

A

Cells talk to themselves or nearby cells

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48
Q

Autocrine Communication

A

Cells talk to themselves
Cells release messenger to bind a receptor on plasma membrane
Triggers a cellular response

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49
Q

Paracrine communication

A

Chemical signal sent to nearby cells
Nearby cells will respond after picking up the message
Cells can communicate locally both chemically and physically

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50
Q

Gap Junctions

A

Tunnels called gap junctions
Creates a passage for small molecules
Quick wya for cells to communicate
Direct transfer of molecules through tunnels/bridges
2 membrane proteins interlock -> form connections called connexons

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51
Q

Osmosis

A

Movement of water down its concentration gradient
High solute concentration = low water concentration
Water crosses through channels called aquaporins
Channel mediated diffusion

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52
Q

Factors affecting osmosis

A

Permeability of membrane (Whether channels are present or not)
Concentration gradient of the solutes (higher concentration gradient = higher speed)
Osmotic pressure of the solution

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53
Q

Solues

A

What is dissolved in solution

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54
Q

Solvent

A

Water, what does the dissolving

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55
Q

Osmoles (Osm)

A

number of solute particles in a soluion

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56
Q

Osmolarity (Osm/L

A

number of osmoles in 1L of solution

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57
Q

High osmolarity

A

Lower the water concentration

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58
Q

Tonicity

A

Ability of a solution to cause osmosis across membranes

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59
Q

Isotonic

A

ECF has the same osmolarity as body fluids

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60
Q

Hypertonic

A

ECF has higher osmolarity than body fluids
Water leaves the cell
Causes shrivel

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61
Q

Hypotonic

A

ECF has lower osmolarity than body fluids
Water enter cell
Causing lyse/growth

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62
Q

Chemical & Electrical Gradient

A

Ions are influences by the charges around them (electrical driving froce)
Positivie ions attracted to a cell with negative charge (electrical gradient)
Ions move down their electrochemical gradient
Until reaching electrochemical equilibrium

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63
Q

Plasma membrane is permeable to potassium

A

Potassium is constantly leaking out of the cell
Causes the inside of the cell to have a negative charge

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64
Q

Chloride doesnt move in

A

Inside of a cell is negaive
Chloride is negative
It is repelled due to both having negative charge

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65
Q

Membrane Potential

A

Electrical poential of a cell membrane
Due to distribution of ions across membranes

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66
Q

Factors R-Membrane Potential

A

Permeability of membrane to various ions
Concenraion gradients of the ions

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67
Q

Sodium Potassium Pump

A

3 Sodiums ions out (Na+) and 2 Potassium ions in (-K+) cell
Maintians charge across the membrane
Preventing the leakage of poassium
Will maintain potassium inside the cell

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68
Q

Excitable cells

A

Rapidly change their membrane potential creates electrical signals
This electrical signal is an action potential
Action potential relies on ion channels called voltage-gated channels

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69
Q

The Neuron

A

Communication via propagation of an action potential
Release of neurotransmitters to carry the signal to the next neuron
The nervous system signals via electrical events within the neurons

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70
Q

Types of Ion channels

A

Mechanically Gated
Chemically Gated (Ligand-gated channels)
Voltage Gated

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71
Q

Mechanically Gated ion channel

A

Open gate due to deformation/stretch across the membrane
Changes shape of the membrane containing channel
Gate opens -> allowing flow of ions

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72
Q

Chemically Gated (Ligand-gated channels) ion channels

A

Respond to a chemical binding to he channel
Chemical binds-> gae opens-> ion flow

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73
Q

Voltage Gated ion channels

A

Respond to voltage change inside he cell
Volage change -> Gate open -> ion flow

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74
Q

Dendrites/Soma (Cell body)

A

input zone
Signals are combing to tell the neuron what is going on
Receiving signals in order for communication to take place
Electrical event called graded poential

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75
Q

Axon Hillock

A

Trigger zone
Decide whether signal gets passed onto the next cell
Threshold - if threshold is reached AP occurs

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76
Q

Axon

A

Conducting zone
Action potential travels here

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77
Q

Axon Terminal

A

Output zone
Signal gets passed onto the next neuron by releasing chemicals

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78
Q

Graded potential

A

Electrical response which varies in its magnitude/size
Dependant on the number of ion channels which open
Mechanical and Chemical channels are responsible for grade potentials

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79
Q

Average RMP for neurons

A

-70mv

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80
Q

Depolarization

A

Cell becomes more positive
Move towards threshold
Sodium coming into the cell

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81
Q

Repolarization

A

Cell returns to the RMP
Threshold -> mVolage change initaiting an action poential (-55mv)

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82
Q

Hyperpolarization

A

Membrane potential is more negative than RMP
Moves away from threshold
Potassium moving out

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83
Q

Graded potenial decay

A

Graded potentials don’t travel all the way down the axon like action potentials
Signal loses strength, due to leakage of charge across the membrane, loss of depolarization
Strength of the initial simulus

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84
Q

Action Potentials

A

All or none - threshold reached or not reached
Require depolorization to reach threshold (-55mv)
Only travel in one direction down an axon
Trigger release of neurotransmitters pass signal

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85
Q

Sodium causes action potentials

A

During RMP
Permeability to potassium ions is greater than sodium
Potassium leakage
During action potential
Sodium channels open (voltage gated ion channels)
Increase membrane permeability to sodium

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86
Q

Sodium Voltage gated channel

A

Two gates -> activation & inactivation gate
Inactivation gate is closed
Another action potential cannot fire in the same neuron
Absolute refractory period
Allows for undirectional travel/flow

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87
Q

Potassium Voltage Gated Channel

A

Only one gate -> activation gate
Slower to open/close than sodium voltage gated channel
Potassium leaving is what causes repolarization and hyperpolarization

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88
Q

Propagation of action poential

A

Action potential traveling down a neuron
Depolarize the axon until it reaches the axon terminal

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89
Q

Steps for Propagation

A

(1) Depolarizing Graded Potential
Movement of sodium
Caused by Mechanical/Chemical sodium gated channels

(2) Sodium rushes into axon hillock
Causes at least a +15mv change (from -70mv to -55mv)
Reaches threshold causing action potential

(3) Sodium travel to regions with resting membrane potential
Causing the next area of the axon to begin depolarization
Moving of sodium causes depolarization of the next sodium voltage gated channels

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90
Q

Action potentials uniderectional

A

Previous parts of the axon are in repolarization
INactivation gate is closed
Channel can ever open again until it is in RMP
This is called the absolute refractory period
Action potetials happen sequentially
Previous channel will always be in absolute refractory

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91
Q

Speed of action potential propagation

A
  1. Resistance of the axon membrane to ion leakage (myelination)
    Inceased ion leakage -> Slower action potential
  2. Diameter of axon
    Large dimater -> Faster conduction
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92
Q

Saltatory conduction

A

Myelin sheath acts like an insulation around axons
Spaces between each cell are the Nodes of Ranvier
Nodes of ranvier contain Sodium & Potassium volage channels
Depolarization only happens at Nodes of Ranvier
Rather than he whole axon
Propagation is faster with myelin
Action potentials are said to leap from node to node

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93
Q

Multiple Sclerosis (MS)

A

Central nervous system disorder
Damage to he myelin sheath
Disrupts he conduction of action potentials along axons
Autoimmune atack which attacks myelin causing damage

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94
Q

Chemical synapse

A

Location of chemical synapse
Axon terminal
Dendrites
Cell body

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95
Q

Presynaptic & Postsynaptic Neurons
Synpase

A

Axon terminal of the presynaptic cell
Plasma membrane of the postsynaptic cell

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96
Q

Presynaptic & Postsynaptic Neurons
Axon terminals

A

Axon terminals depolarization triggers
Calcium to enter the axon terminal through calcium voltage gated
This causes the release of neurotransmitters from synaptic vesicles

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97
Q

Presynaptic & Possynaptic Neurons
Neurotransmitters

A

Neurotransmitters cross the synaptic cleft
Transmit information to the postsynaptic cell by opening chemically-gated channels
Neurotransmitters are returned to axon terminals for recycling
Enzymes in synapse inactive neuroransmitters
Neurotransmiters diffuse out of the synaptic cleft

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98
Q

Events at postsynaptic neuron

A

Neurotransmitter bind receptors on the dendrites/soma of the postsynaptic neuron
Causes a graded potential, referred to as the post-synaptic potential
If there is depolarization of the postsynaptic neuron
Excitatory postsynaptic potential (More Sodium in)
If there is a hyperpolarization of the postsynaptic neuron
Inhibitory postsynaptic potential (More Potassium out, Or Chloride in)
Graded potentials are small
Single postsynaptic potential will not be enough to cause threshold

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99
Q

Principle of summation

A

EPSPS and IPSPS can happen simultaneously in a neuron
Decay happens as they travel towards the axon hillock
Graded potentials sum together at the axon hillock
Maybe threshold is reached maybe not

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100
Q

Central Nervous Sysem

A

Brian and spinal cord
Inegrative control centre

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101
Q

Peripheral Nervous System

A

Peripheral nerves (cranial and spinal)
Communication beween CNS and body

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102
Q

Sensory (Afferent) Division

A

Composed of sensory neurons
Conducts signals from receptors to CNS

103
Q

Motor (Efferent) Division

A

Composed of motor neurons
Conducts signals from CNS to effectors

104
Q

Autonomic Nervous System

A

Controls Involuntary responses

105
Q

Somatic Nervous System

A

Controls voluntary movement

106
Q

Sympathetic Division

A

Mobilises body systems
Flight or fight responses

107
Q

Parasympathetic Division

A

Conserves energy
Rest and digest responses

108
Q

Sensory Receptors

A

Photoreceptors
Mechanoreceptors
Chemoreceptors
Chemoreceptors
Nociceptors
Thermoreceptors
Osmoreceptors

109
Q

Photoreceptors

A

Wavelengths in the visible receptrum

110
Q

Mechanoreceptors

A

Mechanical energy (Stretch/deform/bending)

111
Q

Chemoreceptors

A

Chemical sensitive

112
Q

Nociceptors

A

Pain receptors, tissue damage
Free nerve endings that detect painful stimuli

113
Q

Thermoreceptors

A

Heat & Cold

114
Q

Osmoreceptors

A

Soluble concentration of osmotic activity

115
Q

Classes of sensory receptors

A

Complex neural receptors
Special senses receptors

116
Q

Complex neural receptors

A

Receptor is part of the neuron
Specialized nerve ending
Myelinated axon
Cell body
Responsible for olfaction somatic senses

117
Q

Special senses receptors

A

Specialized receptor
Synapse
Myelinated axon
Cell body

118
Q

Complex neural receptors

A
  1. stimulus
  2. alteration of receptor membrane (sodium channels open)
  3. Local current flow within receptor (Receptor potential - graded potential)
  4. Graded potentials change frequency of action potentials
  5. Action potential propagation to the CNS
119
Q

Special senses Receptors

A

Application of stimulus
Alteration of receptor membrane (sodium channels change)
Local current flow within receptor (Receptor potential- graded potential)
Release of neurotransmitter
Change in post-synaptic membrane potential
Change in frequency of action potentials
Action potentials propagate to CNS

120
Q

Action potentials vs receptor potentials

A

Action potential -> all or none, once initiated will flow down axon
Receptor potentials -> graded, differ in amplitude & dissipate

121
Q

Receptive field

A

Stimulus is stronger
The receptor potential is longer
Frequency of action potentials is higher
stronger release in neurotransmitter
A strong stimulus will excite more receptors

122
Q

Sense of Smell

A

Complex neural receptors
Primary sensory neurons in the olfactory epithelium
Synapse with secondary neurons in the olfactory bulb

123
Q

How do we perceive different smells?

A

We have 350 odor receptors
Combination of signals coming from neurons
Creates the perception of different smells

124
Q

Taste

A

Combination of 5 sensations; sweet, sour, salty, bitter, and umami
2000-5000 taste buds
Each of these taste buds contain 50-150 taste cells
Taste cell is non-neural epithelial cell
Taste cells are special senses receptors

125
Q

Sensory Physiology Structures

A
126
Q

Cortical Anatomy/function of each lobe

A
127
Q

Somatic senses

A

Touch
Proprioception -> Awareness of body movement and location in space
Temperature
Nociceptors (pain)

128
Q

Similarities B/W somatic senses

A

All receptors are neurons
Receptors are located at skin and viscera
Secondary neurons are in the spinal cord
Medulla synapse onto tertiary neurons in he thalamus
Information is sent to the somatosensory cortex

129
Q

Somatic sensory receptors are mechanoreceptors

A

Sensitive to physical distortion of skin

130
Q

Types of mechanoreceptors

A

Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disks
Ruffini’s endings

131
Q

Pacinian corpuscles

A

Deep
Sense of vibration of skin

132
Q

Meissner’s corpuscles

A

Superficial
Responds to fluter & stroking movements

133
Q

Merkel’s disks

A

Superficial
Responds to steady pressure & texture

134
Q

Ruffini’s endings

A

Deep
Responds to skins stretching

135
Q

How do mechanoreceptors differ

A

Adaption rate (Becoming used to the presence of a receptor)
Pacinian and Meissner’s corpuscies are rapidly adapting
Merkel’s disks and Rufinis endings are slowly adapting
Receptive field size
Size- merkel (touch) and meisner (touch)
Ruffini’s (stretch) and Pacinian (vibration)

136
Q

Tactical Acuity

A

Two point discrimination
Smallest seperation beween two points on the skin that is perceived as two points rather than one
Regions with high tactile acuity have small receptive fields

137
Q

Sensory Pathways for somatic senses

A

The somatosensory cortex is located in the parietal lobe
Sitmuli from the left side is going to the right side of the brain

138
Q

Spinal cord

A

Segments of the spinal cord receive sensory input from specific regions
Dermatome -> Area of the spinal cord that receives sensory information from an area of the skin
Dorsal root – sensory
Ventral root – motor

139
Q

Primary Somatosensory Cortex

A

Primary motor cortex is located on the precentral gyrus
Proximity allows for sensory information to quickly trigger motor actions

140
Q

Somatosensory Cortex somatotopy

A

Each body part is represented in a specific area of the somatosensory cortex
Amount of space on the somatosensory cortex devoted to each part is proportional to the snesitivity of that part
The larger the sensitivity the more space in the somatosensory cortex

141
Q

Temperature

A

Sensed by free nerve endings in the epidermis
Thermoreceptors in the brain (cruicial for homeostasis)
There are both warm and cold receptors
They present slow adaption between 20-40 degrees C but they don’t adapt outside this range

142
Q

Pain

A

Sensory and emotional experience
Actual or poential tissue damage
Nociceptors are free nerve endings that detect painful stimuli

143
Q

Pain Fibers

A

Ab (beta)
Respond to mechanical stimuli (touch)
Large & myelinated
Ad (Delta)
Respond to intense mechanical or mechano thermal stimuli, fast pain
Small & myelinated
C
Respond to heat, cold, slow pain
Small & unmyleninated
Thermoreceptors and Noiceceptors
Nociceptors have a higher threshold than thermoreceptors

144
Q

Vision

A

Involves about half of our cerebral cortex
Light is an electromagnetic energy emitted in the form of waves

145
Q

Wavelengths

A

Extremely short wavelengths -> Gamma rays
Long wavelengths -> Radio waves
Visible light -> 400-700nm

146
Q

Pupil

A

Hole in the center

147
Q

Iris

A

The colour of you reye, regulates size of pupil

148
Q

Cornea

A

Clear sheet in front of pupil and iris

149
Q

Sclera

A

The white of your eye (majority of eyeball)

150
Q

Conjunctiva

A

Inside of eyelid

151
Q

Extraocular eye muscles

A

Moves eye

152
Q

Optic nerves

A

Carries signal to brain

153
Q

Fundas

A

Rear region of eye
Central retinal artery & vein

154
Q

Optik disk

A

Where optic nerve exits the retina (blindspot)

155
Q

Macula

A

Center of visual field

156
Q

Fovea

A

Center of macula (highest spatial resolution

157
Q

Retinal processing

A

(1) Light first makes way through
Axons of optic nerve, ganglion cells, amacrine cells, bipolar cells, horizontal cells, gets reflected than activates photoreceptors
(2) Photoreceptors project to bipolar cells (depolarized)
Release neurotransmitter
Initiate action potentials on the ganglion cell
(3) Photoreceptors and bipolar cells are graded potential
Whereas the ganglion cell where action potential occurs
The amacrine and Horizontal cells which help integrate visual signals through lateral interactions

158
Q

Photoreceptors

A

Convert light energy into receptor potentials

159
Q

Rods

A

Highly sensitive to light
Responsible for vision at low light levels

160
Q

Cones

A

Less sensitive to light
Three types of cones
Respond to RBG wavelengths

161
Q

Light Transudction in the dark

A

Photoreceptors are leaky
Sodium & calcium to pass through channels in the plasms membrane
Depolarization of photoreceptors
Triggers neurotransmitter that inhibits activation of the bipolar cell

162
Q

Light Transduction in the light

A

Closing of sodium and calcium channels
Hyperpolarization of rod and cone cell
Less neurotransmitter release
Lesser inhibition allowing the bipolar cell to depolarize

163
Q

Light Transudction recovery phase

A

Sodium and clacium channels do not open immediately
Reduced release of neurotransmitter
This is why there is a lingering sensation of bright stimulus

164
Q

Specialization of the fovea

A

Fovea is responsible for detailed vision, has the highest acuity
Photoreceptors in the fovea are exclusively cones
Cells overlying the fovea are pushed aside
Allowing light to strike the photoreceptors directly
Small receptive field, having much more sensation

165
Q

Receptive fields of the retina

A

Peripheral portions of the retina have many photoreceptors
Converge on a ganglion cell (large receptive fields) (Amplifying effect) (large reception of light)
In fovea few photoreceptors converge on a ganglion cell, allowing for a smaller receptive field

166
Q

Types of eye movements

A

Saccades
Smooth pursuit
Vestibulo-ocular reflex
Vergence

167
Q

Saccades

A

Rapid
Jerky eye movements that quickly move the line of sight
To scan a face or read

168
Q

Smooth pursuit

A

Smooth eye movements
Keep the image of a moving object of interest on the fovea
A flying bird

169
Q

Vestibulo-ocular reflex

A

Stabilizes the eye during head movement
Uses sensory input from the semicircular canals

170
Q

Vergence

A

Used when the object of interest is approaching or moving away

171
Q

Retina Projects to visual cortex

A

Infomration from the left visual field is sent to the right visual cortex
Fibers from the nasal part of either eye cross over at the optic chiasm
fibers from the temporal portion of the right eye and the nasal portion of the left project to the lateral geniculate nucles on the right side
Synapse in the LGN visual signals continue to the primary visual cortex

172
Q

Sound

A

Pressure wves generated by vibrating air molecules
Alternately compressed and released

173
Q

Outer ear

A

Auricle (Pinna)
Auditory canal
Tympanic membrane

174
Q

Auricle (pinna)

A

Moveable in some animals
Directs the sounds into the ear

175
Q

Auditory canal

A

External auditory meatus

176
Q

Middle Ear

A

Ossicles
Eustachain ube

177
Q

Ossicles

A

Three small bones
Transfer the sound from an external environment to the inner ear

178
Q

Tympanic membrane

A

Ear drum
Separates the external ear from them middle ear

179
Q

Innear ear

A

Oval window
Cochlea
Vestibular apparatus

180
Q

Ear canal

A

Funnels and conducts the sound to the middle ear

181
Q

Eustachian tube

A

Connects the middle ear with the pharynx and helps equilibrituate the middle ear pressure

182
Q

Oval and round window of ear

A

Separates the inner ear (filled with air) and the cochlea ( filled with fluid)

183
Q

Cochlea

A

Structures that convert physical motion of the ears structures into a neuronal response

184
Q

Vestibular apparatus

A

Responsible for our balance

185
Q

Sound transudction

A

(1) Sound waves strike the tympanic membrane and become vibrations
Sound wave energy is transferred to three bones of the middle ear
Ossicles (bones) vibrate

(2) Ossicles attached to the membrane of the oval window
Vibrations of the oval window create fluid waves within the cochlea

(3) Cochlea — Where sounds become action potentials
Fluid waves initiated at the oval window
Waves push on the flexible membrane of the cochlear duct

(4) Pressure from the wave releases at the round window
Mechanoreceptors within the cochlear duct transduce movement into action potentials on the auditory nerve

186
Q

Strucures within the cochlea

A

The cochlea duct contains the organ of Corti
Organ of corti sits on the basilar membrane is covered by the tectorial membrane
These membranes are flexible tissues
Move in response to movment of perilymph inside the vestibular duct
Displacement of the basilar and tectorial membranes
Receptor potentials to occur in hair cells located in the organ of corti
Receptor potentials are created when the hair cells begin to bend

187
Q

Hair cells

A

Basilar membrane vibrates the hair cells move back and forth

(1) Bending the biggest hair cell opens mechanically linked ion channels
Depolarizing the hair cell
Release of neurotransmitter increasing the action potential frequency on the afferent nerve

(2) Bending in the opposite direction hyperpolarizes the hair cell
Decreasing the release of a neurotransmitter
Fewer action potentials

188
Q

How is frequency of sound mapped

A

Tonotopy
Fluid waves travel along the basilar membrane

189
Q

Basilar membrane

A

Different part of the basilar membrane are different frequencies
narrow, thick base tuned for high frequencies
Middle portion responds to medium frequencies
Apex, resonds to the low frequencies

190
Q

Coding of sound intensity

A

Increased rate of firing on a single nerve fiber
Multiple sets of neurons with different thresholds
Recruitment of additional neurons as loudness increases

191
Q

Auditory pathway in the CNS

A

Ears -> Medulla (where nerves cross body midline) -> Midbrain (projections to cerebellum) -> Thalamus -> Auditory cortex

Different groups of neurons in the primary auditory cortex encode different frequencies of sound

192
Q

Sound localization

A

Sound takes longer to reach one ear than the other -> Known as interaural timing differences
Timing differences can be very small, they are sensed by coincidence detectors in the brainstem
The sound is going to be louder due to an acoustic shadow produced by the head -> Interaural intensity differences

193
Q

Types of hearing loss

A

Conductive
Sensorineural
Central

194
Q

Conductive hearing loss

A

Sound is unable to be transmitted through th eouter or middle ear. A mechanical defect
Loud sounds rupture ossicle
Ear war
Infection fills middle ear with fluid

195
Q

Sensorineural hearing loss

A

Damage to structure of inner ear that affects hair ells, or to auditory erve (nerve deafness). A transductile or peripheral defect
Loud sounds damage organ of corti
Oxtotoxic drugs damage hair cells
Presbycusis (old age hearing) degenerates cochlea

196
Q

Central hearing loss

A

Damage to auditory pathways upstream from cochlea. A defect in the central nervous system
Tumours, stroke in the central auditory pathways

197
Q

Motor unit

A

A single motor neuron innervates a large number of muscle fibers
Made of motor neuron + all muscle cells (fibers) that it innervates

198
Q

Muscle Force

A

Force is increased by recruitment of more motor neurons and increased activity of motor neurons
Motor nuerons have phasic and tonic responses

199
Q

Phasic

A

Bursting of action potentials when eye moves

200
Q

Tonic

A

Sustained of action potentials sustains contraction

201
Q

Muscle spindles

A

Alpha (a) motor neuron
Innervates extrafusal muscle fibers
Extrafusal fibers create the force
Extrafusal fibers are normal contractile fibers

Gamma (y) motor neurons
Innervate the intrafusal muscle fibers
Tonically active 1a afferent sensory neurons wrapped around intrafusal fibers (sense stretch of the intrafusal fibers) and send information the CNS

202
Q

Contraction of intrafusal/extrafusal fibers

A

Gamma motor neurons fire, and contract the intrafusal fibers
Alpha motor neurons fire and contract the extrafusal fibers

203
Q

Golgi Tendon Organ

A

Sensory receptors that send information the CNS about muscle tension mechanoreceptor
Sensory receptors are attached to 1b afferent sensory neurons
Links muscle and the tendon
Consists of sensory nerve endings interwoven among collagen fibers
Muscle passively stretched (someone pulls on your forearm)
Activity in muscle spindle increases
Activity in golgi tendon organ goes up
Muscle actively contracts
When extrafusal muscle fibers contract by activation of motor neurons,
Spindles unload and decrease their charge rate
Golgi tendon organ firing increases

204
Q

Group 1a

A

Primary afferents
Supply all three types of intrafusal fibers

205
Q

Group 1b

A

Afferent fibers
Branch extensively and wrap around the many collagen fibers that compose the golgi tendon organ

206
Q

Alpha-gamma activation

A

When the muscle actively contracts
Alpha motor neurons fire
Extrafusal fibers contract, and the intrafusal fibers slack
Activity on the muscle spindles will decrease
If only alpha motor neurons were activated only extrafusal fibers contract

207
Q

Alpha-gamma coactivation

A

Both extra and intrafusal fibers contract together
Tension maintained and muscle spindles can still signal changes in length

208
Q

Stretch reflex

A

Load added to muscle = causes muscle to stretch
Muscle and muscle spindle stretch
Muscle spindle afferents to fire more frequently
Alpha motor neuron projects to the muscle
Increases activity towards muscle
Causing contraction and maintain arm position

209
Q

Patellar tendon reflex/knee jerk reflex

A

Tapping the patellar tendon streches the quadriceps femoris
Muscle spindle in quadriceps femoris stretch
Activating 1a afferent to fire action potentials
1a afferent synapse on alpha motor neuron to quadriceps femoris
Muscle contracts and swings leg forward
Collateral 1a afferent excited an inhibitory interneuron in the spinal cord
Inhibitor interneuron inhibits alpha neuron to antagonistic muscle, relaxing it so the leg can swing and extend out

210
Q

Organization of spinal cord

A

The medial parts of the spinal cord gray matter are involved in primary control of posture
The lateral pars are involved in the fine control of distal extremities

211
Q

Primary motor cortex

A

Motor map shows the same disporoportions as somatotopic map in the primary somatosensory cortex of the postcentral gyrus
Musculature used in task requiring fine motor control, occupy a larger space in the primary motor cortex then musculature requiring less precise motor control

212
Q

Corticospinal tract

A

Primary pathway that leaves the motor cortex to innervate motor neurons in the spinal cord
Left side of body is controlled by right motor cortex and right side conrolled by let motor cortex (mostly)
Axons cross over either the brainstem or spinal cord allowing for this to happen

213
Q

Population coding in the motor cortex

A

Cortical motor neurons are directionally tuned
Individual motor neurons cannot precisely specify the direction of an arm because they are tune broadly
Movement direction can be decoded by a population of neurons

214
Q

Brain Machine Interfaces

A

Resoration of motor functions for patients with spinal cord damage or patients with brainstern damage
Invasive BMI’s record neural activity with implanted microelectrodes and use population decoding algorithms to control prosthetic devices, computers, or patients muscles

215
Q

Motor cortex

A

Projects to motor neurons in the spinal cord which project to the muscle. This results in movement
Receives input from cortical association areas, the basal ganglia, and the cerebellum

216
Q

Cerebellum

A

Sits underneath the cortex, on top the brain stem
Sees differences between an intended action and actual action
Gets input from the cerebral coftex, brainstem and spinal cord and sends projects back to them forming a bast loop
Modification of synapses in this loop is crucial for motor adaptation and learning

217
Q

Cerebral deficits/lessons

A

Typical cerebellar diseases include dysmetria and decomposition of movements

218
Q

Cerebellar disease symptoms

A

Wide gait, instability of trunk, irregular staggering steps
Results in lateral veering or falling if severe
Can also be seen with a severe loss of proprioception

219
Q

Projections to the cerebellum

A

Cerebral cortex:Synapse in the pontine nuclei of the pons first, which project up into the cerebellum
Direct sensory input: Vestibular, muscle spindles, other mechanoreceptors
Other brain stem inputs:inferior olive and the locus coeruleus - send modulatory inputs for learning and memory

220
Q

Output of the cerebellum

A

Cerebellar cortex projects to the deep cerebellar nuclei and onto the motor cortex (via the thalamus)
Cortical areas that project to the cerebellum, and the cerebellum projects back to them

221
Q

Cerebellar circuit

A

There are two types of input circuits
Mossy fibers: synapse on granule cells, axons of granule cells form parallel fibers which synapse on purkinje cells
Climbing fibers: synapse directly on purkinje cells
mossy and climbing fibers excite purkinje cells

222
Q

Purkinje cells

A

Provide output of the cerebellum through inhibitory synapses
One pukinje cell can receive input from over a million granule cells (convergence) but only one climbing fiber

223
Q

Basal Ganglia

A

Regulating and planning movements
Receives input from the cortex and projects back to the cortex through the thalamus
Circuit influences brain stem outputs and ultimately neurons of the spinal cord ( Crucial role in planning movements)

224
Q

Organization of the basal ganglia

A

4 interconnected nuclei found in the white matter fo the cerebrum
striatum
Golbus pallidus
Substantia nigra
Subthalamic nucleus

225
Q

Inputs to the basal ganglia

A

Caudate nucleus and the putamen are the input nuclei of the basal ganglia
Almost all cortical areas project to the acaudate or putamen, except primary visual and auditory cortex (temporal and occipital lobe)
Caudate and the putamen receive dopaminergic input from the substantia nigra pars compacta in the midbrain (Increase or increase efficacy of other neurons)

226
Q

Outputs of basal ganglia

A

Caudate and the putamen send output through the globus pallidus and the substantia nigra pars reticulata
The globus pallidus can be further subdivided into an external segment and internal segment for motor control
Output is sent on the superior colliculus (eye movement projection), subthalamic nucleus, the thalamus, and eventually back to the cerebral cortex

227
Q

Activity in basal ganglia

A

Motor neuron cortex excites the putmen neuron
The putamen inhibits to the globus pallidus internal segment neuron (silencing its tonic discharge rate)
The globus pallidus internal segment enuron projects to the thalamus neuron and allows it to fire AP since its tonic inhibition is inhibited
Thalamus neuron projects to the motor cortex neuron

228
Q

Indirect and direct pathways

A

Dopamine 1 receptors increase activity of putamen, but Dopamine 2 receptors inhibit the putamen
The direct pathway facilitates movements
The indirect pathway inhibits movements
Excitatory or inhibitory effect on motor cortex depends on the balance between the direct and indirect pathway

229
Q

Parkinson’s disease

A

Cells in the substantia nigra pars compacta die
Patients los dopaminergic neurons of the substantia nigra pars compacta
Deficits appear when the patient loses 80% of dopaminergic neurons

230
Q

Parkinson’s disease
Typical Symptoms

A

Tremor at rest
Slowness of movement
Rigidity of neck
Minimal face expression

231
Q

Parkinson’s disease
Motor Symptoms

A

Rigid gait
stooped forward
hypokinesia
Slow shuffling steps
Slow movement initiation

232
Q

Process of Parkinsons

A

Cells of substantia nigra pars compacta die, less dopamine release

Less inhibition to putamen cells, meaning it is more actively inhibiting the Globus pallidus external segment

Because there is an increased inhibition from the Putamen to the globus pallidus external, we see a reduced inhibition of the globus pallidus internal segment

Globus pallidus external segment less efficiently inhibits the subthalamic nucleus, meaning there is an increased excitatory effect from the globus pallidus internal segment

This overall excitation of the globus pallidus internal segment from all directions, causes an increased inhibition of the Thalamus leading to a significantly decreased excitation to the motor cortex

233
Q

Treatments of parkinsons

A

Basal Ganglia Structures that can be removed to help Parkinsons are; Either the globus pallidus internal segment or the subthalamic nucleus

234
Q

Four functions of membrane proteins

A

Ion channels
Enzymes
Receptors
Membrane carriers
Structural Function

235
Q

Chemical Gradients

A

Molecules tend to move from areas where they are in high concentration to areas where they are in low concentration. There they move down their concentration gradient

236
Q

Electrical Gradients

A

Recall that many of the solutes in our body carry a change. Positively charged ions move towards negatively charged areas or down their concentration gradient

237
Q

Two factors that affect the cell’s membrane potential

A

The concentration gradients of different ions across the membrane
The permeability of the membrane to those ions

238
Q

Graded potential properties

A

Occur in the soma or dendrites of a neuron
Can be depolarizing or hyperpolarizing
Can be the result of opening mechanically gated or chemically gated ion channels by a stimulus
Graded because the size of amplitude of the electrical event will be directly proportional to the stimulus strength (large stimulus = large graded potential)

239
Q

Neurotransmitter is removed

A

Neurotransmitters are returned to axon terminals for recycling
Enzymes in he synapse inactivate neurotransmitters
Diffuse out of the synaptic cleft

240
Q

Pituitary Gland

A

Pea size gland that has a crucial function essential for life
The site where several hormones are released which control reproduction, body fluid volume, metabolism, growth, adapting to stress, and a variety of other functions

241
Q

Posterior Pituitary

A

Releases two peptide hormones, oxytocin and antidiuretic hormone. Produced by neurons inthe hypothalamus

242
Q

Antidiuretic Hormone

A

Vasopressin, a hormone hat acts on the kidneys to conserve water and regulate our blood volume.

243
Q

Anterior Pituitary

A

Release numerous hormones from endocrine cells found there in response to stimulation from hormones released by the hypothalamus

244
Q

Thyroid Gland

A

Largest endocrine glands, butterfly shaped gland tha is located in the lower neck region, just below the larynx.

245
Q

Hyperthryoidism

A

Producing too much thyroid hormone

246
Q

Hypothyroidism

A

Deficiency in thyroid hormone

247
Q

Adrenal gland

A

Two major regions to the adrenal gland, the outer adrenal cortex and the inner adrenal medulla.

248
Q

Adrenal cortex

A

all hormones made by the adrenal cortex are steroid hormones

249
Q

steroid hormones

A

Androgen, estrogens, progestins, mineralocorticoids, and glucocorticoids

250
Q

Cortisol

A

Carabolic hormone, geneerally causing the breakdown of macromolecules, such as proteins, into their basic building blocks

251
Q

Aldoserone

A

Mineralocorticoid because it affects the transportation of ions by the kidneys. The main stimulus for release is though a complex pathway of different proeins called he renin-angiotensin-aldosterone system

252
Q

Adrenal Medulla

A

Releases a chemical mediator called epinephrine, as well as norepinephrine and dopamine.

253
Q

Pancreas

A

Two major hormones, insulin and glucagon

254
Q

Dermatome

A

Area of the skin that is mainly supplied by afferent nerve fibres from a single dorsal root of the spinal nerve

midterm (4 decks)

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