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biol 364 > respiration pt1 > Flashcards

respiration pt1 Flashcards

1
Q

Why can unicellular and small multicellular organisms rely on diffusion for gas exchange?

A

they have high surface area to volume ratio
larger size limits surface area available for diffusion and increases the diffusion distance

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2
Q

what do larger organisms rely on for gas exchange (2)

A

bulk flow and diffusion

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3
Q

what does bulk flow refer to during gas exchange in larger organisms

A

ventilation (moving air/water over respiratory surface [gill/lung])
circulation (transport of gases in the circulatory system)

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4
Q

What is the Fick equation?
How is it used to understand gas diffusion rate?

A

Rate of diffusion = D * A * (dC/dx)
D= diffusion coefficient
A= area of the membrane
dC/dx= gradient
tells us how rate of diffusion changes if area of membrane or gradient is changed

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5
Q

what is convection, diffusion, and perfusion?

A

convection: bulk flow of air/water towards membrane (ventilate to achieve convection)
diffusion: molecules passing through the membrane
perfusion: blood transport the acquired materials away

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6
Q

modified Fick equation that tells us oxygen consumption or transfer rate

A

MO2= (K*A(PO2 a/w- PO2b))/ t
MO2 refers to oxygen consumption or transfer rate
K= Krogh’s diffusion constant (diffusion coefficient * solubility)
A= surface area of the barrier
PO2 a/w- PO2b= partial pressure gradient for oxygen between blood and air/water
t= thickness of the barrier

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7
Q

what characteristics of a barrier maximize the rate of gas diffusion?

A

large surface area, low thickness, larger partial pressure (by increase in ventilation)

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8
Q

What does Dalton’s Law of partial pressure state?

A

sum of all partial pressures is equal to the total pressure of the mixture
(in a gas mixture each gas exerts its own partial pressure-> exerts independently)

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9
Q

What is the driving force for gas diffusion

A

partial pressure

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10
Q

PO2 at sea level

A

PO2= 159mmHg

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11
Q

what must first happen to the gas molecules in the air in order to diffuse into a cell?

A

first dissolve in liquid

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12
Q

What does Henry’s law state?

A

the concentration of gas in a liquid is proportional to its partial pressure
[G]= Pgas * Sgas
Pgas= partial pressure of the gas
Sgas= solubility of the gas

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13
Q

Why is there a higher [O2] in air than water at the same PO2?

A

because solubility of O2 is higher in air

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14
Q

what happens to O2 solubility in warmer water?

A

solubility is lower

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15
Q

relationship between CO2 and O2 solubility in water

A

CO2 is 30 times more soluble than O2 in water

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16
Q

Boyle’s law + equation

A

P1V1= P2V2
for gases only bc liquids are virtually incompressible

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17
Q

rate of flow (Q) is determined by

A

Q= (delta)P/R
pressure difference inside and outside
R= resistance

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18
Q

why do cilia of pond snail embryos beat faster in hypoxic conditions?

A

to mix things up, increase circulation of new gases to surroundings, enhance O2 delivery to embryo

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19
Q

why do boundary layers exist?
what effects does the boundary layer have?

A

boundary layers exist at a cell surface due to resistance which reduces flow rate
lower flow rate-> medium poorly mixed at cell surface-> low PO2 diff. across membrane-> low diffusion

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20
Q

animals more than a few millimeters thick use one of which 3 respiratory strategies?

A

CIRCULATING THE EXTERNAL MEDIUM THROUGH BODY (sponges, insects)
DIFFUSION OF GASES ACROSS THE BODY SURFACE ACCOMPANIED BY CIRCULATORY TRANSPORT (cutaneous respiration, skin must be thin and moist, most aquatic invertebrates, some amphibians, eggs of birds)
DIFFUSION OF GASES ACROSS A SPECIALIZED RESPIRATORY SURFACE ACCOMPANIED BY CIRCULATORY TRANSPORT (gills+lungs-> thin+ moist, vertebrates)

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21
Q

3 types of ventilation

A

NONDIRECTIONAL (medium flows over surface in unpredictable pattern, maybe some small animal stuck on rock in tidal zone)
TIDAL (medium moves in and out of chamber)
UNIDIRECTIONAL (fish)

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22
Q

from where do gases enter the blood

A

at the respiratory surface

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23
Q

how can relative movement of blood and respiratory medium at respiratory surface affect efficiency of gas exchange?

A

contact time
thickness of membranes
directions of flow

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24
Q

what does little PO2 difference between (exhalant) medium and blood at respiratory surface (just before blood leaves respiratory surface) indicate?

A

little effect of the thickness of respiratory epithelium and/or boundary layer-> gas exchange very efficient

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25
Q

why is exhalant medium PO2 lower than inhalant medium PO2?

A

PO2 decreases bc O2 is taken by blood from the medium

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26
Q

under optimal conditions, blood PO2 will approach…

A

exhaled air PO2

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27
Q

3 ways blood can flow relative to the flow of the medium with unidirectional ventilation

A

concurrent
countercurrent
crosscurrent

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28
Q

disadvantage of concurrent flow

A

medium PO2 start high, blood PO2 start low (high PO2 diff.)
as O2 is taken from medium, PO2 decreases
blood PO2 approaches the lowered PO2 of medium

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29
Q

advantage of countercurrent flow

A

blood PO2 start low, medium PO2 start high
counter current so low O2 medium lines up w/ low O2 blood, high O2 medium lines up w/ high O2 blood
O2 diffusion can occur when medium is high PO2 or low PO2 as blood PO2 is lower
blood PO2 approaches PO2 of fresh O2 filled medium

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30
Q

advantage of crosscurrent flow

A

blood PO2 start low, medium PO2 start high
diff. capillaries calibrate w/ medium of diff. PO2 levels
some blood equilibrates to high PO2 then leaves system
mixture of high PO2 and low PO2 blood allows blood PO2 level higher than exhalent medium

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31
Q

advantages of having specialized respiratory surfaces (gills and lungs) (6)

A

allows rest of skin to be thick/protected
can be protected in body cavity; allows it to remain moist (can select what is breathed in)
high effective surface area
highly vascularized (low diffusion distance)
highly ventilated (w/ control over ventilation rate)
synchronized w/ circulatory system

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32
Q

O2 solubility in air is 30 times greater than O2 solubility in water, how does this impact O2 uptake?

A

to get the same amount of O2, 30 times more water needs to be ventilated than air

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33
Q

water breathers are geared for O2 uptake and don’t need to worry about CO2 excretion because…

A

CO2 solubility in air is similar to water, for the amount of water they use for O2 uptake, water breathers will have enough water to get rid of CO2

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34
Q

Water is more dense and viscous than air. What are the implications for cost of ventilation?

A

need to work harder/ use more energy to move the viscous medium. unidirectional ventilation helps them save energy

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35
Q

how do sponges and cnidarians facilitate gas exchange/ventilation?

A

circulate water through an internal cavity using flagella, gases diffuse directly in and out of cells

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36
Q

how do echinoderms (sea cucumbers) facilitate gas exchange/ ventilation?

A

use muscular contractions to pump water tidally into respiratory tree

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37
Q

how do molluscs facilitate ventilation?

A

contractions of mantle pump water unidirectionally past gills, blood flow is counter current

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38
Q

how do jawless fishes (lamprey and hagfish) facilitate ventilation/ gas exchange?

A

use muscle to pump water through respiratory cavity, water enters mouth and leaves through gill opening
ventilation is unidirectional
blood flow is countercurrent

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39
Q

what changes can agnathans (lamprey) make to their ventilation/ gas exchange when feeding or not feeding?

A

not feeding: similar to hagfish, water flow from mouth to gill and exit through gill opening (unidirectional)
feeding: mouth attached to prey, ventilation tidal through gill openings

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40
Q

steps of ventilation in elasmobranchs

A

expand buccal cavity
draw water into buccal cavity via mouth and spiracles
mouth and spiracles close
muscle around buccal cavity contract->force water past gills and out of gill slits

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41
Q

in elasmobranchs, blood flow is ____ to medium

A

countercurrent

42
Q

what is a special method of ventilation that active teleost (boney) fish can use?

A

ram ventilation (swimming w/ mouth open, swimming musculature results in unidirectional water flow over the gills, energetically efficient bc just using swimming energy)

43
Q

what is special for respiratory structures and ventilation in terrestrial crabs?

A

gills are stiff-> don’t collapse in air
branchial cavity itself is highly vascularized-> act as primary site for gas exchange

44
Q

advantage of the tracheal system in insects

A

air-filled tubes open to outside via spiracle-> O2 directly diffuses into cells
gas diffuse over very small distances
no need for circulatory system for O2
takes advantage of high O2 conc. in air

45
Q

disadvantage of the tracheal system in insects

A

uses a lot of space

46
Q

how does insect ventilation work

A

contraction of abdominal muscles or movements of thorax
can be tidal or unidirectional
expansion and contraction of tracheae

47
Q

5 types of respiratory structures in air breathing fishes

A

reinforced gills that do not collapse in air
highly vascularized mouth or pharyngeal cavity
highly vascularized stomach or intestine
specialized pockets of the gut
lungs
(ventilation of air breathing organ is tidal using buccal force similar to other fish)

48
Q

where do O2 uptake and CO2 excretion occur in Arapaima gigas?

A

O2 uptake from air breathing organ
majority of CO2 excretion occurs across the gills

49
Q

steps/phases blood goes through in water breathing fish

A

-> heart pumps deoxygenated blood to gills
-> blood oxygenated at gills
-> travel to tissues
-> deoxygenated blood goes back to heart

50
Q

steps/phases blood goes through in air breathing fish in normal conditions

A

-> deoxygenated blood passes through heart
-> pumped to gills
-> oxygenated at gills
-> blood travels to tissues
-> deoxygenated blood goes back to heart

51
Q

steps/phases blood goes through in air breathing fish in hypoxic conditions

A

-> deoxygenated blood passes through heart
-> pumped to gills
-> blood goes to lung and oxygenated there
-> blood goes back to heart
-> blood goes through non-functional gill arches
-> blood travels to tissues
-> deoxygenated blood goes back to heart

52
Q

why do air breathing fishes still have functional gill arches

A

gills are still important for ion regulation and acid-base balance

53
Q

why does oxygenated blood coming from the lung pass through non-functional gill arches

A

if oxygenated blood go through functional gill arches in hypoxic water-> animal will lose O2 from blood to water

54
Q

why do deoxygenated blood always need to go through functional gill arches?

A

for CO2 removal

55
Q

what is the gas exchange site on gills and lungs in birds and lungs in mammals called

A

lamellae
parabronchi
alveoli

56
Q

Types of respiratory structures in amphibians (3)

A

Cutaneous respiration
External gills (juvenile salamanders and axolotls)
Simple bilobed lungs (more complex lungs in terrestrial frogs and toads)

57
Q

type of ventilation in amphibians

A

Tidal using buccal force pump

58
Q

Type of ventilation in reptiles

A

Tidal ventilation
Rely on suction pumps to create negative pressure for aspiration
Separation of feeding and respiratory muscles
Mechanisms to change volume of chest cavity

59
Q

Characteristic of bird lungs

A

Stiff, change little in volume
Between posterior and anterior air sacs
Fresh air from outside goes to posterior air sac first

60
Q

Air flow and blood flow through parabronchi

A

Unidirectional air flow
Crosscurrent blood flow

61
Q

Two main parts of respiratory tract in mammals and what they include

A

Upper respiratory tract: mouth, nasal cavity, pharynx, trachea
Lower respiratory tract: bronchi and alveoli (gas exchange surface)

62
Q

Each alveoli is wrapped by…

A

Capillary network

63
Q

Explain the pleural sac of mammalian lungs

A

Fluid-filled balloon that surrounds the lung
Pleural membrane encloses pleural cavity, which is filled with pleural fluid
Outside of pleural membrane is attached to rib cage

64
Q

How does the pleural sac help keep lung expanded

A

Intrapleural sac pressure is subatomic (slightly negative bc chest + lung elastic recoil pulls in opposite directions)
Helps pull wall of lung to chest wall

65
Q

What happens when the pleural membrane is punctured

A

Draws air into intrapleural space bc of negative pressure
Pleural cavity expands
Lung collapses

66
Q

Work required to breathe is influenced by (3)

A

Lung compliance (high compliance = easy to stretch)
Lung elastance (high elastance = easy to return to original shape)
Airway resistance

67
Q

What does fibrotic lung disease do

A

Scarring thickens walls of lungs
Reduces lung compliance
Make inhalation difficult

68
Q

Impact of surfactants to lung compliance

A

Aqueous fluid will make alveoli stick together bc of surface tension cause by h-bonds
Surfactants produced by type II alveolar cells reduce surface tension
Increase lung compliance and reduce work needed to breathe

69
Q

How does emphysema impact the lung

A

Walls of alveoli break down-> changes surfactant quality
Increases lung compliance (walls thinner) but reduce lung elastance
Exhalation usually passive-> exhalation more difficult

70
Q

Formula for airway resistance

A

Flow = deltaP / R
If resistance increases, a greater deltaP is needed to maintain the same airflow

71
Q

Define bronchoconstriction
What can cause this?

A

Constriction: reduction in airway radius
Stimulation of parasympathetic nervous system
Histamine
Irritants

72
Q

Define bronchodilation
What can cause this?

A

Dilation: increase in radius
Stimulation of sympathetic nervous system
Circulating epinephrine
(binds to beta-2 receptors)
High alveolar PCO2

73
Q

Why can PCO2 lead to bronchodilation?

A

High PCO2 -> need to breathe faster and get rid of CO2

74
Q

What causes asthma and how do asthma inhalers work

A

Asthma: excessive bronchoconstriction
Inhalers stimulate beta-2 receptors (induce bronchodilation) to relax muscle

75
Q

What is dead space and what are the two components of dead space during respiration

A

Air that does not participate in gas exchange

Anatomical dead spaces -> volume of trachea and bronchi
Alveolar dead space-> volume of alveoli that are not perfused

76
Q

Why does panting help with cooling down

A

Trachea is an effective cooling region
Takes heat away from the moist surface

77
Q

What are some challenges animals with long necks have

A

Very large dead space
Can’t have high trachea diameter bc need to have large lung to compensate for the dead space

78
Q

ventilation perfusion ratio

A

V (A) / Q
V(A)= alveolar ventilation
Q= cardiac output

79
Q

What does efficient gas exchange at respiratory surface require?

A

Matching of ventilation and blood flow

Air and blood of birds + mammals have about the same O2 content-> V(A)/ Q ratio of 1-> matches O2 delivery at gas exchanger, with ability to transport O2 away

80
Q

How is ventilation- perfusion matching achieved

A

Arterials dilate or constrict to distribute blood to well-ventilated alveoli

Low PO2 in alveolus causes contraction of arteriole

81
Q

Why is constriction of arteriole when low PO2 at alveolus
a) Beneficial
b) Potentially a problem

A

Benefit: low PO2 often indicates an issue w/ the alveoli so restrict blood from going there and send the blood elsewhere, where the alveoli is functional and pick up O2

Problem: in hypoxic environments, breathe low O2, all alveoli have low PO2-> all arterioles constrict-> problem

82
Q

why do animals have respiratory pigments and what type of respiratory pigments exist?

A

solubility of O2 in aqueous fluids is low
respiratory pigments (metalloproteins) contain metal ions which reversibly bind to O2 and increase O2 carrying capacity by 50 fold

83
Q

what are 3 major types of respiratory pigments

A

hemocyanin (arthropods and molluscs, usually dissoved in hemolymph, copper)
hemerythrin (sipunculids, brachiopods, etc, usually found inside coelomic cells. iron)
hemoglobin (vertebrates, nematodes, crustaceans, insects, iron)

84
Q

what is myoglobin?

A

a type of hemoglobin found in muscles
hemoglobin is a tetromer
myoglobin is a monomer

85
Q

why is hemoglobin ONLY and ALWAYS contained in red blood cells?

A

containing Hb in RBCs allow fine-tuning of the micro-environment around Hb to optimize function

86
Q

how does temperature impact O2 solubility

A

lower temp -> higher O2 solubility

87
Q

what is a disadvantage of having high conc. of RBC in blood

A

high viscosity and harder to move the blood

88
Q

maximal unloading occurs at…

A

P50, the PO2 level at which 50% of the hemes (component of Hb) ae saturated with O2
animals alter P50 of Hb to optimize O2 loading and unloading

89
Q

how is hematocrit and Hb levels elevated during stress (exercise, hypoxia, diving)

A

release red blood cells from the spleen

90
Q

as Hb is oxygenated, it goes from what state to what state

A

from T state (oxygenation difficult) to R state (O2 added more easily)

91
Q

what is the level of O2 affinity when P50 is low

A

high affinity

92
Q

what is the level of O2 affinity when P50 is high

A

low affinity

93
Q

what pH and PCO2 changes will reduce oxygen affinity?
why is this change important

A

decrease in pH or increase in PCO2

by stabilizing T state, resulting in right shift of Oxygen eqm curve (P50 increase)

FACILITATES O2 DELIVERY TO ACTIVE TISSUES THAT ARE PRODUCING CO2

94
Q

what is the Bohr effect?
why is it important?

A

changes in pH and PCO2 that stabilizes T state, affect the OEC and thus oxygen affinity

facilitates O2 delivery at tissues and O2 uptake at respiratory surfaces after CO2 is removed and pH increases

95
Q

what change in temperature will decrease oxygen affinity?
why is this important?

A

increase in temperature
stabilizing T state-> right shift OEC
PROMOTES O2 DELIVERY TO WARM MUSCLES DURING EXCERCISE

96
Q

what impact does an increase in organic phosphates have on O2 affinity?

A

increase in organic phosphate conc. -> decrease O2 affinity by stabilizing T state-> right shift of OEC

more O2 loading

97
Q

why are organic phosphates important?

A

without them, P50 will be very low-> low unloading-> tissue won’t get enough O2

important for fine-tuning blood P50

98
Q

organic phosphates for mammals, birds, and reptiles

A

mammals: 2,3 DPG
birds: IP5
reptiles: ATP or GTP

99
Q

what levels are modified during exposure to hypoxia and during development altering Hb-O2 affinity?

A

organic phosphate levels

100
Q

how does adding organic phosphates extend life of blood in blood banks?

A

prevent organic phosphates from being depleted

organic phosphates deleted-> can’t use the blood

biol 364 (6 decks)

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