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Animal Physiology > Respiration > Flashcards

Respiration Flashcards

1
Q

What is respiration?

A

the process in which oxygen is exchanged for CO2 across external environment and cells

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2
Q

What is mitochondrial respiration?

A

the oxygenic process that involves the production of ATP by oxidizing carbohydrates, amino acids, or fatty acids in which oxygen is consumed and CO2 is produced

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3
Q

How is diffusion across respiratory surfaces maximized?

A

increased surface area
thin surfaces

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4
Q

How does Fick’s law of diffusion apply to respiration?

A

the rate of diffusion is increased when the surface area of membrane is maximized and the distance for diffusion is minimized

= larger SA and thinner surface

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5
Q

What are major challenges to respiration for aquatic organisms?

A

O2 is 30x less soluble in water than air = significantly less O2 available to aquatic organisms

O2 is 10000x less mobile in water than air = requires more energy to move the water

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6
Q

Why is O2 consumption and metabolic rate higher in smaller, unicellular organisms?

A

because they rely solely on diffusion for gas exchange = it’s fast and efficient

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7
Q

What do larger organisms require for respiration?

A

bulk flow and gas exchange = a close relationship between respiration and circulation

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8
Q

What is ventilation?

A

when medium (air/water) is moved over a respiratory surface

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9
Q

How does gas exchange occur in larger organisms?

A

ventilation of air/water across respiratory surfaces

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10
Q

How are gases moved throughout a larger organism’s body?

A

the circulatory system

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11
Q

What are 3 non-directional ventilation strategies

A

non-directional ventilation across thin surface

non-directional ventilation across thick surface

tidal ventilation (kinda bidirectional)

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12
Q

What organisms use nondirectional ventilation across thin surfaces?

A

cutaneous respiration in frogs

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13
Q

Describe non-directional ventilation across thin surfaces

A

medium flows over respiratory surface at random to the flow of blood

concentration of O2 in medium is steady and blood picks up O2 from medium quickly = efficient

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14
Q

Describe non-directional ventilation across thick surfaces

A

medium flows over respiratory surface at random to the flow of blood

concentration of O2 in medium is steady and blood slowly picks up O2 from medium = not very efficient

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15
Q

Describe tidal ventilation

A

medium with high O2 is inhaled, medium flows across respiratory surface, medium with low O2 is exhaled

efficient because bringing high O2 medium over respiratory surface and pushing low O2 medium out

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16
Q

What are the 3 types of unidirectional ventilation?

A

concurrent flow - medium flows with blood flow

countercurrent flow - medium flows against blood flow

crosscurrent flow - medium crosses over blood flow

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17
Q

Which type of unidirectional ventilation is really uncommon in nature?

A

concurrent flow - not very efficient

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18
Q

Which type of unidirectional ventilation is really most common in aquatic organisms?

A

countercurrent

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19
Q

Which type of unidirectional ventilation do birds use?

A

crosscurrent

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20
Q

describe concurrent ventilation

A

medium flows in same direction as blood flow in respiratory surface

as blood picks up O2 from medium, medium decreases in O2 = eventually they plateau together at mid level of O2

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21
Q

describe countercurrent ventilation - why is it so efficient?

A

medium flows in opposite direction of blood flow in respiratory surface

as blood uptakes O2, medium continues moving along and allows fresh O2 to come in contact with blood

this method ensures that respiratory surface is always being ventilated by medium with fresh O2

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22
Q

describe crosscurrent ventilation - why is it so efficient?

A

medium flows across blood flow in respiratory surface

as medium flows across capillaries, blood uptakes O2

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23
Q

what is the most efficient strategy for ventilation?

A

crosscurrent

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24
Q

What is the purpose of ventilation?

A

to reduce formation of static boundary layers and ensure gas exchange

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25
Q

Describe unidirectional ventilation

A

medium enters chamber at a different point than it exits

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26
Q

How do aquatic organisms overcome the challenges of respiration (water is more dense, viscous, water contains significantly less dissolved O2)?

A

by utilizing countercurrent ventilation to maximize contact between water with O2 and blood

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27
Q

what structures do water breathing fish have to facilitate respiration?

A

fish gills are made up of several gill arches

each gill arch has primary and secondary lamella

primary lamella stack vertically, secondary lamella are parallel ridges along each primary lamella

secondary lamella are covered in capillaries for gas exchange

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28
Q

How do air breathing fish conduct respiration?

A

fish open their mouth to expand their buccal cavity and draw air into the buccal cavity

fish close their mouth and the buccal cavity compresses pushing the air into the anterior chamber of breathing organ

anterior chamber closes and poster chamber contracts to push air out through operculum

anterior chamber opens and contracts for air to flow into the posterior chamber for gas exchange

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29
Q

What type of respiratory system do insects use? why is this unique?

A

gas exchange occurs via the tracheal system and does not involve the circulatory system to deliver gases

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29
Q

What type of respiratory structures can air breathing fish have?

A

reinforced gills (ex. mud-skippers)
vascularized mouth or pharyngeal cavity (ex. electric eels)
vascularized stomach (ex. catfish)
special gut pockets (ex. bichirs)
lungs (ex. lungfish)

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29
Q

What type of ventilation in air breathing fish?

A

tidal using buccal force

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30
Q

Describe the steps of insect respiration via the tracheal system

A

air filled tubes (tracheae) have spiracles (openings) to external environment

tracheae branch to form tracheoles

abdominal or thorax muscles contract for tidal or unidirectional air flow over spiracles

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31
Q

What type of ventilation do insects use?

A

either tidal or unidirectional

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32
Q

What type of respiratory organs do amphibians have?

A

cutaneous respiration (skin)

bilobed lungs

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33
Q

What type of ventilation occurs in frogs?

A

tidal using buccal pump

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34
Q

What amphibians are exceptions to general amphibian respiration (ex. lungs and/or cutaneous respiration)?

A

Axolotl have external gills only (no lungs)

salamanders can have:
- gill slits
- gills and lungs
- only cutaneous

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35
Q

Explain the steps in frog lung respiration

A

air is drawn into buccal cavity through nares

glottis opens behind buccal cavity

lungs recoil and compress to reduce lung volume

air is pushed out of lungs and out of the nares

nares close and the buccal cavity floor rises to push air into the lungs

glottis closes and gas exchange occurs in lungs

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36
Q

What type of respiratory organs do reptiles have?

A

most have 2 lungs, snakes have 1 or a reduced second

lungs can be really simple sacs or highly divided chambers for more active species

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37
Q

Why might a more active species of reptile have more divided lung chambers?

A

more division = more surface area = more gas exchange

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38
Q

What type of ventilation is used in reptiles? why is it unique?

A

unidirectional!! not tidal as would be expected for lung respiration

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39
Q

What type of pumps are used in generating force for respiration in reptiles?

A

usually aspiration pumps for suction

sometimes also buccal pump

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40
Q

What are the 2 phases of reptile respiration?

A

inspiration and expiration

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41
Q

T or F: reptiles have different muscles for feeding than for respiration

A

true

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42
Q

T or F; Some reptiles are intermittent breathers

A

true - ex. crocodiles

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43
Q

How do non-bird reptiles change the volume of their chest/thoracic cavity to create pressure gradients for respiration?

A

lizards: muscles lining rib (intercostal) contraction/relaxation

turtles/tortoises: abdominal muscle contraction/relaxation

crocodiles: diaphragmaticus muscle contraction/relaxation

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44
Q

How do lungs in birds differ from other reptiles?

A

lungs in birds are stiff and do not change in volume

they are arranged between a series of air sacs that act as bellows (expand/contract)

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45
Q

How and where does gas exchange occur in birds?

A

in parabronchi in lungs

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46
Q

What type of ventilation do birds use?

A

unidirectional crosscurrent

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47
Q

What is the respiratory organ of birds?

A

parabronchi in lungs

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48
Q

How many respiratory circuits are there in birds?

A

2

inhalation circuit
exhalation circuit

  1. inhale
  2. exhale
  3. inhale
  4. exhale
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49
Q

Describe the steps of respiration in birds

A

chest expands for the first inhalation = fresh air flows through bronchi in posterior air sac

chest compresses for first exhalation = fresh air pushed from air sacs into lungs

chest expands for second inhalation = stale air from lungs flows into anterior air sacs

chest compresses for second exhalation = stale air pushed out trachea from anterior air sacs

inhalations are simultaneous

exhalations are simultaneous

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50
Q

How does crosscurrent ventilation in birds occur?

A

parabronchi carrying fresh air extend down and across capillaries carrying blood in opposite direction

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51
Q

What are alveoli?

A

gas exchange surfaces in mammals

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51
Q

What are the 2 main parts of the mammalian respiratory system?

A

upper respiratory tract (mouth, nasal cavity, pharynx, trachea)

lower respiratory tract (bronchi, alveoli both gas exchange surfaces)

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52
Q

What are the 2 cell types of alveoli in mammals?

A

type 1 alveolar cells are thin walled and specialize in gas exchange

type II surfactant cells secrete fluid and reduce surface tension, provide structural support for alveoli and reduce breathing effort

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53
Q

Where are capillaries on the gas exchange surfaces for mammals?

A

capillaries coat the outer surface of alveoli

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54
Q

What are the gas exchange surfaces in mammals?

A

bronchi and alveoli

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55
Q

What are pleural sacs?

A

two layers of cells with space between (pleural cavity) that surround each of the two mammalian lungs

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56
Q

How do mammal lungs stay expanded?

A

the pleural cavity between the 2 ways of the pleural sac contains some pleural fluid to maintain subatmospheric intrapleural pressure = prevents lungs from collapsing

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57
Q

Describe the structure of mammalian lungs

A

chest wall surrounds the pleural sac which surrounds the lungs

bronchi branch extensively throughout the lung with alveoli on ends

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58
Q

describe bronchi

A

the respiratory organ that branches throughout mammalian lungs and contain alveoli on the tips

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59
Q

What type of ventilation do mammals use?

A

tidal

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60
Q

Describe steps of mammal inhalation (inspiration)

A

motor neuron stimulates inspiratory muscles

intercostals and diaphragm contract to move ribs outward and expand thorax

expanded thorax = decreased pressure inside

this increases transpulmonary pressure gradient and causes the lungs to expand and draw in air

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61
Q

Describe steps of mammal exhalation (expiration)

A

motor neurons stop stimulating inspiratory muscles

intercostal and diaphragm muscles relax

volume of thorax decreases causing intrathoracic pressure to increase

lungs passively recoil and push out air

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62
Q

Do mammalian lungs contract and relax?

A

no, they are not muscles, they just expand and recoil in response to other muscles contracting and moving

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63
Q

What causes rapid, heavy breathing?

A

contraction of internal intercostal muscles

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64
Q

how does the intra-alveolar pressure change between mammalian inhalation and exhalation?

A

during inhalation, alveolar pressure is low

during exhalation, alveolar pressure increases

(looks like a sinusoidal wave)

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65
Q

how does the intrapleural pressure change between mammalian inhalation and exhalation?

A

decreases until end of inhalation then increases during exhalation

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66
Q

how does the volume of air moved change between mammalian inhalation and exhalation?

A

the same amount of air is moved in during inhalation as is moved out during exhalation

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67
Q

What is surface tension?

A

the force that pulls a liquid’s surface molecules together at an air-liquid interphase

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68
Q

What are surfactants? What do they do?

A

they are cells in the alveoli that function to reduce surface tension on the alveoli in order to reduce the amount of work needed to expand alveolar volume

overall to increase compliance

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69
Q

What is lung compliance? How is it regulated?

A

the ability of the lungs to stretch during inhalation

controlled by the surface tension in alveolar fluid

70
Q

How do surfactants increase lung compliance?

A

by reducing the surface tension of alveoli by disrupting and decreasing density of water molecules on alveoli surface = reduces alveolar walls and airways sticking together

71
Q

When does surfactant synthesis develop in humans?

A

late gestation

72
Q

What is lung elasticity?

A

the ability of the lung to return to resting volume after it has been stretched for inhalation

73
Q

What happens if lungs have low elasticity?

A

lungs less easily recoil to resting state when respiratory muscles have relaxed and expiration must be active (not passive)

74
Q

What are 4 examples of lung diseases?

A

respiratory distress syndrome

fibrotic lung disease

emphysema

asthma

75
Q

Describe respiratory distress syndrome

A

reduced lung compliance that occurs in premature babies that have not produced enough surfactants

76
Q

Describe fibrotic lung disease

A

reduced lung compliance in which inhalation is difficult caused by lung tissue scarring

causes shallow breathing

77
Q

Describe emphysema

A

Lungs are less elastic due to damaged elastin fibers and alveoli = lungs are more compliant but more likely to collapse and have inflammation

caused for example by smoking

78
Q

Describe asthma

A

a chronic inflammatory disease characterized by bronchiospasm and airway constriction

common symptoms: wheezing, cough, shortness of breath

79
Q

How common is asthma in Canada? how is it treated?

A

~15% occurrence

corticosteroids
beta-adrenergic agonists
antileukotriene

80
Q

What factors influence air flow?

A

airway diameter influences resistance which influences air flow

small diameter = more resistance = less air flow

81
Q

How is higher resistance of an airway to air flow overcome?

A

with a large transpulmonary pressure gradient

82
Q

How is the nervous system involved in air flow and resistance?

A

parasympathetic neurons cause bronchoconstriction (more resistance)

sympathetic neurons can bronchodilation (less resistance)

83
Q

How is lung volume and capacity measured?

A

spirometer

84
Q

What is tidal volume?

A

the volume of air moved in one ventilation cycle

85
Q

What is dead space?

A

the amount of air (of the tidal volume) that isn’t involved in gas exchange

86
Q

What are the 2 components of dead space?

A

anatomical dead space - volume of trachea and bronchi

alveolar dead space - volume of alveoli not permeated

87
Q

What is inspiratory reserve volume?

A

the volume of air inhaled above the resting tidal volume

88
Q

What is inspiratory capacity?

A

tidal volume + inspiratory reserve volume

89
Q

What is expiratory reserve volume?

A

the maximum air that can be forcibly exhaled above resting tidal volume

90
Q

What is vital capacity?

A

the maximum volume of air that can be moved in and out of lungs with a single breath

tidal volume + inspiratory reserve volume + expiratory reserve volume

91
Q

What is total lung capacity ?

A

the sum of the vital capacity + residual volume (volume of air left in the lungs after maximal exhalation)

92
Q

What is alveolar ventilation volume?

A

the volume of fresh air that enters the alveoli with each respiratory cycle

= tidal volume - dead space

93
Q

What is alveolar minute ventilation?

A

the volume of fresh air that enters alveoli every minute

breathing rate (breath pm) * (tidal volume - dead space)

94
Q

How do animals with large volumes of dead space (ex. cranes with long trachea) overcome this?

A

by having larger tidal volumes

bringing in more air

95
Q

How much more soluble is oxygen in air than water?

A

30x more soluble in air than water

96
Q

How soluble is CO2 in water? in air?

A

almost completely soluble in both

97
Q

How do large animals transport gases throughout their bodies?

A

blood via circulatory system

98
Q

T or F: the solubility of oxygen in aqueous solutions is low

A

true

99
Q

What are metalloproteins?

A

respiratory pigments

proteins that contain metal ions

100
Q

What is the function of metalloproteins in respiration?

A

they reversibly bind oxygen and increase the oxygen carrying capacity of aqueous solution in the circulatory system by 50x

101
Q

How much do metalloproteins increase the oxygen carrying capacity of blood?

A

50x increase

102
Q

What are the 3 major types of respiratory pigments in animals?

A

hemoglobins
hemocyanins
hemerythrins

103
Q

What animals have hemoglobins?

A

vertebrates
some nematodes
some annelids
some arthropods

104
Q

What 3 components are in hemoglobins?

A
  1. a globin protein bound to
  2. a heme molecule that contains
  3. iron
105
Q

What metal ion is bound in hemoglobins?

A

iron

106
Q

Where do hemoglobins exist?

A

within blood cells

107
Q

Describe the structure of hemoglobin

A

globin: 4 protein subunits - tetrameric - 2 alpha subunits and 2 beta subunits

bound to a

a heme group containing iron

108
Q

What colour are hemoglobin when oxygenated?

A

red

109
Q

What is myoglobin?

A

a similar protein (but a monomer) to hemoglobin that’s ffound in skeletal and cardiac muscles

110
Q

What animals have hemocyanins?

A

arthropods (crustaceans, arachnids, centipedes)

molluscs

111
Q

Describe the structure of hemocyanin

A

a very large multi-subunit protein composed of up to 48 subunits

contains 2 coppers bound to the protein directly

112
Q

What metal ion is bound in hemocyanin?

A

2 copper ions

113
Q

Up to how many subunits can hemocyanins have?

A

up to 48 subunits

114
Q

T or F: hemocyanin is a massive respiratory pigment

A

true

115
Q

How many oxygen molecules can each hemocyanin protein bind to?

A

one

116
Q

Where are hemocyanins located?

A

they’re dissolved in hemolymph or blood

NOT within blood cells

117
Q

T or F: hemocyanins are within blood cells

A

false!

118
Q

Which respiratory pigments are found within blood cells?

A

hemoglobin

hemerythrins but specifically in coelom blood cells

119
Q

What colour are hemocyanins when oxygenated? deoxygenated?

A

blue when oxygenated
colourless when deoxygenated

120
Q

What animals are hemerythrins found in?

A

invertebrates
ex. sipunculids, priapulids, brachiopods

some annelids

121
Q

What metal ion is contained in hemerythrins?

A

iron

122
Q

Describe the structure of hemerythrins

A

either trimeric or octomeric, each subunit binds 2 iron molecules

123
Q

How many subunits can hemerythrins have?

A

either 3 or 8

124
Q

How many iron molecules can each subunit of hemerythrin bind?

A

2 irons per subunit

125
Q

Where are hemerythrins usually found?

A

in the coelomic cells (blood cells of the coelom)

126
Q

What colour are hemerythrins when oxygenated? deoxygenated?

A

violet-pink when oxygenated
colourless when deoxygenated

127
Q

How is the PO2 related to amount of O2 bound to pigment molecules?

A

as PO2 increases in plasma, more pigment molecules bind to oxygen until saturation

128
Q

What is PO2?

A
129
Q

What is P50?

A

the PO2 at which the respiratory pigment in blood is 50% saturated

130
Q

What does it mean if P50 has a higher value?

A

the pigment has a lower affinity for binding O2

131
Q

How is the % of oxygenated respiratory pigment in blood related to PO2 in plasma?

A

As PO2 in plasma increases, the % oxygenated respiratory pigment in blood increases until saturation

132
Q

T or F: the amount of respiratory pigments in blood is the same in all animals

A

false, it has diversified over evolution

133
Q

How does the amount of respiratory pigments in diving mammals differ from terrestrial mammals?

A

diving mammals have higher levels of blood hemoglobin than terrestrial

134
Q

What is unique about respiratory pigments in Antarctic icefish?

A

they lost the gene for hemoglobin in blood = no hemoglobin

135
Q

How do Antarctic icefish transport O2 if they don’t have hemoglobin?

A

they have low metabolic rates and low demand for O2
and because of cold water temperatures
there’s increased O2 solubility in the water and their plasma

136
Q

How is PO2 related to % saturation of hemoglobin in humans? How does this compare to myoglobin in humans?

A

As PO2 increases, % saturation of hemoglobin increases until 100% saturation

there is a steep increase of % saturation of hemoglobin in myoglobin with a little increase in PO2 (curve is super steep) = 100% saturation occurs much faster

137
Q

What shapes of oxygen equilibrium curves have?

A

hyperbolic or sigmoidal

138
Q

What type of oxygen equilibrium curve does myoglobin have? why?

A

a hyperbolic curve because oxygen binds independently

139
Q

What type of oxygen equilibrium curve does hemoglobin have? why?

A

sigmoidal because cooperativity = higher affinity to O2 because more of its heme groups bind O2

140
Q

What is the Bohr effect?

A

when there’s a decrease in pH or increase in CO2, the O2 equilibrium curve shifts to the RIGHT = O2 affinity is decreased

141
Q

What happens to O2 affinity of pigments when pH is decreased or CO2 is increased?

A

O2 affinity is decreased

Bohr Effect

142
Q

What is the Root Effect?

A

When pH is decreased or CO2 is increased, the O2 carrying capacity is reduced

143
Q

What organs does the root effect occur in?

A

swim bladders and gas glands in fish

144
Q

how does the Bohr effect affect P50?

A

P50 is increased

145
Q

What factors affect oxygen affinity of pigments?

A

pH
PCO2
temperature
organic modulators

146
Q

How does the Bohr effect function in respiration?

A

to facilitate O2 transport to active tissues and O2 binding at respiratory surfaces

147
Q

How does temperature affect oxygen affinity?

A

temperature increases = oxygen affinity decreases (right shift)

P50 is increased

148
Q

How does an increase in temperature affect O2 circulation?

A

increased temperature causes increased O2 delivery to warm muscles during exercise

149
Q

What is an example of an organic modulator that affects O2 affinity?

A

2,3-DPG
2,3-biphosphoglycerate

150
Q

How do organic modulators affect O2 affinity?

A

increased organic modulator decreases O2 affinity = right shift

151
Q

How does increased organic modulators affect O2 transport?

A

organic modulators help unload O2 at tissues

152
Q

What stimulates 2,3-DPG synthesis?

A

anemia and high altitudes

153
Q

What 3 ways is CO2 transported in blood?

A

in the plasma
bound to proteins
as bicarbonate

154
Q

Why is it more effective to transport CO2 than O2 in the plasma?

A

CO2 is more soluble in plasma than O2

155
Q

What is an example of a protein that binds CO2?

A

carbaminohemoglobin

156
Q

What is the reaction forming bicarbonate (HCO3-)?

A

CO2 + H2O <> H2CO3 <> HCO3- + H+

157
Q

What enzyme catalyzes bicarbonate formation?

A

carbonic anhydrase

158
Q

Where is carbonic anhydrase active in vertebrates?

A

red blood cells

159
Q

What is bicarbonate exchanged for in vertebrate plasma?

A

Cl-

160
Q

What is the Haldane effect?

A

deoxygenated blood can carry more CO2 than oxygenated blood

161
Q

What is the relationship between PCO2 and total CO2 content of oxygenated and deoxygenated blood?

A

as PCO2 increases

CO2 in oxygenated blood increases but at a slower rate than in deoxygenated blood

162
Q

What does the shape of CO2 equilibrium curve depend on?

A

the kinetics of bicarbonate formation

163
Q

How does CO2 diffuse out of blood at the respiratory surface? how does this effect the formation of bicarbonate?

A

carbominohemoglobin in the blood releases CO2, causing the bicarbonate reaction to shift left

164
Q

What 2 factors affect the [bicarbonate] and pH of body fluids?

A

PCO2

165
Q

What happens when PCO2 increases?

A

[bicarbonate] increases

pH decreases ([H+] increases)

and reaction shifts right

166
Q

What happens when PCO2 decreases?

A

[bicarbonate] decreases

pH increases ([H+] decreases)

and reaction shifts left

167
Q

What factor affects body fluid pH?

A

ventilation

168
Q

How does hyperventilation affect PCO2?

A

decreased PCO2

169
Q

How does hypoventilation affect PCO2?

A

increased PCO2

170
Q

How is ventilation regulated?

A

rhythmic activation of the central pattern generators in the medulla activate nerves to trigger ventilation

171
Q

What detects changes in CO2, H+ and O2?

A

chemoreceptors

172
Q

What is the primary regulator of ventilation in water-breathers?

A

O2

173
Q

What is the primary regulator of ventilation in air-breathers?

A

CO2

174
Q

What regulates the output of central pattern generators?

A

chemosensory input received by chemoreceptors

175
Q

What type of feedback regulates ventilation?

A

negative feedback

176
Q
A

Animal Physiology (13 decks)

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