Respiration Flashcards
(189 cards)
1
Q
respiration
A
exchange of O2 and CO2 between animals and environment
2
Q
Bulk flow
A
Bulk flow refers to the movement of air (or other fluids) in and out of the lungs, driven by pressure differences, as opposed to the diffusion of individual gases across membranes. It is basically external respiration that allows diffusion to occur.
3
Q
External respiration
A
Getting air/water to exchange sites and into the body
4
Q
Internal respiration
A
Exchange of gases and transport within the body
5
Q
what does respiration involve?
A
gas exchange structure (i.e., lungs), circulation and release to tissues
6
Q
what process in respiration do very small animals (especially invertebrates) skip?
A
bulk transport
7
Q
What are the four components of respiration?
A
- Ventilatory structure: Bulk transport (getting O2 into the lungs/gills)
- Exchange of gases between respiratory medium and circulatory fluid (O2 from environment into blood)
- Transport in body fluids: Adjustments for certain tissue to get O2.
- Exchange of gases between circulatory fluid and tissues (chemicals in cell that regulate how much O2 is dumped from hemoglobin)
8
Q
Fick’s law (2)
What it means + equation
A
- Describes rate of diffusion across a membrane (how much O2 can dissue in animal)
9
Q
The higher the partial pressure gradient (G) in Ficks law means:
A
Higher gradient then potential for gas dissolve greater
10
Q
Gas exchange is influenced by SA to V ratio, explain:
A
Smaller animals have a larger surface area-to-volume ratio, meaning they lose heat more quickly and have higher metabolic rates to compensate. Since volume increases cubically while surface area increases quadratically, larger animals have a lower SA:V ratio and conserve heat more effectively. To sustain their high metabolism, small animals need more oxygen per unit body mass compared to larger animals.
11
Q
Tidal volume
A
Tidal volume (TV) is the amount of air that moves in and out of the lungs during a normal, quiet breath, typically around 500 mL in healthy adult
12
Q
Unidirectional flow vs Tidal flow:
What it is + efficiency?
A
- Unidirectional flow allows for more continuous and efficient oxygen extraction. In unidirectional flow, air or water moves in a single direction through the respiratory system, allowing for continuous and efficient gas exchange. This is seen in fish, where water passes over the gills in one direction, and in birds, where air moves through the lungs in a one-way circuit aided by air sacs. This system prevents mixing of oxygen-rich and oxygen-poor air, maximizing oxygen uptake.
- Tidal flow is simpler but less efficient due to the mixing of oxygen-rich and oxygen-poor air. In contrast, tidal flow, found in mammals, amphibians, and reptiles, involves air entering and exiting through the same pathway, such as the trachea and lungs. Because fresh air mixes with residual air, tidal flow is less efficient in oxygen extraction.
13
Q
Inspiratory reserve volume
A
The extra volume of air that can be inspired with maximal effort after reaching the end of a normal, quiet inspiration
14
Q
Expiratory reserve volume vs residual volume
A
ERV refers to the additional amount of air that can be forcefully exhaled after a normal exhalation. This volume varies depending on lung capacity, physical conditioning, and age. In contrast, RV is the air that remains in the lungs even after a maximal exhalation; it prevents lung collapse and ensures continuous gas exchange between breaths
15
Q
Asthma changes the —–
A
inspiratory capacity and expiratory reserve volume.
Asthma affects lung volumes by altering both inspiratory capacity (IC) and expiratory reserve volume (ERV) due to airway obstruction and inflammation. During an asthma attack, bronchoconstriction and mucus buildup narrow the airways, making it harder to inhale fully and reducing inspiratory capacity (IC)—the maximum amount of air a person can inhale after a normal exhalation. Additionally, the obstruction prevents full exhalation, leading to air trapping in the lungs. As a result, expiratory reserve volume (ERV) decreases because less air can be forcefully exhaled after a normal breath. Over time, this trapped air contributes to increased residual volume (RV) and lung hyperinflation, making breathing even more difficult.
16
Q
How can you increase diffusion rate? (4)
A
- Increase surface area
- Decrease distance of diffusion
- Increase concentration gradient (partial pressure)
- Increase concentration in lungs or decrease concentration in blood
17
Q
Upper airways condition air entering the body, explain:
A
- Mouth and nose filter air goblet cell secretes mucus to humidify air (humidification lower PO2 bc of water vapour)and protect alevoli and also the blood keeps it warm.
18
Q
The smaller the concentration difference, the —- the diffusion rate. If you increase tickness of tissue, —– gas going in.
A
- slower
- less
19
Q
How are lungs adapted to increase diffusion rate?
A
very high surface area, very thin tissue (decreases distance), and constant ventilation to keep concentration gradient high
20
Q
What are examples of conducting zone? (3)
A
bronchioles, bronchi, trachea
21
Q
respiratory bronchioles
A
special bronchioles where gas exchange can occur
22
Q
pleural sac/cavity
A
fluid-filled sac that encompasses lung and provides lubrication for smooth movement and holds lungs open
2 membranes (one by lungs - visceral and one by chest wall - parietal)
23
Q
pleurisy
A
inflammation of pleural sac membrane due to infection
24
Q
diaphragm
A
muscle at base of lungs - connected to pleural sac but not lungs
25
diaphragm shape when relaxed vs contracted
relaxed = arched (lengthens when relaxes)
contracted = flattened (shortens when contracts)
26
Gas gets exchanged only at the
Alveolar sac
| Each sac has multiple alveolus
27
chest wall
rib cage, sternum, thoracic vertebrae, connective tissue, intercostal muscles
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intercostal muscles
in between ribs; 2 sets: external and internal (antagonistic muscles)
connected to pleural sac (along with ribs)
29
external intercostal muscles
outside of ribcage - function is to lift ribcage
30
internal intercostal muscles
inside ribcage - function is to depress ribcage
31
at rest, the lung has a tendency toward collapse - why?
- of weight of chest cavity
- elasticity of lung tissue (always in a slightly stretched state - tendency of recoiling)
- surface tension in alveoli (has tension pulling inwards - collapsing while air inside has outward force)
32
collapse is opposed by
pleural sac and production of surfactant
33
how does the pleural sac oppose collapse?
fluid-filled (think about a syringe, liquids cannot be compressed or expanded) and drags lung along with any force applied on it
pleural sac is attached to diaphragm and ribs hold lung open
34
how does the production of surfactant oppose collapse?
detergent-like substance secreted by cells in alveoli - decreases surface tension in alveoli so they stay open
35
why does surfactant decrease surface tension
cannot blow bubbles with just water (too high surface tension) - need soap to decrease it
36
what is the release of surfactant triggered by?
stretch (inhaling)
37
why is surfactant important for mammalian newborns?
first breath of baby is to break open alveoli - lots of surfactant is produced right before birth to reduce surface tension so baby can inflate lungs
38
what role does the ventilator play for premature babies?
holds lungs open + supplies artificial surfactant
39
infant respiratory distress syndrome
baby is born before surfactant production begins (first breath is unable to open lungs due to high surface tension)
40
what is the consequence of the opposing collapse in the lungs?
there's always some air in the lungs (retention of stale air)
41
3 main parts of the breathing cycle
tidal ventilation, inhalation, exhalation
42
Tidal ventilation
like a tide = air enters and exit on same path
43
what happens during inhalation?
1. contract external intercostals and diaphragm, expansion of chest cavity
2. pulls on pleural sac and generates negative pressure below ambient in pleural fluid
3. fluid follows pleural sac, pulls on lungs, lungs expand, negative pressure in lung so air is sucked in
44
what happens during exhalation at rest?
exhalation is completely passive - weight and elastic recoil makes lung volume smaller, positive pressure inside lung so it pushes air out
45
what happens during exhalation during activity?
same as rest (positive pressure in lung) PLUS contract internal intercostals, contract muscles of abdomen = helps reduce lung volume and increase positive pressure further, expelling air
46
what is a limitation of mammalian lung anatomy?
dead space
47
2 types of dead space
anatomical (structural) and alveolar (functional)
48
anatomical dead space
arises due to conducting structure of lung - volumes of air in conducting zone don't contribute to gas exchange and lungs are open all the time (stale air mixes with fresh air reducing effectiveness)
49
alveolar dead space
not all alveoli are receiving air or blood all the time (so they don't contribute physiologically)
50
physiological dead space
sum of anatomical + alveolar
very significant - normal resting breath = 350 mL fresh air in inhale but lung capacity is 3 L
51
what is the consequence of dead space?
significantly less O2 in air inside lung than in atmospheric air
52
what is the driving force of gases?
partial pressure
53
why is partial pressure used?
gas diffusion into a liquid is more accurately described by partial pressure than concentration gradient
54
what moves O2 into blood and CO2 out of blood?
partial pressure = driving force!
55
Total pressure is dictated by
partial pressure of individual gases
56
Sea level atmospheric air pressure
760 mmHg
57
Partial pressure of O2 at sea level
| Equation
0.21 x 760 = 160 mmHg
58
Partial pressure of CO2 at sea level
0.03 x 760 = ~0 mmHg
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Partial pressure of N2 at sea level
60
Humid air at sea level:
Ptot
Air mixture
- Ptot= 760mmHg (same as dry air)
- Water vapour is up to 4% of air mixture. This can change the other partial pressure of gas. In tropics, air mixture is: N2 = 75%, O2 = 20%, H2O = 4%
| Dry and humid air have different partial pressure compositions.
61
Atmospheric air pressure (Ptot) in Calgary
667 mmHg
62
Ppartial pressure of O2 in Calgary
0.21 x 667 = 140 mmHg
63
Total atmospheric pressure ---- as altitude increases.
- decreases
64
Partial pressure of O2 in lungs is lower than atmospheric because
large presence of water vapour in lungs
| lungs water vapour = 6%
Tropics = water vapour 4%
65
Higher pp of O2/lower pp of CO2 in atmospheric air than lungs does what?
drives O2 into and drives CO2 out of lungs
66
Equation for how long it takes for diffusion from point A to B:
67
What does the solubility of O2 and CO2 in water depend on (3)?
Dissolvability in water depends on:
1. Partial pressure in surroundings (medium: air/water)
2. Temperature (Cold water has more O2)
3. Salinity: More ion in H2O so slower. FW has more O2. Higher salinity means lower O2)
68
How does partial pressure affect solubility of air and water O2 molecules?
Partial pressure in air and water equilibriate and be the same but the # of molecules is different. Diffusion occurs until air and water PO2 match. Air has 35-40X more O2 molecules avaliable than water, if you look at equal volumes even at the same partial pressure gradient. This is because water has hydrostatic pressure and air doesnt.
69
how does temperature affect solubility
cold water means more gas dissolved
70
how does salinity affect solubility?
less salt means more gas can dissolve
71
Is O2's partial pressure higher or lower at the top of Mt. Everest than in Calgary? What about atmospheric pressure (Ptot)?
| Give numbers
- lower
- Lower
| Higher altitude = lower PO2
72
Assuming constant pp, is there more O2 in salt or fresh water at the same temperature?
fresh water
73
Assuming constant pp, is there more O2 in a Petri dish containing fresh water or a plasma sample at same temperature?
fresh water - plasma = H2O based solution but has higher salinity
74
Assuming constant pp, is there more O2 in hot or cold tap water?
cold tap water
75
comparative ventilation
gas exchange surface area (lungs, alveoli, gill tissue, etc.) matches O2 demand
76
as body size increases, how does gas exchange surface area change?
also increases
bigger animals have more cells because they have a greater demand for cellular respiration and O2
77
how does gas exchange surface area differ in endotherms and ectotherms?
more SA in endotherms (i.e., frog and mouse may have same body weight but gas exchange SA higher in mouse)
heat regulation requires more energy and O2
78
bird ventilation steps
inhale #1 = to posterior air sac (expands)
exhale #1 = to rigid lungs and some back to main airway
inhale #2 = to anterior air sac
exhale #2 = out of body
79
what is one difference between bird and mammalian lungs?
bird lungs are rigid - do not change in shape or size
80
why do birds need to extract more O2 than mammals?
because they fly which requires lots of O2
81
do birds have tidal ventilation?
no - one way continuous flow (doesn't go out/in on the same path)
82
does bird ventilation have dead space?
no - stale air and fresh air do not mix (the air that goes back to main airway from posterior air sac is still fresh!)
83
insect ventilation systems tend to involve
a network of gas-filled tubes (no lungs)
84
what is the network of gas-filled tubes in insects called?
tracheal system
85
how does fresh air enter the tracheal system in insects?
through pores of body surface or aquatic insects may have gill-like structures or hollow hairs
86
invertebrates that don't fly use what for gas exchange?
diffusion (no lungs or tracheal system)
87
why are insect ventilation systems so specialized?
flying is energetically costly - air movement through passive diffusion (no active pumping)
88
what are some challenges that might make breathing hard for aquatic organisms?
water has higher density than hair, O2 is less soluble in water than air (low O2 content), water is viscous and heavy (hard to move)
89
Gills can be either (2)
- External (no protective structure around them, sticking out in O2 because solubility of O2 is low so it is easier to extract. In aquatic organisms, dehydration is not a problem
- Internal gill: have hard structure covering them for protection (shrimp might chop them off)
90
fish gills have a specialized type of flow
countercurrent (opposite)
blood: flows posterior to anterior
water: flow anterior to posterior
91
flow of water in/out fish body
active pumping into mouth, over gills and out through operculum opening (anterior to posterior)
92
how does countercurrent flow affect O2 pickup capabilities?
higher efficiency of extraction - consistent concentration gradient exists along whole length of the gill
93
what type of flow do mammalian lungs use?
concurrent (same direction)
may have some limitations but gets the job done (air also has more O2 than water)
94
what type of flow do bird lungs use?
cross-current (specialized flow system) - better than concurrent but not as good at countercurrent
flow of respiratory medium (air) is almost perpendicular to flow of blood (like a grid)
95
why are ventilation and perfusion matched?
too much movement = waste of energy while moving too little = not meeting energy demands
96
perfusion
blood flow
97
V/Q ratio
V = ventilation; Q = perfusion (volumetric flow rate)
e.g. 1:1 = 1 unit of air per 1 unit of blood; 2:1 = 2 units of air per 1 unit of blood
98
V/Q ratio of mammals (whole lung)
1:1
99
V/Q ratio of fishes (whole gill)
~10 (10 units of water:1 unit of blood)
100
challenge for fish in terms of V/Q
water has less O2 than air and fish blood carries half the amount of O2 as mammalian blood (not good at carrying O2)
2 opposing problems
101
how do fishes overcome lower solubility of O2 in water?
increase ventilation (increase V - send more water), reduce blood flow (decrease Q)
102
how do fishes overcome their blood carrying less O2?
reduce water flow (decrease V), send more blood (increase Q)
103
net effect of fish overcoming its 2 challenges of less O2 in water and in blood
an overall increase V and decrease Q to make V/Q ratio ~ 10 (10 units of water for 1 unit blood)
104
what is the underlying issue of low V/Q
too much blood (Q too high) and not enough air (V too low)
105
how does the mammalian lung correct for too much blood - high Q?
too much CO2 present
smooth muscles in alveolar duct are sensitive to CO2 increases - triggers them to relax and opens alveolar duct to let air carry CO2 away
106
how does the mammalian lung correct for too little air - low V?
too little O2 present
vascular smooth muscle in capillaries are sensitive to O2 decreases - contract when O2 low (constricts blood vessels and reduces blood flow Q)
107
what does decreased O2 usually lead to in smooth muscle?
relaxation - but in vascular smooth muscle, causes constriction to decrease Q since V is so low
108
at altitude, how does the partial pressure of O2 change?
decreases
109
at altitude, how does blood flow change?
decreases
110
pulmonary edema
happens at high altitudes (low blood flow) where constriction raises blood pressure in lung and causes rupture of capillaries
also drives fluid out of vessels and into alveoli, reducing gas exchange abilities
111
what is the problem with the dissolved O2 levels in our blood?
not enough to supply tissues
112
metabolic demand at rest (resting metabolic rate, VO2 rest)
consume 250 mL O2/min
113
blood flow at rest
heart circulates 5 L blood/min
114
blood plasma O2 solubility
3 mL O2/L blood (really low solubility)
115
how much O2 does blood plasma deliver?
5 L blood/min x 3 mL O2/L = 15 mL O2/min
(less than our VO2 rest = 250 mL O2/min)
116
steps of oxygen getting taken up by blood + Hb
1. High PO2 in lung causes O2 to dissolve in the plasma (low PO2 in blood)
2. Raise PO2 of blood with dissolution - drives Hb to pick up blood
3. O2 binding to Hb reduces blood PO2
4. Low blood PO2 now lets more O2 dissolve (loops back to step 1)
117
oxygen dissociation curve
shows relationship between amount of O2 dissolved in body and held by Hb
118
what are the axes labels on an oxygen dissociation curve?
y-axis = % saturation of Hb (100% = 4 O2, 50% = 2 O2, etc.)
x-axis = PO2
119
for Hb, what is the shape of the oxygen dissociation curve?
s-shaped - shows cooperativity
increases O2 affinity as more O2 binds
120
for Mb, what is the shape of the oxygen dissociation curve?
square-root (curved) - no cooperativity
only 1 O2 binding site
121
Mb
myoglobin - supplies O2 to muscles
122
lungs on oxygen dissociation curve
at plateau - some wiggle room to change PO2 without affecting O2
123
tissues on oxygen dissociation curve
at increase (slope) - change in PO2 changes saturation
124
exercising muscle uses O2; what does this do to the PO2 in this tissue?
lowers PO2 (decrease due to decrease in O2 saturation)
125
fresh blood arrives to exercising muscle; how does Hb respond to the decreased PO2 in that tissue?
decrease in saturation of O2 = Hb will release its O2
126
how is affinity for Hb for O2 measured?
P50
127
P50
partial pressure needed to saturate Hb to 50%
128
how does affinity for O2 changes with P50?
higher the P50, the lower the affinity
(need to work harder to get Hb to pick up oxygen)
129
myoglobin vs hemoglobin affinity for O2
higher affinity in Mb (lower P50) - O2 preferentially binds to Mb
130
Hb affinity for O2 is reduced by
heat, presence of organic phosphates (ATP), lowered pH, increase in CO2
properties of muscle use (exercise)
131
Bohr shift
right shift in Hb affinity for O2 based on pH (more acidic - pH<7.4)
132
reverse Bohr shift
left shift in Hb affinity for O2 based on pH (more basic - pH>7.4)
133
Hb affinity for O2 at lower pH
lower (higher P50) when acidic
134
Hb affinity for O2 at higher pH
higher (lower P50) when basic
135
why does a lower pH cause lower Hb affinity for O2?
more acidic conditions indicate increased CO2, so encourages Hb to release O2
136
Root shift
down shift in Hb affinity for O2 based on pH
137
which is given more priority: Bohr shift or Root shift?
Root shift (down shift)
138
what happens with a root shift?
max out at <100% saturation
139
which animals can root shift?
some animals like fish (NOT mammals)
140
mechanism for root shift in fish
fill swim bladder - secrete lactic acid into tissues near swim bladder, causes root shift and helps force Hb to release O2 which gets shuttled to swim bladder
some fish do this in eye + brain - keeps metabolism higher here for higher function
141
after exposing a respiratory pigment to H+, you find that its P50 for O2 has increased; how has its affinity for O2 changed?
decreased affinity
142
name 4 ways Hb's affinity for O2 can be reduced
heat, presence of H+ ions, organic phosphates, CO2
143
thinking about the V/Q ratio at the whole-lung scale, if we observe that V is increasing, what is happening?
V = ventilation - breathing faster
144
after CO2 dissolves in water, what happens?
enter carbonic acid reaction
145
carbonic acid reaction
CO2 + H2O ⇔ H2CO3 (carbonic acid) ⇔ H+ + HCO3- (bicarbonate) ⇔ 2H+ + CO3(2-) (carbonate)
146
what catalyzes the carbonic acid reaction?
carbonic anhydrase (enzyme)
147
which is favoured more in the carbonic acid reaction: bicarbonate or carbonate ion?
bicarbonate (yields 1 H+)
148
3 places CO2 can be found in blood
dissolved (20x more soluble than O2), bound to Hb, tied up in a bicarbonate
149
where is the majority of CO2 in blood found?
tied up in bicarbonate (70-80%)
150
what type of CO2 counts toward PCO2?
dissolved CO2 (~10% of CO2)
151
Haldane effect
Hb with less O2 has higher affinity for CO2 and H+ so Hb carries more CO2 and H+
152
chloride shift
rapid anion exchange protein exchanges bicarbonate for chloride ion (moves bicarbonate ion out of the RBC)
153
what range of pH do we tolerate?
7.0-7.6 (blood is usually ~7.4)
154
methods for regulating blood pH
use bicarbonate, get rid of H+, adjust ventilation
155
how do we use bicarbonate to regulate blood pH?
shift carbonic acid reaction toward CO2 + H2O (shift left) to use up extra H+
kidneys: expel bicarbonate (reaction shifts right), causing increase in H+ and lowers pH
156
how is H+ regulated to regulate blood pH?
kidneys: expels H+, raises pH
proteins: "soak up" H+ (including some H+ on Hb) to raise pH - very effective
157
difference between changing pH in blood vs water
500,000x more H+ required to changes pH of blood than water
158
most of blood pH regulation is through
breathing (adjusting ventilation)
159
how do we adjust ventilation to regulate blood pH?
respiratory alkalosis or respiratory acidosis
160
respiratory alkalosis
breathe faster - increases V which increases V/Q ratio which decreases CO2 in blood; this uses up H+ in carbonic acid reaction (to replenish CO2) and raises pH
161
respiratory acidosis
breathe slower - decreases V and lowers V/Q ratio which causes build-up/backlog of CO2, pushing carbonic acid reaction toward H+ and lowers pH
162
how else do aquatic animals regulate blood pH?
exchange ions over skin and gills
163
how are ions exchanged in aquatic animals to regulate blood pH?
1. active H+ pumps - use ATP to move H+ outside of body (raises pH)
2. pump bicarbonate out through chloride shift and carbonic acid reaction shifts right to replenish + increases H+ (lowers pH)
164
2 categories of sensors for respiratory gases
peripheral sensors (PNS) and central sensors (CNS - monitor cerebrospinal fluid)
165
what is sensed to control respiratory gases?
O2 and pH (proxy for CO2)
166
3 major sensors in mammals
aortic arch, carotid arteries, medulla
167
aortic arch
peripheral sensor, shuttle blood to body from heart - sense O2, blood volume and hematocrit
168
carotid arteries
peripheral sensor, supplies blood to brain - sense O2, blood volume and hematocrit
169
medulla
central sensor, at base of brain leading to spinal cord - senses pH in CBSF
170
why do air-breathing animals primarily monitor pH?
always have 21% O2 in air, O2 is consumed and CO2 is produced at same rate, both are moved using the lungs at the same time
SO if we monitor for CO2, we end up with right amount of O2
171
role of O2 sensors in air-breathing animals
back-up plan - we don't use these sensors in healthy, normal conditions unless O2 levels get very low
172
water-breathing animals primarily monitor
O2 - peripheral sensors
173
air-breathing animals primarily monitor
pH (CO2) - central sensors
174
why do water-breathing animals primarily monitor O2?
- very little O2 in water
- O2 levels in water vary a lot (e.g. temp affects solubility)
SO must adjust breathing to compensate for changes in O2
175
to control respiratory gases, how do we respond to change?
increase or decrease ventilation
176
how does your breathing changes when you start to exercise (ways mammals change V)?
breathe faster or breathe deeper
177
hypoxia
low O2 in tissues - a form of respiratory stress
178
why is hypoxia rare for air-breathers under normal function?
tons of O2 present in air
179
causes of hypoxia
breathing very slowly, lung diffusion limitations, altitude, suffocation (not enough O2 in air), impaired ability to carry O2 in blood
180
what are some examples of lung diffusion limitations that could lead to hypoxia?
infant respiratory distress syndrome, pulmonary edema, emphysema (loss of alveolar SA, stiff lungs)
181
what would impair ability to carry O2 in blood?
severe blood loss, anemia, CO poisoning
182
why is hypoxia more common in water-breathers
limited O2 levels in water
183
how are the low levels of O2 in water dealt with by water breathers?
increase V, grow more gill tissue (increase SA), metabolic depression (reduce BMR to reduce O2 consumption)
184
how is respiratory stress dealt with by diving mammals?
some hypoxic tissues during dives - can prioritize which tissues get O2
185
O2 demands varies based on
activity level
186
why is our O2 demand non-zero at rest?
we have non-zero MR (BMR)
187
O2 solubility in blood is low so it -----
binds to hemoglobin
188
The biggest problem for humans to have external lungs is:
Dehydration
189
What is the end point of the O2 gas you are breathing in from external respiration?
Mitochondria respiration to generate ATP
