Respiration Flashcards
1
Q
Assuming fluid volume and pressure is the same for all cases, would you find more molecules of oxygen in: salt or fresh water, at the same temperature?
A
Fresh water, the more salinity = less oxigen
2
Q
Assuming fluid volume and pressure is the same for all cases, would you find more molecules of oxigen in: Fresh water or a blood plasma sample, at the same temperature? (no RBC here)
A
Fresh water because in the plasma there are ions, so there is salinity that will reduce O₂.
3
Q
Assuming fluid volume and pressure are the same for all cases, would you find more molecules of oxygen in: Hot or cold tap water
A
Cold water
4
Q
What is the most accurate way to measure metabolic rate
A
Heat produce
5
Q
Factors influencing the evolution of respiratory systems
A
- Organism size
- Metabolic rates
- Habitat
6
Q
Habitat
A
Environment, high - low altitude, hot - cold water
7
Q
The larger the animal ________ oxygen is consumed
A
Less
8
Q
Smaller animals consume ______ oxygen
A
More
9
Q
What characteristics of an habitat would influence the level of oxygen available?
A
- Altitude
- Salinity
- Temperature
10
Q
Four components of respiration
A
- Bulk transport
- Exchange of gases between respiratory medium & circulatory fluid
- Transport in body fluids
- Exchange of gases between circulatory fluid & tissues
11
Q
Ventilation = Bulk transport step
A
Exchange of respiratory medium between environment and the respiratory organs
12
Q
Types of flow
A
- Unidirectional flow
- Tidal flow: lungs
13
Q
What’s the function of the mouth & nose?
A
- Filter air
- Humify air
14
Q
Characteristic of epitelial cell?
A
They replace themselves overtime, it surrounds the organs to potent them
15
Q
Most important transporter?
A
Na/K channel
16
Q
How does humification change pressure of oxygen?
A
Humification lowers oxygen pressure by increasing microbial oxygen consumption, reducing soil aeration through water retention, and driving oxygen-consuming chemical reactions.
17
Q
Components of the mammalian respiratory system
A
- Lung
- Upper and lower airways
- Chest wall
- Pleura
- Pulmonary circulation
- Components of nervous system that regulate respiration
18
Q
Where does the oxygen gets exchange in the body?
A
Alveolar sac
19
Q
Tidal volume
A
Amount of air inhaled or exhaled in a single breath during normal, resting breathing.
20
Q
Features of the conducting zone
A
- Mucus escalator: globet cells (GC) secrete mucus that captures particulates
- Cilia (C): beat upward to move mucus to pharynx
21
Q
Cystic fibrosis
A
Genetic diseases affecting globet cells, thickened mucus and t’s hard to breathe.
22
Q
Where is the mutation of cystic fibrosis?
A
CFTR gene, cystic fibrosis transmembrane conductance regulator
23
Q
Features of the respiratory zone
A
- Super thin tissue & huge surface area
- Coated with watery solution
- Macrophages
24
Q
Phospholipids in the alveolar sacs?
A
They increase the surface area of the alveolar sacs
25
Reasons of alveoli towards collapse
1. Elastic fiber: rubber bands, pull inwards, shrinking alveoli
2. Surface tension: watery fluid coats iside of alveoli, pull inwards, opoosed by surfactant, which reduces surface tension
26
Fetus breathing
- The fetus lungs are collapsed
- In the lead up to birth, a fetus will produce tons of surfactants, reducing surface tension keeping it open
27
If the baby don't produce surfactant. What problems do you expect to see?
Colapse of the lungs
28
Cortisteroid therapy
Enhances surfactant production, prevents respiratory problems after birth.
29
Pleural sac surrounds the lungs, how are they?
- Fluid-filled sac that encompasses lungs and provides lubrication for smooth movement and hold lungs open
- 2 membranes (one by lungs - visceral and one by the chest wall - parietal)
30
What does the pleural sac do?
Pressure holds lungs open
31
Pleurisy
Inflammation of the pleural sac membrane due to infection
32
Your friend thinks you two should build your own meter- long snorkels for an upcoming tropical excursion. Is a bad idea?
Yes, it’s a bad idea. A meter-long snorkel would make it very difficult to breathe due to several issues:
1. Dead Air Space – The longer the snorkel, the more exhaled CO₂ stays in the tube, leading to rebreathing stale air instead of fresh oxygen. This can quickly cause dizziness, headaches, or even unconsciousness.
2. Water Pressure – At just one meter underwater, the pressure on your lungs increases, making it harder to inhale through a long tube. Your diaphragm isn’t strong enough to pull in air against that pressure difference.
33
Which ventilation do insects have?
Tidal ventilation, insects breathe sing tracheal system of gas-filled tubes that reach all tissues
34
Which muscles are very active in insects?
Flight muscles are very active, showing tracheoles inside muscles fibers.
35
Which are the adantages of having air sacs in insects?
- Improves gas exchange
- Increase gas exchange efficiency
- Enhance ventilation
- Play a role in buoyancy (flotabilidad)
36
In which insects do we see air sacs
- Larger insects
- High metabolic demand
- Flying insects
- Low oxygen availability
- Aquatic insects
37
Bird ventilation
There is an unidirectional air flow and ventilation in birds is highly efficient.
38
Why is the bird ventilation so efficient?
- Maximizing oxygen exchange
- Facilitates continuous movement of air to enhance oxygen delivery
- Helps reduce weight during flight
- Support metabolic rate
39
Gas exchange in branchial breathing in bony fish (teleost)?
It occurs in secondary lamellae on each of the filaments
40
What is good about having lamellae in each fiber?
That they have much more surface in contact of oxygen, more capacity of breathing
41
Respiration
Exchange of CO₂ and O₂ between animals and environment
42
What does respiration involve?
Gas exchange structure (i.e. lungs), circulation and release o tissues
43
What process in respiration do very small animals (especially invertebrates) skip?
Bulk transport
44
Bulk transport
Ventilation of large volumes of air via a gas exchange structure (lungs)
45
What happens after bulk transport?
Diffusion into circulatory system, then diffusion into tissues
46
Fick's law
describes rate of diffusion
rate = K x A x ((C2-C1)/L)
K = constant, A = SA, C = concentration (2 = lungs; 1 = blood), L = distance of diffusion
47
how can you increase diffusion rate?
increase surface area, decrease distance of diffusion, increase concentration gradient (increase concentration in lungs or decrease concentration in blood)
48
how are lungs adapted to increase diffusion rate?
very high surface area, very thin tissue (decreases distance), and constant ventilation to keep concentration gradient high
49
lung structure in order
trachea > bronchi > bronchioles > respiratory bronchioles > alveolar ducts > alveolar sac > alveoli
50
conducting zone
bronchioles, bronchi, trachea
51
respiratory zone
where respiration occurs
respiratory bronchioles, alveolar ducts, alveolar sac, and alveoli
52
trachea
tube in throat - linked to pharynx in humans
53
respiratory bronchioles
Special bronchioles where gas exchange can occur
54
Metalloproteins
Proteins that contain a metal ion cofactor
55
Haemoglobin
Found in blood, with iron, containing heme group, tetrameric protein with 4 subunits
56
Myoglobin
Found in the muscles, iron containing heme group, monomeric protein, major difference with haemoglobin is higher affinity than haemoglobin
57
What does it mean a high affinity
Chances of the molecule being release are lower
58
When haemoglobin is deoxygenated which color does it has?
Blue, dark brown
59
Haemocyanins
Found in the haemolymph, it's copper based with respiratory pigment, found in mollusc and arthropods, oxygenation changes the pigment from colourless to blue
60
Animals that don't have respiratory pigments?
Antartic notothenioid fish (Icefish). There is abundant oxygen
61
What roles does the conducting zone play?
- Has mucus escalator: globet cells secret mucus, cillia beat upward to move mucus to pharynx (then swallowed)
- Captures particulates (like dust)
62
Features of the respiratory zone (specifically alveoli)
Super thin tissue (0.2-15), huge surface area (1 human lung = 250 million alveoli, 65 sq m), thin and coated with watery solutions (act like bubbles - high surface tension)
63
Diaphragm
Muscle at base of lungs, connected to pleural sac but not lungs
64
Diaphrahm shape when relaxed vs contracted
- Relaxed = arched (lengthens when relaxes)
- Contracted = flattened (shortens when contracts)
65
Chest wall
- Rib cage
- Sternum
- Thoracic vertebrae
- Connective tissue
- Intercostal muscles
66
Intercostal muscles
In between ribs: 2 sets, eternal and internal (antagonistic muscles), Connected to pleural sac (along the ribs)
67
External intercostal muscles
Outside ribcage function is to lift the ribcage
68
Internal intercostal muscles
Inside ribcage, function is to depress ribcage
69
At rest, the lung has a tendency towards collapse, why?
- Weight of chest cavity
- Elasticity of lung tissue (always in a slightly stretched state, tendency of recoiling)
- Surface tension in alveoli (has a tension pulling inward, collapsing while air inside has outward force)
70
Collapse is opposed by
Pleural sac and production of surfactant
71
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
72
How does the production of surfactant oppose collapse?
Detergent like substances secreted by cells in alveoli, it decreases surface tension in alveoli so they stay open
73
Why does surfactant decrease surface tension
Cannot blow bubbles with just water (too high surface tension), need soap to decrease
74
What is the release of surfactant triggered by?
Stretch, inhaling
75
What role does the ventilator play for premature babies?
Hold lungs open + supplies artificial surfactant
76
Infant respiratory distress syndrome
Baby is born before surfactant production begins (first breath is unable to open lungs due to high surface tension)
77
What is the consequence of the opposing collapse in the lungs?
There's always some air in the lungs (retention of state air)
78
3 Main parts of the breathing cycle
Tidal ventilation, inhalation and xhalation
79
Tidal ventilation
Like tide = air enters and exits on the same path
80
What happens during inhalation?
1. Contract external intercostals and diaphragm
2. Pull 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
81
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
82
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
83
What is a limitation of mammalian lung anatomy?
Dead space
84
2 types of dead space
Anatomical (structural) and alveolar (functional)
85
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)
86
Alveolar dead space
Not all alveoli are receiving air or blood all the time (so they don’t contribute physiologically)
87
Physiological dead space
sum of anatomical + alveolar
very significant: normal resting breath = 350 mL fresh air in inhale but lung capacity is 3 L
88
What is the consequence of dead space?
Significantly less O₂ in air inside lung than in atmospheric air
89
What is the driving force of gases?
Partial pressure
90
Why is partial pressure used?
Gas diffusion into a liquid is more accurately described by partial pressure than concentration gradient
91
What moves O₂ into blood and CO₂ out of blood?
Partial pressure = driving force!
92
Partial pressure
Portion of total pressure that a single gas is exerting
93
Sea level atmospheric air pressure
760 mmHg
94
Partial pressure of O₂ at sea level
0.21 x 760 = 160 mmHg
95
Partial pressure of CO₂ at sea level
0.03 x 760 = ~0 mmHg
96
Partial pressure is dependent on
Altitude
97
Atmospheric air pressure in Calgary
667 mmHg
98
Partial pressure of O₂ in Calgary
0.21 x 667 = 140 mmHg
99
Partial pressure of O₂ in lungs is lower than atmospheric because
large presence of water vapour in lungs
100
Higher pp of O₂/lower pp of CO₂ in atmospheric air than lungs does what?
Drives O₂ into and drives CO₂ out of lungs
101
What does the solubility of O₂ and CO₂ depend on?
Dissolvability in water depends on:
1. partial pressure of gas
2. temperature
3. salinity
102
How does partial pressure affect solubility?
Higher pressure gradient means more dissolved gas—gas dissolves until pp in fluid = pp in air
103
How does temperature affect solubility
Cold water means more gas dissolved
104
How does salinity affect solubility?
Less salt means more gas can dissolve
105
Is O₂’s partial pressure higher or lower at the top of Mt. Everest than in Calgary?
Lower
106
Assuming constant pp, is there more O₂ in salt or fresh water at the same temperature?
Fresh water
107
Assuming constant pp, is there more O₂ in a Petri dish containing fresh water or a plasma sample at the same temperature?
fresh water—plasma = H₂O-based solution but has higher salinity
108
Assuming constant pp, is there more O₂ in hot or cold tap water?
Cold tap water
109
Comparative ventilation
Gas exchange surface area (lungs, alveoli, gill tissue...) matches O₂ demand
110
As body size increases, how does gas exchange surface area change?
It also increases; in bigger animals, they have more cells because they have a greater demand for cellular respiration and O₂.
111
How does gas exchange surface area differ in endotherms and ectotherms?
More surface area in endotherms (for example, frogs and mice may have the same body weight, but gas exchange surface area is higher in mice).
Heat regulation requires more energy and O₂.
112
Bird ventilation steps
1. Inhale 1 = to posterior air sac (expands)
2. Exhale 1 = to rigid lungs and some back to main airway
3. Inhale 2 = to anterior ai sac
4. Exhale 2 = out of body
113
What is one difference between bird and mammalian lungs?
Bird lungs are rigid, do not change in shape or size
114
Why do birds need to extract more O₂ than mammals?
Because they fly which requires lots of O₂.
115
Do birds have tidal ventilation?
No, they have one way continuous flow (doesn't go out/in on the same path)
116
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)
117
Insect ventilation systems tent to involve
Insects use a tracheal system of branching tracheae and tracheoles to deliver oxygen directly to tissues. Spiracles regulate airflow, and body movements or pumping aid ventilation, enabling gas exchange without a circulatory system.
118
What is the network of gas- filled tubes in insects called?
Tracheal system
119
How does the fresh air enter the tracheal system in insects?
Fresh air enters the tracheal system in insects through spiracles, which are small openings on the insect's exoskeleton. These spiracles regulate airflow by opening and closing, allowing air to enter and exit the tracheal system.
120
Invertebrates that don't fly use what for gas exchange?
Invertebrates that don't fly typically use diffusion across their body surface or gills for gas exchange. Oxygen diffuses directly through the skin or external structures, like gills, where it is absorbed and carbon dioxide is released.
121
Why are insect ventilation system so specialised
Insect ventilation systems are specialized for efficient gas exchange, directly delivering oxygen to tissues. This bypasses the circulatory system, supporting high metabolic demands, especially during flight or active behaviors.
122
What are some challenges that might make breathing hard for aquatic organisms?
Challenges for aquatic organisms in breathing:
1. Low oxygen concentration in water.
2. Higher water temperature reduces oxygen.
3. Water pollution decreases oxygen and damages gills.
4. Salinity changes affect gas exchange.
5. Low water flow limits oxygen access.
6. High metabolic demand increases oxygen need.
123
Gills
Gills are specialized organs in aquatic organisms that extract oxygen from water through thin, feathery structures, allowing efficient gas exchange.
124
Gills can be either
Gills can be either external or internal. External gills are exposed to the environment, while internal gills are located inside the body, often protected by a structure like a gill cover or operculum.
125
Fish gills have specialized type of flow
Fish gills use a countercurrent flow system, where water flows opposite to blood, maximizing oxygen exchange by maintaining a concentration gradient for efficient diffusion of oxygen into the blood and carbon dioxide out.
126
Flow water in/out fish body
Water enters a fish’s mouth, flows over the gills for oxygen absorption, and exits through the gill slits or operculum. This unidirectional flow enables continuous oxygen uptake and carbon dioxide removal.
127
How does countercurrent flow affect O₂ pickup capabilities?
Countercurrent flow in fish gills maximizes oxygen pickup by maintaining a concentration gradient. As water and blood flow in opposite directions, oxygen continuously diffuses from the water into the blood, ensuring that oxygen absorption is efficient throughout the entire gill surface. This system allows fish to extract a high percentage of available oxygen.
128
What type of flow do mammalian lungs use?
Mammalian lungs use tidal flow, where air moves in and out of the lungs in a bidirectional manner. Air is inhaled into the lungs and exhaled out, with oxygen being absorbed into the blood and carbon dioxide being expelled during each cycle.
129
What type of flow do bird lungs use?
Bird lungs use unidirectional flow. Air flows in one direction through the lungs, passing through a series of air sacs. This system allows for continuous oxygen extraction, even during both inhalation and exhalation, making it highly efficient for meeting the high metabolic demands of flight.
130
Why are ventilation and perfusion matched?
Ventilation (airflow) and perfusion (blood flow) are matched to optimize gas exchange. This ensures that oxygen-rich air reaches well-perfused areas of the lungs, maximizing O₂ uptake and CO₂ removal. Mismatched ventilation and perfusion can lead to inefficient gas exchange and impaired oxygenation.
131
Perfusion
Perfusion is the process of delivering oxygenated blood to tissues and organs through the circulatory system. In the lungs, perfusion refers to blood flow through the pulmonary capillaries, allowing gas exchange with the air in the alveoli.
132
V/Q ratio
The ventilation/perfusion (V/Q) ratio is the relationship between airflow (ventilation) and blood flow (perfusion) in the lungs. A normal V/Q ratio ensures efficient gas exchange. An imbalance can lead to conditions like hypoxia (low oxygen) if ventilation or perfusion is impaired.
133
V/Q ratio of mammals (whole lung)
The V/Q ratio for the whole lung is 0.8. This means that ventilation is slightly lower than perfusion, ensuring efficient gas exchange.
134
How is a healthy lung in mammals?
V/Q = 0.8 = 1 L of air reaching the alveoli and ~ 1.2 L of blood perfusing the lungs
135
V/Q ratio of fishes (whole gill)
The V/Q ratio for the whole gill is typically around 10. This means that ventilation (water flow over the gills) is much higher than perfusion (blood flow), ensuring efficient oxygen extraction from water, which has a much lower oxygen content than air.
136
Challenge of fish in terms of V/Q
Fish face the challenge of maintaining a high V/Q ratio (around 10) because water contains much less oxygen than air. To compensate, they must move large volumes of water over their gills, which requires energy. Efficient countercurrent exchange helps maximize oxygen uptake despite this challenge.
137
How does fishes overcome lower solubility of O₂ in water?
Fish overcome the low oxygen solubility in water by using a countercurrent exchange system in their gills, maintaining a steep O₂ gradient for efficient diffusion. They also have a high ventilation rate (moving large volumes of water over gills) and specialized hemoglobin with a high oxygen affinity to maximize O₂ uptake.
138
How does dishes overcome their blood carrying less O₂?
Fish compensate for lower O₂-carrying capacity by having hemoglobin with a high oxygen affinity, Bohr and Root effects (allowing O₂ unloading where needed), and efficient countercurrent exchange in gills to maximize O₂ uptake. Some species also increase red blood cell production or adjust gill surface area to enhance oxygen transport.
139
Net effect of fish overcoming its 2 challenges of less O₂ in water and in blood
By optimizing gill ventilation, countercurrent exchange, and hemoglobin function, fish maximize O₂ uptake and delivery to tissues. This allows them to efficiently extract and transport oxygen despite the low O₂ availability in water and limited blood-carrying capacity.
140
What is the underlying issue of low V/Q
A low V/Q ratio means that perfusion (blood flow) is greater than ventilation (airflow), leading to inadequate oxygenation of the blood. This can result from blocked airways, lung disease, or impaired ventilation, causing hypoxia and reduced gas exchange efficiency.
141
How does the mammalian lung correct for too much blood - high Q?
The mammalian lung corrects for high perfusion (high Q) by adjusting ventilation (V). When there is too much blood flow, local mechanisms like hypoxic vasoconstriction help redirect blood to areas with better ventilation. This maintains the balance between ventilation and perfusion, optimizing gas exchange.
142
How does the mammalian lung correct for too little air - low V?
When ventilation (V) is too low, the mammalian lung corrects by increasing ventilation rate or depth, a process controlled by chemoreceptors that detect low oxygen or high carbon dioxide levels. This helps improve airflow to poorly ventilated areas, optimizing gas exchange and balancing the V/Q ratio.
143
How does the mammalian lung correct for too little air - low V?
1. Increased breathing rate: More frequent breaths to bring in more air.
2. Increased tidal volume: Deeper breaths to improve gas exchange.
3. Vasodilation: Dilates blood vessels in the lungs to enhance blood flow.
4. Activation of chemoreceptors: Detect low O₂ or high CO₂, signaling the brain to increase ventilation.
144
What does decreased O₂ usually lead to in smooth muscle?
Decreased O₂ typically leads to vasoconstriction in smooth muscle, particularly in pulmonary arteries. This response, known as hypoxic pulmonary vasoconstriction, helps redirect blood flow to areas of the lungs with higher oxygen levels, optimizing oxygen exchange.
145
At altitude, how does the partial pressure of O₂ change?
At higher altitudes, the partial pressure of O₂ decreases because the atmospheric pressure is lower. Although the percentage of oxygen in the air remains constant, there is less total oxygen available for the body to absorb, making it harder to oxygenate tissues.
146
At altitude how does blood flow change?
At altitude, blood flow to the lungs may initially decrease due to hypoxic pulmonary vasoconstriction, which directs blood away from poorly ventilated areas of the lungs. Over time, the body compensates by increasing red blood cell production to improve oxygen transport, and blood flow may adjust to enhance oxygen delivery to tissues.
147
Pulmonary edema
Pulmonary edema is the accumulation of fluid in the lungs' alveoli, impaired gas exchange and causing difficulty breathing. It can be caused by conditions like high-altitude exposure (high-altitude pulmonary edema, or HAPE), left-sided heart failure, or lung injury. Symptoms include shortness of breath, coughing, and fatigue.
148
What happens when you have a lot of carbon dioxide in your blood?
Decrease if pH; the O₂ will not bind hemoglobin
149
What is the problem with the dissolved O₂ levels in out blood?
The problem with dissolved O₂ levels in our blood is that oxygen has low solubility in plasma. Only a small fraction of the body's oxygen is dissolved directly in the blood, and this amount is insufficient to meet the body's demands. Most oxygen is carried by hemoglobin in red blood cells, which enhances oxygen transport to tissues.
150
Metabolic demand at rest (resting metabolic rate, VO₂ rest)
The resting metabolic rate (VO₂ rest) refers to the amount of oxygen consumed by the body at rest to maintain basic physiological functions, such as breathing, circulation, and cell maintenance. It is typically measured in milliliters of oxygen per minute (mL/min) and reflects the energy required to sustain these essential processes without physical activity.
151
Blood flow at rest
At rest, blood flow is primarily directed to vital organs, such as the brain, heart, and kidneys, which have high metabolic demands
152
Blood plasma O₂ solubility
Oxygen has low solubility in blood plasma. Only about 1-2% of oxygen in the blood is dissolved directly in plasma, with the majority (about 98%) being carried by hemoglobin in red blood cells. The low solubility of oxygen in plasma is one reason why hemoglobin is essential for efficient oxygen transport throughout the body.
153
How much O₂ does blood plasma deliver?
Blood plasma delivers a small amount of oxygen—only about 1-2% of the total oxygen content in the blood. The majority (98-99%) of oxygen is transported by hemoglobin in red blood cells, which significantly enhances the blood's capacity to deliver oxygen to tissues.
154
Steps of oxygen getting taken up by blood + Hb
1. Oxygen enters the lungs: Air with oxygen is inhaled into the lungs, where it diffuses across the alveolar membrane into the blood in the capillaries.
2. Oxygen binds to hemoglobin: In the capillaries, oxygen binds to hemoglobin (Hb) in red blood cells, forming oxyhemoglobin.
3. Oxygen transport: Hemoglobin carries the oxygen through the bloodstream to tissues and organs.
4. Oxygen release: In the tissues, oxygen is released from hemoglobin due to a lower partial pressure of oxygen (Bohr effect), allowing it to diffuse into cells for metabolism.
155
Oxygen dissociation curve
Shows the relationship between the partial pressure of oxygen (PO₂) and the percentage of hemoglobin saturated with oxygen. At high PO₂ (in the lungs), hemoglobin binds to oxygen efficiently, while at low PO₂ (in tissues), hemoglobin releases oxygen. The curve is sigmoidal, reflecting cooperative binding, where the binding of one oxygen molecule increases hemoglobin's affinity for subsequent oxygen molecules.
156
What are the axes labels on an oxygen dissociation curve?
- The x-axis represents the partial pressure of oxygen (PO₂), typically measured in mmHg or kPa.
- The y-axis represents the percentage of hemoglobin saturation with oxygen (% saturation).
157
For Hb, what is the oxygen dissociation curve?
The oxygen dissociation curve for hemoglobin (Hb) shows how hemoglobin's oxygen-binding affinity changes with varying levels of oxygen partial pressure (PO₂). The curve is sigmoidal because hemoglobin exhibits cooperative binding: as one oxygen molecule binds, it increases hemoglobin's affinity for additional oxygen molecules. At high PO₂ (in the lungs), hemoglobin binds oxygen tightly, while at low PO₂ (in tissues), hemoglobin releases oxygen more readily.
158
For Mb, what is the shape of the oxygen in the dissociation curve?
The oxygen dissociation curve for myoglobin (Mb) is hyperbolic, unlike hemoglobin's sigmoidal curve. Myoglobin has a higher affinity for oxygen and binds oxygen more readily at lower partial pressures. This curve reflects myoglobin’s role in storing oxygen in muscles and releasing it when oxygen levels are low during muscle activity.
159
Lung on the oxygen dissociation curve
In the lungs, where the partial pressure of oxygen (PO₂) is high, hemoglobin is nearly fully saturated with oxygen, which corresponds to the steep part of the oxygen dissociation curve. At high PO₂, hemoglobin binds oxygen efficiently, maximizing oxygen uptake from the alveoli into the blood.
160
Tissues on dissociation curve
In the tissues, where the partial pressure of oxygen (PO₂) is low, the oxygen dissociation curve shifts to promote oxygen release. As PO₂ decreases, hemoglobin's affinity for oxygen decreases, and it releases oxygen more readily to the tissues. This corresponds to the flat portion of the curve, where hemoglobin unloads oxygen efficiently to meet the metabolic demands of tissues.
161
Exercising muscle uses O₂; what does this do to the PO₂ in this tissue?
As exercising muscles use oxygen, the partial pressure of oxygen (PO₂) in the tissue decreases. This drop in PO₂ promotes the release of oxygen from hemoglobin, shifting the oxygen dissociation curve to the right and enhancing oxygen delivery to the muscle cells to meet their increased metabolic demands.
162
Fresh blood arrives to exercising muscle; how does Hb respond to the decreased PO₂ in that tissue?
As fresh blood arrives in the exercising muscle with a lower PO₂, hemoglobin responds by releasing oxygen more readily. The decreased PO₂ causes a rightward shift in the oxygen dissociation curve (Bohr effect), lowering hemoglobin's affinity for oxygen and facilitating the release of oxygen to the tissues that need it most during exercise.
163
How is affinity for Hb for O₂ measured?
Hemoglobin's affinity for oxygen is often measured by the P50 value, which is the partial pressure of oxygen (PO₂) at which hemoglobin is 50% saturated with oxygen. A lower P50 value indicates higher affinity, meaning hemoglobin binds oxygen more tightly. A higher P50 value indicates lower affinity, meaning hemoglobin releases oxygen more readily.
164
P50
P50 is the partial pressure of oxygen (PO₂) at which hemoglobin is 50% saturated with oxygen. It is used to measure hemoglobin's affinity for oxygen. A lower P50 indicates a higher affinity for oxygen (hemoglobin binds oxygen more tightly), while a higher P50 indicates a lower affinity (hemoglobin releases oxygen more easily).
165
How does affinity for O₂ changes with P₅₀?
As P50 increases, hemoglobin’s affinity for O₂ decreases. This means that at a higher P50, hemoglobin releases oxygen more easily. Conversely, a lower P50 indicates a higher affinity for oxygen, meaning hemoglobin binds oxygen more tightly and holds onto it longer.
166
Myoglobin vs hemoglobin affinity for O₂?
Myoglobin has a higher affinity for O₂ than hemoglobin, allowing it to store oxygen in muscles. Hemoglobin has a lower affinity in tissues, releasing oxygen where it's needed, with its affinity changing depending on oxygen levels.
167
Hb affinity for O₂ is reduced by
Hemoglobin's affinity for O₂ is reduced by factors like increased CO₂, lowered pH (Bohr effect), increased temperature.
168
Bohr effect
The Bohr shift refers to the decrease in hemoglobin's affinity for oxygen in response to increased CO₂ and decreased pH (higher acidity, releases more O₂), promoting oxygen release to tissues that need it. CO₂ also binds to the respiratory pigments, forming carbaminohemoglobin, decreasing the oxygen affinity
169
Reverse Bohr effect
The reverse Bohr effect occurs when CO₂ levels decrease and pH increases, typically in the lungs. This causes hemoglobin to bind oxygen more readily, enhancing oxygen uptake from the lungs into the blood.
170
Hb affinity for O₂ at lower pH
At lower pH (more acidic conditions), hemoglobin's affinity for O₂ decreases, promoting oxygen release to tissues. This is due to the Bohr effect.
171
Hb affinity for O₂ at higher pH
At higher pH (more basic conditions), hemoglobin’s affinity for O₂ increases, promoting oxygen binding. This is part of the reverse Bohr effect, occurring in the lungs.
172
Why does a lower pH cause lower Hb affinity for O₂
A lower pH (higher acidity) causes hemoglobin to undergo a conformational change, reducing its affinity for oxygen. This helps release oxygen to tissues where it's needed most, a response known as the Bohr effect.
173
Root effect
Is a phenomenon that occurs mostly in fish hemoglobin, it's were an increased proton or carbon dioxide concentration (lower pH) lowers hemoglobin's affinity and carrying capacity for oxygen. It can be distinguished from the Bohr effect were only the affinity to oxygen is reduced
174
Which is given more priority: Bohr shift or Root shift?
The Bohr shift is generally given more priority in most organisms, as it regulates oxygen release in response to changes in CO₂ and pH in tissues. The Root effect is more specific to certain species (like fish) and is important for extreme oxygen release in particular tissues, such as the retina.
175
What happens with a root shift?
During the Root effect, a decrease in pH reduces hemoglobin’s ability to bind oxygen, causing a more significant release of oxygen than usual. This is especially important in tissues with very low pH, allowing for greater oxygen delivery to those areas, such as in the eyes or muscles of certain species.
176
Which animals can root shift?
The Root effect is observed in certain fish, such as salmon and trout, as well as some amphibians and reptiles. It allows these animals to release more oxygen in tissues with very low pH, such as the retina or muscle during strenuous activity.
177
Mechanism for root shift in fish
In fish, the Root effect occurs when a drop in pH (due to increased CO₂ or lactic acid) causes hemoglobin to lose its ability to bind oxygen. This is due to conformational changes in hemoglobin, which significantly reduces its oxygen affinity, enhancing oxygen release to tissues, especially in areas like the retina where oxygen demand is high.
178
After exposing a respiratory pigment to H+, you find that its P50 for O₂ has increased, how has its affinity for O₂ changed?
An increase in P50 indicates a decreased affinity for O₂. The respiratory pigment now releases oxygen more easily, which is typically seen when the pH decreases (more acidic conditions), as in the Bohr effect.
179
Name 4 ways Hb's affinity for O₂ can be reduced
1. Heat
2. Organic phosphates
3. Low pH (=lots of H+)
4. Increased CO₂
180
Thinking about the V/Q ratio at the whole-lung scale, if we observe that V is increasing, what is happening?
If V (ventilation) is increasing, it means that more air is being delivered to the lungs. If Q (perfusion) remains constant, this leads to a higher V/Q ratio, which can indicate improved ventilation relative to blood flow, potentially improving oxygenation.
181
After CO₂ dissolves in water, what happens?
After CO₂ dissolves in water, it reacts with water to form carbonic acid (H₂CO₃), which then dissociates into hydrogen ions (H⁺) and bicarbonate ions (HCO₃⁻). This process lowers the pH of the solution, contributing to acidification.
182
Carbonic acid reaction
The carbonic acid reaction is:
CO₂ + H₂O ↔ H₂CO₃ ↔ H⁺ + HCO₃⁻
This reaction shows how carbon dioxide combines with water to form carbonic acid, which then dissociates into hydrogen ions (H⁺) and bicarbonate ions (HCO₃⁻), contributing to the regulation of pH in blood and tissues.
183
What catalyzes the carbonic acid reaction?
The carbonic acid reaction is catalyzed by the enzyme carbonic anhydrase. This enzyme speeds up the conversion of CO₂ and water into carbonic acid, which then dissociates into hydrogen ions and bicarbonate ions.
184
Which is favoured more in the carbonic acid reaction: bicarbonate or carbonate ion?
In the carbonic acid reaction, bicarbonate (HCO₃⁻) is favored more. At physiological pH, bicarbonate is the predominant form, while carbonate (CO₃²⁻) only forms under more alkaline (higher pH) conditions.
185
3 places O₂ can be found in blood
1. Dissolved in plasma (1-2% of total O₂)
2. Bound to hemoglobin in red blood cells (98-99% of total O₂)
3. Bound to myoglobin in muscle cells (a small amount for storage and oxygen release).
186
Where is the majority of CO₂ in blood found?
The majority of CO₂ in blood is found as bicarbonate ions (HCO₃⁻) in plasma, accounting for about 70% of total CO₂. The rest is either dissolved in plasma (about 7%) or bound to hemoglobin as carbaminohemoglobin (about 23%).
187
What type of CO₂ counts towards PCO₂?
Dissolved CO₂ in plasma counts towards PCO₂. Only the CO₂ that is physically dissolved in the plasma, not bound to hemoglobin or converted to bicarbonate, contributes to the partial pressure of CO₂ (PCO₂).
188
Haldane effect
The Haldane effect refers to the phenomenon where deoxygenated hemoglobin has an increased capacity to carry CO₂. As oxygen is released from hemoglobin in tissues, hemoglobin's ability to bind CO₂ increases, promoting CO₂ uptake from tissues and its transport to the lungs for exhalation.
189
Chloride effect
The chloride effect refers to the exchange of chloride ions (Cl⁻) for bicarbonate ions (HCO₃⁻) across the red blood cell membrane. This occurs as CO₂ is converted into bicarbonate in the blood, helping to maintain electrochemical balance during CO₂ transport.
190
What range of pH do we tolerate?
Humans typically tolerate a blood pH range of 7.35 to 7.45. Outside this range, especially below 7.0 or above 7.8, can lead to serious physiological disturbances.
191
Methods for regulating blood pH
To raise pH (reduce H+ in blood)
- Rid of excess of CO₂: respiratory alkalosis (breathe faster)
- Rid of excess H+: proteins in blood soak up H+, kidneys removes excess, buffer by reacting with bicarbonate, when H+ is from processes other than breathing
To lower pH (increase H+ in blood)
- Hold onto more CO2, respiratory acidosis (breathe slower)
- Kidney removes bicarbonate from blood, drives carbonic acid reaction to the right
192
How do we use bicarbonate to regulate blood pH?
Bicarbonate (HCO₃⁻) helps regulate blood pH by acting as a buffer. When blood becomes too acidic (low pH), bicarbonate binds to excess H⁺ ions, reducing acidity. When blood becomes too basic (high pH), carbonic acid (H₂CO₃) dissociates to release H⁺ ions, lowering pH.
193
How is H+ regulated to regulate blood pH?
1. Respiratory system: CO₂ is exhaled, reducing H⁺ production since CO₂ combines with water to form carbonic acid (H₂CO₃), which dissociates into H⁺ and HCO₃⁻.
2. Renal system: The kidneys excrete H⁺ ions or reabsorb bicarbonate (HCO₃⁻), adjusting blood pH by either removing excess acid or conserving base.
194
Difference between changing pH in blood vs water?
In blood, pH is tightly regulated by buffer systems (like bicarbonate), the respiratory system, and the renal system, allowing for precise control. In water, pH is more influenced by external factors (like CO₂ levels) and can be harder to regulate without buffers, often resulting in larger fluctuations.
195
Most of blood pH regulations is through
Most blood pH regulation is through the bicarbonate buffer system, supported by the respiratory system (adjusting CO₂ levels) and renal system (excreting H⁺ or reabsorbing HCO₃⁻).
196
How do we adjust ventilation to regulate blood pH?
To regulate blood pH, ventilation adjusts to control CO₂ levels. Increased ventilation expels more CO₂, reducing H⁺ concentration (raising pH). Decreased ventilation retains CO₂, increasing H⁺ concentration (lowering pH). This helps maintain the pH within the normal range.
197
How else do aquatic animals regulate blood pH?
1. Active proton pumps, move H+ out of the body
2.Chloride shift: move bicarbonate out of the body
198
How are ions exchanged in aquatic animals to regulate blood pH?
Aquatic animals regulate blood pH by exchanging H⁺ ions for Na⁺ or Cl⁻ ions across their gills or other specialized membranes. This ion exchange helps balance the pH by removing excess acid (H⁺) from the blood or environment. This process often involves acid-base transporters that actively move ions in and out of cells.
199
2 Categories of sensors for respiratory gases
1. Chemoceptors: These detect changes in O₂, CO₂, and pH levels, primarily in the carotid and aortic bodies.
2. Central chemoreceptors: Located in the brainstem, they monitor CO₂ and pH changes in cerebrospinal fluid to regulate ventilation.
200
What is sensed to control respiratory gases?
The body senses changes in O₂ levels, CO₂ levels, and pH to control respiratory gases. Peripheral chemoreceptors detect changes in O₂ and CO₂, while central chemoreceptors in the brainstem primarily monitor CO₂ and pH levels in cerebrospinal fluid.
201
3 Majos sensors in mammals
- Central sensor
- Primary sensor
- Peripheral sensor
202
Aortic arch
Curved portion of the aorta that connects the ascending aorta to the descending aorta. It gives rise to major arteries that supply oxygenated blood to the head, neck, and upper limbs. The aortic arch also contains chemoreceptors that monitor blood oxygen, carbon dioxide, and pH levels to help regulate breathing.
203
Carotid arteries
The carotid arteries are two major blood vessels (left and right) in the neck that supply oxygenated blood to the head, brain, and face. They contain chemoreceptors that detect changes in O₂, CO₂, and pH levels, helping regulate respiratory control by sending signals to the brainstem.
204
Medulla
The medulla is part of the brainstem that controls vital functions such as heart rate, blood pressure, and respiration. It contains central chemoreceptors that monitor the pH and CO₂ levels in cerebrospinal fluid, regulating breathing rate and depth to maintain homeostasis.
205
Why do air-breathing animals primarily monitor pH?
Air-breathing animals primarily monitor pH because it is directly influenced by CO₂ levels, which reflect changes in metabolism and respiratory activity. Since CO₂ is converted to carbonic acid, which lowers pH, monitoring pH allows the body to regulate CO₂ levels and maintain proper blood acid-base balance and respiratory function.
206
Role of O₂ sensors in air-breathing animals
The role of O₂ sensors in air-breathing animals is to detect changes in oxygen levels in the blood. These sensors, located in the carotid bodies and aortic bodies, help regulate breathing by signaling the respiratory centers in the brain when O₂ levels drop, prompting an increase in ventilation to restore adequate oxygenation.
207
Water breathing animals primarily monitor
Water-breathing animals primarily monitor CO₂ levels and pH to regulate their respiratory activity. Since CO₂ dissolves in water and forms carbonic acid, changes in CO₂ directly affect pH, making it a critical factor for regulating ventilation and maintaining homeostasis.
208
Air breathing animals primarily monitor
Air-breathing animals primarily monitor pH to regulate breathing. Since pH is influenced by CO₂ levels, which are tightly linked to metabolic activity, monitoring pH helps maintain proper CO₂ levels and acid-base balance in the body.
209
Why do water breathing animals primarily monitor O₂?
Water-breathing animals primarily monitor O₂ because oxygen availability in water is much lower than in air. To ensure adequate oxygen supply for metabolism, they adjust ventilation rates based on O₂ levels. Monitoring O₂ helps them optimize gas exchange in environments where oxygen can be scarce.
210
To control respiratory gases, how do we respond to change?
1. Increased CO₂ or decreased O₂ stimulates chemoreceptors (in the carotid bodies, aortic bodies, and brainstem).
2. This triggers the medulla to adjust breathing rate and depth, increasing ventilation to remove excess CO₂ or bring in more O₂.
3. In some cases, the kidneys also help by adjusting blood pH through the excretion or retention of H⁺ or bicarbonate.
211
How does your breathing changes when you start to exercise (ways mammals change V)?
1. Increased ventilation (V): The breathing rate and depth (tidal volume) increase to bring in more O₂ and remove more CO₂.
2. Stimulated chemoreceptors: Increased CO₂ and decreased O₂ levels trigger chemoreceptors, signaling the brain to increase respiratory effort.
3. Activation of accessory muscles: Muscles involved in respiration (like diaphragm and intercostals) work harder, increasing lung volume and improving gas exchange.
212
Hypoxia
Insufficient oxygen in the tissues or blood. It can occur due to various factors, including low atmospheric oxygen, respiratory diseases, or impaired circulation. Hypoxia triggers compensatory mechanisms like increased ventilation and heart rate to improve oxygen delivery.
213
Why is hypoxia rare for air-breathers under normal function?
Hypoxia is rare for air-breathers under normal function because oxygen levels in the atmosphere are relatively high, and respiratory systems are efficient at extracting oxygen. Additionally, chemoreceptors help regulate breathing to maintain adequate oxygen levels, preventing hypoxia under typical conditions.
214
Causes of hypoxia
1. Reduced oxygen availability (e.g., high altitudes, low atmospheric O₂).
2. Respiratory diseases (e.g., asthma, COPD, pneumonia) that impair gas exchange.
3. Circulatory issues (e.g., heart failure, anemia, shock) that limit oxygen transport.
4. Blockage or obstruction of airways (e.g., choking).
5. Carbon monoxide poisoning which interferes with oxygen binding to hemoglobin.
215
What are some examples of lung diffusion limitations that could lead to hypoxia?
1. Thickened alveolar-capillary membrane (e.g., pulmonary fibrosis), which reduces gas exchange efficiency.
2. Emphysema (destruction of alveolar walls), leading to reduced surface area for oxygen diffusion.
3. Pulmonary edema, where fluid in the alveoli interferes with gas exchange.
4. Ventilation-perfusion mismatch, where areas of the lung receive inadequate blood flow for the amount of air they receive, limiting oxygen uptake.
216
What would impair ability to carry O2 in blood?
1. Anemia, where low hemoglobin levels reduce O₂ transport capacity.
2. Carbon monoxide poisoning, which binds to hemoglobin more strongly than O₂, preventing O₂ binding.
3. Abnormal hemoglobin (e.g., sickle cell anemia), where the hemoglobin structure impairs O₂ binding and release.
4. Reduced hemoglobin concentration due to blood loss or insufficient production.
217
why is hypoxia more common in water-breathers?
Because oxygen levels in water are much lower than in air, and oxygen solubility in water is limited. Additionally, factors like water temperature, salinity, and pollution can further reduce oxygen availability. As a result, aquatic animals are more susceptible to hypoxia, especially in environments with low oxygen concentrations.
218
how are the low levels of O2 in water dealt with by water breathers?
1. Efficient gill structures: Gills have a large surface area and thin membranes for maximum gas exchange.
2. Countercurrent exchange: Water flows in the opposite direction to blood in the gills, maximizing O₂ uptake.
3. Increased ventilation: Many aquatic animals increase the rate of water flow over their gills during low O₂ conditions.
4. Oxygen storage: Some species, like fish, store O₂ in their blood or tissues to use during low-oxygen periods.
5. Behavioral adaptations: Certain species migrate to areas with higher oxygen concentrations when needed.
219
how is respiratory stress dealt with by diving mammals?
1. Increased oxygen storage: They have a higher concentration of myoglobin in muscles and hemoglobin in blood to store oxygen.
2. Bradycardia: During dives, they slow their heart rate to conserve oxygen and reduce oxygen consumption in non-essential tissues.
3. Selective vasoconstriction: Blood flow is redirected from non-essential areas (like the skin and digestive system) to vital organs (brain, heart, muscles).
4. Lung collapse: Some species collapse their lungs at depth to prevent nitrogen absorption and avoid nitrogen narcosis, preserving oxygen for essential functions.
5. Efficient use of oxygen: They have a high capacity for utilizing oxygen in their muscles, allowing for longer dives without reaching hypoxia.
220
how is respiratory stress dealt with by carps (goldfish)?
1. Increased gill ventilation: They increase the rate of water flow over their gills to enhance oxygen uptake.
2. Behavioral adaptations: When oxygen levels are low, they move to areas with higher oxygen concentrations or swim closer to the water surface.
3. Anaerobic metabolism: In extreme cases, such as during hypoxia, they can switch to anaerobic metabolism for short periods, although this is less efficient.
4. Use of supplemental oxygen: Some species of carp can also extract oxygen from the air through specialized structures like labyrinth organs when oxygen levels in water are critically low.
221
O2 demands varies based on
- Activity level: Higher during exercise or increased movement.
- Body size: Larger animals generally have higher O₂ demands.
- Metabolic rate: Higher metabolic rates increase O₂ needs.
- Environmental conditions: Temperature, oxygen availability, and water salinity affect oxygen demand.
- Developmental stage: Growth and reproduction often increase O₂ consumption.
222
how can O2 demand higher than the VO2 max (aerobic MR) be met?
1. Anaerobic metabolism: The body switches to anaerobic pathways (e.g., lactate production) to generate energy without requiring oxygen, though less efficiently.
2. Increased heart rate and ventilation: These physiological responses aim to temporarily supply more O₂, although they cannot fully meet the demand.
3. Oxygen debt: After intense activity, the body works to repay the O₂ debt by restoring oxygen levels and clearing byproducts like lactate.
223
O2 needs during submaximal activity (
O₂ needs are met through aerobic metabolism, with increased heart rate and ventilation to deliver enough oxygen without accumulating lactate.
224
O2 deficit on O2 demand vs time graph
O₂ deficit is the lag between the start of exercise and the point where O₂ supply meets O₂ demand. It represents the amount of energy produced anaerobically until aerobic metabolism catches up.
225
EPOC
EPOC (Excess Post-Exercise Oxygen Consumption) refers to the increased rate of oxygen intake after exercise, as the body works to restore energy reserves, clear lactate, and return to resting state. It reflects the oxygen debt incurred during intense activity.
226
how does EPOC change with activity
EPOC increases with the intensity and duration of activity. More intense and longer exercises lead to a greater oxygen debt, resulting in a higher EPOC as the body requires more time and oxygen to recover, restore energy stores, and clear metabolic byproducts like lactate.
227
why is our O2 demand non-zero at rest?
Our O₂ demand is non-zero at rest because the body requires a baseline amount of oxygen for maintenance of vital functions, such as heart and brain activity, cell metabolism, and maintaining body temperature. This is reflected in the resting metabolic rate (RMR).
