Gas Transport Flashcards
Explain the two sites where gas exchange occurs in the human body.
in the lungs, where oxygen is picked up and carbon dioxide is released at the respiratory membrane, and at the tissues, where oxygen is released and carbon dioxide is picked up
Which is more soluble in blood, O2 or CO2?
CO2
What is the function of respiration?
to provide oxygen for use by body cells during cellular respiration and to eliminate carbon dioxide, a waste product of cellular respiration, from the body
Use this image to explain why countercurrent flow is more effective than concurrent flow of blood.
At a certain point there is no net difference in concentration, thus no movement of oxygen.
What is external respiration?
External respiration is the exchange of gases with the external environment and occurs in the alveoli of the lungs.
What is internal respiration?
Internal respiration is the exchange of gases with the internal environment and occurs in the tissues.
Does gas exchange occur do to active or passive diffusion? Why?
Passive. no energy is required to move O2 or CO2 across membranes. This simply occurs because of pressure gradients.
List the 3 main variables in the diffusion rate equation.
A = cross sectional area
X = diffusion distance
P = partial pressure gradient
What are some features of alveoli that make them the optimal site for gas exchage?
High cross sectional area, highly vascularized, thin
Where does perfusion occur in mammals?
Capillaries; movement of O2 to capillaries
How does the anatomy of the human lung maximize diffusion?
highly permeable and thin respiratory membrane
thin blood capillary membranes
large SA throughout the lungs.
What are physiological challenges faced by birds in respiration?
lower pressure and concentration at higher altitudes, low temperatures
Explain the composition of vertebrate blood.
Plasma, red blood cells, white blood cells
What do red blood cells do?
Red blood cells carry oxygen from the lungs to the tissues
Explain the shape of a red blood cell and how this is important for its function.
- The mature human red blood cell is small, round, and biconcave; it appears dumbbell-shaped in
profile - The cell is flexible and can pass through extremely small blood vessels
What is a red blood cell’s membrane composed of?
Lipids and proteins.
Do red blood cells have a nucleus?
No.
What is the important protein contained in red blood cells?
Hemoglobin.
Why is respiratory pigment important for gas transport?
It significantly increases the oxygen concentration in blood.
What are respiratory pigemnts?
Respiratory pigments are metalloproteins which circulate in body fluids and undergo
reversible chemical combination with oxygen.
Give two exmaples of respiratory pigments.
- Hemoglobin (in erythrocytes or red blood cells of blood)
- Hemocyanin (in hemolymph)
What is hemoglobin called when bound to oxygen? What colour is it?
Oxyhemoglobin. bright red
What is hemoglobin called when CO2 binds? What colour is it?
Carbaminohemoglobin – burgundy colored
How many heme units does each hemoglobin molecule have? What does this mean for oxygen binding?
4; 4 O2 molecules can bind.
What is contained in heme?
Iron
What is the hemoglobin saturation range in a healthy individual with normal hemoglobin levels?
95%-99%
How does oxygen bind to hemoglobin?
Oxygen molecules reversibly binds with iron
Do oxygen and carbon dioxide have the same binding sites on hemoglobin?
No
What happens as more oxygen binds to hemoglobin? As more dissociates? What is this called?
Binding of the first oxygen molecule causes a conformational change in hemoglobin that allows the second molecule of oxygen to bind more readily.
After the first oxygen molecule dissociates and is “dropped off” at the tissues, the next oxygen molecule dissociates more readily. Called cooperativity.
Is the rate of gas exchange the same in all tissues? Explain,
Highly active tissues, such as muscle, rapidly use oxygen to produce ATP, lowering the partial pressure of oxygen in the tissue to about 20 mm Hg, increasing rate of gas exchange.
Is venus blood completely deoxygenated? Explain.
Although venous blood is said to be deoxygenated, some oxygen is still bound to hemoglobin in its red blood cells. This provides an oxygen reserve that can be used when tissues suddenly demand more oxygen.
What is the partial pressure of oxygen in the alveoli?
104 mm Hg
What is the partial pressure of oxygen in the blood?
40 mm Hg.
What is the main point of this curve?
as PP increases, Hb affinity for O2 increases. Graph shows Hb’s relationship at different PP of oxygen. Relationship between hemoglobin and oxygen at different interfaces in the body.
what is the relationship between oxygen partial pressure and hemoglobin saturation?
As the partial pressure of oxygen
increases, a proportionately
greater number of oxygen
molecules are bound by heme.
How does temperature affect oxygen dissociation/saturation?
Higher temperature promotes faster dissociation (helpful in active tissues that release energy as heat); lower inhibits dissociation
How does BPG affect oxygen dissociation/saturation?
-BPG increases dissociation regardless of pressure (BPG production stimulated by hormones like androgens and thyroid hormones)
How does pH affect oxygen dissociation/saturation?
low pH = increased dissociation from hemoglobin; lower inhibits it (Bohr effect)
Why is cooperativity important in respiratory pigements?
Blood pigments with cooperativity significantly increases the partial pressure of oxygen required in order to release 80% of O2 as opposed to those that do not have cooperativity.
What does a decrease in pH do to the dissociation curve? An increase?
decrease = shift to right; increase = shift to left.
What is P50?
In biochemistry, p₅₀ represents the partial pressure of a gas required to achieve 50% saturation of a particular protein’s binding sites.
What is the Bohr effect?
a
decrease in the
amount of O2 bound
to Hb in response to
a lowered blood pH
resulting from an
increase in CO2
What happens to the dissociation curve when temperature is increased?
increase in temp = shift to right
What factors affect oxygen-hemoglobin affinity?
- partial pressure of oxygen
- Temperature
- partial pressure of carbon
dioxide - pH
- organophosphates
exercise (lactic acid build up)
What factors shift the saturation curve to the left?
decrease in temp, decrease in CO2 pressure, decrease in BPG, increase in pH
What factors shift the saturation curve to the right?
Increase temp, increase PCO2, increase BPG, decrease pH
What are the two ways in which oxygen moves through the body?
Majority bound to Hb, rest is dissolved in plasma (Hb therefore maximizes amount of O2 in red blood cells)
What are the 3 ways CO2 is transported through the blood and in what proportions?
10% in plasma (dissolves more), 30% bound to hemoglobin (protein part, not heme), 60% converted to bicarbonate, which dissolves in the blood.
WHy does carbonmonoxide poisoning occur?
Hb has higher affinity for CO than O2, decreases amount of O2 delivered to the tissues
What can be used to treat CO poisoning? How does it work?
In a hyperbaric chamber, the atmospheric pressure is increased, causing a greater amount of oxygen than normal to diffuse into the bloodstream of the patient.
What is the simplest type of circulatory system?
Open
What group of organisms use an open circulatory system?
Arthtropods.
What is an open circulatory system?
Circulatory fluid does not follow in vessels but rather it bathes each of the body cells in the
body cavity
What is the trade-off for using an open circulatory system?
Requires less energy but less efficient in distribution of nutrients. Meets the specific needs of the small organisms that use it.
Explain the closed circulatory system of an earthworm.
- Have blood with oxygen-binding hemoglobin
- Distribution network of blood vessels
- Pumping mechanism involves multiple disconnected simple heart chambers (each chamber provides own driving force for blood flow.)
Explain the closed circulatory system in fish.
- Closed loop system
- Two connected chambers (one atrium and one ventricle)
Where is the site of countercurrent exchange in fish?
Gill capillaries
Explain the closed circulatory system of amphibians.
- Closed loop system
- Three connected chambers (two atrium and one ventricle)
mixed oxygenated and deoxygenated blood in the single ventricle
Explain the closed circulatory system in mammals.
- Closed loop system
- Four connected chambers (two atrium and two ventricle)
deoxygenated and oxygenated are separated
What do the right and left sides of the heart do?
The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs. The left side of the heart pumps blood to the rest of the body.
What do arteries do? What is the main artery?
. Arteries take blood away from the heart. The main artery of the systemic circulation is the aorta
What is blood flow like in the arterioles?
arterioles as resistance vessels, because given their small lumen, they dramatically slow the flow of blood from arteries.
Why are capillaries the site of gas exchange?
Large SA, small X, thus site of gas exchange
Explain the structure and function of veins.
Veins are blood vessels that bring blood high in carbon dioxide back to the heart. Veins are not as thick-walled as arteries, since pressure is lower, and they have valves along their length that prevent backflow of blood away from the heart
What can be compared between blood vessels?
(a) vessel diameter, (b) total cross-sectional area, (c) average blood pressure, and (d) velocity of blood flow.
What is the flow rate (velocity) through a pipe mainly controlled by?
The diameter.
Where is blood pressure highest?
Pressure is the highest closest to the pump
Why is slow blood flow good in capillaries?
slowing of blood flow in capillaries maximizes gas exchange
What are adaptations that make respiration in birds optimal for flight?
Breathing cycle: 2 inhales and 2 exhales per cycle
Larger lungs increase ventilation
cross current gas exchange and large hearts
high capillarity
higher Hb affinity for O2
