Blood
Blood carries hemoglobin which carries O₂ and CO2.
O₂ and CO₂ are transported by diffusion.
- Oxygenated Blood
- Is bright red in color.
- Deoxygenated Blood
- Is dark red in color.
- Appears blue through our skin and in educational models.
- Hemoglobin
- A protein used to transport oxygen.
- Contains 4 heme molecules that bind to O₂ and CO2.
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- Gas molecules bind to Fe (iron) molecules in the heme.
Blood Buffering
Three forms CO₂ takes.
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Raw CO₂ in the blood.
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CO₂ bound with heme.
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CO₂ in bicarbonate that is easily dissolved in blood. As CO₂ concentrations increase, the form CO₂ takes changes.
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This allows for extremely high concentrations to be carried in the blood and creates higher diffusion gradients with O2.
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As concentration gradients fill up, different forms of CO₂ are used to store more molecules.
CO₂ varies in form between carbonic acid and bicarbonate. Easy to transition forms to not fall in either direction.
- H2CO3 Carbonic Acid
- ?
- HCO3- + H+ Bicarbonate
- Acidifies the blood.
Two way conversion between Carbonic Acid and Bicarbonate without enzymes (depends on concentration gradient).
- Carbonic Anhydrase
- An enzyme.
- Converts 2 way carbonic acid to (CO₂ + H₂O).
- Facilitates two-way reactions to bind CO₂ and O₂ back and forth.
- Concentration of CO₂ drives which way the reaction occurs.
Hemoglobin has 2 way binding with CO₂ and O₂ depending on pH (concentration of CO2).
CO₂ is primarily transported in the form of HCO3-.
CO₂ is non-polar and can seep through cellular membranes.
Ions are more soluble in water. CO₂ forms acid in your blood and lowers pH. Must be kept in balance.
Hearts
- Coronary Tissues
- Heart muscles
- Atrium
- Receiving chamber for blood from the body.
- Ventricle
- Pumps blood out to the rest of the body.
- Pulmonary Circuit
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Heart > Lung > Heart
- Systemic Circuit
- All of body tissue.
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Heart > Rest of Body > Heart
Blood Pressure
- Blood Pressure
- Pressure exerted on blood vessel walls varies between systolic (max) and diastolic (min).
- Diastolic
- When your heart is at rest between beats.
- Systolic
- When your heart is actively beating.
Evolution of Hearts
- Atrium partial septate (separation)
- Atrium complete septate (separation)
- Ventricle partial septate (separation)
- Ventricle complete septate (separation)
- Two-Chambered Hearts
- Most Fishes
- Single circuit
- Single atrium and single ventricle
- Most fishes don't have lungs so they don't have a need for a dedicated lung circuit.
- Lung Fishes
- Have a modified circulatory system
- Double atrium, deoxygenated and oxygenated blood is mixed.
- Three-Chambered Hearts
- Amphibians
- Have a double circuit.
- Oxygenated blood and deoxygenated blood mix.
- Three-Chambered Heart w/ Septum
- Reptiles
- Partially divided ventricle
- Four-Chambered Heart
- Crocodiles, birds, mammals
- Oxygenated blood and deoxygenated blood are kept completely separate.
- Human Heart Four-Chambered Heart
- Body to right atrium
- Atrium to right ventricle
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- Ventricle away to lungs
- Lungs back to left atrium
- Atrium to left ventricle
- Aorta from left ventricle out to the body.
Study Guide
- What protein carries oxygen in your blood?
- What metal ion is required to carry oxygen?
- How many proteins for the complex that is a single hemoglobin molecule?
- How many oxygen molecules (O2) are bound by hemoglobin?
- If we absorb oxygen through breathing from fresh air, by gas diffusion down a concentration gradient, why do we need hemoglobin at all?
- What gases does Hemoglobin bind & transport?
- Which acidifies blood: cellular respiration, or gas exchange in the gills/lungs?
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What enzyme acidifies blood by using CO2 to generate H2CO3 and H+?
- where does this happen in the body
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What enzyme de-acidifies blood by using HCO3- and H+ to generate CO2?
- where does this happen in the body
- Where is O2 found in the blood (see Canvas Home page image).
- Where is CO2 found in the blood (see Canvas Home page image).
- What helps hemoglobin “offload” oxygen to the tissues (listen to video).
- What does “pulmonary” refer to?
- What is the “pulmonary” circulation vs. the “systemic” circulation?
- What animals have two chambered lungs?
- What animals have three chambered lungs?
- What animals have four chambered lungs?
- what is the evolutionary step between aquatic animals with a heart that breathe through gills as adult animals, and partially-terrestrial animals that have rudimentary lungs.?
- At which evolutionary step does oxygenated blood stop mixed with the deoxygenated blood – when they are kept completely separate during circulation?
- What is the difference between a closed circulatory system, as compared to an open one?
- In 4-chambered hearts, which ventricle pumps blood to the lungs? Why does that happen?
- In 4-chambered hearts, which ventricle pumps blood out to the body?
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Is blood flow in birds and mammals unidirectional or bidirectional?
- Blood flow is unidirectional, though we have concurrent flow for efficient blood oxygen saturation.
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Does oxygenated/deoxygenated blood mix?
- Not in birds or mammals.
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At what stage in the phylogenetic tree do the ventricles become completely separated?
- When a 4-chambered heart evolves in birds, large reptiles, and mammals.
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Why is high or low blood pressure bad
- It can damage capillaries or lead to insufficient nutrients/oxygen/heat to extremities.
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What is systole and diastole?
- diastole is when the heart is at rest.
- systole is when the heart is squeezing.