7.3 Physiology of the Cardiovascular System Flashcards
In the circulatory system, where does the largest drop in blood pressure occur?
In the Arterioles.
This is important, because the capillaries are unable to withstand the high pressure of the arteries.
What is the relationship between:
Pressure, cardiac output, and total peripehral resistance?
Pressure= Cardiac output x Total Peripheral resistance
What things can increase resistance in the blood vessle?
The longer a blood vessel is, the more resistance it offers
The larger the diameter, the less resistance it offers
(kind of like the axon and moving of electricity down it)
What monitors blood pressure?
Baroreceptors, which are specialized neurons that detect changes in the mechanical forces on the walls of the vessel.
Also, juxtaglomerular cells play a role
What things can react to blood pressure to increase it? (x3)
- RAAS system/ aldosterone
- Catecholamines
- ADH
What drives the flow of ions, gasses and other metabolites across the capillaries?
Concentration gradients
How does heme in the hemoglobin respond to oxygen?
cooperative binding
When oxygen first attaches, it changes shape to make it more attractive to the oxygen, creating a positive feedback loop until all the four points are bound.
Once all are bound, the heme changes again, decreasing the overall affinity for oxygen.
How is carbon dioxide removed from the tissues?
- Very little in the blood, because it’s non-polar and doesn’t dissolve.
- Very little in hemoglobin, because of low affinity.
- Most exists as bicarbonate ion (HCO3)
What enzymes in in RBC for CO2 and what does it do?
- enzyme= carbonic anhydrase
- Catalyzes the combination reaction between CO2 and H20 to form carbonic acid. Carbonic acid, a weak acid, will dissociate into a proton and the bicarbonate ion. Because they are ions, they have high solubility, making them easier to effect metabolic transport.
- This is reveresed once they reach the lung, so you can exhale CO2.
What happens when there’s too much CO2?
It creates an acidic environment, shifting the equation to the right.
The protons (H+) can actually bind to hemoglobin, reducing hemoglobin’s affinity for oxygen.
This is ok, because it allows for more oxygen to unload in the tissue.
This is known as the Bohr effect
What causes a right shift of the oxyhemoglobin curve? (x4)
1. Increased CO2
2. Increased H+
3. Increased temperature
4. Exercise (2,3-biphosphoglycerate (2,3-BPG), which is a side product of glycolysis.
How do kidneys compensate for changes in pH?
If it is too alkalotic, the kidneys can increase the excretion of bicarbonate which can bring back the pH back to normal.
They can also secrete protons as well.
How do nutrients go from the GI to systemic circulation?
Carbohydrates and amino acids are absorbed into the capillaries of the small intestine and enter circulation via the hepatic portal system.
Lipids are absorbed in lacteals in the small intestine, bypassing the hepatic portal circulation, and entering systemic circulation via the thoracic duct.
What is:
Hydrostatic pressure:
Osmotic Pressure:
Oncotic Pressure:
Hydrostatic pressure: Force that the blood exerts against the vessel walls (i.e. blood pressure)
Osmotic Pressure: Sucking pressure, generated by solutes as they attempt to draw water into the bloodstream.
Oncotic Pressure: osmotic pressure generated by proteins.
the balance of these pressures is called Starling Forces
What does the endothelium do do cause clots?
It exposes the underlying connective tissue, which contains collagen and a protein called tissue factor. When platelets touch this, they begin to aggregate.
Coagulation factors sense this, and activate the clotting cascade.
What is the end point of the clotting cascade?
Thromboplastin changes prothrombin to form thrombin.
Thrombin then converts fibrinogen to fibrin. Fibrin can aggregate like a net, forming a clot.
