Physiology-Properties of CV System Flashcards
You are getting your swell on at the gym because of an increase in blood flow to your muscles. What type of blood vessel plays the largest role in getting your swell on?
Arterioles. They have strong muscular walls that can close the arterioles or relax and dilate the arterioles, allowing more blood to pass to the capillaries.
You are deployed and see many injuries from IED blasts, including massive hemorrhage. Injury to what blood vessels in an IED blast would result in the most blood loss?
Technically the venous system. It holds the highest percentage of blood compared to the other blood vessels.
What vessels have the greatest amount of cross-sectional area in the circulatory system?
Capillaries > Veins > Arteries > Aorta
Why does blood flow more quickly in the aorta than in the capillaries?
velocity = flow / area. The volume of blood flowing per minute is the same through all tissues, so if cross-sectional area is smaller, velocity will be greater as in the aorta.
What might happen if a patient happened to have the same arterial pressure in their pulmonary artery as in the aorta?
The lungs would fill with blood. There is a much lower pressure in the pulmonary system because the blood just needs to pass by the lungs so it can pick up oxygen.
A patient goes into shock and immediately his nervous system takes control to try and elevate his blood pressure. What are the targets of the nervous system to accomplish this?
- Increases force of heart contractions 2. Contracts large venous reservoirs to increase amount of blood available 3. Constricts arterioles to increase blood accumulation in arteries.
How do you calculate blood flow through a blood vessel?
Ohm’s law. F is blood flow, ΔP is the pressure difference (P1 - P2) between the two ends of the vessel, and R is the resistance.
What physiological property is an electrical insulator between the atria and ventricles?
Fibrous skeleton
What muscles squeeze the heart horizontally during systole? Longitudinally?
Horizontally = Deep bulbospiral muscle. Longitudinally = Superficial bulbospiral muscle
What is the definition of an arteriole histologically? Physiologically?
Histologically = 2 layers of smooth muscle. Physiologically = vessel smaller than 100 microns in diameter
How do arteries, veins and capillaries differ in their compositions (size, wall thickness, elastic tissue, smooth muscle and fibrous tissue)?
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Where do you typically find the lowest pressure in the cardiovascular system?
Right atrium
How does the pressure in the vessels and chambers of the heart change going from the right atrium to the vena cava?
RA = 0-5 mmHg. RV diastole = < RA pressure, RV systole = 25 mmHg. PA = 10 mmHg. LA diastole = > RA pressure. LV diastole = > RV pressure. LV systole = 120 mmHg. Aorta systole = 120 mmHg. Aorta diastole = 80 mmHg. Systemic capillaries = 20 mmHg. Vena cava = 5 mmHg.
What factors contribute to vascular resistance in the left heart?
(Mean arterial pressure - Right atrial pressure) / Cardiac Output(L/min)
What factors contribute to vascular resistance in the right heart?
(Mean pulmonary arterial pressure - Left atrial pressure) / CO (L/Min)
How can you calculate pressure, flow or resistance in the cardiovascular system?
Ohm’s Law.
Why do you see an increase in resistance as blood moves into arterioles?
The ratio of vessel wall to lumen is highest in arterioles.
Who is the freeway and who is the drive thru of the cardiovascular system?
The aorta is the freeway, it gets blood out quickly, has one small pipeline and doesn’t stop to talk to anyone. The capillaries are the drive thru. They slow down blood flow and have more cross-sectional area so you can exchange nutrients.
