Exam 2 – Cardio Ch 15 Flashcards
What happens if you put more pressure into an artery?
The blood pressure will go up
Why can a vein blow up more than an artery?
It is thin walled
What is vascular distensibility?
The fractional increase in volume for each mmHg rise in pressure
How do you calculate vascular distensibility?
Increase in volume / (increase in pressure x original volume)
Which is more distensible, veins or arteries? By how much
Veins
8 times more than arteries
What is vascular capacitance?
The total quantity of blood that can be stored in a given portion of the circulation for each mmHg
What does capacitance equal?
Distensibility x volume
Which has a large capacitance, veins or arteries? By how much?
Veins
24 times bigger than arteries
How do you calculate vascular compliance?
Increase in volume / increase in pressure
What is systolic pressure?
The height of the pressure pulse (120 mmHg)
What is diastolic pressure?
The lowest point of the pressure pulse (80 mmHg)
What is pulse pressure?
The difference between systolic and diastolic pressure (40 mmHg)
What factors dampen pulse pressures in the peripheral arteries?
Intensity of pulsations
Degree of damping
What happens to the intensity of pulsations in the smaller arteries?
It becomes progressively less
What is the degree of damping proportional to?
The resistance of small vessels and arterioles an the compliance of the larger vessels
What are factors that effect mean pressure?
Cardiac output
Peripheral resistance
What are factors that effect pulse pressure?
Stroke volume
Arterial compliance
What does total peripheral resistance come from?
Metarteriole
What is stroke volume?
How much blood comes out with each stroke
Compared to younger people, what do older people with arterial compliance have?
A higher push pressure
What does an increase in stroke volume cause for pulse pressure?
An increase in pulse pressure
What does a decrease in arterial compliance cause for pulse pressure?
An increase in pulse pressure
What does a given change in volume within the arterial tree result in?
Larger increases in pressure than in veins
What happens when veins are constricted?
Large quantities of blood are transferred to the heart thereby increasing cardiac output
What happens to blood pressure when there is more blood on the artery side than the venous side?
It increases
What is the ausculatory method?
The most commonly used method for measuring systolic and diastolic pressure
What are korotkoff sounds?
Sounds of blood flow (systolic pressure)
What are ways to measure systolic and diastolic pressures?
Pressure cuffs or oscillometric cuffs
Doppler method
Direct
What is the direct method of measuring systolic and diastolic pressures?
A catheter is placed into the artery
What is the normal systolic blood pressure of dogs and cats? Diastolic?
140-160 mmHg
Less than 90 mmHg
What is the normal systolic blood pressure of a horse? Diastolic?
112 +/-14 mmHg
70 +/-14 mmHg
At what systolic pressure is it considered to be hypertension?
160 mmHg
What percentage of blood is in veins?
60%
What is blood transferred into? What does it do?
Arterial system
Maintain arterial pressure
What can serve as blood reservoirs?
Spleen
Liver
Large abdominal veins
Venus plexus
What else is the spleen a special reservoir for?
RBCs
It is important in horses
What is pressure in the right atrium called?
Central venous pressure
What is the level of right atrial pressure or central venous pressure normally?
Zero
What is right atrial pressure determined by?
The balance of the heart pumping blood out of the right atrium and the flow of blood from the large veins into the right atrium
What are factors that increase right atrial pressure?
Increased blood volume
Increased venous tone
Dilation of arterioles
Decreased cardiac function
What do compressional factors tend to cause?
Resistance to flow in large peripheral veins
What do increases in right atrial pressure cause?
Blood to back up into the venous system, thereby increasing venous pressures
What may abdominal pressures interfere with?
Venous return to the heart, especially in ruminants
What do venous valves and “venous pump” do?
Keep pressures peripheral veins low
