Flashcards in Peripheral Vasculature Deck (37):
What happens to blood flow after you eat a big meal?
It is shunted to the GI system.
Are capillaries different in each system?
YES. They are different in the liver, skin, brain, and muscle. (ex. capillaries are tight in the brain (BBB) and testes (BTB), but leaky in the kidney).
How do the pulmonary and systemic circuits compare in terms of pressure?
The systemic circuit is higher in pressure than the pulmonary circuit.
Should we think about the arteries as a separate organ system?
Should we think about the veins as a separate organ system?
YES, they are very compliant.
Should we think about capillaries as their own system?
Why shouldn't you jump in the pool after eating a big meal?
because the blood in your body is shunted to your GI tract and when you recruit the muscles you need for swimming, there is less blood flow and therefore less O2 being delivered to them, making cramps much more likely.
What happens to blood flow when you work out and start to overheat?
the blood flow gets dissipated to the extremities to release heat.
Does the arterial or venous system have higher O2 tension?
In what system does high BP occur?
the arterial system (not the venous system)
Is the arterial or venous system more compliant?
**What is the most important characteristic of the aorta?
it is elastic and acts as a secondary pump!
Where is the greatest cross sectional area?
capillaries because there are billions of them
**What is the most important characteristic of the vena cava?
it is compliant (can hold large volumes at LOW pressure)
Is elasticity the inverse of compliance?
What happens to the amount of smooth muscle as we move toward the precapillary sphincter?
it increases. This is good, because if you are in shock due to a major car accident and have internal bleeding, you need blood flow to be shunted toward the internal organs, so the precapillay sphincters of the skin will constrict, reducing blood flow to the skin where it isn't needed.
Do the capillaries have smooth muscle?
NO. they are very thin and only have a single layer of endothelium.
Where is blood volume greatest?
in the venous compartment
What is the hematocrit?
% of RBCs per unit volume. The hemoglobin is what makes up this hematocrit.
Where is the greatest pressure in the vasculature at any one time?
In the aorta.
Where is the largest pressure drop at any one time?
at the level of the arterioles
Is there still pressure at the level of the capillaries?
YES because you need some pressure for filtration
Where is velocity the greatest and lowest, respectively?
velocity is greatest in the aorta, and lowest in the capillaries.
What is the velocity of blood in the vena cava (relative to the velocity of the aorta)?
about 2/3 that of aortic velocity (so it picks back up after the capillaries). biphasic looking curve (looks like a water glass)
Where is pressure the lowest?
What is the Windkessel effect?
accounts for the shape of the arterial blood pressure waveform in terms of the interaction between the SV and the compliance of the aorta and large elastic arteries
Aka: buffers pressure changes of the aorta
How does pulse pressure?
difference between systolic and diastolic pressure (120-80= 40).
What is pulse oximetry?
method to quantitatively evaluate the % of arterial blood hemoglobin that is saturated with O2 after leaving the heart by using 2 different LEDs that are placed on the finger. One LED emits red light (660nm) and the other emits an infrared light (940nm). These lights pass through tissue and are absorbed by oxy-hemoglobin differently than deoxy-hemoglobin. The photometer can then detect a % based on the ratio of light absorbed.
Does more or less light pass through the pulse oximeter if you are hypoxic?
LESS, and therefore you will see a lower O2 saturation %.
What will you hear when taking BPs at peak systolic pressure?
turbulent flow (Korotkoff sounds)
Do the kidneys have tight or leaky capillaries?
What do the kidneys regulate?
volume, electrolytes, and BP
Do cortical and medullary nephrons have similar or different vascular beds?
different. These are involved in reabsorbing fluids and electrolytes so we don't waste them.
What pressure is at work when blood enters the capillaries?
hydrostatic pressure, responsible for filtration
What pressure is at work when blood exits the capillaries?
osmotic pressure, responsible for reabsorption
How can we get CVP (central venous pressures)?
using a SWAN catheter placed right outside of the heart in the SVC