Flashcards in CVT 101 Vascular Unit PP Deck (52)
Average diameter of cells:
0.02 mm or 20 microns
How many miles of vasculature in the body?
There are about 60,000 miles of vasculature in the adult body.
a pump, a series of distributing and collecting tubes, and an extensive system of thin vessels that permit rapid exchange between blood and tissues.
3 circulatory circuits:
Distribution of blood volume-
Venules, veins, vena cavae:
What can veins do in the event of a massive hemorrhage or during exercise?
The veins can shunt blood over to the arterial side to maintain core blood pressure in the event of massive hemorrhage and to maintain blood flow during exercise.
What do Arteries do and what are they made up of?
1. Carry blood away from heart
2. More elastic tissue proximally, to absorb energy during systole, then put energy back into system during diastole, thus maintaining flow between heartbeats
3. More smooth muscle distally, which increases arterial stiffness and resistance to flow
What does pulsatility mean?
how much it travels from the mean
What do Arterioles do and what are they made up of?
1. Connect arteries with capillaries
2. Large smooth-muscle component in walls
3. Stopcocks of the vascular system; control of flow and resistance 4. Smooth muscle response to sympathetic nerve activity, local conditions (chemistry)
What are Capillaries and what do they do?
1. Connect arterioles and venules
2. Capillary beds...(not simple)
3. One layer of endothelial cells
exchange of substances in and out of cells
4. They are very small and have no pulsatility
How big are Capillaries ans what is there transit time?
4. 8 microns in diameter (~ one RBC)
5. 10 billion capillaries; total surface area for exchange = 500 m2
6. Transit time: 1–3 seconds, during which all diffusion must take place (diffusion rate vs. distance...)
What do Venules do and what are they made up of?
1. Gather blood from capillaries and send to veins
2. No smooth muscle tissue; just endothelial and connective (i.e., just intima and adventitia)
What are Veins and what do they do?
1. Return blood to heart
2. Venous reservoir; capacitance; 2/3 of total blood volume at rest (some say 3/4)
3. Low pressure, high volume; total CSA about 4 times that of corresponding arteries
How many leaflets do vein valves have? Where are there more valves?
Valves: two leaflets; sinus (for better function) prevent reflux site of thrombus formation
There are more valves in the lower extremities because of hydrostatic pressure.
How does the Deep system and superficial system in lower extremities work?
flow moves from superficial to deep via perforating veins with one-way valves
What are the two main superficial veins?
Great saphenous vein and the small saphenous vein
What does the Muscle pump in legs do during relaxation and contraction?
soleal sinuses (also site of thrombus formation)
When the muscle pump is relaxed the blood flows in
When the muscle pump is contracted blood flows out
What are soleal sinuses, where are they, and how do they work with the muscle pump?
they are little pouching structure in the soleals muscle that gather the venous blood and rout the blood to the posterior tibial vein where it is pushed out of the leg. The bellows of the muscle pump.
What is the Portal system and where does it start and end?
1. Begins and ends as capillaries
2. Connects digestive loop with liver, hepatic veins, and IVC 3. RBC–hemoglobin cycle
3. this is the only loop that begins as capillaries in the digestive track and ends as capillaries in the liver.
What are the three layers of wall tissue?
1. Tunica adventitia
2. Tunica media
3. Tunica intima
What is the Tunica adventitia?
outer layer made up of connective tissue
What is the Tunica media?
middle layer with smooth muscle cells, elastin, and collagen Composition of this layer determines the vessels' mechanical properties
What is the Tunica intima?
smooth inner lining of vessels; single layer of endothelial cells Normally has anti-clotting, anti-platelet properties; interruption of these may start most vascular disease— both atherosclerosis and thrombosis
What is the Vasa vasorum (vessel-vessels)?
blood supply to the vascular tissue
What are the five types of vessels?
What is blood considered to be?
What is hematocrit and what is the normal percentage?
formed particles in blood, usually about 42% ±
What are RBCs?
hemoglobin that carries O2 throughout the body
We make and destroy about 200 billion a day
What are platelets?
initiate healing process, but also initiate plaque and thrombus Thombocytopenia: heparin therapy complication