Exam 3: Atrerial Venous Lymphatic systems Presentations Flashcards
What are two factors that affect pulse pressure?
- Stroke volume output of the heart 2. Compliance of the arterial tree
Pulse pressure =
stroke volume/arterial compliance
what are conditions that cause abnormal contours of the pressure pulse wave?
-Aortic valve stenosis *diameter of the aortic valve opening is reduced significantly, and the aortic pressure is decreased significantly. *blood flow through the aortic valve is diminished - atherosclerosis. -Patent ductus arteriosus -Aortic regulation
What is patent ductus arteriosus?
- Half or more of the cardiac output flows back into the pulmonary artery and lung blood vessels. - diastolic pressure falls very low before next heartbeat.
What is Aortic regurgitation?
- the aortic valve is absent or will not close completely - Aortic pressure may fall all the way to 0 between heartbeats.
t/f is compliance is low, vessels are less able to expand
true
Why does mean pressure lie closer to diastolic than systolic?
Because about 60% of the cardiac cycle is spent in diastole and 40% in systole.
What are factors that regulate right atrial pressure?
- ability of the heart to pump blood out of the right atrium/ventricle -tendency of blood to flow into the right atrium
What can pressure in the right atrium be related to?
Central venous presure
What are factors that increase venous return (and increase right atrial pressure)?
-increased blood volume -increased peripheral venous pressures due to increased large vessel tone -Dilation of arterioles
When do large veins offer resistance?
- In a person lying down the pressure in peripheral veins is +4 to +6 mmHg greater than the right atrial pressure - When intra-abdominal pressure increases, the venous pressure in the legs must increase above the abdominal pressure before blood can flow from the legs to the heart through the abdominal veins.
List the characteristics of arterioles:
-small arterioles control blood flow to each tissue -local conditions in tissue control diameters of arterioles. -arterioles are highly muscular —continuous muscular coat is lost in metarterioles.
Characteristics of capillaries:
-Smooth muscle fiber encircles capillary at point where it originates from a metarteriole (precapillary sphincter) -Capillary wall: has a unicellular layer of endothelial cells, thin basement membrane -total wall thickness = 0.5 micrometers -internal capillary diameter
Define slit pores in capillaries:
(intercellular clefts); spacing of 6-7nm -allow for rapid diffusion of water, water soluble ions, and small solutes
Define plasmalemmal vesicles of capillaries
-formed from caveolins -play a role in endocytosis and transcytosis
List some organs that have capillaries with pores
liver, GI tract, kidneys
What is the most important factor regulating vasomotion?
concentration of oxygen in the tissues.
t/f osmosis is the most important means for the exchange of substances between the blood and the interstitial fluid.
False, diffusion is the most important
_________ substances can diffuse readily through the capillary cell membranes.
Lipid-soluble, they include oxygen and carbon dioxide
____________ substances diffuse through the intercellular pores/clefts.
non-lipid-soluble
Rate of water diffusion through the capillary membrane is ______ faster than the flow of plasma within the capillary
80x
The rate of diffusion is ___________ proportional to concentration differences of the diffusing substance
directly
What is the passage of substance through the interstitium mostly via diffusion rather than flow?
- because of the large numbers of proteoglycan filaments found in the intersitium -rivulets that allow flow through the interstitium do sometimes form.
What determines the net filtration pressure when using the startling forces?
sum of: - capillary pressure (outward force) -interstitial fluid pressure ( inward force) - capillary plasma colloid osmotic pressure (inward force) - Interstitial fluid colloid osmotic pressure (outward force)
What do startling forces determine?
direction of diffusion into or out of a capillary
capillary filtration coefficient
takes into consideration the number and size of pores filtration = Kf x NFP
What happens when fluid enters the lymphatics
the lymph vessel walls contract momentarily and pump fluid in to the blood circulation. this creates a slight ( -) pressure in the interstitial spaces.
Filtration at arterial end of capillary has a total outward force of______?
41mmHg capillary pressure (30 mmHg) negative interstitial free fluid pressure (3 mmHg) interstitial fluid colloid osmotic pressure (8mmHg)
Filtration at arterial end of capillary has a force of fluid moving inward with a total pressure of ________.
28 mmHg plasmid colloid osmotic pressure 29 mmHg
What is the net outward pressure in filtration at arterial end of capillary?
13 mmHg
For filtration at he venous end of capillary, what is the total inward force?
Plasma colloid osmotic pressure 28 mmHg
The outward force for filtration at venous end of capillary is ?
21 mmHg
Accounting for the net inward and net outward forces for filtration at the venous end of capillary, the total net inward force is?
7 mmHg
The lymph vessels possess 1-way valves and the lymph flow reaches maximum when interstitial pressures rise slightly above atmospheric pressure. What factors can also increase lymph flow? give 4 examples
- Elevated capillary hydrostatic pressure
- decreased plasma collid osmotic pressure
- increased interstitial fluid colloid osmotic pressure
- increase permeability of capillaries
The rate of lymph flow = interstitial fluid pressure x activity of lymphatic pump
