ap biology lab #10 physiology of the circulatory system
TRANSCRIPT
Blood pressure is a measurement of the force applied to the walls of the arteries as the heart pumps blood throughout the body. Blood pressure is determined by the strength of contraction, amount of blood pumped into the arteries, the viscosity of the blood, and the size and flexibility of the arteries.
fluids exert fluids exert force force against against surfaces surfaces they come they come in contact in contact withwithhydrostatic pressure
fluids flow fluids flow from high from high pressure to pressure to areas of areas of low low pressurepressure
fluids fluids flow flow fasterfaster in in narrower narrower pipes… pipes…
than than wider wider pipespipes
BUT -even BUT -even though though capillaries are capillaries are
smallersmaller than than arteries; we arteries; we have have moremore capillaries capillaries
Therefore: Therefore: greater greater cross-cross-sectional sectional area of area of capillariescapillaries
ThereforeTherefore, , fluids flow fluids flow fasterfaster in in arteriesarteries than than capillariescapillaries
This is a This is a good thing, good thing, b/c gas b/c gas exchange exchange can take can take place in place in the the capillariescapillaries
Blood Blood exerts a exerts a pressure pressure against the against the
wall of wall of the vessel the vessel in which it in which it is flowing.is flowing.
At the arterial end of acapillary, blood pressure is
greater than osmotic pressure,and fluid flows out of the
capillary into the interstitial fluid.
CapillaryRedbloodcell
15 m
Tissue cell INTERSTITIAL FLUID
Capillary
Net fluidmovement out
Net fluidmovement in
Direction of blood flow
Blood pressure
Osmotic pressure
Inward flow
Outward flow
Pre
ssur
e
Arterial end of capillary Venule end
At the venule end of a capillary, blood pressure is less than osmotic pressure, and fluid flows from the interstitial fluid into the capillary.
Figure 42.14
• One type of cardiovascular disease, atherosclerosis– Is caused by the buildup of cholesterol within arteries
Figure 42.18a, b
(a) Normal artery (b) Partly clogged artery50 µm 250 µm
Smooth muscleConnective tissue Endothelium Plaque
Figure 42.9
Artery Vein
100 µm
Artery Vein
ArterioleVenule
Connectivetissue
Smoothmuscle
Endothelium
Connectivetissue
Smoothmuscle
Endothelium
Valve
Endothelium
Basementmembrane
Capillary
•All blood vessels
–Are built of similar tissues
–Have three similar layers
•Arteries have thicker
walls
–To accommodate the high pressure of
blood pumped from the
heart