Chapter 14: The Cardiovascular System: Blood, Blood Flow, and Blood Pressure Flashcards
The Starling forces drive the movement of fluid into and out of capillaries. These four forces are:
(1) capillary hydrostatic pressure (2) interstitial fluid hydrostatic pressure (3) capillary osmotic pressure (4) interstitial fluid osmotic pressure
(p. 415)
What is capillary hydrostatic pressure?
the pressure exerted by the presence of fluid inside the capillary (p. 417)
What is interstitial fluid hydrostatic pressure?
the pressure exerted by the presence of fluid outside the capillary
What is capillary osmotic pressure?
the osmotic force due to the presence of proteins in plasma
What is interstitial fluid osmotic pressure?
osmotic force due to the presence of proteins in interstitial fluid
Capillaries are the primary site where exchange of nutrients and waste products occurs between _____ and ______.
blood and tissue
p. 412
Capillaries are the smallest blood vessels, measuring only ___ long and ______ in diameter, about the width of a red blood cell. Capillary walls are thin (0.5 µm), consisting of a single layer of endothelial cells surrounded by a _______ ________. The small diameter and thin wall provide a small diffusion distance between blood and the surrounding interstitial fluid.
1 mm
5 - 10 µm
basement membrane
(p. 412)
A micrometer (µm) (a.k.a. micron) is one-__________ of a meter. In meters, this is _______.
For reference, a typical bacterium is _ to __ µm long, and the diameter of a human hair is about __ to __ µm.
millionth
1 × 10−6 m
1 - 10 µm
20 - 180 µm
[Wikipedia; metricconversions.org]
Although capillaries are small, extensive branching results in 10 - 40 billion capillaries in the human body, providing a surface area for exchange between blood and tissue of approximately ___ square meters. In fact, almost all cells of the body are within ____ of a capillary. Capillaries do not exist in isolation, but rather occur in networks called _________ ____.
600
1 mm
capillary beds
[p. 412]
Because of their extensive branching, the total cross-sectional area of capillaries is considerably greater than that of the other blood vessels. Thus as blood enters capillary beds, the velocity of blood flow ________. Velocity of blood flow through capillaries is about ___ mm/sec, allowing approximately 1 second for exchange between blood and tissue to take place, ample time for simple diffusion.
decreases
0.1
[p. 413, in Principles of Human Physiology]
_____ _________ between endothelial cells of capillary walls within the central nervous system produce a functional barrier between blood and cerebrospinal fluid, the blood-brain barrier. Most capillaries, however, are considerably “leaky” and are classified as either ________ or ________, based on their degree of “leakiness”.
tight junctions
continuous or fenestrated
[p. 413, in Principles of Human Physiology]
In continous capillaries, which are more common, the endothelial cells are joined together such that the spaces between them are relatively narrow. These capillaries are _____ ________ to substances having small molecular sizes and/or high lipid solubility and are somewhat less permeable to small water-soluble substances (sodium, potassium, glucose, amino acids). The permeability of continous capillaries to proteins and other macromolecules is ____ ___ because these substances can neither readily cross membranes of endothelial cells nor easily penetrate the gaps between cells.
highly permeable
very low
p. 413
In fenestrated capillaries, the endothelial cells possess relatively large pores that allow for the rapid diffusion of small water-soluble substances. The size of fenestrations varies in different tissues, with some being large enough for proteins or entire cells to pass through. Fenestrated capillaries are found primarily in organs whose functions depend on the rapid movement of materials across capillary walls, including the ______, _____, _________, and ____ ______. In the liver, the presence of fenestrated capillaries allows newly synthesized proteins such as _______ or clotting factors to enter the plasma. In bone marrow, fenestrated capillaries allow newly formed blood cells to enter the circulation.
kidneys, liver, intestines, and bone marrow
albumin
p. 413
