Ch_20_Test_7 Flashcards
What is the primary function of arteries?
Carry blood away from the heart
Are arteries oxygenated or deoxygenated?
Oxygenated EXCEPT for pulmonary circulation and umbilical vessels of a fetus
What do capillaries directly serve?
Contact tissue cells and directly serve cellular needs
What is the primary function of veins?
Carry blood toward the heart
Are veins oxygenated or deoxygenated?
Deoxygenated EXCEPT for pulmonary circulation and umbilical vessels of a fetus
What are the two major systems in the blood circulatory system?
Venous system, Arterial system
What are the types of vessels in the venous system?
Large veins, Lymphatic vessels, Lymph nodes, Lymphatic system, Small veins, Venules, Capillaries
What are the types of vessels in the arterial system?
Elastic arteries, Muscular arteries, Arteriovenous anastomosis, Lymphatic capillary, Sinusoid, Arterioles, Terminal arteriole, Metarteriole, Precapillary sphincter, Capillaries
Name the structures in the venous and arterial system
what are the tissue layers in the artery?
Tunica intima (Endothelium and subendothelial layer)
Tunica media (smooth muscle and elastic fibers)
external elastic lamina
Tunica externa (collagen fibers)
what are the tissue layers in the vein?
Tunica intima (Endothelium and subendothelial layer)
Tunica media (smooth muscle and elastic fibers)
Tunica externa (collagen fibers)
Label the tissue layers in the artery and vein
What are the three types of arteries based on size and function?
Conducting arteries, Distributing arteries, Arterioles
What are the three structural types of capillaries based on permeability?
Continuous capillaries, Fenestrated capillaries, Sinusoidal capillaries
what is the capillaries with the most permeability?
sinusoidal capillaries
what is the capillaries with the medium permeability?
fenerstrated capillaries
what is the capillaries with the least permeability?
continuous capillaries
What are capillary beds?
Networks of 10-100 capillaries
At any given time, three-fourths of body’s capillaries are shut down
What controls flow within a capillary bed?
Precapillary sphincters
What happens when precapillary sphincters relax and contract?
Relaxed: Capillaries are well perfused with blood, Contracted: Blood bypasses the capillary
What is the driving pressure for systemic blood flow?
MAP (mean arterial pressure) – CVP (central venous pressure)
What is the purpose of venules and terminal arterioles in a capillary bed?
Venules: Blood flows through true capillaries, Terminal arterioles: Blood flows through metarteriole thoroughfare channel and bypasses true capillaries
What is the major influence on venous return?
Blood pressure gradient
What is the main force that contributes to venous return?
Blood pressure
Label the structures of the precapillary sphincter relaxation and contraction
What are veins primarily known for?
Capacitance vessels (blood reservoirs)
“old sock”
What mechanisms aid in venous return?
Skeletal muscle pump, Thoracic (respiratory) pump, Cardiac suction of expanding atrial space, Vasoconstriction of veins under sympathetic control
What is the key function of capillaries in the body?
Exchanges between the blood and surrounding tissues
what are characteristics of veins?
Subjected to relatively low blood pressure
Collapse when empty, expand easily
Steady blood flow, low pressure
Larger veins have some smooth
muscle allowing venomotor response
What adaptations do larger veins have to aid blood flow?
Larger lumens, Valves to prevent backflow of blood
What is capillary exchange?
Two-way movement of fluid across capillary walls
What is blood flow in terms of blood supply?
Blood flow: amount of blood flowing through an organ, tissue, or blood vessel in a given time;
What are the substances that undergo capillary exchange?
Water, oxygen, glucose, amino acids, lipids, minerals, antibodies, hormones, wastes, carbon dioxide, ammonia
What is the term for the flow of blood back to the heart?
Venous return
what is perfusion in terms of blood supply?
Perfusion: flow per given volume or mass of tissue in a given time
What are some mechanisms that aid in venous return?
Pressure gradient, Skeletal muscle pump, Thoracic (respiratory) pump, Cardiac suction of expanding atrial space, Vasoconstriction of veins under sympathetic control
how is blood supply expressed?
Blood supply to a tissue can be expressed in terms of flow and perfusion
What is the average adult resting cardiac output?
5.25 L/min
at rest, how is the blood flow rate?
At rest, total flow is quite constant, and is equal to the cardiac output
what is pressue for systemic blood flow?
∆P for systemic blood flow = MAP – CVP
look at PP
what are the BP changes over the different arteries and veins?
Look at PP
what is hypertension?
high blood pressure
May be acute during fever, physical exertion, emotional upset
Chronic resting BP > 140/90
Can weaken arteries, cause aneurysms, promote atherosclerosis
what is hypotension?
chronic low resting BP
May be acute adaptations during orthostatic hypotension
Caused by blood loss, dehydration, anemia
what happens to BP as age increases?
BP tends to rise with age:
Arteriosclerosis — stiffening of arteries due to deterioration of elastic tissues of artery walls
Atherosclerosis — build up of lipid deposits that become plaques
what are the categories of BP?
See PP
what influences BP?
BP determined by cardiac output, blood volume, and resistance to flow.
what is cardiac output?
Cardiac output regulated by the heart
what is blood volume?
Blood volume regulated mainly by kidneys
what is resistance influenced by?
Resistance influenced by:
Blood viscosity
Vessel length
Vessel radius
what occurs in capillaries?
The most important blood in the body is in the capillaries
Only through capillary walls are exchanges made between the blood and surrounding tissues
what is capillary exchange?
two-way movement of fluid across capillary walls
Water, oxygen, glucose, amino acids, lipids, minerals, antibodies, hormones, wastes, carbon dioxide, ammonia
what is venous return?
The flow of blood back to the heart
how does venous return occur?
-Pressure gradient
Blood pressure is the most important force in venous return
7 to 13 mm Hg venous pressure toward heart
Venules (12 to 18 mm Hg) to central venous pressure: point where the venae cavae enter the heart (~5 mm Hg)
-Gravity drains blood from head and neck
Low pressure gradient, thus other mechanisms also required
what are other mechanisms for venous return?
-Skeletal muscle pump in the limbs
Contracting muscle squeezes blood
out of the compressed part of the vein
-Thoracic (respiratory) pump
Inhalation — thoracic cavity expands and thoracic pressure decreases, abdominal pressure increases, forcing blood upward
Blood flows faster with inhalation
-Cardiac suction of expanding atrial space
-Vasoconstriction of veins under sympathetic control
