What is the delivery system of dynamic structures that begins and ends at the heart?
Blood vessels
What type of blood vessel carries blood away from the heart
Arteries
Is the blood carried by arteries oxygenated or de-oxygenated?
Oxygenated
Name the exceptions in arteries - the areas where the blood carried by arteries is NOT oxygenated.
pulmonary circulation and umbilical vessels of the fetus
Which blood vessels are contact tissue cells that directly serve cellular needs?
Capillaries
Which blood vessels care blood from cells and organs towards the heart?
Veins
How many layers to arteries and veins have?
Three
What is the central blood-containing space in arteries and veins?
Lumen
How many layers do capillaries have?
One
What is the layer of capillaries called?
Endothelium wiht a sparse basal lamina
What are the layers of arteries and veins called?
Tunica externa, tunica media, tunica intima
What is the tunica media composed of?
smooth muscle and sheets of elastin
What controls vasoconstriction and vasodilation in the tunica media of vessels?
sympathetic vasomotor nerve fibers
What is the tunica externa composed of?
collagen fibers that protect and reinforce
In the tunica externa of larger vessels, what helps nourish the external layer?
vasa vasorum (arteries supply artery, vessel supplies vessel)
What are the types of arteries?
Elastic (conducting) and Muscular (distributing)
What is located in all three tunics of elastic arteries?
elastin
What are the elastic/conducting arteries?
aorta and its major branches
The elastic arteries give rise to branches called?
muscular arteries
What do the muscular/distributing arteries and arterioles do?
deliver blood to body organs; active in vasoconstriction
What are the smallest arteries that lead to capillary beds?
arterioles
What do arterioles do?
control flow into capillary beds via vasodilation and vasoconstriction
What do arterioles lead to?
tissues/groups of cells to supply the blood
What are microscopic blood vessels that are only one cell thick?
capillaries
What helps stabilize capillary walls and control permeability?
pericytes (structural cells)
Where are capillaries NOT found?
cartilage, epithelia, cornea and lens of the eye
What are the functions of capillaries?
exchange of gases, nutrients, wastes, hormones, etc.
What are the types of capillaries?
continuous, fenestrated, and sinusoidal
Which type of capillary is abundant in the skin and muscles?
continuous capillaries
Which type of capillary forms the blood-brain barrier?
continuous capillaries
Which type of capillaries have tight junctions that connect endothelial cells, and intercellular clefts that allow the passage of fluids and small solutes?
continuous capillaries
Which type of capillary has some endothelial cells that contain pores?
fenestrated capillaries
Which type of capillary is more permeable than continuous capillaries?
fenestrated capillaries
Which type of capillary functions in absorption or filtrate formation in the small intestines, endocrine glands and kidneys?
fenestrated capillaries
Which type of capillary has fewer tight junctions, larger intercellular clefts, and large lumens?
sinusoidal capillaries
Are sinusoidal capillaries usually fenestrated?
yes
Which type of capillary allows large molecules and blood cells to pass between the blood and surrounding tissues?
sinusoidal capillaries
Which type of capillary is found in the liver, bone marrow, and spleen?
sinusoidal capillaries
What are interwoven networks of capillaries that form the micro-circulation between arterioles and venules (starting points for the venous system)?
capillary beds
What are the types of vessels that comprise capillary beds?
vascular shunt and true capillaries
What is the thoroughfare channel in capillary beds that directly connects the terminal arteriole and a post-capillary venule?
vascular shunt
What type of blood vessel in capillary beds branch off the metarteriole or terminal arteriole?
true capillaries
What regulates blood flow into true capillaries?
precapillary sphincters
What are formed when capillary beds unite?
venules
What is very porous and allows fluids and WBCs into tissues?
venules
What are formed when venules converge?
veins
Which type of blood vessel has thinner walls and larger lumen than corresponding arteries?
veins
Is blood pressure lower in veins than in arteries?
yes
Veins called capacitance vessels contain how much of the blood supply?
65%
Veins have adaptations that ensure the return of blood to the heart. They are:
large diameter lumens and valves that prevent the backflow of blood
What are flattened veins with extremely thin walls (in the coronary sinus of the heart and dural sinuses of the brain)?
venous sinuses
What are interconnections of blood vessels?
vascular anastomoses
What provides alternate pathways to a given body region, common at joints, in abdominal organs, the brain and the heart?
arterial anastomoses
What is an example of arteriovenous anastomoses?
vascular shunts of capillaries
What is the volume of blood flowing through a vessel, organ, or the entire circulation in a given period?
blood flow
How is blood flow measured?
ml/min
Blood flow is equivalent to what?
the cardiac output for entire vascular system
What is the force per unit area exerted on the wall of a blood vessel by the blood?
blood pressure
How is blood pressure measured?
mm Hg
What provides the driving force that keeps blood moving from higher to lower pressure areas?
the pressure gradient
What is the opposition to flow, a measure of the amount of friction blood encounters?
resistance
Where is resistance in circulation generally found?
in the peripheral systemic circulation (limbs)
What are the sources of resistance to circulation?
blood viscosity, total blood vessel length, and blood vessel diameter
What are the factors of resistance that remain relatively constant?
blood viscosity and blood vessel length
What is due to formed elements and plasma proteins?
blood viscosity
Resistance varies inversely with the fourth power of ?
vessel radius
What are the major determinants of peripheral resistance?
small-diameter arterioles
What dramatically increases resistance?
abrupt changes in diameter or fatty plaques from atherosclerosis
Blood flow is directly proportional to the ?
blood (hydrostatic) pressure gradient
Blood flow is inversely proportional to ?
peripheral resistance
What results when flow is opposed by resistance?
blood pressure
Systemic pressure is highest where?
in the aorta
The steepest drop in pressure occurs where?
in arterioles
Arterial blood pressure reflects two factors of the arteries close to the heart. They are?
elasticity (compliance or distensibility) and volume of blood forced into them at any time
Arterial blood pressure: What is the pressure exerted during ventricular contraction?
systolic pressure
Arterial blood pressure: what is the lowest level of arterial pressure?
diastolic pressure
Arterial blood pressure: what is the difference between systolic and diastolic blood pressure?
pulse pressure
Arterial blood pressure: what is the pressure that propels the blood to the tissues?
mean arterial pressure (map)
mean arterial pressure (MAP) =
diastolic pressure + 1/3 pulse pressure
Pulse pressure and MAP both __________ with increasing distance from the heart.
decline
What type of blood pressure ranges from 15 to 35 mm Hg?
capillary blood pressure
What would rupture fragile, thin-walled capillaries?
high blood pressure
Which type of blood pressure changes little during the cardiac cycle and has a small pressure gradient?
venous blood pressure
What are the factors aiding venous return?
respiratory pump, muscular pump, vasoconstriction of veins under sympathetic control
What describes pressure changes created during breathing, which moves blood toward the heart by squeezing abdominal veins as thoracic veins expand?
respiratory pump
What describes the contraction of skeletal muscles that "milk" blood towards the heart and valves prevent backflow?
muscular pump
Maintaining blood pressure requires cooperation of what?
heart, blood vessels, and kidneys
What are the main factors influencing blood pressure?
cardiac output, peripheral resistance, and blood volume
What is determined by venous return and neural and hormonal controls (that go into the kidneys)?
cardiac output
What is a cluster of sympathetic neurons in the medulla that oversee changes in blood vessel diameter?
the vasomotor center
Where are baroreceptors located?
carotid sinuses, aortic arch, and the walls of large arteries of the neck and thorax
Chemoreceptors respond to what?
rise in CO2, drop in pH or O2
Which adrenal hormones cause generalized vasoconstriction and increase cardiac output?
norepinephrine and epinephrine
What, when generated by kidney release of renin, causes vasoconstriction?
angiotensin II
What hormone, when secreted by the heart, causes blood volume and blood pressure to decline, causing general vasodilation?
atrial natriuretic peptide
What hormone causes intense vasoconstriction in cases of extremely low blood pressure?
antidiuretic hormone (ADH) (vasopressin)
Increased blood pressure or blood volumen causes the kidneys to do what?
eliminate more urine, reducing blood pressure
Antiogensin II is a what?
potent vasoconstrictor