Lecture 13 - Blood Vessels Flashcards
What are the three major types of blood vessels?
Arteries
Capillaries
And veins
Arteries
Carry blood away from heart
In systemic circulation the carrry oxygenate blood
In pulmonary circulation carry deoxygenated
Veins
Carry blood toward heart
In systemic circulation the carrry deoxygenated blood
In pulmonary circulation carry oxygenated
Capilaries
Can directly exchange gases and nutrients with tissues o meet cellular demands
Connect arterioles an venules
What are the three walls of blood vessels?
Tunica intima (endothelium)
Tunica media (smooth muscle and elastin)
Tunica externa (loosely woven collagen fibers)
Tunica intima
reduces friction between the vessel walls and blood.
Tunica media
controls vasoconstriction and vasodilation of the vessel.
Tunica external
protects, reinforces, and anchors the vessel to
surrounding structures.
Elastic/conducting arteries
contain large amounts of elastin, allowing these vessels to withstand the pressure changes of the cardiac cycle
Muscular/distributing arteries
deliver blood to specific body organs and have the greatest proportion of tunica media of all vessels, making them more active in vasoconstriction.
Arterioles
smallest arteries and regulate blood flow into capillary beds through vasoconstriction and vasodilation.
Continuous capillaries
most common and allow passage of fluids and small solutes.
Fenestrated capillaries
more permeable to fluids and solutes than continuous capillaries.
helps with absorption in the small intestines and filtration in the kidneys.
Sinusoid capillaries
leaky capillaries that allow large molecules to pass between the blood and surrounding tissues, such as in the liver, spleen or bone marrow.
Anastomosis
connection between blood vessels that supply blood to the same region of the body.
allow blood to have alternative routes to reach tissues and return to heart, in case one blood vessel is damaged or blocked.
Metarterioles
unique feature of the circulatory system around the intestines
A cuff of smooth muscle called a precapillary sphincter surrounds each capillary and acts as a valve to regulate blood flow into the capillary or keep the blood in thoroughfare channels.
Venules
formed where capillaries converge and allow fluid and white blood cells to move easily between the blood and tissues.
Join to form veins
Lumen
Space in middle o blood vessel where blood passes
Blood flow
volume of blood flowing through a vessel, organ, or the entire circulation in a given period and may be expressed as mL/min.
Blood pressure
the force per unit area exerted by the blood against a blood vessel wall and is expressed in millimeters of mercury (mmHg).
Resistance
measure of the friction between blood and the blood vessel walls.
related to blood viscosity, blood vessel length, and blood vessel diameter.
Why happen to blood flow when blood pressure increases?
Blood flow increases
What happen to blood flow when resistance increases?
Blood flow decreases
Peripheral circulation
refers to circulation in all of the blood vessels outside of the heart and coronary vessels.
Peripheral resistance
most important factor influencing local blood flow.
Vasoconstriction or vasodilation can dramatically alter local blood flow, while systemic blood pressure remains unchanged.
Systemic blood pressure
highest in the aorta and declines throughout the pathway until it reaches 0 mmHg in the right atrium.
Arterial blood pressure
relatively high because the arteries close to the heart can be stretched and a large volume of blood is forced into them at during ventricular systole.
Diastolic pressure
occurs when the ventricles enter diastole, the aortic valve closes, and the walls of the aorta recoil
maintains pressure at 70-80 mmHg, so that blood continues to flow forward into the smaller vessels.
Pulse pressure
difference between diastolic and systolic pressure
Capillary blood pressure
is low, ranging from 15–40 mm Hg, which protects the capillaries from rupture but still adequate to ensure exchange between blood and tissues.
Venous blood pressure
is low, not pulsatile, and changes very little during the cardiac cycle, reflecting cumulative effects of peripheral resistance.
Hypertension
High blood pressure
Increase in systolic/ diastolic pressure
Hypotension
Low blood pressure
Due to individual variation, only concern if blood flow to tissues becomes inadequate
Capillary blood pressure
low, ranging from 15–40 mm Hg, which protects the capillaries from rupture but is still adequate to ensure exchange between blood and tissues.
Venous blood pressure
low, not pulsatile, and changes very little during the cardiac cycle, reflecting cumulative effects of peripheral resistance.
Circulatory shock
any condition in which blood volume is inadequate and cannot circulate normally, resulting in blood flow that cannot meet the needs of a tissue.
Hypovolemic shock
results from a large-scale loss of blood
It may be characterized by an elevated heart rate and intense vasoconstriction.
Vascular shock
occurs with normal blood volume but extreme vasodilation, resulting in poor circulation and a rapid drop in blood pressure.
Transient vascular shock
due to prolonged exposure to heat, such as while sunbathing, resulting in vasodilation of cutaneous blood vessels.
Cardiogenic shock
occurs when the heart is too inefficient to sustain normal blood flow
