Vessels and Circulation Part 1 Flashcards
Heart
The mechanical pump that propels the blood through the vessels
What do BVs transport?
Oxygen, nutrients, and wast products
The heart and BVs for a:
Closed-loop system
True or False:
Blood vessels are rigid and immobile
FALSE
They pulsate and change shape and course in accordance with the body’s needs
________ circulation consists of the blood vessels that extend to and from the body tissues
Systemic
_______ circulation consists of the vessels that take the blood to the lungs for gas exchange and then return oxygenated blood to the heart
Pulmonary
Three main classes of BVs
Arteries, capillaries, and veins
Arteries
Convey blood away from the heart to the body tissues
What do arteries branch into and what occurs here?
Capillaries, where gas and nutrient exchange occur
Veins
Return blood to the heart
Anastomosis
Site where two or more vessels merge to supply the same body region
What can arterial anastomoses provide?
They can provide alternate blood supply routs to tissues and organs
Anatomical end arteries
Vessels whose terminal branches do not anastomose (e.g. Renal Artery)
What happens if an anatomical end artery becomes blocked?
The tissues will be deprived of oxygen and an “infarct” develops
True or False:
Veins tend to form many more anastomoses than do arteries
True
Functional end arteries
anastomoses are so small that arteries may be considered end arteries (e.g. coronary arteries)
Three layers (tunics) of BVs
Tunica intima or interna (inner layer) Tunica media (middle layer) Tunica externa or adventitia (outer layer)
What is the tunica intima/interna made up of?
Layer of simple squamous epithelium (endothelium)
What is the Tunica Media made up of?
Smooth muscle under autonomic control
Narrowing of the blood vessel lumen
Vasoconstriction
Widening of the blood vessel lumen
Vasodilation
What is the tunica externa/adventitia made up of?
Areolar CT w/ elastic and collagen fibers & nerve fibers
What is the function of the tunica externa/adventitia?
Helps anchor the vessel to other tissues, protects & supports vessels
Vasa Vasorum
Small blood vessels that supply the cells of the wall
Compared to a vein, the lumen diameter of an artery is
Narrower than a vein
Compared to a vein, the general wall thickness of an artery is
Thicker than vein
Artery cross-sectional shape vs. Vein cross-sectional shape
Artery retains its shape, while the vein tends to flatten and collapse
Thickest tunic of an artery
Tunica Media
Thickest tunic of a vein
Tunica Externa
Elastic/Collagen fibers in artery vs. in vein
More in the artery than in the vein
Compared to veins, how does the blood pressure differ in arteries?
BP is higher in arteries
How do the SYSTEMIC blood oxygen levels differ in arteries and veins?
In arteries, blood is high in O2
In veins, blood is low in O2
How do the PULMONARY blood oxygen levels differ in arteries and veins?
In arteries, blood is low in O2
In veins, blood is high in O2
Three basic types of arteries
elastic arteries
muscular arteries
arterioles
(based on artery size and function)
What are the characteristics of elastic areteries, where are they found, and what are some examples?
Thick-walled, high proportion of elastic fibers throughout tunica media
Near the heart
Example: Aorta, pulmonary arteries, brachiocephalic trunk, common carotid, and iliac
What are the functions of elastic arteries?
Dampen BP changes associated with heart contraction
Passive accommodation results in smooth flow of blood
What are the characteristics of muscular arteries?
Think tunica media, more smooth muscle
Elastic fibers restricted to internal and external lamina
True or False
Arterioles are not under autonomic control
False
Vasoconstriction and vasodilation occur in arterioles
Common Arterial Disorders
Arteriosclerosis
Atherosclerosis
Hypertension
Aneurysms
Arteriosclerosis
Hardening of the arteries
Atherosclerosis
Fatty deposits build up in the inner lining of an artery, eventually causing it to narrow and restrict blood flow
Aneurysms
Ballooning and/or rupture of the vessel
Cardiac infarct and Cerebral infarct
Blockage of blood flow to heart/brain resulting from occlusion of the lumen of arteries
Atherosclerosis Risk Factors
Genetics, hypercholesterolemia, sex (male), age, smoking, hypertension
Capillaries
Smallest blood vessels, connect arterioles to venules
What tunica do Capillaries contain?
Tunica lamina consisting of a basement membrane and endothelium
What is the function of a Capillary?
Allow gas and nutrient exchange between the blood and the body tissues to occur rapidly
True or False:
Capillary beds function independently
False
Capillaries are fed by metarteriole with precapillary sphincter
What is the continuation of the metarteriole called?
Thoroughface channel
Three types of capillaries
Continuous capillaries
Fenestrated capillaries
Sinusoids (discontinuous capillaries)
Where are continuous capillaries found?
Muscle, skin, lungs, CNS
Where are fenestrated capillaries found?
GI tract, kidney, endocrine glands
Where are sinusoids found?
Suprarenal glands, spleen, liver, anterior pituitary
True or False
Arteries hold more of the body’s blood at rest than veins
False
Veins hold about 60% of the body’s blood at rest
Venules
Merge from veins
Thinner walls and less muscle
Mostly elastin in tunica media
Tunica externa is thickest wall
How do veins prevent blood backflow?
Valves
Skeletal muscle pump
As skeletal muscles contract, veins are squeezed to help pump the blood toward the heart
Varicose Veins
Dilated, tortuous veins
Caused by nonfunctional valves
Most common in lower limb
Causes: Genetics, aging, stress, standing, obesity, pregnancy
Deep Vein Thrombosis
Blood clot or thrombus, most serious complication is PE
Common in sural (calf) or femoral (thigh) region
Causes: pregnancy, “economy class syndrome”
Systolic BP
during ventricular contraction (120)
Diastolic BP
during ventricular relaxation (70)
Hypertension
Chronically elevated BP
Damage to vessel wall –> thickening of wall –> decrease in lumen size
Pulmonary Circulation
Carrying deoxygenated blood from right side of the heart to the lungs, then returning newly oxygenated blood to left side of the heart
