Blake_Anatomy_09_Vessels pt 1 Flashcards
Blood vessels functions:
Transport O2, nutrients and waste, to and from body tissues
Heart and blood vessels form a __________ system
closed-loop
Can blood vessels change their course in accordance with the body’s needs?
Yes
Blood vessels are often named for____
Body region they traverse or the bone next to them
Some blood vessels are named for ____
the structure they supply
Arteries and veins that travel together __________
sometimes share the same name (vascular or neurovascular bundle)
Systemic circulation
the blood vessels that extend to and from the body tissues
Pulmonary circulation
The vessels that take the oxygenated blood to the heart tissues themselves
3 main classes of blood vessels
Arteries, Capillaries, Veins
Anastomosis
the site where two or more vessels merge to supply the same body region
Anatomical end arteries
vessels whose terminal branches do not anastomise. In the event that these vessels become blocked, theh tissues will be deprived of oxygen and an “infarct” develops (eg. Kidneys, spleen, brain)
Functional end arteries
anastomoses are so small that arteries may be considered end arteries (eg. coronary arteries)
Do veins or arteries form more anastomoses
Veins
Tunics (or layers) of blood vessels (5)
- Form a wall of blood vessels
- surround the lumen
- Tunica Intima - endothelium
- Tunica media - smooth muscle and elastic fibers
- Tunica externa (adventitia) - collagen fibers.
Tunica Intima (3)
- Tunica Interna
- Innermost layer of blood vessel wall
- commosed of a layer of simple squamous epithelium, called endothelium
Tunica Media (2)
- Middle Layer of Vessel wall
- composed of circularly arranged layers of smooth muschle cells under autonomic control
Changes in vessel diameter (3)
- Contraction of smooth muscle
- vasoconstriction
- vasodilation
Tunica Externa (4)
- Tunica Adventitia
- Outermost layer of blood vessel
- Composed of and areolar connective tissue that contains elastic and collagen fibers, and nerve fibers
- anchors vessel to other tissues, protects and supports vessel
Pulmonary arteries (fx)
carry deoxygenated blood to the lungs
3 basic types of arteries
elastic
muscular
arterioles
As an artery’s diameter decreases (2)
Corresponding decrease in elastic fibers
relative increase in smooth muscle
Elastic Arteries (3 facts + 5eg)
- Conducting arteries (large diameter/large lumen)
- Thick-walled, near heart
- high proportion of elastic fibers throughout tunica media
- includes: Aorta, pulmonary arteries, brachiocephalic trunk, common corotid, iliac
Functional Properties of Elastic arteries (2)
- dampen BP changes associated w/ heart contraction
- Passive accomodation results in smooth flow of blood
Muscular Arteries (3)
- Distributing arteries, distal to elastic arteries, medium sized
- Thick tunica Media (more smooth muscle)
- Elastic fibers restricted to internal and external elastic lamina
Arterioles
- smallest arteries
- Generally less than 6 layers of smooth muscle in tunica media
- loss of layers with decreasing size
Arteriosclerosis
hardening of the arteries
Atherosclerosis
fatty deposits and occlusion
aneurysm
ballooning and/or rupture of the vessel
Capillaries (4)`
- smallest Vessels (connect arterioles to venules)
- Slightly larger than single erythrocytes
- contain only tunica intima, (but this consists only of basement membrane and endothelium)
- allow gas and nutrient exchange
Capillary beds (3)
- do not fx independently
- fed by metarteriole with precapilary sphincter, its continuation is called thoroughfare channel
- true capillaries are branches of metarteriole
Metarteriole
central canal of capillary bed
3 basic kinds of capillaries
continuous
fenestrated
sinusoids (discontinuous)
Veins (4)
- Drain capillaries and return blood to heart
- walls are relatively thin and the vein lumen is larger
- blood pressure is lower in veins than arteries
- hold about 60% of bodies blood
Systemic vs Pulmonary Veins
- Systemic veins carry blood to the right atrium of the heart
- Pulmonary veins carry oxygenated blood to the left atrium of the heart
How do veins prevent blood from pooling in the limbs
- one way valves to prevent backflow
- deep veins contain skeletal muscle pumps
what directly causes vericose veins?
nonfunctional valves
