blood vessels part 1 Flashcards
blood path of arteries
arteries
to arterioles
to capillaries
Blood path drained
capillary beds drained by venules
to veins
to great veins
largest to smallest of veins and arteries
veins; great vein vein venule capillary arteries: elastic artery muscular artery arteriole capillary
vessel anatomy
oiutermost to innermost layer: tunica externa
tunica media
tunica intima endothelium
venules and arterioles only have the first and last layer
capillaries only endothelium
tunica intima
Lines the lumen or interior – endothelium - slick
tunica media
Smooth muscle – changes diameter of the vessels – increases or decreases blood pressure
tunica externa
Composed of fibrous connective tissue – supports and protects the vessels
blood volume porportions greatest to least
veins and venules (65%)
arteries and arterioles (13%)
pulmonary vessels 9
heart and capillaries 7
velocity flow on chart
fast through arteries and arterioles, slow through capillaries, fast through venules and veins
blood pressure on chart
high blood pressure at arteries, low through capillaries and veins
surface area to volume on chart
small surface area to volume ratio all except high at capillaries
what factors affect diffusion happening at capillary beds
low pressure
high surface area to volume ratio
slow moving
very thin (one cell thick)
why are artery walls much thicker than veins
Must be able to expand as blood is forced into them and recoil passively (aids circulation)
Tunica Media is heavier
veins not exposed to high pressure
Elastic arteries characteristics
– largest diameter, lowest resistance, elasticity contributes to maintain blood pressure, “auxiliary pumps”, not involved in vasoconstriction
muscular arteries
“distributing arteries,” involved in vasoconstriction/dilation to small exten
Arteriole
most resistance, main agent of vasoconstriction/dilation to control blood flow to specific regions
arteriole controlled by
Controlled by hormone, nerve, chemical influences
think cold hands/nose/ears during thermoregulation
Why do capillaries have less resistance than arterioles
The change in diameter between arterioles to capillaries is smaller, shorter blood vessels, and less pressure all contribute
Vein Valves
Found only in lower limbs to help oppose force of gravity while upright.
Arteriosclerosis
“hardening of the arteries
Atherosclerosis
clogged arteries, plaque build up
treatment for plaque build up
stent
varicose veins
bulging, swollen, purple, ropy veins, seen just under your skin, caused by damaged valves within the veins
also old age
Aneurysm
aneurysm is an abnormal bulge in the wall of a blood vessel
most common in aorta
aneurysm treatments
stent
fill with rope
block off flow
Raynaud’s
spasms of the small arteries of the fingers and toes, brought on by exposure to cold or excitement
white cold fingers
blood flow
volume of blood flowing through
Blood Pressure
force exerted on vessel walls
Resistance
opposition to flow (friction)
Resistance influenced by
blood viscosity
blood vessel length & diameter
Vital signs
pulse and blood pressure, along with respiratory rate and body temperature
pulse
pressure wave caused by the expansion and recoil of arteries
Hypotension
low blood pressure
Systolic pressure below 100 mm Hg
Often associated with long life and lack of cardiovascular illness
Hypertension
high blood pressure
Sustained elevated arterial pressure of 140/90 or higher
May be transient adaptations during fever, physical exertion, and emotional upset
Often persistent in obese people
Prolonged hypertension is a major cause of
heart arrhythmias, heart failure, vascular disease, renal failure, and stroke
Hypotension can cause
Loss of consciousness
Fatigue, dizziness, lethargy
Prolonged low BP can lead to loss of organ function due to insufficient perfusion
Circulatory Shock
Blood vessels are inadequately filled
Blood cannot circulate normally
Results in inadequate blood flow to meet tissue needs
perfusion triangle
heart
blood vessels
blood
