Vasculature - 04 Flashcards
what are the 4 divisions of the aorta?
arch of the aorta, ascending aorta, thoracic aorta, abdominal aorta
celiac trunk
gives rise to blood to things such as proximal segment of GI tract e.g. liver, stomach, part of duodenum
what are the unpaired arteries supplying the GI tract?
celiac trunk, superior and inferior mesenteric arteries
superior mesenteric artery
supplies remainder of small intestine not covered by celiac artery and all of the colon until the descending portion
inferior mesenteric artery
supplies the colon; sigmoid colon and rectum
GI tract blood supply
has many anastomoses to ensure blood flow is always going to as many segments as possible of the intestine
what are the paired arteries of the abdominal aorta?
lumbar arteries, renal arteries, gonadal arteries and suprarenal arteries
what does the SVC drain?
head, neck, chest, upper limbs
what veins are part of the coronary circulation?
Great cardiac vein, middle cardiac vein, small cardiac vein, anterior cardiac vein, coronary sinus
what does the IVC drain?
abdomen, pelvis, lower limbs
what are the major abdominal and pelvic veins?
L and R suprarenal veins, renal veins, lumbar veins, gonadal vein
hepatic portal system
a capillary bed turns into a vein and then becomes another capillary bed elsewhere 9Liver); capillary bed accepts nutrients from GI wall and is delivered to 2nd capillary bed in liver to process nutrients and eliminate waste
arteries
carry blood away from heart
capillaries
site of gas and nutrient exchange
veins
return blood to the heart (blood reservoirs)
what are the 3 layers of an artery?
tunica intima, tunica media, tunica externa
tunica intima
innermost later lining BV containing endothelium, basement membrane and internal elastic lamina
tunica media
middle layer of BV wall where smooth muscle is found within arteries; allows us to change diameter of arteries to regulate BP, regulate blood flow to an organ/divert blood flow, contains more elastic fibers (external elastic lamina)
tunica externa
aka tunica adventitia, consists of elastic and collagen fibers
vasa vasorum
small vessels that supply blood to outer part of the larger vessels
what are the 3 layers of a vein?
tunica intima, tunica media, tunica externa; however there are no elastic fibres and the wall thickness is much smaller due to low pressure of blood in the veins; veins also have valves
elastic arteries (conducting arteries)
initial arteries coming off the heart, lots of elastic tissues and conduct blood away to heart and branch off into distributing arteries
- must handle pressure from contractions and provide pressure b/w heartbeats
- full of elastic fibers
- stretch and recoil
muscular arteries (distributing arteries)
medium sized and have thick, muscular tunica media and have ability to cause tone in BV; capable of greater vasoconstriction/dilation to adjust rate of flow
arterioles
resistance vessels with smaller and thinner walls, have the greatest effect on BV
capillary structure
exchange vessels that only have 1 layer (endothelium + basement membrane) to allow for exchange of nutrients within body
throughfare channel
major pathway of blood through a capillary; when cold, this is often the only one open in the skin
how is blood flow controlled in capillary beds?
little aggregations of smooth muscle within vessel that act like a sphincter - pre-capillary sphincter
what are the 3 types of capillaries?
continuous, fenestrated, sinusoidal
continuous capillaries
continuous layer of endothelial cells tightly glued to one another + to basement membrane; minimal fluid getting out into tiss. - important in brain, lungs, muscles
fenestrated capillaries
have little pores in the capillary beds, pores formed by endothelial cells, allow for nutrient exchange and some filtration, small enough that formed elements cannot pass through - useful in kidneys, choroid plexus
sinusoid capillaries
huge gaps b/w endothelial cells (big enough for cells to move through), basement membrane incomplete. found in red bone marrow b/c it is where RBC and WBC are derived and need to enter blood; found in liver b/c of large nutrients from GI tract
hydrostatic pressure
the pressure within a blood vessel that tends to push fluids and nutrients out of the vessel into tissues, formed elements and large proteins often don’t cross
fluid movement at the arterial end of a capillary
net filtration
oncotic pressure
the pressure of water to move back into the capillary, as the result of the presence of formed elements and proteins in the vessel
fluid movement at the venous end
net reabsorption; some fluid has already been lost to tissues but will contain some waste that needs to be drawn back
Starling’s Law of the Capillaries
fluid movement is governed by 4 forces: blood hydrostatic pressure, interstitial oncotic pressure, blood oncotic pressure, interstitial hydrostatic pressure
what are the two methods of aiding venous return?
skeletal muscle pump and respiratory pump
skeletal muscle pump
contraction of muscle compresses deep veins and “milks” blood back to the heart
respiratory pump
inhalation moves the diaphragm down and increases pressure in the abdomen, compressing abdominal veins and forcing blood back to the heart
blood distribution
60% blood volume is in systemic veins and venules, blood is diverted from it in times of need; less blood volume is in the systemic arteries and arterioles (~15%)
