Vasculature Flashcards
Four divisions of the aorta
Arch
Ascending
Thoracic
Abdominal
What makes up the descending aorta?
Thoracic + abdominal aortas
Unpaired abdominal aortic arteries (x3)
Celiac trunk
Superior mesenteric a.
Inferior mesenteric a.
Celiac trunk supply
Supplies the liver, stomach, spleen, pancreas + duodenum
Superior mesenteric a. supply
Supplies the pancreas, SI and part of LI
Inferior mesenteric a. supply
Supplies the rest of the LI
Paired abdominal aortic arteries (x4)
Suprarenal
Renal
Gonadal
Lumbar arteries (x4): common iliac = last pair
Paired abdominal/pelvic veins (x4)
Suprarenal
Renal
Gonadal
Lumbar
Where do inferior + superior mesenteric veins drain?
Hepatic portal vein
Where does blood go after the hepatic portal vein?
Sinusoids of the liver (detoxifies, then goes back into general circulation)
Why does venous blood from GI organs go to the liver before IVC?
Allows for filtration of the blood before returning to the heart (detoxifies)
Function of a conduit vessel + example
Transport blood –> regions of body
Aorta
Function of a distribution vessel + example
Distribute blood specifically to different organs
Femoral a.
Function of a resistance vessel + example
Allows for resistance in circulation
Arterioles
Function of a exchange vessel + example
Movement of gases/fluids/nutrients in and out of blood
Capillaries
Function of a capacitance vessel + example
Reservoir for blood
Veins
Function of a lymph vessel + example
Maintains fluid balance
Lymphatics
Layers of arteries
Superficial –> deep
Tunica intima: endothelium (smooth, secretes NO), basement membrane & internal elastic lamina (holes for diffusion)
Tunica media: SM cells (regulate diameter, stretch) & external elastic lamina (fenestrations + stretch)
Tunica externa: elastic + collagen fibers, vaso vasorum (nourishes outer walls when there is not enough diffusion)
Layers of veins
Intima: endothelium, basement membrane
Media: much inner than a. (SM cells)
Externa: elastic + collagen + vaso vasorum
Differences between veins and arteries
Walls of veins = thinner
Veins = no elastic layers but they have valves
Characteristics of elastic arteries
Expand when BP increases & recoils when BP decreases
*Pressure reservoir –> storage of mechanical energy
During recoil = converts stored potential energy –> kinetic energy
Atherosclerosis & elastic arteries
Walls of arteries become stiffer –> less stretching
Heart has to work harder during ventricular relaxation to maintain a good rate of BF
Characteristics of muscular arteries
More elastic fibers in tunica media
More vasoconstriction/dilation to adjust rate of flow
Distributing arteries to direct BF
Purpose of arterioles
Regulate BF into capillary networks to body tissues (regulates resistance)
What is a metarteriole?
Terminal end of an arterial –> form branches + supply capillary beds
Proximal ends have SM cells that regulate BF
What are precapillary sphincters?
At metarteriole-capillary junction –> monitor BF into the capillaries
Relaxed = blood into capillary bed
*This helps regulate where BF is needed
Capillary composition
Mostly composed of endothelial cells
Has pericytes: contractile cells that wrap around the endothelial cell to regulate capillary BF
Types of capillaries (x3)
Continuous: has a continual layer of endothelial cells (brain, lungs, CTs)
Fenestrated: lots of fenestrations = filtration (kidney)
Sinusoid: wide fenestrations + incomplete basement membrane, allows big molecules to pass through (bone marrow & liver)
Capillary exchange: simple diffusion
Happens through intercellular clefts or fenestrations or right through endothelial cells
Lipid soluble molecules = through membrane
Water soluble molecules = through intracellular clefts
Capillary exchange: transcytosis
Transport via vesicles
For large, lipid-insoluble molecules (insulin)
Capillary exchange: bulk flow
Passive process –> large # of molecules will move together in same direction
Filtration from capillaries into interstitial fluid
Reabsorption from interstitial fluid into capillaries
Starling’s Law
Promote filtration: blood hydrostatic pressure & interstitial oncotic pressure
Promote reabsorption: blood oncotic pressure & interstitial hydrostatic pressure
What happens if filtration greatly > reabsorption?
Fluid accumulation (edema) in the interstitial space
What gives rise to blood osmotic pressure?
Large molecules that cannot pass into the interstitial fluid
Ways to aid venous return (x2)
Skeletal muscle pump: contraction of muscle milks blood towards heart
Respiratory pump: inhalation = diaphragm moves down = increased abdominal pressure = compression of abdominal vessels = blood moves towards heart
What does a higher venous return mean?
Higher preload = higher stroke volume = higher CO to tissues
What are the principle blood reservoirs?
Systemic veins and venules
What allows for veins to act as blood reservoirs?
Thinner walls allow for distention
