PATH 3610 Lecture Notes - Lecture 2: Oncotic Pressure, Vascular Resistance, Peripheral Edema
14 May 2018
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Week 2: Things Vascular
- equine amnion: arteries → arterioles → capillaries → venules → veins
- one of the most important factors is maintaining a vascular system
- vascular system: a transportation system for cells, nutrients and wastes and
it is important in maintaining a normal fluid and electrolyte balance, fluid in
mammals ins blood
Blood: components of blood
- red blood cells erythrocytes, RBCs: carry oxygen,
- white blood cells leukocytes, WBCs: protect body from foreign invaders
and infectious disease
- platelets
- plasma (serum plus clotting proteins): all fluid
o water and electrolytes
o proteins
▪ albumin
▪ clotting proteins
▪ globulins (including immunoglobins)
- serum (fluid without clotting proteins): albumin, globulins
- centrifugation: RBC components at the bottom, white line is the WBC and the
rest is fluid
o 40% approx. is RBC
- Starling was a scientist who identified a number of counteracting forces
responsible for maintaining normal blood and tissue fluids
- Blood pressure: created by elastic and muscular forces exerted by vessel
wall (peripheral resistance) and the heart (cardiac output), highest in
arteries
Capillary bed
- capillary are a bunch of fluid filled channels
- more capillary space in body than there is blood → how are we alive?
Because not every capillary has a lot of blood flowing through
- transfer site where there is usually a single layer of endothelium separating
the blood from the tissue
- precapillary sphincter: entrance to the capillary bed, composed of muscle,
system to regulate flow in that area
o regulates whether blood flows through the capillary or not
o excessive pressure would damage the bed and tissue so it has a gate
keeper function
- Blood flow in capillary
o Cap blood pressure is low, but must be maintained in a narrow range
to ensure a net movement of fluid from blood vasculature into tissues
o The movement of fluid in the extracellular compartment around
tissue cells will increase oncotic pressure in vascular system →
albumin and other proteins create this oncotic pressure
o As blood moves from arterial to venous side, hydrostatic pressure is
overcome by the oncotic pressure
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o Increase in oncotic pressure = net flow of water back into vascular
system
o Excessive fluid in extravascular space is removed by lymphatic system
- Endothelial cells: endo = inside and thelial = body/organisms
o line blood vessels, caps, venules, veins, arterioles
o whole vascular system is lined by these cells
o they have little gaps in between them which can open and close
o blood leaks out if something kills the endothelial cells
o haemorrhage = blood leaking out of vascular system
Oedema (EDEMA) = medical term for swelling
- excess fluid in a tissue ( interstitial or extravascular space) or a body cavity
or space
o 60% of body is water and 2/3 of it is inside cell → 1/3 that is outside
is extracellular fluid
- Effusion is another name for excess fluid in a body cavity
- edema (swelling that occurs outside a joint) vs effusion (swelling within a
joint)
- frostbite photo: edema because lots of degeneration
o infusion because inflammatory edema
- Starling forces of hemodynamics
o Hydrostatic pressure: controlled by the precapillary sphincter
o Precapillary sphincter controls pressure in capillary and that pressure
forces fluid out of the capillary and into the tissue. The fluid then
passes around the cell and goes back into the capillary as the pressure
drops from beginning of the capillary to the end
o Albumin → in protein, a substance that absorbs fluid,
o Oncotic pressure rises as fluid leaves
- Oedema divided into
o Inflammatory oedema: altered permeability of endothelium, direct
damage to endothelium (burns) increases permeability
o Non inflammatory oedema: alternations to the forces at the venous
end of the capillary, with reduction in oncotic pressure or increase in
hydrostatic pressure, everything else
▪ Examples
• Ascites (hydroperitoneum): accumulation of protein
containing fluid in abdomen, excessive fluid in
abdominal cavity
• Hydropericardium: peri = around, cardium = heart,
excessive fluid within the pericardium sac
• Hydrothorax: excessive fluid within the thorax
• Peripheral edema (outside parts not central): excessive
fluid in extravascular space of peripheral tissue → feet,
hands and other external appendages
• not necessarily a disease → excessive edema is
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Equine amnion: arteries arterioles capillaries venules veins. One of the most important factors is maintaining a vascular system. Vascular system: a transportation system for cells, nutrients and wastes and. Blood: components of blood it is important in maintaining a normal fluid and electrolyte balance, fluid in mammals ins blood. Red blood cells (cid:523)erythrocytes, rbc(cid:495)s(cid:524): carry oxygen, White blood cells (cid:523)leukocytes, wbc(cid:495)s(cid:524): protect body from foreign invaders and infectious disease. Starling was a scientist who identified a number of counteracting forces responsible for maintaining normal blood and tissue fluids. Blood pressure: created by elastic and muscular forces exerted by vessel wall (peripheral resistance) and the heart (cardiac output), highest in arteries. Capillary bed capillary are a bunch of fluid filled channels. Because not every capillary has a lot of blood flowing through transfer site where there is usually a single layer of endothelium separating the blood from the tissue.
