Capillary Dynamics and Exchange Flashcards
blood circulation:
high blood pressure ->
low blood pressure ->
high blood pressure -> (aorta)
low blood pressure -> (vena cava)
how much oxygen do veins hold?
75%
what blood vessels have the thickest walls?
The arteries have thicker, more muscular walls because they withstand higher pressures from receiving blood directly from the heart
thickest to thinnest inside diameter of blood vessels
vena cava ->arteriole -> aorta -> venule -> vein -> artery
capillary function
Exchange of materials between the blood and tissue cells
Several kinds of capillaries; some are “leakier” than others
ONLY ENDOTHELIUM
Fick’s law of diffusion
Rate of diffusion is dependent on the concentrations difference between the tissues (S), the area available for diffusion (A), and the distance (delta X) between the tissue
Continuous capillaries
- Most widespread and abundant type
- Lines the walls of all:
arteries and veins
arterioles and muscular venule
capillaries and postcapillary venule
skeletal, smooth, and cardiac)
Skin, lungs, and connective tissue
Pores are present
Fenestrated capillary
- Lines secretory and excretory organs
Exocrine and endocrine glands
GI tract mucosa
Kidney glomeruli
Brain choroid plexus - Presence of fenestrae
Discontinuous epithelium (capillary)
- Leakiest of all capillary epithelia
- Present in:
Hepatic sinusoids
Spleen
Bone marrow - Junctions between endothelial cells are not completely closed and the basement of the membrane is incomplete
- Resulting openings are large and DO NOT restrict passage of plasma proteins
- Limit the passage of blood cells
Hydrostatic pressure
when the blood plasma moves along the artery with certain velocity, it pushes against the vessel wall
Colloid osmotic pressure (oncotic)
form of osmotic pressure exerted by proteins, notably albumin, in a blood vessel’s plasma (blood/liquid)
Ultrafiltration
process results in net movement out of the capillary. The amount leaving is the process determined by Starling’s forces:
- Capillary hydrostatic pressure
- Interstitial hydrostatic pressure
- Plasma colloid osmotic pressure
- Interstitial fluid colloid osmotic pressure
Fluid exchange across the endothelium
*will be on the exam
- Occurs through bulk flow
- 4 factors play a role in fluid exchange:
The hydrostatic pressures in the capillary and interstitial fluids
The colloid osmotic pressures in the capillary and interstitial fluids
the lymphatic system consists of:
Lymph
Lymphatic vessels
Structures and organs containing lymphatic tissue
Red bone marrow
the lymphatic system functions are:
Drain excess interstitial fluid
Transport dietary lipid
Carry out immune responses
Vessels begin as lymphatic capillaries
Closed at one end
Passes through lymph nodes
Encapsulated organs with masses and B & T cells
Unite to form rage lymphatic vessels
*one way system valves
Lymph formation
- More fluid filters out of blood capillaries than returns to them by reabsorption
- Excess filter fluid (about 3L/day) drains into lymphatic vessels and become lymph
- Important function of lymphatic vessels to return lost plasma proteins to blood stream
Edema
- Swelling caused by too much fluid in the body’s tissue
- Filtration exceeds that of reabsorption = edema occurs
- Fluid that builds in the interstitial fluid returns to the circulation via lymphatic system
edema causes
- Increased capillary hydrostatic pressure: venous congestion
- Decreased plasma colloid osmotic pressure: hypoproteinemia
- Increased capillary permeability: toxin, hypoxia, allergy
The endothelium secretes chemicals that
- Increase cardiac output
- Decrease heart rate
- Inhibit platelet aggregation and control blood vessel diameter
- Nourish the cells in the outer half of the blood vessel
Inhibit platelet aggregation and control blood vessel diameter
Choose the correct statement:
- For an artery and vein of the same diameter, the vein - has a thicker wall
- Veins contain valves and arteries do not
- Blood pressure is lower in arteries than in veins
- When empty, an artery is more likely to be collapsed than a vein
Veins contain valves and arteries do not
A continuous capillary has _____ but not _____.
- Tight junctions; fenestrations
- Intercellular clefts; tight junctions
- Intercellular clefts; endothelial cells
- Fenestrations; tight junctions
Intercellular clefts; tight junctions
Which of these is not a function of the lymph nodes?
- House lymphocytes and macrophages
- Filter lymph
- Produces red blood cells
- Produce lymphocytes
produces red blood cells
The walls of the lymphatic vessels are similar to those of cardiovascular_____.
- Arteries
- Veins
- Capillaries
- Distributing arteries
veins
Lymph is prevented from flowing backwards by _____.
- Blood pressure
- Suction form the contracting lymph nodes
- One-way valves
- Cilia lining the lymphatic system
one-way valves
