Blood Distribution/Capillary Exchange/Lymphatics Flashcards
Where is the majority of blood distributed
Systemic veins and venules, they act as blood reservoirs
How does the body divert blood from the blood reservoirs
Vasoconstriction
At rest what organs receive the largest amount of blood flow
- Liver
- Kidney
- Muscle
- Brain
organized most to least (25%, 20%, 20%,15%)
During exercise what organs receive the largest amount of blood flow
-Muscles
What are the 3 basic mechanisms substance enter and leave the capillaries.
- Diffusion
- Transcytosis
- Bulk flow
All can happen at once
Rank the speed of the 3 transportation mechanisms in the capillaries from fastest to slowest
- Bulk flow
- Diffusion
- transcytosis
Describe diffusion at the capillary level
-O2 and small sized nutrients out of the capillary, CO2 and certain waste into the capillary
down their concentration gradient
-more delicate and more directed at certain substances
Describe transcytosis at the capillary level
- Cell preforms endocytosis, creates a vesicle and transports the vesicle across the cell and then preforms exocytosis and releases the contents
- used for large lipid-insoluble molecules such as insulin and certain antibodies
What is the blood brain barrier
areas in the brain have continuous capillaries w/ very closely packed endothelial cells surround by Astrocytes that block many substances from passing out of the capillary
What parts of the brain lack the blood brain barrier and allow free capillary exchange
Hypothalamus, pineal gland, pituitary gland
Areas used for sensing body/blood changes or excreting hormones
Describe bulk flow at the capillary level
passive process driven by pressure differences by which a large amount of fluid and solutes moves in and out of the capillaries
- things can move up their concentration levels
- very efficient
What are the 2 pressure driven mechanisms of bulk flow
- Filtration
2. Reabsorption
Describe filtration in bulk flow
Pressure driven movement of fluid and solutes from blood to interstitial fluid
-composed of blood hydrostatic pressure (BPH) and Interstitial fluid osmotic pressure (IFOP)
Describe the role of blood hydrostatic pressure (BPH) and Interstitial fluid osmotic pressure (IFOP) in filtration
BPH pushes fluid out of the capillary, from BP pushing against vessel walls
IFOP pull fluid solutes out of the capillary
Is interstitial fluid osmotic pressure a large or small pressure
small, because limited protein in interstitial fluid
Describe resorption in bulk flow
Pressure driven movement of fluid and solutes from interstitial fluid to blood
-composed of blood colloid osmotic pressure (BCOP) and interstitial fluid hydrostatic pressure (IFHP)
Describe the role of blood colloid osmotic pressure (BCOP) and interstitial fluid hydrostatic pressure (IFHP) in resorption
BCOP pulls fluids and solutes from the interstitial space to the capillary, d/t proteins in blood
IFHP pushes fluid and solutes from the interstitial space into the capillaries
What is the normal pressure associated w/ interstitial fluid hydrostatic pressure (IFHP)
0, unless there is a pathology
What is net filtration pressure (NFP)
NFP =(BHP+IFOP)-(BCOP-IFHP)
- determines whether volumes of blood and interstitial fluid remain steady or change
- usually measured at arteriole and venule ends of capillary
What does Sterling’s law of the capillaries state
It states that the volume of fluid and solutes reabsorbed is NEAR the volume of fluid and solutes filtered
If net filtration pressure (NFP) is positive it promotes….
Filtration
-this is what is usually found at arteriole
If net filtration pressure (NFP) is negative it promotes….
Resorption
-this is what is usually found at venule
True or False normally all filtered fluids/solutes at the arteriole side of the capillary is reabsorbed at the venule side of the capillary
False, the fluid/solutes, ~15% not reabsorbed enters the lymphatic capillaries
What does the lymphatic system transport
- fluid and solutes that did not make it back to blood circulation
- small proteins (from damage) or large particulate matter
- lipids from the GI tract
What tissues do not have lymphatic drainage nearby
- Superficial layers of the skin
- CNS
- Endomysium of muscle
- Bones
The lymphatic vessels of which body regions drain into the thoracic duct
- Lower part of the body
- L thorax
- L arm
- L side of head/neck
Where does the thoracic duct empty
junction of the L internal jugular vein and L subclavian vein
The lymphatic vessels of which body regions drain into the right lymphatic duct
- R thorax
- R arm
- R side of the head and neck
Where does the right lymphatic duct empty
junction of the R internal jugular vein and R subclavian vein
What is Virchows Node
- enlargement of the supraclavicular lymph node (closet to thoracic duct)
- it is highly suspicious for mets Ca from the Abd, Pelvis, or L thorax
-only palpable
What is Troiser Sign
-Virchows Node that can be seen in addition to palpated
Describe edema
an abnormal increase in interstitial fluid , caused by excessive filtration or inadequate resorption
Give examples of edema caused by excessive filtration
- Increased capillary pressure, increases BHP
- Destruction of capillary walls allowing proteins to enter interstitial space thus increasing interstitial fluid osmotic pressue (IFOP)
Give an example of edema caused by inadequate resorption
-Decreased plasma protein (kidney dz, liver dz, malnutrition, burns), lower blood colloid osmotic pressure
