Lymphatics Flashcards
Throughout the vascular system, blood pressure _________.
Decreases
Where in the vascular system is the cross sectional area the highest? What does this mean for blood pressure and blood flow velocity?
Capillaries
Slowest blood flow velocity
Low blood pressure
How are solutes (lipid soluble and water soluble) exchanged at capillaries?
Lipid soluble (oxygen, carbon dioxide, urea) - through cell membrane
Water soluble (sodium, potassium, chloride, glucose) - through pores (intercellular clefts, fenestrations)
At capillaries, what moves through the cell membrane?
Lipid soluble SOLUTES (oxygen, carbon dioxide, urea)
At capillaries, what moves through pores? Specifically, what are these pores?
Water soluble SOLUTES (glucose, potassium, sodium, chloride).
Pores = intercellular clefts and fenestrations
What do starling’s forces refer to in capillaries? What do they determine?
Hydrostatic pressure and colloid osmotic pressure.
Determines the EXTENT of filtration and absorption.
Define hydrostatic pressure
Pressure a fluid exerts on capillary walls
In to out (draws water out of capillaries)
Define osmotic pressure
Pressure which opposes hydrostatic (due to large solutes, e.g., plasma proteins)
Out to in (draws water into capillaries)
What are the values for:
- HP arteriole side
- OP arteriole side
- NET arteriole filtration pressure
- HP venous side
- OP venous side
- NET venous filtration pressure
- NET overall
HP arteriole side = 35 mmHg out
OP arteriole side = 25 mmHg in
NET arteriole filtration pressure = 10 mmHg OUT
HP venous side = 17 mmHg out
OP venous side = 25 mmHg in
NET venous filtration pressure = -8 mmHg (8 mmHg IN)
NET overall = 2mmHg out, therefore net leakage of fluid out of cells into
Is there a net leakage / net influx of fluid at cells? How much per day?
Net leakage of fluid at cells into the interstitial space (2mmHg outwards is net filtration pressure). This goes into the lymphatic system.
20L leaves capillaries per day. 75-85% reabsorbed. 4-8L taken up by lymphatic system
How much fluid is taken up by the lymphatic system every day? What % is this?
20 L fluid leaves capillaries per day due to filtration
75-85% of fluid is reabsorbed
4-8 L taken up by lymphatics
How does left heart failure affect fluid distribution?
Left heart failure - pulmonary congestion - increase pressure in pulmonary capillaries
How does right heart failure affect fluid distribution?
Right heart failure - systemic congestion - increase pressure in systemic capillaries
Increases hydrostatic pressure - increase filtration - decrease reabsorption - fluid accumulates in tissue (lymphatics takes some away, but not all) - can cause oedema (swollen feet and ankles)
How does histamine affect fluid distribution? Where is it released from?
Released by mast cells (involved in immunity - bite, stings, inflammation)
Increases permeability of capillaries - fluid leaves capillaries - oedema
How could plasma protein concentration decrease? What effect would this have?
Decrease plasma protein - lower osmotic pressure - decrease reabsorption - oedema
Due to:
- lack of protein in diet
- liver disease / sclerosis
- kidney disease
How can kidney disease affect fluid distribution?
Damaged kidney may excrete plasma proteins in urine. Therefore decreased osmotic pressure - decreased reabsorption - oedema
How could liver disease or liver sclerosis affect fluid distribution?
Prevents liver from forming plasma proteins - decreased osmotic pressure - decreased reabsorption - oedema
What are 2 major functions of lymphatics?
Return excess fluid and protein from extracellular tissue to main circulation (also fat absorption)
Filtration of tissue fluid at lamp nodes (immune - contain phagocytic cells and lymphocytes)
Define lymph
Similar to blood plasma (not cells) with very low plasma protein concentration
Lymphatic capillaries have _______ _________ that ______ each other - they are not ______ like tight junctions. They also have _________ which are anchored to _______ and as fluid accumulates in the interstitium, _________ is applied to the _______, which opens ______ and ensures blood flows into the lymph vessels.
Lymphatic capillaries have FLAPLIKE MINIVALVES that OVERLAP each other - they are not FUSED like tight junctions. They also have FILAMENTS which are anchored to FLAPS and as fluid accumulates in the interstitium, TENSION is applied to the filaments, which opens FLAPS and ensures blood flows into the lymph vessels.
Lymphatic capillaries are permeable to what?
Proteins, cells, bacteria
Where are lymphatic vessels found?
In skin - travel along superficial veins
Deep - travel along arteries
Lymphatic collecting vessels have _________
Valves
Which lymphatic vessels have valves?
Lymphatic collecting ducts
Of the 8L of blood reabsorbed from lymphatic system per day, where is this reabsorbed?
40% at lymph nodes = 3.2 L
60% at subclavian vein = 4.8 L
What do lymph nodes contain?
Macrophages
What occurs at lymph nodes?
Filtration + immune system activation
Name three sets of superficial lymph nodes
Cervical nodes (in neck) Axillary nodes (under arm) Inguinal node (in groin)
What does a swollen lymph node indicate?
If there is an infection, the lymph nodes will likely be swollen. (Infection likely on the heart side)
Name 5 other lymphoid organs
Tonsils, thymus gland, spleen, Peyer’s patches, appendix
Trunks and ducts have __________. What does this do?
Smooth muscle in their wall - when stretched, it responds by contracting to move lymph
What is the role of valves?
Ensure unidirectional movement
What moves lymph through vessels?
Smooth muscle in wall. Valves.
Respiratory pump, skeletal muscle pump, pulse pump
Why may lymph nodes be removed in a cancer patient?
Cancer cells can be taken up into lymphatic system and establish themselves in lymph nodes.
What are the consequences of lymph node removal? How can this be overcome / treated?
Often tends to result in oedema as fluid cannot be drained as the lymph node is no longer there. .
Exercise recommended to promote circulation and fluid movement.
