Human Phys 4.5 Flashcards
What is the lymphatic system?
Accessory route for fluid and protein to flow from interstitial spaces to the blood
What is the lymphatic system important in preventing?
Edema
What is lymph derived from?
Interstitial fluid that flows into the lymphatics
What is the lymphatic system a major route for?
Absorption of nutrients form the GI tract
What does the lymphatic system play an important role in?
Immune system
What does fluid that does not re enter the capillary at the venous end do?
It is returned to the systemic circulation via lymphatics (about 1/10)
What is the total daily lymph flow?
2-3 L
What are endothelial cells anchored to?
Surrounded connective tissue via anchoring filaments
What do the endothelial cells overlap to create?
Valve like structures
What happens to lymph flow at low pressure?
It is reduced
What is lymph flows relationship to pressure?
They both increase together
Why does lymph flow plateau at 2 mmHg?
Due to excess pressure compressing the outside surfaces of the larger lymphatics
What does the compression force in lymph flow balance?
Increasing entry of fluid
What happens during the expansion phase in lymph flow?
Hydrostatic pressure in the interstitium exceeds that inside the initial lymphatic causing microvalves to open and fluid to enter
What happens during the compression phase of lymph flow?
Hydrostatic pressure inside the initial lymphatic rises, closing the microvalves and opening the secondary lymph valves, causing fluid to flow downstream
What happens when lymph vessels become stretched?
Smooth muscle cells contract
What do valves prevent in lymphatics?
Backward flow
How much pressure can be generated in large lymph vessels?
50-100 mmHg
What do the external pumps do in lymph flow?
Contraction of surrounding muscles
Movements of body parts
Arterial pulsations adjacent to lymphatics
Compression of tissues by objects outside the body
How much can lymph flow increase during exercise?
10-30 fold
What are the key roles of the lymphatic system?
Controls concentration of proteins in the interstitial fluid
Controls volume of interstitial fluid
Controls interstitial fluid pressure
