Lecture 8 - Lymphatic system Flashcards
What is the lymphatic system?
A route by which fluid, fat, cells, and protein flow from interstitial spaces back to the blood.
Major route for absorbing GI nutrients also, also immune system and tissue fluid homeostasis.
What is the lymph composed of?
Varying concentrations of protein, milky because of fat from digestion, large particles too like bacteria and leukocytes
How does lymph get into the lymphatic microcirculation?
Loose endothelial cells have gaps that act like unidirectional valves, letting fluid in but not letting it out. There are some smooth muscle cells in lymph vessel that act like a pump too.
What are four factors that intermittently compress lymph nodes?
- Skeletal muscle contractions
- Movements of body parts
- Arterial pulsations
- Compression of tissues by objects outside body
The lymphatic system controls…
protein and lipid concentration
- the volume and pressure of interstitial fluid
Describe the difference between acute and chronic blood flow control
Acute is within seconds to hours and involves rapid vasodilation of blood vessels, chronic is days to months so an increase or decrease in physical sizes and numbers of blood vessels supplying the tissues.
What are the two major theories for local blood flow control?
Oxygen demand and vasodilator theories
Oxygen demand theory for blood flow control:
More O2 present, precapillary sphincters close, vice versa.
What are some vasodilator substances?
NO, adenosine, CO2, lactic acid, histamine, etc
Prevent excess vasodilation by…
Washing away vasodilator substances with increased blood flow
How does the body keep up with increased blood flow required during heavy exercising?
Heart output approximately triples, and all capillaries will open.
What gives burning feeling during strenuous contraction?
Capillaries will have to close leading to buildup of lactic acid.
What is sympathetic regulation during blood flow?
Veins constrict to increase venous return, increase in blood pressure and local vasodilation
What are the four vasoconstrictors?
NAVE:
Norepinephrine, angiotensin II, vasopressin, endothelin
What are the five vasodilator agents?
BSHNP:
Bradykinin, serotonin, histamine, prostaglandins, NO
