BL3101 Presentation Homeostasis, circulatory & immune system

1. BL3101 Presentation Homeostasis, circulatory & immune system A Tom & ‘Shudder’ production/ PowerPoint presentation

2. Situation: The net outward fluid pressure at the arterial end is greater than the net inward pressure at the venous end. This will result in a net outflow of fluid from the circulatory system into tissues. HOWEVER…(omg), this does not happen in a person of normal health. Why? WHY??!!

3. A little about capillaries • Capillaries have thin walls (one cell thick) with variable gaps between endothelial cells. • Structurally leaky, it is easy for fluid and other small particles to move out of them into the interstitium. • But the gaps are too small for blood cells to exit. • The interstitial fluid has a similar composition to that of blood — except for cells and large proteins. • In addition to the permeability of capillaries, other forces play an important part in fluid movement.

4. An idiot's guide to interstitial fluid • The exchange of substances between blood and the body cells occurs in the capillaries. • Capillaries are specialized for exchange of substances with the interstitial fluid. • No cell in the body is more than 100 micrometers from a capillary. • Interstitial fluid surrounds and bathes the cells. • This fluid is continually being replaced by fresh fluid from blood in the circulatory system. • Body cells take up nutrients from the interstitial fluid and empty wastes into it. • By maintaining a constant pH and ionic concentration of the blood, the pH and ionic concentration of the interstitial fluid is also stabilized. • Although fluid leaves and returns to the capillaries, blood cells and large proteins remain in the capillaries.

5. At the arterial end of capillaries, blood pressure forces fluid out and into the surrounding tissues. • As blood moves through the capillary, the blood pressure decreases so that near the veinule end, less is leaking into the surrounding tissues. • The arrows on the diagram above represent the movement of blood into and out of the capillary. • Long and thick arrows are used to represent a large amount of fluid movement. • The total amount of movement out of the capillary is approximately equal to the amount of movement into the capillary. • The lymphatic capillaries collect excess fluid in the tissues.

6. Although we were told to find out why fluid from the circulatory system will not flow out in a person of normal health, we decided that it would be good to also explain why abnormal, I mean, not-so-healthy people have fluid from the circulatory system overflow into the tissues.

7. Capillary leak syndrome Capillary Leak Syndrome, a rare medical condition where the number and size of the pores in the capillaries are increased which leads to a leakage of fluid from the blood to the interstitial fluid, resulting in dangerously low blood pressure (hypotension) and multiple organ failure due to limited perfusion*. *perfusion is the process of nutritive delivery of arterial blood to a capillary bed in the biological tissue.

11. Bibliography(is that spelt right?) http://en.wikipedia.org/wiki/Perfusion http://en.wikipedia.org/wiki/Capillary_leak_syndrome http://en.wikipedia.org/wiki/Interstitial_fluid http://www.massageandbodywork.com/Articles/DecJan2005/edema.html http://www.colorado.edu/kines/Class/IPHY3430-200/image/figure10d.jpg http://www.cvphysiology.com/Microcirculation/M010_edema.gif http://137.222.110.150/calnet/AnatCirc/image/one-way%20flow%20of%20lymph%20in%20a%20lymph%20capillary.jpg http://www.jdaross.cwc.net/capillary_dynamics.jpg http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20100/Bio%20100%20Lectures/Organ%20Systems/Circulatory%20System/Circulatory%20System.htm

12. Rejoice!You survived the presentation!!!! Clapping would be nice…