BIO 241 1st Edition Lecture 9 Outline of Last Lecture I. Arterial anatomyII. Arterial propertiesIII. Arterial typesIV. ArteriolesV. CapillariesVI. Capillary typesVII. Venules and veinsOutline of Current Lecture II. Blood reservoirsIII. Capillary exchangeIV. What determines bulk flow?V. Net filtration pressure (arterial end)VI. Net filtration pressure (venous end)VII. Review of capillary exchangeVIII. HemodynamicsIX. Blood pressureCurrent LectureII. The percentage of blood reservoirs are broken down below:Capillaries = 5%Heart = 8%Pulmonary vessels = 12%Arterial system = 15%Venous system = 60%The venous system is mainly the skin, liver, and spleen.III. There are three capillary exchange mechanisms. Diffusion of water helps exchange these products. Vesicular transport aids is capillary exchange by traveling through the vein. It is the least important. The third mechanism is bulk flow. This occurs by constant filtration and reabsorption. Plasma and interstitial fluid are always exchanging. It comes out of the capillary and in the interstitial fluid.IV. Four things control bulk flow. These can get pretty extensive so I broke them into paragraphs.The first is the one you know. Blood hydrostatic pressure (BHP) is an outward force of about 30 mmHg on the arterial end and 10 mmHg on the venous end. The pressure decreases down the capillary because the capillary is leaking fluid down the capillary (30 → 10).The second is the interstitial fluid hydrostatic pressure (IFHP). It is an inward force of 0 mmHg under normal conditions.The third is blood colloid osmotic pressure (BCOP). It is an inward force of around 28 mmHg. Plasma proteins (albumins, globulins) produced by the liver aid in osmosis/diffusion of products.Water comes in the capillaries since it is an inward force. The fourth is interstitial fluid osmotic pressure (IFOP). It is an outward force of about 8 mmHg.Although the values vary somewhat, this diagram depicts bulk flow well.V. The four things mentioned above contribute to the net filtration pressure (NFP). For the arterial end, it is the outward - inward forces, more specifically (BHP + IFOP) - (BCOP + IFHP). Furthermore, it is (30+8) - (28+0). Therefore, the NFP at the arterial end is 10 mmHg. Because the pressure is positive, it is filtrating more than it is reabsorbing. VI. The NFP at the venous end is a negative pressure. It is found by the same equation above, but the numbers are (10+8) - (28+0), which is equal to -10 mmHg. Because the pressure is negative, it is reabsorbing more than filtrating. VII. So, let’s review. If BHP > net osmotic pressure, then filtration occur. If BHP < net osmotic pressure, then reabsorption occurs. If a diseased liver stops making plasma proteins, then reabsorption isn’t strong enough and filtration occurs. This causes a person to swell up. Starling’s Law of Capillaries is that 85-90% of materials are reabsorbed and the other 10-15% goes to the lymphatic system, and then returns to the blood. VIII. Hemodynamics (of or relating to the flow of blood within the organs and tissues of the body) relates to four measurements. The first is blood flow (mL/min) which is how much blood flows in a certain time. The second is perfusion (mL/min/g) which is how much blood flows per minute per gram of tissue. The brain and heart have a high perfusion rate since these take the most oxygen out of blood. The third is blood flow velocity (cm/min). It is about 4 meters/second. This is how far blood travels in a certain period. The fourth is total cross-sectional area (TCSA) (cm2). This is found by adding the diameter of a vessel and its branching vessels. The aorta has a diameter of about 2.5 cm. The greater the pressure difference between two points, the greater the blood flow. Capillaries have the highest total cross-sectional area. Something to remember is that the lower the velocity, the higher the TCSA. This is because smaller vessels like capillaries are meant for distribution and exchange which requires slowerblood flow. They want to exchange materials, not go fast. Flow can be found by the difference inpressure divided by resistance. The greater the resistance, the less that flows. IX. The principal determinants of blood pressure (BP) is cardiac output, blood volume, and peripheral resistance. These all have a direct impact on BP. Peripheral resistance is related to three things. One is blood viscosity which is the thickness of blood. Blood is five times thicker than water. Vessel length determines resistance because more blood vessels require more bloodpressure. This is why overweight people are directed to lose weight: less blood vessels requires a lower blood pressure. The third is vessel radius which can be explained similar to length: larger radius equals lower blood