The exchange of materials between tissue fluid and cells



The exchange of materials between tissue fluid and cellsWatch the video clip ‘Capillary exchange’The blood carries many materials around the body. For example:oxygen, which is required for cellular respiration and energy releaseproducts of digestion, which are transported to the liver to be processed or stored – eg glucoseurea, which is produced in the liver when excess proteins are broken downhormones from the site of production to the necessary cells of the body. Blood capillaries are vital for the exchange of materials between the blood and cells of the body. They transport blood to every cell in the body.Two ways in which materials are exchanged between blood capillaries and body cells are:passive diffusionthe movement of soluble molecules from areas of high concentration to areas of low concentration without the need for energybody cells are surrounded by interstitial (tissue) fluid, which acts as an intermediary between the substances that are moving between the capillaries and the cellsthe interstitial (tissue) fluid essentially takes on the same composition of small soluble molecules as the arterial blood travelling through the capillarybulk flow (pressure filtration)occurs when there is more pressure inside the capillary than outside, and causes the fluid to be pushed out of the capillary, through pores, and into the interstitial (tissue) fluidcan also be called pressure filtration or ultra filtrationmost plasma proteins are retained inside the capillary as they are too large to fit through the pores. Tissue fluid (interstitial fluid) supplies cells with glucose, oxygen and other substances. Carbon dioxide and other metabolic wastes diffuse out of the cells and into the tissue fluid to be excreted through the circulatory system.The tissue fluid can return to the blood via diffusion/reabsorption through the capillary wall or travel into the lymphatic system from where it is returned to the blood.Go to and go through concepts 1-4. Answer the questions below as you go through the material. Be sure to read the review sections and try the practice activities, too.1. What is a crucial (important) aspect of the vascular system?2. a. What are the 3 types of blood vessels, as listed on this website? What are the 2 others that we learned about in class?b. Draw a cross-sectional picture of each of those 3 blood vessel types, showing its different tissue layers.3. What are some special adaptations in veins that help return blood to the heart? What else (outside of the veins) helps to return blood to the heart?4. What is the pulmonary circuit? What is the systemic circuit? Which structures are a part of each of these circuits?5. What is the function of capillaries? Describe the process that takes place through the capillary endothelium.6. In the section for “concept 3: capillary function”, there are examples of the exchange happening at the pulmonary capillaries, and at the systemic capillaries. Describe which molecules are moving and in which direction for each situation.Pulmonary CapillarySystemic CapillaryO2CO2AmmoniaGlucose + Amino AcidsWater7. a. Describe how blood pressure changes in the different types of blood vessels.b. Describe what influences blood pressure in the arterial system.Go to and scroll through the information to complete the questions below.1. Fill in the blanks.a. ______________ carry blood away from the heart toward capillaries.b. ______________ return blood to the heart.c. ______________ are the sites of exchange with surrounding tissues.2. Fill in the blanks.Arteries and veins have ____ layers in their walls. _______________ as the outer layer, ________ the middle layer, and the smooth inner lining is _____________.3. In the picture below, please correctly identify which is an capillary, artery, or vein4. What is the purpose of valves in veins?5. What is special about the walls of capillaries? Why is this important?6. Using the picture below as a reference, describe the movement/exchange of molecules at the arterial side of the capillaries, and at the venule side of the capillaries. Include the movement of oxygen, carbon dioxide, water, nutrients (glucose and amino acids), and wastes. What special job do plasma proteins and large molecules do in capillary-tissue exchange? 7. As blood vessels branch, their total cross-sectional area increases. What happens to the pressure and velocity of the blood as a result?32518358890008. Arteries may become partially or fully blocked by fatty deposits called________. This condition is called__________________. If blood flow in coronary arteries is blocked, this is a heart attack. If blood flow in the brain is blocked, stroke will occur. Blood pressure is proportional to cardiac output (the rate at which the heart beats times the volume pumped with each beat) and peripheral resistance (resistance increases as length of a vessel increases or width decreases). Narrowing of vessels by atherosclerosis is one of a number of factors that will increase blood pressure. Write a formula for blood pressure.Why do you think it is important to maintain blood pressure?What is the name for high blood pressure? Low blood pressure? ................
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