6.2b: The Transport System
17/10/2013 § 1 Comment
Apparently blood is a tissue, not just a liquid. In fact, blood is a liquid tissue; isn’t that so strange. What we think of as blood is actually a combination of different kinds of blood cells and a fluid called plasma that holds a great many things including waste products and dissolved nutrients. The role of blood is to transport these materials throughout the body, but also to bring heat from warmer parts to colder parts of the body.
Blood also consists of two main kinds of cells: we know of them as red blood cells and white blood cells. Red blood cells, here appropriately titled erythrocytes, hold haemoglobin and are in charge of increasing the blood’s oxygen-carrying capacity. White blood cells, here they are called leucocytes, are our little fighters and they mainly fight off disease. There are two kinds of leucocytes for this unit and they are: phagocytes, which take care of foreign material that enter our body, and lymphocytes, which produce antibodies that our system needs.
And a little on the structure of blood vessels. The layers involved in the structure of blood vessels are the following three:
- tunica intima, intima meaning the innermost layer, made up of epithelium cells; this layer creates a low-friction lining
- tunica media, media meaning the layer in the middle, made up of circular muscle fibres and elastin fibres; this layer can stretch and contract to accommodate and pump blood
- tunica adventitia, hahaha, I can’t translate adventitia, sorry, which is made of longitudinal collagen and elastin fibres; this layer makes the wall strong and links it to surrounding tissue
DATA BASED QUESTIONS
Page 225, Chapter 20 Question #1
- i. Identify the cells labelled I and II. I = erythrocyte, II = lymphocyte
- ii. Outline the characteristics of these cells that allowed you to identify them. I = the erythrocyte is a solid coloured cell and doesn’t have anything inside of it, II = lymphocytes have things inside them, based on Figure 10
b) Distinguish between the cells labelled II and III. Both cells are leucocytes, but cell II is a lymphocyte and cell III is a phagocyte.
- i. The actual diameter of the erythrocytes is 7 µm. Calculate the magnification of the micrograph. The magnification is 10714286x.
- ii. Using this magnification, calculate the actual diameters of the largest and smallest leucocytes in the micrograph. Largest leucocyte = 12.1µm, smallest leucocyte = 8.4µm