In our last class you were introduced to the excretory system and the kidney. Lets do a quick recap of what was learnt:
1. The excretory system is the system responsible for the elimination of metabolic wastes from our bodies.
2. Metabolic wastes are wastes produced as a result of metabolic reactions; that is reactions which occur inside our cells.
3. Some waste metabolic products are carbon dioxide and urea.
4. Excretion should not be confused with egestion. Excretion is the removal of metabolic wastes while egestion is the removal of solid (undigested) wastes. Egestion is the waste produced as a result of passing through our digestive system.
Here is the PowerPoint which we did on the 31st Jan, 2013, as well as the video which we looked at.
11th Feb, 2013
In our last class you were introduced to the functions of the kidney as well as the diseases which affect the kidneys as well as the composition of urine. We also started a little on the liver and we are to continue on the diseases which affect the liver.
Lets do a quick recap:
1. The main function of the kidney is to filter waste products from the blood and pass it out of the body (remember this is metabolic waste) and to regulate the amount of water and salts in the body.
2. Urine is the main form in which waste is eliminated from the body. Urine consists of mainly water, urea, mineral salts and other waste products.
3. The kidneys may become infected by bacteria or damages by long term use of illegal or medicinal drugs. For example kidney stones which are formed by not drinking enough water.
4. When a person kidney(s) fail they may need to undergo dialysis. The blood is drawn from the patients arm and allowed to circulate through a dialysis machine which removes wastes and excess water; the blood is then returned to the body.
Below is the PowerPoint which was done in class
15th Feb, 2013
The skin is another one of our main excretory organs and it is referred to as the largest organ in the body. Metabolic wastes in the form of sweat is excreted by our skin which consists of many pores which allows the sweat to exit.
The skin consists of two parts:
1. the inner part or "dermis"
2. the outer part or epidermis
The skin is also contained of different tissues:
1. Epidermal tissue
2. Adipose tissue
3. Blood tissue
The Excretory System
Diagram of The Excretory System and the Kidney
Above is a simple diagram of the excretory system, remember how to correctly label the diagram as well as the rules for drawing in Biology.
Here are a few reminders:
1. Use a hard, sharpened HB pencil or a mechanical pencil
2. Never use crayons, markers, color pencil etc, while drawing
3. Drawings should never be shaded
4. Your drawing lines should be smooth, clean and continuous. That is, consider each line and draw without removing the pencil from the paper.
5. There should be no gaps in the drawing
Labels should either be in all CAPITAL LETTERS or all in common letters. Letters should never be joined. Do not write in any "fancy" script make your letters neat and legible.
6. The labels should be written horizontally, neatly and accurately spelt.
7. All label lines should be drawn horizontally with the use of a ruler and a pencil with a sharp point. They should point clearly to the intended part.
8. Label lines should not be crossed. They should not be drawn with arrow heads or dots.
9. All drawings should have a full underlined title written in CAPITAL LETTERS beneath the drawing
(Guidelines for drawing taking from: "A Laboratory Guide for SBA" By: Angus and Dawn Marryshow)
I do hope everyone located their livers by now :)
The main function of the liver is detoxification. When food is digested it is taken to the liver where harmful substances are detoxified or removed. For example alcohol is broken down in the liver.
Hepatitis is also another disease which is an inflammation of the liver. Heavy consumption of alcohol can lead to chronic hepatitis. Chronic hepatitis leads to cirrhosis
Cirrhosis is a disease which affects the liver, it is formed when fibrous tissue forms over living liver cells.
The picture to the left shows the differences between a health liver and a a liver afflicted with cirrhosis.