Excretion

         The purpose of this topic is to enable you to....

• Investigate the phenomena in the Life Sciences (LO1)

1. Finding out the structure and position of the various excretory organs by using a model or wall chart.

2. Constructing a model of a nephron

3. Dissection of a sheep's kidney

• Construct and apply Life Sciences Knowledge (LO2)

1. Describing filtration, selective re-absorption and tubular secretion in a nephron.

2. Explaining homeostatic control of water and salts by the kidney.

3. Describing the hormonal regulation of the kidney's functions.

• Apply Life Sciences Knowledge (LO3)

1. The causes and prevention of diseases and injuries of the kidney.

2. The use of modern medical technology such as dialysis and kidney transplants to enhance the lives of person with kidney failure.

                   The flow chart below shows the inter-relationship between the different parts of this Module

                    FLOW CHART SHOWING VARIOUS ASPECTS OF EXCRETION.

1. What is excretion ?                                                                                                                                                                                                    Excretion is the process by which waste products of metabolism and other non-useful materials are eliminated from an organism.  

2. Why is excretion necessary ?                                                                                                                                                                                        As a result of metabolism, harmful waste products such as carbon dioxide and nitrogenous wastes are produced. Accumulation of these wastes in a cells would affect the normal functioning of these cells. Eventually all metabolism will stop. Excretion which is the removal of waste products formed by metabolism, ensures that these waste products do not build up to toxic (poisonous) levels.  

3. The excretory organs and their functions.                                                                                                                                                                     The gut, lungs, skin, liver, kidneys and bladder all play a role in excretion                                                                                                                                      .                                                                                                                                                                                                                           The Gut                                                                                                                                                                        In grade 10 you learnt that faeces is passed out through the anus by a process known as defaecation or egestion. Faeces consist mainly of matrial that we have eaten, but was not digested, or could not be digested. Since these are not produced by metabolic activities of the body, faeces is not considered to be an excretory waste, and the gut is not considered to be an excretory organ!                                                                                                                       .                                                                                                                                                                                                                                  The Skin                                                                                                        

• • 1.                                                                                                                                                   The longitudinal section of Human skin                                                                                                                                                                          The Sweat glands in the skin extract mainly water some salts and a little urea (Which is a nitrogen containing or nitrogenous waste) from the blood and from sweat. When we respire, we lose sweat through the surface of the skin. In this way, the skin excretes excess salts and urea.                                                .                                                                                                                                                                                                                                  The  Urinary Bladder

• • 1.                                                                                                                                                      The longitudinal section through a male bladder                                                                                                                                                        The bladder stores the urine formed by the kidneys temporarily i.e Until it is passed out of the body by the process reffered to as urination.

    2. The Lungs                                                                                              

• • 1.                                                                                                                                                    You have already learn't, in grade 10, how  the lungs excrete carbon dioxide and water in the form of water vapour. The following points will help you refresh your memory:

    2.   # Oxygen is used to release energy from food during the process of cellular respiration.

    3.   # In addition to energy, the breakdown of the food also releases carbon dioxide and water.

    4.   # If the carbon dioxide level is allowed to accumulate in the tissues it will form carbonic acid which will poison the cells.

    5.   # The carbon dioxide from the tissues diffuse into the blood and is carried to the lungs in the form of bicarbonate ions, in solution in the blood plasma and    as carbomino    hemoglobin.                                                                                                                                                                                          #Gas exchange in the lungs removes carbon dioxide from the blood and sheds it into the alveoli of the lungs.                                                                       # The carbon dioxide leaves the lungs, together with water vapour during exhalation                                                                                                                                                                                                                                                                                                                                                     The Liver                                                                       

• • • 1.    You have learned, in grade 10 that proteins are digested into amino acids. You also learned that, when these amino acids are carried to the liver by blood vessels, excess amino acids are broken down to form urea. This process is called de-amination. Urea is transported by the blood to the kidneys. In the kidneys, urea together with the substances all together form urine.                                                                                                   The Kidneys

more info  Blood that passes through the kidney contains metabolic waste substances such as urea and uric acid. The kidneys filter the blood of these waste substances and use them together with water and saltsform urine. The details of the process will be studied later in this module.                                               

          "NOTICE!!!"

As you can see the above is the structures or organs that deals with excretion in our bodies. The focus now will be with the kidneys that I want you to go and investigate the causes and prevention of diseases and injuries of the kidney. Do a reseach and find out about the use of modern medical technology such as dialysis and kidney transplants to enhance the lives of person with kidney failure.

NOTE*

• Do a research on digestive system and answer the questions that are asked. Please ensure that all the questions are answered and work as individually because you have to know the work by heart as it is essential for your academic development. Download the copy of the assignment and submit on the 18th of November 2013, remember that you have to email your work.

"NB"

Submit the work by emailing to my address johnkhoza370@gmail.com as an attachment before or on the 18th of November 2013.You can download  and print the activity to work smart. Keep Moving Forward!!!!!!