WEEK 10
Posted: Wed Jun 17, 2015 5:28 am
LESSON 22
TOPIC: EXCRETORY SYSTEM
SUB-TOPIC
I. Meaning of Excretion
II. Excretory organs and their functions
III. Excretion and the need for it
IV. Excretory Products/Wastes
Meaning of Excretion
Excretion is the process by which an organism gets rid of metabolic waste products from the body. These waste products, if they are not removed, may be toxic and harmful to the body. Excretion can also be defined as removal or elimination of substances absorbed by the intestine that are not used for growth, repair or respiration. Removal of undigested food (faeces) is not excretion, it is egestion. Excretion is the removal of Carbondioxide and water produced during respiration.
Excretory Organs and their Functions
The Excretory organs include: Kidneys, Skin, Lungs and Liver.
The Kidney: The kidney is the urinary system. Kidneys are two bean-shaped organs located in the abdominal region of the body. They help in removing urine from the body. Urine contains 96% water, 2% salt and 2% urea.
Functions of Kidney
1. It helps to remove the poisonous liquid wastes [urine] from the body
2. It purifies the body by removing toxic and harmful materials from the blood
3. It helps to regulate the amount of water and salt in the body.
The Skin: The skin is the external part of the body and protects the inner structures. The human skin is made up of two layers, namely
(i)The Epidermis: the very outer layer and (ii) The Dermis: The inner layer otherwise called true skin.
FUNCTIONS OF THE SKIN
1. Skin protects the body from mechanical injury and bacterial infections
2. It helps in temperature regulation, that is, layer of fat under the skin act as insulator while evaporation of sweat cools the body.
3. Skin act as a sense organ, that is, it contains sensory cells that makes one respond to the stimuli of touch, pains, pressure, coldness or hotness.
The Lungs: Oxygen from the air breathed in is used during respiration by our body cells. The waste gases such as carbon (iv) oxide and water vapour are sent out into atmosphere through the lungs. The lungs excrete carbon (iv) oxide and water vapour which are by-products of respiration. The lungs function both as respiratory and as excretory organ
The Liver: Liver, largest internal organ of the human body that performs more than 500 different functions, all of which are essential to life. It’s essential functions include helping the body to digest fats, storing reserves of nutrients, filtering poisons and wastes from the blood, synthesizing a variety of proteins, and regulating the levels of many chemicals found in the bloodstream.
Functions of Liver
1. Liver helps in storing energy in form of glycogen
2. It produces bile for the digestion of lipids or fats
3. It helps in clearing toxic substances such as drugs and alcohol from the blood stream
4. Vitamins are stored in the liver
5. Liver is the body’s chemical factory, that is, it produces several important proteins found in the blood, globin and several other chemicals that help in healing wound.
EVALUATION
1. What is excretion?
2. Is excretion and egestion the same?
3. Mention the four excretory organs we have
4. State the components of urine
5. Which of the organs is important? Support your answer with four reasons.
LESSON 23
The Need for Excretion
Excretion is the removal of harmful waste products of metabolic activities from the human body. If this process of excretion does not take place, wastes accumulate in the body and may poison or destroy the body. The need for excretion includes the following:
i. It is necessary to remove toxic and harmful waste products from the body
ii. To maintain salt content of the body
iii. To remove excess water from the body
Excretory Products/Wastes
The waste products removed by different excretory organs in man include:
Excretory Organs Waste products
Kidney
Skin
Lungs
Liver Urine
Sweat(salt, water, urea)
Carbon(iv) oxide and water vapour
Bile pigment
EVALUATION
1. State three reasons why excretion is needful.
2. List the organs of the body and their waste products.
Practice Test 1
Practice Test 2
Practice Test 3
Practice Test 4
TOPIC: EXCRETORY SYSTEM
SUB-TOPIC
I. Meaning of Excretion
II. Excretory organs and their functions
III. Excretion and the need for it
IV. Excretory Products/Wastes
Meaning of Excretion
Excretion is the process by which an organism gets rid of metabolic waste products from the body. These waste products, if they are not removed, may be toxic and harmful to the body. Excretion can also be defined as removal or elimination of substances absorbed by the intestine that are not used for growth, repair or respiration. Removal of undigested food (faeces) is not excretion, it is egestion. Excretion is the removal of Carbondioxide and water produced during respiration.
Excretory Organs and their Functions
The Excretory organs include: Kidneys, Skin, Lungs and Liver.
The Kidney: The kidney is the urinary system. Kidneys are two bean-shaped organs located in the abdominal region of the body. They help in removing urine from the body. Urine contains 96% water, 2% salt and 2% urea.
Functions of Kidney
1. It helps to remove the poisonous liquid wastes [urine] from the body
2. It purifies the body by removing toxic and harmful materials from the blood
3. It helps to regulate the amount of water and salt in the body.
The Skin: The skin is the external part of the body and protects the inner structures. The human skin is made up of two layers, namely
(i)The Epidermis: the very outer layer and (ii) The Dermis: The inner layer otherwise called true skin.
FUNCTIONS OF THE SKIN
1. Skin protects the body from mechanical injury and bacterial infections
2. It helps in temperature regulation, that is, layer of fat under the skin act as insulator while evaporation of sweat cools the body.
3. Skin act as a sense organ, that is, it contains sensory cells that makes one respond to the stimuli of touch, pains, pressure, coldness or hotness.
The Lungs: Oxygen from the air breathed in is used during respiration by our body cells. The waste gases such as carbon (iv) oxide and water vapour are sent out into atmosphere through the lungs. The lungs excrete carbon (iv) oxide and water vapour which are by-products of respiration. The lungs function both as respiratory and as excretory organ
The Liver: Liver, largest internal organ of the human body that performs more than 500 different functions, all of which are essential to life. It’s essential functions include helping the body to digest fats, storing reserves of nutrients, filtering poisons and wastes from the blood, synthesizing a variety of proteins, and regulating the levels of many chemicals found in the bloodstream.
Functions of Liver
1. Liver helps in storing energy in form of glycogen
2. It produces bile for the digestion of lipids or fats
3. It helps in clearing toxic substances such as drugs and alcohol from the blood stream
4. Vitamins are stored in the liver
5. Liver is the body’s chemical factory, that is, it produces several important proteins found in the blood, globin and several other chemicals that help in healing wound.
EVALUATION
1. What is excretion?
2. Is excretion and egestion the same?
3. Mention the four excretory organs we have
4. State the components of urine
5. Which of the organs is important? Support your answer with four reasons.
LESSON 23
The Need for Excretion
Excretion is the removal of harmful waste products of metabolic activities from the human body. If this process of excretion does not take place, wastes accumulate in the body and may poison or destroy the body. The need for excretion includes the following:
i. It is necessary to remove toxic and harmful waste products from the body
ii. To maintain salt content of the body
iii. To remove excess water from the body
Excretory Products/Wastes
The waste products removed by different excretory organs in man include:
Excretory Organs Waste products
Kidney
Skin
Lungs
Liver Urine
Sweat(salt, water, urea)
Carbon(iv) oxide and water vapour
Bile pigment
EVALUATION
1. State three reasons why excretion is needful.
2. List the organs of the body and their waste products.
Practice Test 1
Practice Test 2
Practice Test 3
Practice Test 4