Page 113 - Biology Form Two

Biology for Secondary Schools
Blood
Task 5.4
Search the library internet sources for
the main components of blood.
FOR ONLINE READING ONLY
Blood is a specialised fluid tissue
in humans and other vertebrates. It
consists of four main components
which are plasma, red blood cells, white
blood cells, and platelets. Its major
function is to transport oxygen gas and
nutrients throughout the body. It also
removes waste products from the body,
transports hormones, and forms blood
clots that prevent excessive loss of
blood upon injury. Also, it is involved function of plasma is to transport the
in immune response to infections. An
adult human has about 4 to 6 litres of
blood. The pH of blood is 7.4.
Activity 5.3: Examine the components
of blood
Materials
Prepared slides of blood components,
microscope, a pencil, and a notebook
Procedure
1. Mount the prepared slide of blood
on the microscope.
2. Observe the specimen using low
power, medium power, and high
power objective lenses.
3. Describe what you have observed.
Student’s Book - Form Two
BIOLOGY FORM 2 NEW.indd 107
BIOLOGY FORM 2 NEW.indd 107
Plasma
This is a mild alkaline pale-yellow
fluid of blood. Approximately 55% of
blood is plasma. It is mostly made up
of water. Other substances in the plasma
include dissolved proteins (for example
albumins, globulins, and fibrinogen),
dissolved salts, enzymes, oxygen, and
food nutrients. Plasma also contains
other components like antibodies,
hormones, and clotting factors. These
substances make up 8% of plasma while
water makes up 92%. Plasma carries
blood components throughout the body
along the circulatory system. The major
following substances:
(i) nutrients from the digestive system
to other parts of the body;
(ii) red blood cells containing oxygen
to the tissues and carbon dioxide
to the heart and lungs;
(iii) wastes such as carbon dioxide and
urea to the excretory organs;
(iv) white blood cells and antibodies
to sites of infection;
(v) hormones to the target organs;
(vi) mineral ions such as sodium,
potassium and chlorides to ensure
ionic balance in the body; and
(vii) platelets to bleeding sites to initiate
blood clotting.
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05/10/2024 15:36:38