Human body performs different activities like a machine e.g. Digestion
of food, respiration, excretion of waste products from body, etc.
For all these activities there are
different systems in our body. Let’s start some useful information about our body.
Circulatory System
The food which we eat is digested
through digestive system. Digested food is supplied to all parts of the body
where it is used. How this food is supplied to all parts is used. How this food
is supplied to all parts and cells of the body? How does oxygen, which is
required for respiration, comes through lungs, reach each and every cell?
Similarly, how carbon dioxide is transported to lungs for removal?
Heart
Heart is strong muscular organ which
acts like a pump. It lies in the center of the chest cavity, a little to the
left. Our heart is nearly the size of our first. Muscles of heart can contract
and relax. By contraction and relaxation of muscles blood circulates in the
blood vessels. Touch palm side of the writs of one hand at the base of the
thumb with fingers of the other hand. What do you feel? You will feel throbbing
of the blood vessels. This is called pulse rate we can understand the pumping
action of heart.
Interesting information:-
The pulse rate of a young healthy person
is 70 times per minute while in children it is higher.
The pulse rate of a young bird is
nearly 500 times per minute.
Blood Vessels
Observe back of your hand with fist
tightly closed. Do you see any blood vessel? There are three types of blood
vessels in our body. The vessels that carry blood from heart to other parts of
the body are called arteries.
Most of the
arteries carry blood which is rich in oxygen (Oxygenated).
That is why it is
bright red in color. The digested food also dissolves in the blood and with it
reaches all parts of the body.
The vessels which bring blood from all
parts of the body back to the heart are called veins. Mostly veins carry blood
poor in oxygen so the colour of the blood in them is not bright red. Besides
this blood, the veins contain carbon dioxide, extra water, waste and harmful
materials which during circulation reach the excretory organs.
Arteries divide and re-divide into
smaller vessels which are called capillaries. Infect these are the vessels
through which exchange of gases, food and waste substances takes place between
blood and the body cells. The capillaries gradually unite to form large blood
vessels (veins) through which blood come back to heart.
Composition of Blood
Blood is a red colored fluid which circulates
within the body. It is composed of red blood cells, white blood cells,
platelets and a yellowish fluid called plasma.
Red Blood Cells
These are red in color. Their function
is to take oxygen from lungs and carry it to all cells.
White Blood Cells
These are colorless. They are larger
than the red blood cells. Their function is to defend the body. They engulf and
destroy the germs.
Platelets
The function of platelets is to help
the blood in clotting in case of injury.
Plasma
Plasma mainly consists of water,
digested food particles, carbon dioxide, waste and harmful materials.
Causes of Heart Diseases
Heart is an organ which has to work
all the time in the life of an organism. So it needs continuous supply of
blood. The insufficient supply of blood due to any reason would lead to
deficiency of oxygen. This may cause heart attack. In addition to this there
may be other reasons for heart disease. Some important causes are:-
·
Increase
in the amount of cholesterol in the blood.
·
High
blood pressure.
·
Smoking
and taking alcohol.
·
Easy
and lazy life-style.
·
Sometimes
blood gets clotted in vessel supplying blood to the heart. This situation can
also cause heart attack.
Preventive Measures for Heart Diseases
v Go for a walk daily.
v Stop excessive use of gee and other fatty foods.
v Drinking and smoking should be avoided
completely.
v Make proper exercise a routine.
v Do not look for easy ways of life and do not
hesitate to do physical work.
v Live a simple life and avoid tension.
Excretory System
The extra water, salts and harmful
materials from all parts of the body are dissolved in the blood. God has
provided a system in our body that removes these wastes from the blood. This
system is called excretory system. Our excretory system consists of two kidneys,
excretory ducts and urinary bladder.
Inside the belly (abdomen) two kidneys
are resent which are bean shaped. They separate extra water, salts and harmful
materials from the blood. An excretory duct originates from each kidney that
takes urine form the kidney to a sac-like structure called bladder. Urine keeps
on collecting in the bladder. When it is fully filled we have feeling for
urination. Urine is passed out
of the body through the tube.
Interesting Information:-
Certain amount of water and salts is excreted
by our skin.
Skeleton and Muscular System
We have to move our body in order perform our
routine activities. Movement is produced by the muscles which are present on
the bones. The body of every person has a unique shape. This is also due to
bones and muscles. Imagine, if our body had no bones, how it would look like?
Yes, without bones the body would be a heap of flesh. The frame of bones in a
body is called skeleton.
Do you know?
Our body consists of 206 big and small
bones.
The upper most in the skeleton is the skull. The spine (vertebral
column) provides support to the skull.
The vertebral column of many small
bones called vertebrae (sing: vertebra). To the spine behind the neck vertebrae
are attached shoulder bones. Bones of hands and arms are joined to the shoulder
bones. Next to this the ribs are attached to vertebral column. To the lower
part of the vertebral column is attached the hip bones along with the bones of
legs and feet.
Functions of Skeleton Protection
Bones protect the
delicate parts of our body. For example, skull protects brain and ribs protect
our heart and lungs.
Muscles
Muscles are specific tissues which
help in the movement of body parts. All the movements of the body, for
instance, from blinking of eye to movement of legs are due to muscles. Muscles
also protect our body. Muscles are attached to the bones by special tissues
which are called tendons.
Nervous System
Nervous system controls all the
functions of our body. If sends messages from one part of the body to another
and coordinates different functions. Brain, spinal cord and nervous system.
Brain and Their Parts
Brain works like a complex computer
which continuously receives messages, understands them and then sends messages
to the other parts of the body. It is protected in a strong box or bones, the
skull.
Our brain consists of nearly
100,000,000,000 nerve cells which are continuously working day and night.
Human
brain is divided into three main parts:
(1)
Fore Brain (2)
Mid Brain (3) Hind Brain
Fore Brain
This is the largest part of the brain.
It receives information from environment through ears, eyes, nose, tongue and
skin. It also controls and coordinates many other functions.
Mid Brain
Mid brain is small and lies under the
fore brain. It regulates the movements of different parts of the body.
Hind Brain
Hind brain connects the brain with spinal cord.
It controls breathing, swallowing heartbeat and flow of blood, etc.
Spinal Cord
The hind brain is connected with
spinal cord. Spinal cord is like a long cord which is protected by vertebral
column. We perform all activities with the help of brain and spinal cord. Some
of our actions are under the control of our will. These are called voluntary
actions. For example, opening of mouth, movements of hand in different directions
for writing, etc.
Some actions are performed without our
will. These are called involuntary action. For example arm is automatically
withdrawn if the hand touches a hot pan. Similarly eyes are automatically
closed when there is a sudden flash of light. Involuntary actions in response to
external stimuli are called reflex actions.
Reproductive System
In an organism the system which is concerned with
the continuity of race is call reproductive system. The reproductive organs are
different in males and females.
Male Reproductive System
Two male reproductive organs or gonads
are present in the body of a male. Sperms are formed in them, which pass out of
the body through a tube.
Female Reproductive System
Reproductive system of female consists
of two ovaries. Eggs are produced in each ovary. Eggs are passed out of the
body through reproductive tubes. Sperm and egg fuse to form a cell called
zygote. Zygote divides and re-divides and develops into a new individual.
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