Food, water and oxygen are the products that are carried by blood to every part of the body.

The circulatory system consists of three major organs, i.e., blood, blood vessels and heart.

The heart is located in the chest cavity with its lower tip slightly tilted towards the left.

The red coloured pigment of RBC that carries oxygen with it is called haemoglobin.

Blood is a fluid tissue which connects all the parts of body with each other.

Blood contains WBC which forms the defense of our body. They eat antigens and fights aganist infections.

Kidney is the major excretory organ and nephrons are its functional units.

Exchange of substances between arteries and veins occurs via capillaries.

The water in which these organisms live brings them food and oxygen as it enters their bodies.

The faster heartbeats signify that heart is pumping more blood to the organs as they need increased oxygen and energy supply.

In our heart, the right side and left side is completely separated by a septum. The septum does not allows oxygenated and deoxygenated blood to mix.

Platelets help in clotting of blood when we get injured and thus bleeding is stopped. In their absence we will bleed excessively which may endanger our life and prove fatal.

Valves in veins maintains flow of blood only in one direction i.e., from body organs to heart.

(a) Part 1: Kidney
Part 2: Ureter
Part 3: Urinary Bladder
Part 4: Urethra
(b) Function of 1 (Kidney): Helps in filtration of blood. Function of 3 (Urinary Bladder): Receives and collects urine from kidneys.

(a) In dialysis blood is filtered periodically through an artificial kidney.
(b) In the event of kidney failure