The document summarizes the key differences between fish, reptile, and human hearts. It notes that fish hearts are two-chambered with one atrium and ventricle and no separation between chambers. Reptile hearts vary, with some like lizards having a three-chambered heart with mixing of oxygenated and deoxygenated blood, while crocodiles and turtles have a four-chambered heart like birds and mammals. Human hearts are four-chambered with complete separation of oxygenated and deoxygenated blood into two pressure systems.

1. FISH HEART...
• Fishes have two chambered heart.
• It consist of one atrium and one ventricle.
• Fish hearts have no separation between
the atrium or the ventricle.

2. DIAGRAM OF FISH HEART

3. REPTILE HEART

The reptilian heart such as the lizards, have three chambered heart with
two atria and one, partially divided, ventricle.
 So, there will be mixing of oxygenated and deoxygenated blood.
 But, for some reptiles such as the crocodiles and turtles. they have four
chambered heart, with two atria and two ventricle.
 Just like birds and mammals.

4. Reptile
heart

5. HUMAN HEART
 Human have four chambered heart.
 They have complete separation of oxygenated and deoxygenated
blood.
 This creates two different blood pressure.
 Low pressure: blood pumped into the lungs.
 High pressure: oxygenated blood pumped to the body.

6. Human
heart

7. SIMILARITIES BETWEEN
H U M A N & R E P T I L I A N H E A RT.
 Mammals and reptiles both have two atria, pulmonary artery on
the left and aorta on the right.
 The pulmonary artery carries deoxygenated blood to the lungs.
 Aorta transports oxygenated blood to the rest of the body.

8. BLOOD CELLS
Red blood cells
-erythrocytes-
White blood
cells
-leukocytes-
BLOOD
CELLS
Platelets
-thrombocytes-

9. RED BLOOD CELLS
 Main transporters of oxygen throughout the body.
 Contain the pigment haemoglobin, which gives the cells
their reddish colour .
 Circulate throughout the body, bringing oxygen to the
tissues and picking up carbon dioxide, the waste product
formed in the cells.

10. WHITE BLOOD CELLS
 Larger than erythrocytes.
 Main function is to fight against injury and disease.
 They destroy bacteria in the body by engulfing and digesting them
during phagocytosis.
 White blood cells increase in number when there is an allergic
reaction or infection in the body.

11. PLATELETS
 They are the smallest of the blood cells.
 Main function is to start the blood-clotting process.
 They react to a wound by stimulating the damaged vessel to produce
sticky structures that the platelets can attach to, creating a platelet plug
to stop bleeding.
 They also secret a chemical that causes the blood vessel to constrict
until a clot can form.