The document compares and contrasts the heart structures of fish, reptiles, and humans. Fish have a two-chambered heart with one atrium and one ventricle, while reptiles and humans have three-chambered and four-chambered hearts respectively with separated atria and ventricles. The document also outlines the key cell types in blood and their functions, including erythrocytes carrying oxygen, leukocytes providing immunity, and thrombocytes involved in clotting and growth factors.

1. Heart structure of fish, reptiles,
and human
&
Functions of hematocyte

2. Fish heart
VENTRICLE,
Deoxygenated
blood flow
out to artery
ATRIUM,
deoxygenated
blood flow from
vein

3. Reptilian heart (most reptilian)
Left atrium
Right
atrium
Right
ventricle
Left ventricle
Septum

4. Human heart
Right
atrium
Left
atrium
Left
ventricle
Right ventricle
Septum

5. Differences
Fish
Reptile (most, not all)
Human
2 chambered: 1 atrium and 3 chambered (4 in case of
1 ventricle
crocodilians) : 2 atria and 1
ventricle
4 chambered : 2 atria and 2
ventricles
Single circulatory system
Double circulatory system
Double circulatory system
Only deoxygenated blood
flow through
Both deoxy and
oxygenated blood flow
through, possibility of
mixing
Both deoxy and
oxygenated blood flow
through, but strictly not
mixed
No septum
Partially dividing septum
Complete septum

6. Similarities
• Made up of cardiac muscle and connecting
tissue
• Lies in the anterior part of body cavity, dorsal
to the gut
• Surrounded by pericardium

7. Functions of hematocyte
• Erythrocytes - carry oxygen and collect carbon
dioxide through the use of hemoglobin
• Leukocytes - defending the body against both
infectious disease and foreign materials
• Thrombocytes - involved in hemostasis,
leading to the formation of blood clots
• Thrombocytes – produce growth factor