heart

4.  This provides an overview of the evolutionary path to the
mammalian heart from the beginnings of life (about four billion years
ago ) to the present.
 Early cardiac development involves the formation of a heart tube,
looping of the tube and formation of chambers. These processes are
highly similar among all vertebrates, which suggest the existence of
evolutionary conservation of the building plan of the heart.
 The first heart‐like organ appeared in our biological history over 500
million years ago (Mya) and has undergone many changes and
adaptations during its evolution from a single‐layered tube with own
contractility supporting an open circulatory system, to a powerful
four‐chambered muscular pump devoted to loading and unloading a
large amount of blood around a closed, valved circuit circulatory system.

5.  The heart is an unpaired organ but its origin is bilateral.
 In an embryo the mesenchyme forms a group of endocardial
cells ... below the pharynx
 arranged to form a pair of thin endothelial tubes fuse to
form
 single endocardial tube below the pharynx.
 The splanchnic mesoderm lying below the endoderm folded
around
 endocardial tube ->two-layered
 will form the heart muscular wall of the heart and an outer
thin epicardium or visceral pericardium.
 transverse septum is formed behind the heart which divides
the coelom into two chambers,
 1. anterior pericardial cavity enclosing the heart and a
 2. posterior abdominal cavity.
 The heart is a straight tube but it increases in length and
becomes S-shaped because its ends are fixed. Appearance of
valves, constriction, partitions in the heart, and differential
thickenings of its walls form three or four chambers in the
heart.

9.  Fish-- Gills 2 Chambered Heart
2 accesory Chambers
(Under Water ,Aquatic).
 Amphibian- Lungs 3 Chambered Heart
2 accesory Chambers
 Reptiles- Lungs 3 Chambered Heart
2 accesory Chambers
 Birds- Lungs 4Chambered Heart
 Mammels Lungs 4Chambered Heart

11. Human Heart
• Is a muscle
• Moves 2,000 gallons of blood each day
• Beats between 60 to 100 times per minute

12. Circulatory System
Open circulatory
System
Eg:- Invertebrates
(Arthropoda,
Earthworm,
Butterfly,Dragonfly)
Closed circulatory
System
Vertebrate
Fish

13.  Atrium
 Ventricles
 Sinus Venous
 Conus Arteries/Bulbous Arteries
 Aorta
 Vena Cavae
 Pulmonary Arteries

15.  Transport
Transport gases, namely oxygen (O2) and carbon
dioxide (CO2), between the lungs and rest of the body
Transport nutrients from the digestive tract and storage
sites to the rest ofthe
 body
Transport waste products to be detoxified or removed by
the liver andkidneys
Transport hormones from the glands in which they are
produced totheir target cells
Transport heat to the skin so as to help regulate body
temperature

16. arteries veins capillaries
Carry blood awayfron Carry blood backto Exchange of water,
the heart. the heart.(contain oxygen, carbon dioxide
The aorta is the valves) and many other
largest artery. The vena cava is the nutrients ,wasteand
largest vein. chemicals substances
between blood .

17. Blood delivers oxygen to all
the body cells tostay alive.
We need healthy living
cells. Without oxygen,
thesecells would die.
If the oxygen richblood
doesn´t circulate as it
should , we woulddie.

18. The right side of your heart receives blood
from the body and pumps it to the lungs.
The left side of your heart receives blood
from the lungs and pumps it out to the body.