The document summarizes the development of the human cardiovascular system from early embryonic stages through adulthood. It describes how the primitive heart tube forms and begins to loop, resulting in the formation of chambers. Key events include atrial and ventricular septation, as well as the formation of valves. The conduction system and role of the heart in circulating blood is also overviewed. Throughout development, the human heart resembles that of different animal hearts as complexity increases.

1. Emily Todd
Michelle Rodrigues
Caileigh Allegrini
Jenny Alvarado

2. What does the human
cardiovascular system consists
of?
 The cardiovascular system consists of
the heart, blood vessels, veins and
arteries.

3. Why is the heart important?
 The heart is one of the most important organs in the
entire human body.
 It is one of the first organs to form. Why? Because it
when the embryo first starts, it recieves the
necessary nutrients from its surroundings, but as the
embryo grows, it becomes hard for the nutrients to
reach all the cells.
 The heart functions as a pump and is composed of
muscle.
 The heart pumps blood, which carries all vital
materials through our body.
 Our entire body relies on the heart.

4. How does the heart begin?
 The heart derives from Mesoderm.
 Mesoderm is the middle layer of an
embryo in early development.

5. The Primitive Heart
 The primitive heart tube is the earliest stage of
heart development.
 The primitive heart tube consists of the bulbus
cordis,
a ventricle, atrium, sinus venosus, and
vitelline veins.
 All five embryonic dilatations of the
primitive heart develop into the adult
structures of the heart.
 The primitive hearts begins beating
once it has formed

6. Embryonic Heart Looping:
 The linear tube begins to bend upward
to the right.
 Why does lopping occur?
Looping occurs because it’s the hearts
way of transforming the single heart tube
to a more complex structure with two atria
and two ventricles.

7. Embryonic Heart Looping:
 The heart continues bending which causes
chamber structures to form. The heart forms two
atriums and one large ventricle. As bending
continues, the heart divides that one large
ventricle in half, which ultimately leaves you with a
left and a right ventricle are. The total of chambers
formed in the heart during looping is 4.

8. Partitioning of the heart
includes:
 AtrialSeptation:
 Ventricular Septation:
 Atrioventricular Valve formation:
 Division of the outflow tract:

9. Atrial septation:
 This process occurs during week 5 of development.
 How?
 The septum primum grows from the ventral and
posterior walls of the atrium.
 The septum secundum forms a ridge on the dorsal
and posterior walls of the atria, but doesn’t not fuse
with endocardial cushioning, allowing the foramen
ovale to remain open, which allows maternal
circulation until the baby is born.
 EMBED VIDEO HERE
 http://www.youtube.com/watch?v=NCDdoSfdQBo

10. Ventricular Septation:
 Ventricular septation is a complex
process involving many surrounding
structures to form dividing ridges
positioned at various planes.
 This eventually leads to a complete
separation of the right and left ventricles.

11. Development of the outflow
tract:
 What is the outflow tract?
The Outflow tract is a portion of the left
ventricle of the heart through which blood
passes in order to enter the greater
arteries.
 The first indication of a developing
septum is the appearance of two ridges
projecting into the outflow tract from
opposite sides. these ridges spiral in
counter-clockwise direction up the
developing outflow tract.

12. Stages of development the fetal
heart resembles the structures
of animals hearts

13. FISH VS EARLY STAGES OF
HEART
In the early stages when the heart looks
like a tube, it is similar to a fish heart.

14. FROG VS TWO CHAMBER
HEART
when the fetus heart begins to take shape
and form two chambers, it resembles a
frog’s heart

15. TURTLE VS THREE
CHAMBER HEART:
After the fetal heart has developed two
atriums and one large ventricle, it looks
similar to a snake or turtle heart.

16. Does the heart continue
changing?
 At birth you have a fully functional
heart, which does not under go any
drastic changes as you get older.
 As you grow and get bigger, your heart
gets bigger too.

17. Invertebrates
 Simple heart and vessels
 Open circulatory system
 Single circulation

18. Vertebrates
 Heart, blood vessels
(veins, arteries, capillaries), blood
 Closed circulatory system
 Double circulation
 Increase in metabolic demand

19. Single vs. Double
Circulation
 Single: One atrium, one ventricle, the
heart draws in deoxygenated blood in a
single atrium and pumps it out to a
ventricle. Includes a two chambered
heart
 Double: Pathway that enables the blood
to flow from the heart to lungs and return
back to the heart for systemic
circulation. Includes a three or four
chambered heart

20. Fish
 Single circulation
 Four chambers: sinus
venosus, atrium, ventricle, bulbus
arteriosus
 One way valves including the sino atrial
valve and atrioventricular valve prevent
the backflow of blood between chambers
 Semilunar valve (located in bulbus
arteriosus) to prevent reverse blood flow
from the ventral aorta

21. Evolution
 The transition from aquatic life to
terrestrial life brought about many
different accommodations to the new
modes of life

22. Amphibians
 Three chambers: right atrium, left atrium,
one ventricle
 Right and left atrium divided by an
interatrial septum
 Has a sinus venosus and conus arteriosus
 Has two semilunar valves and an
atrioventricular valve
 Spiral valve within the conus arteriosus
 The ventricle of a frog heart lacks a septum
but has a trabeculae instead
 Double circulation

23. Reptiles
 Three chambers: two atria, one ventricle
 Ventricle divided into the cavum
venosum, cavum pulmonale, and cavum
arteriosum
 Cardiac shunt cuts off blood supply to
lungs
 One-way lunar valves at the conus
arteriosus and an atrioventricular valve
 Double circulation
 Conus arteriosus and a smaller sinus
venosus than amphibians and fish

24. Crocodile
 Four chambers: two atria, two ventricles
 Ventricle has a complete septum
 Unique feature called foramen of
Panizza that cuts off blood supply to
lungs while diving
 pair of atrioventricular valves

25. Mammals & Birds
 Four chambers: two atria, two ventricles
 Double circulation
 Sinus venosus is minimized into a patch of Purkinje fibers
(AKA sinoatrial node)
 Birds have very small sinus venosus
 Conus arteriosus is transformed into pulmonary and aortic
trunk
 Considered the perfect heart due to complete internal
heart septa
 Oxygenated and deoxygenated blood can never mix
 The chance of backflow of blood becomes greater with
increase in heart chambers
 Valves developed in the heart to prevent backflow of
blood into the wrong chambers

26. Mammalian Heart Valves
 The human heart has 4 heart valves:
 Bicuspid mitral valve
 Tricuspid valve (right atrioventricular
valve)
 Aortic valve
 Pulmonary valve (semilunar valve)

27. Heart Valves
 Bicuspid mitral valve: separates the
left atrium from the left ventricle
 Tricuspid valve: separates the right
atrium from the right ventricle
 Aortic valve: separates the base of
the left ventricle with the aorta
 Pulmonary valve: separates the
base of the right ventricle with the
pulmonary artery

28. Anatomy & Function of Mitral
Valve
 Prevents the backflow of blood into the atrium
 2 cusps
 4-6 cm2 in size
 Opening surrounded by fibrous ring known as the
mitral valve annulus
 Valve cusps do not balloon into the left atrium
because of the chordae tendineae
 Chordae tendineae are attached to papillary muscles
and valve cusps
 The intraventricular pressure forces the valve to
close when the left ventricle contracts
 Tendons help the cusps fit together and prevent the
valve from opening in the wrong direction

29. Mitral Valve Prolapse (MVP)
 Most common heart valve abnormality
 Effects mostly women between the
ages of 20-40
 One or both of the flaps are too large
 Mitral valve does not close evenly with
each heartbeat
 Causes regurgitation (the backward
leaking of blood) – leads to heart
murmur

30. Symptoms & Treatments
 Symptoms: chest pain, irregular
heartbeat, increased heart beat after exertion, other
blood flow complications
 In rare cases: formation of blood clots on the
valve, puts patient at high risk for stroke
 Treatment: medications, specifically beta-
blocker, surgery to repair or replace the mitral valve
 Severe mitral regurgitation often leads to an
enlarged heart causing heart failure
 Severe cases where the valve cannot be
repaired, only replaced, the patient is subject to a
lifetime of blood thinners to prevent blood clotting.

31. Physiology of the heart
 Conduction system
 Transportation of the blood in the heart

32. Conduction system
How the heart contracts!
 heart contracts as a direct result of electrical
potential that travels through the myocardium
cells of the heart.
 There are 5 components to the conduction
system that aid in the contraction of the heart:
Sinatrial (SA) node
Atrioventricular (AV) node
Bundle of His
Left/Right bundle branches

33. Conduction system
 The SA node ( the pacemaker) located at the top of the right
atria is the portion of this system that generates the impulse;
providing the stimulus for contraction.
 The impulse continues to the AV node. At the AV node which is
located at the bottom portion of the right atria, the atria is
contracted and the electrical impulse is paused, because the
atria needs to complete its contraction.
 Once the contraction is complete the electrical impulse is
passed through the bundle of his, and then to the left/ right
bundle branches that are located within the interventricular
septum, and lastly to the Purkinje fibers.
 The Purkinje fibers are located in the muscle walls of the
ventricle. Since the ventricle of the heart is very large it is
essential that the Purkinje fibers depolarize the contractile cells
of both ventricles; causing them to contract.
http://www.youtube.com/watch?v=te_SY3MeWys

34. Transportation of the Blood in
the Heart
 Occurs in 2 phases: Diastole Phase ( relaxation of the atria and the ventricles)
Systole Phase ( Ventricles contract)
 In the Diastole Phase, which occurs first in the heart represents the relaxation of the
atria and ventricle as it refills with blood. During this time the atrioventricular valves are
open.
 Deoxygenated blood enters through the superior and inferior vena cava to the right
atria. Since the atrioventricular valve (which separates the atria from the ventricle) is
opened, the blood can continue through the atria into the right ventricle.
 As the blood enters through the right ventricle an impulse from the SA node is created
and allows the right atria to contract. The right atrium empties out all its blood into the
right ventricle, and the atrioventricular valve closes to prevent the back flow of blood.
 At the right ventricle and electrical impulse from the Purkinje fibers allows the ventricle
to contract, this is the beginning of the Systole phase which occurs when the ventricles
are contracted. The blood pushes through the opened pulmonary valve (one of the
semi lunar valves) to the pulmonary artery.
 The deoxygenated blood then travels to the lungs where carbon dioxide is released
and oxygen is absorbed.

35. Transportation of the Blood in
the Heart
 Once oxygenated the blood returns to the heart it enters
in through the pulmonary veins and there is another
Diastole phase. The pulmonary veins carrying oxygen rich
blood continues flowing to the left atrium. The mitral valve
(one of the atrioventricular valves) is opened, so blood
can easily flow to the left ventricle. Once again the SA
node triggers an impulse and contracts, so does the left
atria. The blood is emptied in the left ventricle and the
mitral valve closes.
 From the left ventricle the Systole phase occurs. The
Purkinje fibers contract and the left ventricle moves blood
through the aortic valve (one of the semi lunar valves) to
the aorta, where it is distributed to the rest of the body.
http://www.youtube.com/watch?v=JA0Wb3gc4mE

36. References
 Amsel, Sheri. “Glossary (What Words Mean) with Pictures!.” Bicuspid valve (mitral
valve). Exploring Nature Educational Resource. © 2005 - 2012. December 14,
2012.<http://exploringnature.org/db/detail.php?dbID=13&detID=188>
 What the Health Magazine. [Internet]. Published by What the Health Magazine. [cited
2012 Dec 10] Available from
http://whatthehealthmag.files.wordpress.com/2011/02/818pills.jpg
 Warkentin, D.S. 2012. Mitral Valve Prolapse [Internet]. Summit Medical Group; [cited
2012 Dec 10]. Published by RelayHealth. Available from
http://www.summitmedicalgroup.com/library/adult_health/car_mitral_valve_prolapse/
 Cardiac Conduction System [Internet]. 2009 Nov 21.):John Winters;.
Available from:
http://ecg-experts.blogspot.com/2009/11/cardiac-conduction-system.html
mdmedicine . 2011 April 11. Heart Conduction System [Internet] .
Available from:
http://mdmedicine.wordpress.com/2011/04/24/heart-conduction-system/
Wapcaplet . 2006 June 6. Diagram of the Human Heart
[Internet].:Sodipodi. Available from:
http://en.wikipedia.org/wiki/File:Diagram_of_the_human_heart_%28cropped%29.svg

37. References
 Bailey R. Circulatory System-Types of Circulatory Systems [Internet]. Education
Biology. About.com; [cited 2012 Nov 29]. Available
from:http://biology.about.com/od/organsystems/a/circulatorysystem.htm
 Di Salvo TG, Acker MA, Dec GW, Byrne JG. 2010. Mitral valve surgery in
advanced heart failure. J Am Coll Cardiol 55(4):271-82.
 Franklin CE. Axelsson M. Physiology: An actively controlled heart valve. Nature
2000 Aug 24;406(6798):847-8.
 Kardong KV. Vertebrates: comparative anatomy, function, evolution. 6 ed. New
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