Sheep Heart Dissection

1. TJ Medical Society 2008
A Presentation brought to you by:
Alison Jarmas, Jerry Liu, Nikhil Prakash, Jimmy Wu, Judy Zeng, and
the Officer Corps.

2. Blood Circulation and AtriaBlood Circulation and Atria

3. Blood enters heart through
veins: Superior vena cava and
Inferior vena cava.
Heart muscles in atria contract-
push blood into ventricles
Ventricles force blood through
the arteries.
Blood, oxygenated by lungs,
flows into left chambers of the
heart
Aorta pushes blood from heart
to the body

4. Blood FlowBlood Flow
 Deoxygenated Blood Deoxygenated Blood
 Oxygenated Blood Oxygenated Blood
Blood from tissues throughout body Blood from tissues throughout body 
Superior and Inferior vena cava Superior and Inferior vena cava 
Right Atrium Right Atrium 
Tricuspid Valve Tricuspid Valve 
Right Ventricle Right Ventricle 
Pulmonary Semilunar Valve Pulmonary Semilunar Valve 
Pulmonary Artery Pulmonary Artery 
LungsLungs 

5. Blood FlowBlood Flow
 Deoxygenated Blood Deoxygenated Blood
 Oxygenated Blood Oxygenated Blood
Pulmonary Veins 
Left Atrium 
Bicuspid (Mitral) Valve 
Left Ventricle 
Aortic Semilunar Valve 
Aorta 
Body Tissue 

7. Hearts have right
and left atria
Atria relax to fill
with blood
Atria contract to
release blood to
body
Chambers of heart
with thin walls

8. Diastole and SystoleDiastole and Systole

9. Consists of cyclic periods of high or low blood
pressure, measured in mmHg
Systole – all four heart chambers simultaneously
contract to propel blood through the cardiovascular
system; causes increased pressure on arterial walls
Diastole – the period of relaxation during which blood
flows back into the atria and ventricles; causes
decreased pressure on arterial walls
Represented as systole/diastole (ie. 120/80)

10. RED – aortic pressure
BLUE – left ventricular pressure
YELLOW – left atrial pressure

11. Ventricles and the “Cardiums”Ventricles and the “Cardiums”

12. Ventricles
Myocardium –
muscle tissue
Endocardium – tissue
that lines the interior
of heart
Pericardium – sac
that contains heart
and roots of great
blood vessels

13. Valves, Muscles, TendinaeValves, Muscles, Tendinae

14. http://www.mitroflow.com/immagini/bassa/0_2005127191719-patients_chambers.jpg

15. Allows blood to enter ventricles
Prevents backflow into atriums
Connected to papillary muscles by chordae
tendinae
Tricuspid (right AV)
◦3 membrane flaps between right atrium and
ventricle
Bicuspid (mitral or left AV)
◦2 membrane flaps between left atrium and
ventricle

16. Prevents backflow from arteries to ventricles
3 small membranous pockets; crescent-
shaped flaps of endocardium
Pulmonary (right)
◦Connects pulmonary trunk to right ventricle
Aortic (left)
◦Connects aorta to left ventricle

17. Flaps of muscles connected to various valves
on one end by chordae tendinae and to
ventricular walls on the other
Stabilize valves

18. “heartstrings”
Connective tissues connecting valves to
papillary muscles
Prevent valves from being turned inside out

19. www.byedr.com/medicine/1781-medicine-5.html

20. AortaAorta

21. The largest artery in the body: stems from LV
and brings oxygenated blood to all parts of body
in systemic circulation.
Diagram of Aorta in SHEEP

22. Pulmonary CirculationPulmonary Circulation

23. Serves to oxygenate the depleted blood
Circuit led in to by the pulmonary trunk (artery)
Systemic circulation  vena cava  right atrium
 right ventricle  pulmonary artery (right and
left)  lungs (capillary beds)  pulmonary veins
(right and left)  left atrium  left ventricle 
aorta  systemic circulation

24. Arterioles intertwined with tubular bronchioles
bring deoxygenated blood away from the heart
Capillary beds in the saclike alveoli have
increased surface area for gas exchange by
diffusion (facilitated by a partial pressure
gradient)
Venules carry newly
oxygenated blood
back to the heart

26. A blood vessel that ALWAYS carries blood
toward the heart
Generally contains deoxygenated blood,
except for the pulmonary and umbilical veins
Path: Right Atrium  Right Ventricle 
Pulmonary Arteries  Lungs  Becomes
oxygenated
Very low blood pressure- rely on skeletal-
muscle pump
Smallest veins are the venules

27. Three Layers
◦Tunica Adventitia: Outer
covering of vessel;
composed of connective
tissue, collagen, and
elastic fiber
◦Tunica Media: Middle
layer; composed of
smooth muscle and elastic
fiber
◦Tunica Intima: Inner layer;
composed of an elastic
membrane lining and
smooth endothelium

28. Types:
Portal and
Nonportal
Superficial and Deep
Pulmonary and
Systemic
Major Ones:
Great Saphenous
vein (GSV) – located
in lower limbs
Pulmonary veins:
carry oxygenated air
to the lungs
Jugular Vein
Inferior and
Superior Vena Cava

29. Cranial/Caudal Vena CavaCranial/Caudal Vena Cava

30. Cranial/Caudal Vena Cava

31. ArteriesArteries

32. Arteries are a type of blood vessel
in the circulatory system. They
generally carry blood away from
the heart to the rest of the body.
The further away from the heart,
the smaller the arteries get until
they become arterioles

33. Arteries are tough on the outside,
muscular in the middle to help force blood
throughout, and smooth on the inside.
Generally arteries are thicker than veins
because they need to withstand greater
pressure

34. Aorta
Common carotids
Common iliacs
Pulmonary trunk

35. Arterioles, Venules, CapillariesArterioles, Venules, Capillaries

36. 
http://www.deconstructdesign.com/st_projects/mm_mania_2003/the_heart/functions.htm
Capillaries are the connectors between
arterioles and venules.
◦Smallest blood vessels that are involved in
regulation of osmotic pressure (internal body
heat)
◦Capillary wall consists of only the endothelium.
Venules are small blood vessels that allow
deoxygenated blood to flow from capillary
beds to veins.
◦Has endothelial membrane, muscle/elastic tissue,
and fibrous connective tissue.

37. Arterioles are the
blood vessels from
the arteries to the
capillaries.
Blood pressure in
arteries = result o
work needed to
pump cardiac
output through
the vascular
resistance.

38. © TJHSST Medical Society 2007-2008