sheep heart dissection

TJ Medical Society 2008

A Presentation brought to you by:

Alison Jarmas, Jerry Liu, Nikhil Prakash, Jimmy Wu, Judy Zeng, and the Officer Corps.

Blood Circulation and AtriaBlood Circulation and Atria

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

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

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

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

Diastole and SystoleDiastole and Systole

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)

RED – aortic pressureBLUE – left ventricular pressureYELLOW – left atrial pressure

Ventricles and the Ventricles and the “Cardiums”“Cardiums”

Ventricles Myocardium –

muscle tissue Endocardium –

tissue that lines the interior of heart

Pericardium – sac that contains heart and roots of great blood vessels

Valves, Muscles, TendinaeValves, Muscles, Tendinae

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

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

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

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

Stabilize valves

“heartstrings” Connective tissues connecting valves to

papillary muscles Prevent valves from being turned inside out

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

AortaAorta

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

Pulmonary CirculationPulmonary Circulation

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

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 newlyoxygenated bloodback to the heart

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

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

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

Cranial/Caudal Vena CavaCranial/Caudal Vena Cava

Cranial/Caudal Vena Cava

ArteriesArteries

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

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

Aorta Common carotids Common iliacs Pulmonary trunk

Arterioles, Venules, Arterioles, Venules, CapillariesCapillaries

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.

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.

© TJHSST Medical Society 2007-2008