Pages 356-363

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Includes the heart and the blood vessels Functions:

◦ Deliver oxygen/nutrients to cells/tissues◦ Remove carbon dioxide/waste products

Blood is the transport vehicle

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Location◦ Thoracic cavity◦ between the lungs within the inferior mediastinum

(the central chamber of the thorax) Orientation

◦ Pointed apex directed toward left hip◦ Base points toward right shoulder

About the size of a human fist

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(a)

Superiorvena cava

Pulmonarytrunk

Diaphragm

Aorta

Left lung

Pericardium(cut)

Apex ofheart

(b)

Diaphragm

2nd rib

Midsternal line

Sternum

The heart is enclosed by the pericardium

Pericardium—a double-walled (2 layered) sac

◦ Fibrous pericardium is loose and superficial◦ Serous membrane is deep to the fibrous pericardium and

composed of two layers:1. Parietal pericardium: outside layer that lines the inner

surface of the fibrous pericardium2. Visceral pericardium: lies directly on heart; also known

as the epicardium

◦ Serous fluid fills the space between the layers of pericardium

lubricates; prevents friction from the beating heart

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Pericardium

Myocardium

Pulmonarytrunk

Fibrous pericardium

Parietal layer ofserous pericardium

Pericardial cavityEpicardium(visceral layerof serouspericardium)

MyocardiumEndocardium

Heart chamber

Heartwall

Three layers comprise the walls of the heart:1. Epicardium Most superficial; connective tissue (This is the visceral pericardium)

2. Myocardium Middle layer- the one that contracts Mostly cardiac muscle

Desmosomes hold cells together gap junctions allow electrical wave to flow cell to cell

3. Endocardium Inner layer known as endothelium

Endothelial cells are a layer of thin squamous cells with vascularity A specialized type of epithelial cell

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Pericardium

Myocardium

Pulmonarytrunk

Fibrous pericardium

Parietal layer ofserous pericardium

Pericardial cavityEpicardium(visceral layerof serouspericardium)

MyocardiumEndocardium

Heart chamber

Heartwall

Right and left side are separate pumps Four chambers:

Atria -right and left (on top) Receiving chambers

Ventricles -right and left (on bottom) Discharging chambers

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(b) Frontal section showing interior chambers and valves.

Left atrium

Left ventricle

Right atrium

Right ventricle

Interventricular septum ◦ Separates the two ventricles

Interatrial septum ◦ Separates the two atria

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Left pulmonary artery

Superior vena cava

(b) Frontal section showing interior chambers and valves.

Aorta

Left atrium

Left pulmonary veins

Pulmonary semilunarvalve

Left atrioventricularvalve (bicuspid valve)

Aortic semilunar valve

Left ventricle

Interventricular septum

Myocardium

Visceral pericardium(epicardium)

Right pulmonaryartery

Right atrium

Right pulmonaryveins

Fossa ovalis

Right atrioventricularvalve (tricuspid valve)

Right ventricle

Chordae tendineae

Inferior vena cava

Oxygen-poor blood flows from the right side of the heart to the lungs

Oxygen-rich blood returns to the left side of the heart from the lungs

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Oxygen-rich blood flows from the left side of the heart (via the aorta) to body tissues

(oxygen is used at the cellular level; carbon dioxide is returned to circulation via veins for elimination from the body)

Oxygen-poor blood returns to the right side of the heart via the superior vena cava

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Capillary bedsof lungs wheregas exchangeoccurs

Venae cavae

Pulmonary veins

Aorta and branches

Leftatrium

Leftventricle

Heart

Capillary bedsof all body tissueswhere gas exchangeoccurs

Pulmonaryarteries

Pulmonary Circuit

Rightatrium

Rightventricle

Systemic Circuit

KEY:

Oxygen-rich, CO2-poor blood

Oxygen-poor, CO2-rich blood

Four valves:◦ Atrioventricular (AV) valves—between atria and

ventricles Bicuspid (mitral) valve (left side of heart) Tricuspid valve (right side of heart)

◦ Semilunar valves—between ventricle and artery Pulmonary semilunar valve Aortic semilunar valve

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Allow for unidirectional flow; prevent backflow

Open/close in response to pressure changes in heart

Leaky valves are ok… to a degree Valves that cannot close correctly cannot

prevent backflow Valves that are damaged (due to infection)

require more forceful contraction This leads to a weak heart and potential heart failure

This link shows a summary of the process of blood flow: http://highered.mheducation.com/sites/0072495855/student_vie

w0/chapter22/animation__the_cardiac_cycle__quiz_2_.html

This link shows a step by step process of flow: http://www.sumanasinc.com/webcontent/anima

tions/content/humanheart.html

This link shows a valve replacement!! Very cool https://www.youtube.com/watch?v=C-sIdppyaP

Q

The heart has its own circulatory system

Coronary arteries—branch from the aorta to supply the heart muscle with oxygenated blood

Cardiac veins—drain the myocardium of blood and dump into the Coronary sinus (located posterior and inferior)

From the sinus, blood empties into the right atrium and is returned to pulmonary circulation for re-oxygenation at the lungs

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Superior vena cava

Right pulmonary artery

Pulmonary trunk

Right pulmonaryveins

Right atrium

Right coronary artery

Anterior cardiac vein

Right ventricle

Small cardiac vein

Inferior vena cava

Aortic arch

Left pulmonary artery

Left pulmonary veins

Left atrium

Left coronary artery

Left ventricle

Great cardiac vein

Apex