Anatomy Notes #4

Anatomy Notes #4 - The Cardiovascular System (Ch. 19) Most...

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The Cardiovascular System (Ch. 19) Most body cells are stationary and therefore incapable of: ـ Procuring food and O 2 ـ Moving away their own wastes Need a means of transporting these substances within the body: o Blood – the river that transports substances necessary for life H 2 O, nutrients, O 2 , hormones, waste o Cardiovascular system – hardware that transports blood Heart – pump Blood vessels – pipes Size, Shape and Position of the Heart Hollow, 4 chambered muscular organ for pumping blood The size of your clenched fist Located in the thoracic cavity in the: o Mediastinum – medial cavity between the lungs Well protected by bone: o Vertebral column posteriorly o Sternum anteriorly o Ribs anterior, and laterally Cone shaped: o Apex Inferior end, tilts left Contacts the diaphragm o Base Broad superior part where vessels attach The Pericardium Loose fitting fibroserous sac that encloses and protects the heart Isolates the heart from other thoracic organs Resists excessive expansion of the heart Anchored to the diaphragm and great vessels above Composed of 2 layers: 1) Fibrous Pericardium Outermost (superficial) Tough fibrous dense CT Inelastic Anchors heart to diaphragm, sternum and large vessels 2) Serous Pericardium Inner layer Composed of simple squamous epithelium overlying thin areolar CT Thinner, slippery smooth Composed of 2 layers: a) Parietal pericardium o Fused to the inside of the fibrous pericardium b) Visceral Pericardium o Lies on the surface of the heart itself o Also called epicardium Then there is a space between the 2 serous layers: Pericardial cavity o Contains and slippery, lubricating fluid: Pericardial fluid
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Secreted by serous pericardium Lubricates heart as it contracts Allows heart to beat almost without friction The Heart Wall – composed of 3 layers 1) Epicardium Outer layer AKA Visceral pericardium 2) Myocardium Thick, middle layer of cardiac muscle Its muscle fibers spiral around the heart Thickness varies throughout the heart o Depends on force of contraction needed to eject blood o Thickest portion surrounds the left ventricle 3) Endocardium Forms the smooth inner lining of the chambers and valves Simple Squamous epithelium overlying thin areolar CT It is continuous with Endothelium lining blood vessels The Chambers The heart has four: Two Atria Right and left, superior chambers Receive blood returning to the heart: o Venous blood Travels in veins Usually deoxygenated Right Atrium o Receive venous blood from 3 veins: 1) Superior Vena Cava Drains the body superior to the diaphragm 2) Inferior Vena Cava Drains the body inferior to the diaphragm 3) Coronary Sinus Drains the heart muscle itself Left Atrium o Receives blood from 4 pulmonary veins: 2 from the right lung and 2 from the left lung Oxygenated blood goes back to heart
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This note was uploaded on 11/06/2010 for the course BIOL 64 taught by Professor Debban during the Fall '10 term at CSU Fresno.

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Anatomy Notes #4 - The Cardiovascular System (Ch. 19) Most...

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