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Compendium 6 - How Do Things Get Around The Body? (Heart - 2 Pumps in 1…
Compendium 6 - How Do Things Get Around The Body?
Heart - 2 Pumps in 1
Functions
Regulate BP; routing blood; ensuring one-way blood flow; regulating blood supply; changes to match needs
Location
In mediastinum; shape - blunt rounded point-cone on top, flat at base; size of a closed fist
Pericardium
Fibrous -
tough outer layer; prevents over distention; acts as anchor
Parietal -
thin, transparent, inner layer; simple squamous
Visceral -
covers heart surface
Wall
3 layers of tissue
Epicardium -
serous membrane; smooth outer surface
Myocardium -
middle layer; composed of cardiac muscles cells (contractility)
Endocardium -
smooth inner surface
Pectinate -
muscles ridges in auricles & right atrial wall
Trabeculae carnae -
muscular ridges & columns on inside walls of ventricles
Chambers
Atria (superior)
right atrium -
3 major openings to receive blood returning from body
left atrium -
4 openings to receive blood from pulmonary veins
Ventricles (anterior)
atrioventricular canals -
openings between atria & respective ventricles
right -
opens to pulmonary trunk
left -
opens to aorta
interventricular septum -
between the two ventricles
Great Vessels
blood into heart - into right atrium (superior & inferior vena cava), left atrium (left & right pulmonary veins); blood out of heart - out of right ventricle (pulmonary trunk); left ventricle (aorta)
Valves
atrioventricular (AV valves) -
leaf-like cusps attached to cone-shaped papillary muscles by tendons (chordae tendineae); right has 3 (tricuspid), left has 2 (bicuspid); when open, blood flows from A to V, when closed blood exits ventricle
Semilunar -
right (pulmonary); left (aortic); cusp is shaped like cup; when filled, valve closes (stop backflow); when empty, valve opens, blood exists heart
Pulmonary Circulation
capillary exchange oxygenated blood into left atrium blood flows into left ventricle, left ventricle contracts & pushed blood out through aorta (ascending, aortic & descending); delivered to all cells & tissues in body for nutrients/gas/fluid exchange; blood re-enters right atrium through vena cava
Circulation System
Arteries & Veins
Tunica externa (adventitia):
connective tissue
Tunica intima -
endothelium
Tunica media -
smooth muscle cells arranged circularly around the blood vessel
Vasoconstriction -
smooth muscles contract, decreases in blood flow
Vasodilation -
smooth muscles relax, increase in blood flow
Capillaries
Substances move through capillaries by diffusion
Capillary beds –
extensive networks for exchange
Wall consists of endothelial cells (simple squamous epithelium), basement membrane and a delicate layer of C.T.
Blood
Compositions
Plasma 55% (proteins 7%, water 91%, other solutes 2%); Buffy coat (platelets 250-400 thousands, WBC 5-10 thousands); Formed elements 45% (RBC 4.2-6.2 millions)
Functions
Transport -
gases, nutrients, wastes, processed molecules, hormones & enzymes
regulation on body temperature, pH & osmosis
clotting
RBC
no nucleus; bi-concave shape to increase SA & oxygen carrying capacity; 98.5% of O2 attached to hemoglobin protein, 1.5% dissolved in plasma
Cardiovascular System (Heart, Blood vessels, Capillary Beds & Blood)
Transport fluid, nutrients, waste products, gases & hormones
Exchange materials between blood, cells & extracellular fluid
Plays role in immune response, blood pressure & regulation of body temperature
For transportation (constant supply of oxygen, & waste removal; exchange of materials) & pumping (generating BP & routing blood flow)