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Ch. 13 – Cardiovascular/Circulatory System

I. IntroductionA. The blood vessels form a closed tube

that carry 7,000 liters of blood away from the heart, to the cells, and back againB. Vessels – 5 types

1. the heart pumps blood thru arteries, then to

smaller arterioles, to tiny capillaries

Arteries are thick vessels adapted for

carrying high-pressure blood away from the heart

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2. capillaries are the sites of nutrient, electrolyte, gas, & waste exchange

3. capillaries return blood to small venules, then onto larger

veins Veins are thinner than

arteries & return blood to the heart

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13 - 3This is what happens when blood is drawn

from a deeper artery, rather than a superficial vein

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C. Two Circuits1. Pulmonary Circuit – sends

deoxygenated blood to lungs (to pick up O2 and drop off CO2)

2. Systemic Circuit – sends oxygenated blood and nutrients to all body cells and removes wastes

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II. Structure of the HeartA. The heart is a hollow,

muscular pump within the thoracic cavity

B. Coverings of the Heart1. Pericardial sac encloses the heart

a. fibrous pericardium - outer, tough connective tissue

b. parietal pericardium - lines fibrous pericardium

2. visceral pericardium (epicardium) – surrounds the heart

3. pericardial cavity – fluid filled space b/t sac & v.p. to reduce friction

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C. Wall of the Heart – 3 layers1. Epicardium - outermost layer

made of connective tissue; houses capillaries, coronary arteries, & cardiac veins

2. Myocardium – thickest, middle layer that consists of cardiac muscle

3.Endocardium - inner layer; lines inside of heart

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D. Heart Chambers 1. The heart has 4 chambers –

2 atria & 2 ventriclesa. Atria receive blood

returning to the heart and have thin walls & flap-like auricles projecting from their exterior

b. The thick-walled ventricles pump blood to the body

2. Each also has an atrioventricular (A-V) valve to ensure one way flow of blood

3. A septum divides the atrium & ventricle on each side

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Deoxygenated BloodSuperior & Inferior vena cavaRight atriumTricuspid valveRight ventriclePulmonary ValvePulmonary trunk2 Pulmonary arteries

Capillaries of LUNGS

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E. Path of Blood through the Heart

Oxygenated Blood4 Pulmonary veinsLeft atriumBicuspid/Mitral valveLeft ventricleAortic valveAorta

Cells of the Body

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1. A-V valves open & close using chordae tendinae (heart strings), attached to papillary muscles

Valves prevent backflow of blood into atria

2. Pulmonary & Aortic valves are also known as Semi-Lunar valves, due to their crescent shapes

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http://goo.gl/ugRY04 (Blood Flow)Circulatory System rap!

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F. Blood Supply to the Heart Muscle 1. Coronary arteries feed the

heart muscle (myocardium) with O2, from the aorta

2. Cardiac veins drain CO2-ridden blood from the myocardium

& carry it to the superior and inferior vena cavae

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III. Heart Actions

A. Blood pressure is the force of blood against the inner walls of arteries (120/60) systolic pressure over diastolic pressure

B. The cardiac cycle consists of:1. Atria beating in unison (atrial systole) 2. Contraction of both ventricles (ventricular systole = systolic pressure)3. The entire heart relaxes for a moment

(diastole = diastolic pressure)

C. Pulse - ventricle contraction felt in arteries

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D. Heart Sounds – due to vibrations in heart tissues as blood rapidly changes velocity within the heart

1. Heart sounds can be described as "lubb-dupp" sounds or“Korotkoff” sounds

2. “lubb” occurs as ventricles contract (Tricuspid & Bicuspid valves close)

3. “dupp” occurs as ventricles relax (Pulmonary & Aortic valves close)

LISTEN: http://goo.gl/ugRY04http://goo.gl/bv7gDi

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IV. Cardiac Conduction System

A. A few clumps of cardiac muscle tissue initiate & distribute impulses through

the myocardium, from 1 intercalated disk of a cardiac muscle cell to the next disk

B. Sinoatrial (S-A) Node – a pacemaker1. a small, elongated mass of

tissue beneath the epicardium

2. located in the R-atrium, near the opening of the superior

vena cavae3. w/o outside agents, the nodal

cells spread impulses to cause the heart to contract

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C. Path of Stimulation1. S-A node sends impulse & the

atria contract simultaneously, sending blood into the ventricles

2. The impulse then travels to the atrioventricular (A-

V) node & onto the A-V bundle at the top of the septum3. About halfway down

the septum, the A-V bundle branches into Purkinje fibers

4. Purkinje fibers spread to papillary muscles that form whorls in the walls of the ventricles

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5. When impulses reach Purkinje

fibers, the ventricles contract with a twisting motion, forcing blood into the aorta and pulmonary trunk

LOOK & LISTEN:

Cardiac Conduction & Sounds http://goo.gl/ugRY04

Arrhythmias http://goo.gl/rsLwlJ

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D. Electrocardiogram (ECG or EKG)1. a recording of the electrical

changes that occur in the myocardium during a cardiac cycle

2. body fluids can conduct electrical currents, so such changes

can be detected on the surface of the body

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3. Patterns P wave: depolarization of atrial fibers that lead to atrial contraction QRS complex: when rapid depolarization in ventricular fibers comes to an end (at the same time, atrial fibers repolarize, but are immeasurable) T wave: repolarization of ventricular muscle fibers

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Time b/t intervals can signal heart problems