THE HEART. Position of the Heart human heart is about the size of a fist lies in the thoracic cavity w/in the mediastinum (area from sternum to vertebrae,

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Position of the Heart

human heart is about the size of a fist

lies in the thoracic cavity w/in the mediastinum (area from sternum to vertebrae, between the lungs)

tilted @ angle so its inferior surface lies against the diaphragm

Parts of the Heart Base of the heart

is its superior border

Apex of the heart is lowest point

Major Heart Structures:the Pericardium Outer Layer: Fibrous Pericardium

tough, attaches to diaphragm

Inner Layer: Serous Pericardiumdbl membrane: ○ outer parietal: attaches to fibrous pericardium ○ inner visceral layer: covers cardiac muscle

between the 2: pericardial cavity filled with serous fluid

Wall of the Heart

3 layers1. outer epicardium

same as visceral pericardium

2. middle myocardium cardiac muscle

3. inner endocardium thin layer of endothelium that lines

inside chambers of the heart & valves

Surface Features of the Heart

4 chambers of heart:2 atria form the base ○ Auricles (ear-like) pouch-like extensions

tip of left ventricle forms the apexSulci: grooves where coronary blood vessels

& adipose tissue that externally mark the boundaries between the 4 heart chambers○ coronary sulcus: separates atria from

ventricles○ anterior & posterior interventricular sulcus:

separate 2 ventricles

Right Atrium Receives

deoxygenated blood from SVC & IVC

Right Atrium

inside surface has honeycombed appearance & ridges called pectinate muscles

wall separating rt & lt atrium= interatrial septum: in fetus hole called foramen ovale (blood shunts from rt atrium lt atrium avoiding pulmonary circulation); when scarred over called fossa ovalis

Right Ventricle receives blood

from right atrium sends blood to

pulmonary trunk lungs to be oxygenated

Right Ventricle inside has ridges

of muscles called trabeculae carnae: largest ones called papillary muscles: have string-like cords called cordae tendinae

Right Ventricle

separated from left ventricle by: interventricular septum

Left Atrium receives

oxygenated blood thru 4 pulmonary veins

delivers blood to left ventricle

seen on posterior surface of heart

Left Atrium

thin-walled identifiable characteristic: 4

pulmonary veins entering it

Left Ventricle

receives oxygenated blood from left atrium

sends blood to systemic circulation thru Aorta

has thickest muscle (pumps blood the farthest)

4 Heart Valves control 1-way flow of blood 2 AV valves

between atria & ventriclesTricuspid : rt AV valveMitral : lt AV valve, aka bicuspid

2 semilunar valvesblood exits rt ventricle thru Pulmonary

(semilunar) valveblood exits lt ventricle thru Aortic

(semilunar) valve

AV Valves Tricuspid valve Mitral Valve

Semilunar Valves Pulmonary Valve Aortic Valve

Blood Flow thru the Heart

thinner walled atria receive blood returning to heart from veins

pressure of blood in filled atria opens the AV valves & most of the blood flows into ventricles

both atria contract simultaneously to pump remaining blood into ventricles

Blood Flow thru the Heart

when atria have stopped contracting AV valves close

Ventricles contract together forcing semilunar valves open

walls of left ventricle thicker providing more force to pump blood thru systemic circulation

Blood Flow thru the Heart

Ventricular Systole: when both ventricles are contractingAV valves closeSemilunar valves open

Ventricular Diastole: when both ventricles relaxedSemilunar valves closeAV valves open

Cardiac Cycle

Systemic & Pulmonary Circulation

Heart Sounds

Auscultation: listening to body sounds

1 heartbeat produces 2 heart sounds: lub-dub

heart murmurs: abnl heart sounds usually due to valve abnl



when ventricles contract a blood pressure wave is produced that travels in the arteries and can be felt as your pulse

radial pulse: check over radial artery

carotid artery pulse: check over carotid artery

Calculate Pulse

Count the # of beats in 15 s and multiply x 4

If the math is too difficult count for 30 s and multiple x 2

Blood Pressure

pressure exerted by blood against blood vessel walls

highest in the aorta & large elastic arteries & decreases as arteries get smaller & further from heart

Systolic Blood Pressure

top # on a BP pressure generated by ventricular

systole normal adult: ~120

Diastolic BP

bottom # on BP pressure exerted during ventricular

diastole normal adult: 60- 80

Arterial Blood Pressure

normal adult ~ 120/80

normal venous BP: ~16 mm Hg

BP Measurement Sphygmomanometer: BP cuff usually use brachial artery use correct size cuff


pump used to inflate cuff to a pressure > the systolic pressure:puts pressure on the artery, flattens it,

& stops blood flow in the arterypressure slowly released from cuff as

stethoscope used to auscultate over brachial artery


reported in mm Hg as pressure in cuff becomes <

pressure in artery…examiner will hear a sound can be heard, caused by the turbulent flow of blood as artery goes from flattened normal