the heart cardiovascular system - 3
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The HeartCardiovascular System - 3
for student copy
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 Pericardium– dbl 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 apex– Sulci: 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 & ventricles– Tricuspid : rt AV valve–Mitral : lt AV valve, aka bicuspid
• 2 semilunar valves– blood exits rt ventricle thru
Pulmonary (semilunar) valve– blood 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 contracting– AV valves close– Semilunar valves open
• Ventricular Diastole: – when both ventricles relaxed– Semilunar valves close– AV 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
• http://www.blaufuss.org/tutorial/index1.html
Pulse• 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• pump used to inflate cuff to a
pressure > the systolic pressure:– puts pressure on the artery, flattens it, &
stops blood flow in the artery– pressure slowly released from cuff as
stethoscope used to auscultate over brachial artery
BP• 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
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