The Heart Flashcards Preview

BMS101 > The Heart > Flashcards

Flashcards in The Heart Deck (25):

What the heart does

-Great Veins

-Heart propels blood to and from most body tissues via arteries and veins

Arteries: Blood vessels that carry blood away from the heart
Veins: Blood vessels that carry blood back to the heart
Great Vessels: arteries and veins entering and leaving the heart (have a relatively large diameter)


General characteristics & Functions of the Heart (3)

-defn. of blood pressure

-Blood flow is unidirectional
-Acts like 2 side-by-side pumps (work at same rate and pump same volume of blood)
-Develops blood pressure through alternate cycles of wall contraction & relaxation

Blood pressure=force of the blood pushing against the inside walls of blood vessels
-minimum blood pressure essential to circulate blood throughout body


Pulmonary vs Systemic circulation

Pulmonary: Conveys deoxygenated blood from right side of heart to lungs to be oxygenated (and to release CO2)
Systemic: Moves oxygenated blood from left side of heart to systemic cells of rest of body
-deoxygenated blood return to right side


Basic flow of blood (heart, lungs, body)

Right side of heart -> lungs -> left side of heart -> systemic tissues of body -> back to right side of heart


Position of the heart



-Slightly left of midline, deep to the sternum in the mediastinum (compartment of the thorax)
-Base of heart= posterosuperior surface of heart - is mainly left atrium
-superior border is formed by the great arterial vessels & superior vena cava
-Apex: inferior conical end
-inferior border formed by right ventricle





-2 Parts

-is a tough sac that the heart is enclosed in
-Restricts heart's movement and prevents it from overfilling w/ blood
2 parts:
1. Firbrous pericardium: outer covering of tough, dense CT
-attached to diaphragm and base of great vessels
2. Serous pericardium: inner portion = thin, double-layered serous membrane subdivided into;
i) Parietal layer (lines surace of fibrous pericardium)
ii) Visceral layer (aka Epicardium - covers outer surface of heart)
-b/w 2 layers = pericardial cavity where serous fluid secreted to lubricate movement of heart


Anatomy of Heart Wall

-3 layers;
1. Epicardium: outermost layer - also known as visceral layer
-serious membrane & areolar CT
-as we age more fat is deposited - becomes thicker and more fatty
2. Myocardium: Middle layer
-composed of cardiac muscle tissue (is thickest layer)
*is where heart attacks occur
3. Endocardium: internal surface of heart & external surfaces of heart valves
-simple squamous epithelium & layer of aerolar CT


External Heart Anatomy


-4 hollow chambers; 2 small atria & 2 larger ventricles
-anteroinferior borders of atria = muscular extension called AURICLE
-Coronary Sulcus: deep groove that separates the atria and ventricles


Atria (general facts)

-Thin walled chambers located supriorly
-receives blood returning from both circulations & passes to ventricle on each side


Ventricle (general facts)

-inferior chambers
-2 large arteries (pulmonary artery & aorta) leave at superior pole


4 Valves in the heart

1. Right atrioventricular (tricupsid)
2. Pulmonary semilunar
3. Left atrioventricular (bicupsid or mitral)
4. Aortic semilunar


Right atrium

-what it receives
-3 veins that drain into it
-associated valve

-Receives venous (deoxygenated) blood from heart, muscles & systemic circulation
-3 veins drain into it;
1. Superior vena cava
2. Inferior vena cava
3. Coronary sinus
-Right atrioventricular valve separates right atrium from right ventricle
-forced closed when right ventricle begins to contract - prevents blood backflow


Right Ventricle

-What it receives


-Receives deoxygenated blood from right ventricle (through right atrioventricular valve)
-Intraventricular septum forms thick wall between right and left ventricles
-Has large, irregular muscular ridges on inner wall = trabeculae carneae
-typically 3 cone-shaped muscle projections = papillary muscles
-anchor thin strands of CT w/ collagen fibres called chordae tendineae (attach to tricuspid valve)
-superior end (or roof) = conus arteriosus (smooth area)
-beyond this = pulmonary semilunar valve (marks end of ventricle & beginning of pulmonary trunk)


Left Atrium

-what it receives
-how separated from left ventricle

-Oxygenated blood from lungs travels through pulmonary veins to left atrium
-separated from left ventricle by left atrioventricular valve (tricuspid)
-forced shut when left ventricle contracts in similar fashion to closing of right antrioventricular valve


Left Ventricle

-Wall typically 3 x thicker than right
-superior end (roof) = aortic semilunar valve
-marks end of ventricle and beginning of aorta
-pressure of blood backflowing onto valve is what closes them


Semilunar valves

-2 types
-Mechanism of action w/ contraction and relaxation

-either pulmonary or aortic
-located in roof of right & left ventricles
-each one composed of three thin, half-moon shaped, pocketlike semilunar cusps
-When ventricles contract, blood pushes cusps against arterial trunks
-when ventricles relax, some blood flows back - enters pockets of cusps & forces them toward midline & closes them


Coronary Circulation

-Right & left coronary arteries travel w/in coronary sulcus & supply heart wall muscle w/ oxygen & nutrients
-coronary arteries are only branches given off by ascending aorta just superior to aortic semilunar valve


Right coronary artery - 2 branches and what they supply

-branches into 2 arteries
1) Marginal artery: supplies to right border of the heart
2) Posterior interventricular artery - supplies the posterior surface of the left and right ventricles


Left coronary artery - 2 branches and what they suply

-branches into 2 arteries;
1) Anterior interventricular artery (aka left anterior descending artery) - supplies anterior surface of both ventricles and most of interventricular septum
2) Circumflex artery - supplies left atrium and ventricle


Coronary Veins

-3 major veins

-what they all drain into

-Venous return of blood from heart muscle walls
-occurs through 3 major veins;
1. Great cardiac vein
2. Middle cardiac vein
3. Small cardiac vein
*all three drain into large vein (called coronary sinus) that drains into right atrium


Composition of myocaridum

-composed of cardiac muscle fibres
-contract as a single unit - all connected w/ low resistance cell-to-cell junctions called gap junctions
-gap junctions comprise the intercalated discs (shared by adjacent cardiac muscle fibres)
*electrical impulse distributed immediately & spontaneously throughout myocardium


Conducting system of the heart

-how it contracts
-Sinoatrial node - what it does
-Atrioventricular node
-how impulse travels w/in heart

-Contracts autorhythmically (initiates own heartbeat external of nerves)
-Electrical impulse comes from specialised cardiac muscle = Sinoatrial (SA) node (or pacemaker)
-located on posterior wall of right atrium (adjacent to opening of superior vena cava)
-SA node generates 70-80 impulses per minute under parasympathetic control
-Impulses travel to left atrium & atrioventricular (AV) node located in floor of right atrium
-electrical activity leaves AV node into AV bundle which extends into interventricular septum -then divides into left and right bundles


Purkinje fibres

-Left and right bundles w/in septum pass impulse to conduction cells called Purknje fibres - begin at apex of the heat
-spread impulse superiorly from apex to all of the ventricular myocardium


Systole & Diastole

Systole = contraction of the heart
Distole = relaxation of the heart - when each chamber relaxes and chamber fills with blood


Coordinated sequence of heart chamber contractions (4)

1.SA node generates an impulse
2. Both atria contract almost simultaneously while ventricles are relaxing
3. Impulse goes to AV node and then to the ventricles
4. Ventricles contract while atria relax