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ANATOMY 1120 > Cardiorespiratory System- The Heart > Flashcards

Cardiorespiratory System- The Heart Flashcards

1
Q

Overview of the cardiovascular system

A
  • The heart is the center of this system
  • The heart connects to blood vessels that transport blood between the heart and all body tissues
  • 2 basic types of blood vessels are arteries (transport blood away from the heart) and veins (transport blood back to the heart)
  • Arteries tend to carry blood high in oxygen, whereas veins carry blood low in oxygen (except for pulmonary veins)
  • The arteries and veins entering and leaving the heart are called great vessels because of their large diameter
  • Consists of 2 blood circulations: pulmonary and systemic
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2
Q

What is the general role of the heart?

A
  • It’s anatomy ensures the unidirectional flow of blood remains constant (backflow of blood is prevented by valves within the heart)
  • Acts like two side-by-side pumps that work at the same rate and pump the same volume of blood: one directs blood to lungs for respiratory exchange and the other directs to body tissues for nutrient and respiratory gas delivery
  • Develops blood pressure through alternating cycles of heart wall contraction and relaxation
  • BP is the force of blood pushing against the inside walls of the vessels
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3
Q

What is the pulmonary circulation?

A
  • Starts with right side of heart pumping deoxygenated blood through pulmonary arteries to lungs
  • After oxygen pickup and carbon dioxide release, pulmonary veins carry blood to left side of heart
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4
Q

What is systemic circulation?

A
  • Left side of the heart pumps oxygenated blood through systemic arteries to body cells
  • Nutrients, respiratory gases and wastes are exchanged
  • Systemic veins carry blood back to the right side of the heart
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5
Q

What is the position of the heart?

A
  • Located slightly left to the midline of the body
  • Deep to the sternum in a space called the mediastinum
  • The heart is slightly rotated: right border is located more anteriorly and left border is located more posteriorly
  • Base of the heart: its posterosuperior surface is mainly the left atrium
  • Superior border: formed by great arterial vessels and superior vena cava
  • Apex: inferior conical end
  • Inferior border: formed by the right ventricle
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6
Q

What is the pericardium?

A
  • A tough sac with serous lining that encloses the heart
  • Restricts heart movements so that it moves only slightly within the thorax
  • Composed of a fibrous pericardium which is the outer sac and a serous pericardium that is composed of parietal and visceral layers of membrane
  • The pericardial cavity is the thin space between serous layers that contains serous fluid which decreases friction in the heart
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7
Q

What makes up the heart wall structure?

A
  • Epicardium: Visceral layer of serous pericardium and areolar connective tissue
  • Myocardium: Cardiac muscle and is the thickest of the 3 layers
  • Endocardium: Internal surface of heart chambers that is simple squamous epithelium and areolar connective tissue
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8
Q

What makes up the external anatomy of the heart?

A
  • Composed of 4 hollow chambers: 2 superior (smaller atria) and 2 inferior (larger ventricles)
  • Right atrium: feeds right ventricle which then feeds the pulmonary trunk (pulmonary circulation then occurs)
  • Left atrium: feeds left ventricle which then feeds the aorta (systemic circulation then occurs)
  • Coronary sulcus: groove separating atria and ventricles
  • Anterior interventricular sulcus and posterior interventricular sulcus are located between left and right ventricles
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9
Q

What makes up the internal anatomy of the heart?

A
  • Has 4 hollow chambers : right atrium, right ventricle, left atrium, left ventricle
  • Has 4 valves: 2 atrioventricular (closure causes first heart sound “lubb”) and 2 semilunar at the base of the great arteries (closure causes second heart sound “dubb”)
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10
Q

What is the fibrous skeleton of the heart?

A
  • The dense regular connective tissue between atria and ventricles
  • Provides structural support: fibrous rings anchor the hearts valves
  • Acts as an electrical insulator
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11
Q

What is the right atrium of the heart?

A
  • Receives venous blood from the heart and systemic circulation through 3 large veins: superior vena cava, inferior vena cava and coronary sinus
  • Interatrial septum separates the right atrium from the left
  • Pectinate muscles are ridges that line the inside of the atrial wall
  • Right atrioventricular valve ensures that there is one-way blood flow from the right atrium to the right ventricle through the atrioventricular opening
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12
Q

What is the right ventricle of the heart?

A
  • Receives deoxygenated blood from right atrium
  • Interventricular septum is the thick wall between right and left ventricles
  • Trabeculae carneae are muscular ridges on the inside of both ventricles
  • Papillary muscles are cone shaped projections that anchor to the trabeculae carneae
  • Conus arteriosus is a smooth funnel shaped region at the superior end of the right ventricle and leads to the pulmonary semilunar valve (ensures one-way flow between the ventricle to pulmonary trunk)
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13
Q

What is the left atrium of the heart?

A
  • Oxygenated blood from the lungs travels through the pulmonary veins to the left atrium
  • Left atrioventricular valve controls the flow between left atrium and left ventricle
  • The valve is forced shut when the left ventricle contracts
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14
Q

What is the left ventricle of the heart?

A
  • Pumps blood through the entire systemic circulation
  • Generates very high pressure
  • Aortic semilunar valve controls flow from left ventricle to aorta (located at superior end of the left ventricle)
  • Left ventricular wall tends to be 3 times thicker than the right
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15
Q

What is coronary circulation?

A
  • The right and left coronary arteries travel within the coronary sulcus and supply the heart wall with oxygen and nutrients
  • The coronary arteries branch off ascending aorta just superior to the aortic semilunar valve
  • Right coronary artery: branches to right marginal artery to supply the right border of the heart and branches to the posterior interventricular artery to supply posterior surfaces of right and left ventricles
  • Left coronary artery: branches to the anterior interventricular artery to supply the anterior surface of both ventricles and most of the interventricular septum. Also branches to the circumflex artery to supply the left atrium and ventricle
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16
Q

Where does venous return of blood occur?

A
  • Occurs through 3 major veins: great, middle and small cardiac veins
  • They all drain into the coronary sinus which then drains into the right atrium
  • Great cardiac vein: runs alongside anterior ventricular artery
  • Middle cardiac vein: runs alongside posterior ventricular artery
  • Small cardiac vein: runs close to the right marginal artery
17
Q

How does the contraction of heart muscle occur?

A
  • Cardiac muscle fibers contract as a whole unit because they are connected with gap junctions
  • Gap junctions: parts of intercalated discs between adjacent fibers. They distribute each electrical impulse immediately and spontaneously throughout the myocardium
18
Q

What is the heart’s conduction system?

A
  • The heart exhibits autorhythmicity, by creating its own heartbeats
  • The conducting system consists of specialized cells that start and propagate electrical impulses to contractile cells
  • The electrical impulse begins at the sinoatrial node (SA) which is the heart’s pacemaker
  • The SA node is located on the posterior wall of the right atrium, adjacent to the opening of the superior vena cava
  • The impulse from the SA node travels via gap junctions to the left atrium and atrioventricular node (AV) on the floor of the right atrium
  • The impulse is paused at the AV node, delaying activation of ventricles as they fill with blood
  • Impulse leaves AV node and enters the atrioventricular bundle (bundle of His), extending into the interventricular septum
  • Once impulse reaches interventricular septum, the AV bundle divides into left and right bundles (bundle branches)
  • The bundle branches then pass the impulse to purkinje fibers that begin at the heart’s apex
  • Purkinje fibers then spread the impulse superiorly from the apex to the whole ventricular myocardium
19
Q

What is an electrocardiogram?

A
  • The heart beat wave of electrical currents within the heart
  • P wave: atrial depolarization
  • QRS complex: ventricular depolarization and atrial repolarization
  • T wave: ventricular repolarization
20
Q

What is the innervation of the heart?

A
  • Heart is innervated by the sympathetic and parasympathetic divisions of the autonomic nervous system
  • Their fibers make up the cardiac plexus and either speed up or slow heart rate but do not initiate it
  • Sympathetic innervation: starts with neurons T1-T5 segments of the spinal cord (this increase heart rate and the force of heart contraction)
  • Parasympathetic innervation: starts with neurons in the medulla oblongata via the left and right vagus nerves (this decreases heart rate but has no effect on the force of heart contraction)
21
Q

What is the cardiac cycle?

A
  • The time from the start of one heartbeat to the start of the next
  • Cycle includes both contraction (systole) and relaxation (diastole) of the heart’s chambers
  • One cycle consists of 5 stages:
    1. Atrial contraction and ventricular filling
    2. Isovolumetric contraction
    3. Ventricular ejection
    4. Isovolumetric relaxation
    5. Atrial relaxation and ventricular filling
22
Q

What happens with aging and the heart?

A
  • Decreased tissue elasticity with age often impairs heart valve function
  • Decreased efficiency of heart’s conduction system can impair heart’s ability to pump extra blood needed during stress
  • High blood pressure increases work required of heart and can lead to problematic hypertrophy of myocardium

ANATOMY 1120 (25 decks)

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