Anatomy & Physiology of the Cardiovascular System Flashcards
Apex
Lowest part of heart formed by inferolateral L ventricle.
Projects anteriorly and to the left at level of 5th intercostal space and left mid-clavicular line.
Base
Upper border of heart involving left atrium, part of right atrium, and proximal great vessels.
Lies at 2nd intercostal space.
Aorta
Largest artery that carries blood from heart to body. Ascends from left ventricle, arches to the left (arch of aorta) and then becomes the thoracic aorta then abdominal aorta.
Inferior vena cava
Vein that returns blood from lower body and viscera to right atrium.
Pulmonary arteries
Carries deoxygenated blood from the right ventricle to the left and right lungs.
Pulmonary veins
Carry oxygenated blood from right and left lungs to the left atrium.
Superior vena cava
Vein that returns blood from the head, neck, and arms to the right atrium.
Right AV valve
Tricusbid valve. Between RA and RV.
Left AV valve
Mitral or bicusbid valve. Between LA and LV.
Aorta valve
Aortic semilunar valve. Between LV and aorta
Pulmonary valve
Pulmonary semilunar valve. Between RV and pulmonary artery
Coronary arteries
Network of progressively smaller vessels that carry oxygenated blood to the myocardium. Arise from the ascending aorta.
R Coronary artery branch: Sinus node artery
R atrium
R Coronary artery branch: Right marginal artery
R ventricle
R Coronary artery branch: Posterior descending artery
Inferior walls of both ventricles
Inferior portion of the interventricular septum
L Coronary artery branch: Circumflex artery
L atrium
Posterior and lateral walls of the L ventricle
Anterior and inferior walls of L ventricle
L Coronary artery branch: Left anterior descending artery
Anterior portion of interventricular septum
Coronary veins
Great, middle, and small cardiac veins drain into the coronary sinus and empty into the R atrium.
Thebesian veins arise in the myocardium and drain into all chambers of the heart, but primarily into the R atrium and ventricle.
Cardiac conduction system
Sinoatrial (SA) node > Atrioventricular (AV) node > common AV bundle or bundle of His > R and L bundle branches > Purkinje fibers
P wave
Atrial depolarization
PR segment
AV nodal delay, time for atrial depolarization and conduction from SA node to AV node. Normal duration in 0.12-0.20 seconds.
QRS complex
Ventricular depolarization and atrial repolarization. Normal duration duration is 0.06-0.10 seconds.
ST segment
Time in which ventricles are contracting and emptying
T wave
Repolarization of ventricles
TP interval
Time during which ventricles are relaxing and filling
Bachmann’s bundle
Conducts cardiac impulse from R to L atrium
Innvervation of the heart
Vagus and sympathetic cardiac nerves converge to form the cardiac plexus at the base of the heart.
Sympathetic influence achieved by release of epinepherine and nonepinepherine. Sympathetic nerves stimulate heart to beat faster (chronotropic effect) and with greater force (inotropic effect).
Parasympathetic influence achieved via acetylcholine release from vagus nerve. Slow heart rate (chronotropic effect) primarily through influence on the SA node.
Baroceptor reflex
Baroreflex helps to maintain blood pressure. Baroreceptors are mechanoreceptors that detect pressure changes. Arterial baroreceptors (high pressure receptors) and cardiopulmonary receptors (low pressure receptors).
Bainbridge reflex
An increase in venous return stretches receptors in the R atrium, which sends vagal afferent signals to the cardiovascular center of the medulla. This inhibits parasympathetic activity, increasing HR.
Chemoreceptor reflex
Chemoreceptors located in the carotid bodies and aortic body respond to changes in pH and blood oxygen tension.
At arterial partial oxygen pressure of <50 mmHg or with acidosis, the chemoreceptors stimulate respiratory centers and increase the depth and rate of ventilation.
Activation of the parasympathetic system causes reduced HR and contractility.
Valsalva maneuver
Forced expiration against a closed glottis causes increased intrathoracic pressure, decreased venous return, and increased central venous pressure. This results in decreased CO and blood pressure, which is sensed by baroreceptors. This causes increased HR and contractility through sympathetic stimulation. When the glottis opens, venous return increases, increasing HR and contractility. The increase in BP leads to decreased HR through parasympathetic stimulation.
Preload
Tension in L ventricular wall at end of diastole.
Afterload
Forces that impede the flow of blood out of the heart, pressure in peripheral vasculature, compliance of aorta, and mass and viscosity of blood.
Stroke volume
Volume of blood ejected by each contraction of the L ventricle. Normal ranges from 60-80 mL depending on age, sex, and activity.
Cardiac output
Amount of blood pumped from L or R ventricle per minute. CO = SV x HR. Normal CO for an adult male at rest is 4.5 to 5.0 L/min, with women producing slightly less. CO can increase up to 25 L/min during exercise.
Venous return
Amount of blood that returns to R atrium each minute. Venous return must equal CO when averaged over time.
Hypovolemia
Decreased blood volume, specifically plasma.
Causes include bleeding, dehydration from vomiting, diarrhea, sweating, severe burns, and diuretic medications for hypertension.
Signs/symptoms include orthostatic hypotension, tachycardia, and elevated temperature.
Hypervolemia
Increased blood plasma, fluid overload
Causes include excess fluid intake (IV or blood transfusion) and sodium or fluid retention (heart failure, kidney disease).
Signs/symptoms include swelling in legs, ascites (fluid in abdomen), and fluid in lungs.
Plasma
Liquid component of blood, in which blood cells and platelets are suspended.
Made up of water, electrolytes, and protein.
Accounts for more than half of the total blood volume. Important in regulating blood pressure and temperature.
Red blood cells
RBC/Erythrocytes make up about 40% of blood volume.
Contain hemoglobin, which allows binding with oxygen.
Decreased RBC (anemia) can result in less blood oxygen, causing fatigue and weakness.
Increased RBC (polycythemia) makes the blood too thick, increasing the risk of stroke and heart attack.
Blood platelets
Platelets/thrombocytes assist in blood clotting.
Low number of platelets (thrombocytopenia) increasing risk for bruising and abnormal bleeding.
High number of platelets (thrombocythemia) increasing risk of thrombosis, which may result in stroke or heart attack.
White blood cells
WBC/leukocytes protect against infection. Low number (leukopenia) increases the risk of infection. High number (leukocytosis) can indicate infection or leukemia. 5 main types of WBCs
Neutrophils
Protect against infection by ingesting bacteria and debris
Lymphocytes
3 main types:
T lymphocytes and natural l killer cells: protect against viral infection and can detect/destroy some cancer cells
B lymphocytes: develop into cells that produce antibodies
Monocytes
Ingest dead or damaged cells and defend against infectious organisms
Eosinophils
Kills parasites, destroys cancer cells, and involved in allergic response
Basophils
Participate in allergic response
QT interval
Time for both ventricular depolarization and repolarization. Ranges from 0.20-0.40 seconds, depending on HR.
