Anatomy of Heart & Physiology

apex of heart

lowest part of heart, formed by inferolateral part of L ventricle; projects anteriorly and to L at level of 5th intercostal space and L midclavicular line

base of heart

upper border of heart, involving L and R atria and proximal portions of great vessels; approx below 2nd rib at level of 2nd intercostal space


endothelial tissue lining interior of heart chambers and valves


serous layer of pericardium; contains epicardial coronary arteries and veins, autonomic nerves, and lymphatics


thick contractile middle layer of muscle cells forming bulk of heart wall


double-walled connective tissue sac surrounding outside of heart and great vessels


body's largest artery; conduit of blood from heart to body. Begins at upper part of L ventricle, ascends, arches, and descends

inferior vena cava

vein returning blood from the lower body and viscera to the R atrium

pulmonary arteries

artery that carries deoxygenated blood from R ventricle to the L and R lungs

pulmonary veins

veins carrying oxygenated blood from L and R lungs to L atrium

superior vena cava

vein returning venous blood from head, neck, and arms to R atrium

What is the name of the right AV valve?

tricuspid valve (three leaflets)

What is the name of the left AV valve?

bicuspid or mitral valve (two leaflets)

What is the flow of blood through the heart?

- deoxy blood from superior and inferior vena cava's enters RA- blood goes through tricuspid valve to the RV- RV contracts and blood is pumped through pulmonary valve to pulmonary trunk- blood distributes to L and R pulmonary arteries that serve L and R lungs respectively- blood gets oxygenated in lungs and dumps off CO2 in pulmonary capillaries- oxygenated blood returns via pulmonary veins to LA- LA contracts and blood goes through bicuspid/mitral valve into LV- LV contracts and blood goes through aortic valve to the aorta where it is distributed to coronary and systemic circulation

What is normal ejection fraction and how do you calculate it?

normal: 55-70%stroke volume divided by L ventricular end-diastolic volumeBEST INDICATOR OF CARDIAC FUNCTION

What is the typical lifespan of a RBC?

120 days

What are the coronary arteries?

smaller vessels carrying oxygenated blood to the myocardium; arise from ascending aorta just beyond where it exits from the LV

What are the main branches of the R coronary artery?

- sinus node artery- R marginal artery- posterior descending artery

Where does the sinus node artery supply blood to?

R atrium

Where does the R marginal artery supply blood to?

R ventricle

Where does the posterior descending artery supply blood to?

inferior walls of bilat ventricles; inferior portion of interventricular septum

What are the main branches of the L coronary artery?

- circumflex artery- L anterior descending artery (LAD)

What does the circumflex artery supply blood to?

- L atrium- L ventricle

Where does the L anterior descending artery supply blood to?

- anterior portion of interventricular septum

What veins drain into the coronary sinus?

- great cardiac vein- small cardiac vein- middle cardiac veincoronary sinus empties into R atrium

Where are the thebesian veins located and where do they drain?

- arise in myocardium- drain into all chambers of the heart (primarily R atrium and R ventricle)

What is the cardiac conduction system order?

SA node (normal pacemaker of heart) > internodal tracts > AV node > bundle of His > R/L bundle branches > Purkinje fibersBachmann bundle conducts cardiac impulse preferentially from R > L atrium

What is the sympathetic influence on the heart?

- release of epinephrine and norepinephrine- sympathetic nerves stimulate heart to beat faster (chronotropic effect)- sympathetic nerves stimulate heart to beat with greater force (inotropic effect)

What is the parasympathetic influence on the heart?

- release of acetylcholine from vagus nerve- parasympathetic nerves slow HR (chronotropic effect) via influence on SA node

What is the baroreceptor reflex?

- reflex which maintains BP- consists of arterial baroreceptors (high pressure receptors located @ carotid sinus, aortic arch, origin of subclavian)- consists of cardiopulmonary receptors (low pressure receptors)- sympathetic activation = incr cardiac contractility, incr HR, venoconstriction, arterial vasoconstriction = high BP- parasympathetic activation = decr HR, decr in contractility = low BP

What is defined as the intrinsic strength of a heart contraction?


What is the bainbridge reflex?

- increase in venous return causes stretch of R atrium - causes vagal afferent signals to be sent to the cardiovascular center in medulla- results in increased HR and inhibition of parasympathetic activity(increased HR b/c incr preload present)

What is the chemoreceptor reflex?

- chemosensitive cells in carotid bodies and aortic body respond to changes in pH and blood oxygen tension- if arterial partial oxygen pressure is <50mmHg or there is acidosis, chemoreceptors stimulate respiratory centers which increase depth and rate of ventilation- this reduces HR and contractility

What is the valsalva maneuver?

- forced expiration against a closed glottis- causes increased intrathoracic pressure, increased central venous pressure, decreased venous return- results in decr cardiac output and BP sensed by baroreceptors -> leads to incr HR and contractility- when glottis opens, venous return increases and BP and contractility increase leading to decr in HR


tension in ventricular wall at end of diastole


forces impeding flow of blood out of the heart (primarily pressure in peripheral vasculature, compliance of aorta, mass and viscosity of blood)

stroke volume; what is normal values?

volume of blood ejected by each contraction of the L ventriclenormal = 60-80 ml depending on age, sex, activity

cardiac output; what is normal?

amount of blood pumped from L or R ventricle per minuteCO = SV x HRnormal = 4.5-5.0 L/min for adult male at rest with women producing slightly less (can increase up to 25 L/min during exercise)

venous return

amount of blood returning to R atrium per minutemust equal CO when averaged over time

What is hypovolemia and what are s/s?

- decr blood volume (especially plasma)- s/s: orthostatic hypotension, tachycardia, elevated body temp

What are s/s of hypervolemia?

- swelling in legs, ascites, fluid in lungs

What is plasma?

- liquid component of blood (more than half of total blood volume)- consists of blood vessels and platelets- regulates BP and temp

What are red blood cells?

- make up ~40% of blood volume- contain hemoglobin, protein giving blood red color and allows binding to O2- # of RBCs too low = decr carrying of O2 = anemia = weakness and/or fatigue- # of RBCs too high = polycythemia = blood too thick = incr risk of heart attack or stroke

What are thrombocytes? Too many? Too few?

- platelets- too many = thrombocythemia = incr risk for stroke or heart attack- too few = thrombocytopenia = incr risk for bruising or bleeding

What are leukocytes? Too many? Too few?

- WBCs- too many = leukocytosis = infection or leukemia- too few = leukopenia = increased risk for infection

What are the 5 main types of WBCs?

- neutrophils- basophils- eosinophils- lymphocytes- monocytes

WBC type: protect body against infection by ingesting bacteria and debris


WBC type: 3 main types (T, natural killer, B) that can protect against viral infections, destroy some cancer cells, and produce antibodies


WBC type: ingest dead or damaged cells and help defend against infectious organisms


WBC type: kill parasites, destroy cancer cells, involved in allergic responses


WBC type: participate in allergic responses


T4 articulates with which ribs

ribs 4 and 5

What are the principal muscles of inspiration?

diaphragm and external intercostals

What is in the upper respiratory tract?

nasal cavity, pharynx, larynxpurpose for gas conduit, humidify/cool/or warm inspired air, and filter foreign matter before it can reach alveoli

What is the lower respiratory tract?

from larynx to alveoli in lungs

Trachea divides into R and L main bronchi at what structure?

carina (at level of T4 and sternal angle)

How many lobes in each lung? Where is the lingula?

R lung = 3 lobes (upper, middle, lower)L lung = 2 lobes (upper and lower)lingula = L upper lobe = analogous to R middle lobe

Parasympathetic innervation of the smooth muscles of the lungs, bronchi, and pulmonary blood vessels is via what nerve?

vagus n

What do chemoreceptors in the medulla respond to?

increased in partial pressure of CO2 and hydrogen ion by increasing ventilation

What do peripheral chemoreceptors in the carotid bodies respond to?

changes in partial pressure of CO2, hydrogen ion concentration, hypoxemia by increasing ventilation

How many mL of O2 is dissolved in 100 mL of arterial blood?

0.3 mL O2