A&P: Chapter 18: Cardiovascular System- Heart Anatomy

blood flow through the heart

1. the superior vena cava, inferior vena cava, and coronary sinus receives blood from the body, and heart 2. deoxygenated blood fills the right atrium 3. as the right atrium contracts, the right atrioventricular valve (tricuspid valve) opens and the deoxygenated blood flows into the right ventricle 4. as the right ventricle contracts, the pulmonary semilunar valve opens, and the deoxygenated blood flows into the pulmonary trunk 5. the deoxygenated blood flows from the pulmonary trunk into the lungs to be oxygenated 6. the oxygenated blood returns to the heart via four pulmonary veins 7. to fill the left atrium 8. as the left atrium contracts, the left atrium ventricular valve (bicuspid or Mitral valve) opens, and oxygenated blood fills the left ventricle 9. as the left ventricle contracts, the aortic semilunar valve opens 10. the blood flows into the aorta to be returned to the body and heart

At autopsy, the heart is weighed and compared to normal values. Why?

A heavier than normal heart suggests a heart problem may have contributed to, or caused, the person's death.

small cardiac vein

cardiac vein drains the right inferior margin of the heart into the coronary sinus

Major coronary arteries

left coronary artery-> anterior interventricular artery-> circumflex artery right coronary artery-> right marginal artery

myocardium

muscle layer that contracts

What causes the sound "lub" ?

Atrioventricular valves close

function of blood vessels

BV walls are designed to accomplish a task such as maintain blood pressure (arteries), allow for exchange (capillaries), and return blood to the heart (veins)

what are the great vessels?

superior vena cava, right pulmonary artery, right pulmonary veins, inferior vena cava, aorta, left pulmonary artery, and left pulmonary veins

Too little fluid (dry pericarditis)

too little serous fluid is produced by the cells of serous membrane the beating heart rubs against the inside of the fibrous sac which results in pericardial friction rub and intense, shearing pain deep to the sternum scar tissue forms (adhesions) and can alter the function of the sac and heart

infarction

total blockage, no oxygen will be delivered to the area supplied by the artery and the cardiac cells will perish

cardiac muscle vs. skeletal muscle- supply of ATP

CM: Areobic only (more mitochondria) SM: Aerobic and anaerobic (fewer mitochondria)

cardiac muscle vs. skeletal muscle- tetanus possible

CM: No SM: Yes

cardiac muscle vs. skeletal muscle- pacemaker cells present

CM: Yes SM: No

cardiac muscle vs. skeletal muscle- t-tubules

CM: fewer, wider SM: abundant

cardiac muscle vs. skeletal muscle- sarcoplasmic reticulum

CM: less elaborate; no terminal cisterns SM: elaborate; has terminal cisterns

cardiac muscle vs. skeletal muscle- Source of calcium for contraction

CM: sarcoplasmic reticulum and extracellular fluid SM: sarcoplasmic reticulum only

Cardiac muscle vs. skeletal muscle- structure

CM: striated, short, branched, one or two nuclei per cell SM: striated, long, cylindrical, multinucleate

cardiac muscle vs. skeletal muscle- gap junctions

CM: yes SM: no

cardiac muscle vs. skeletal muscle- calcium binds to troponin

CM: yes SM: yes

cardiac muscle vs. skeletal muscle- contracts as a unit

CM: yes, gap junctions create a functional syncytium SM: No, motor units must be stimulated individually

endocarditis

Inflammation of the endocardium may involve the lining, heart valves, and /or chordae tendineae bacterial or fungal infections spread via the blood, autoimmune disorder, or as a complication of a mechanical heart valve

Apex

Points anteriorly and inferiorly to the left

what causes the sound "dup"?

Semilunar valves close

left ventricle (LV)

a high pressure system that pumps blood to the entire body via the largest artery of the body, the aorta

right ventricle (RV)

a low pressure system that pumps blood to the lungs for gas exchange via the pulmonary trunk/arteries

angina pectoris (choked chest)

a painful condition caused by transitory blood flow to the myocardium, may occur under times of stress (artery spasm) or when oxygen demand increases (sitting vs. walking)

pericarditis

a problem with the heart sac that results in too little fluid (dry pericarditis) or too much fluid (wet pericarditis or pericardial effusion) inflammation can be caused by a microbial infection or post-cardiac surgery. It also occurs with no known cause

ischemia

a restriction in blood supply to tissues, causing a shortage of oxygen and glucose needed for cellular metabolism (to keep tissue alive) due a partial obstruction

myocardial infarction (MI or Heart Attack)

a sudden, complete blockage of an artery, loss of blood flow results in diminsihed oxygen reaching the myocardium, the cells cannot function without oxygen and will die, scar tissue forms and the heart wall is weakened

Atrioventricular (AV) valves- structure

aattached to and supported by the heart's cardiac skeleton, chordae tendineae anchor AV valves to papillary muscles the strings function to prevent the valve leaflets moving back into the atria (everting) during ventricular contraction (systole)

How many gallons of blood are pumped in a lifetime?

about 1 million barrels of blood during an average lifetime- that's enough to fill more than 3 supertankers

How many times does the hear beat per day?

approximately 100,000 times in one day, and 35 million times in a year.

What is the weight of a heart?

approximately 9-12 ounces the size of the hear reflects body size to some degree

anterior interventricular artery

branches off the left coronary artery delivers blood to the interventricular septum and the anterior wall of the ventricles

circumflex artery

branches off the left coronary artery supplies the left atrium and posterior wall of the left ventricle

right marginal artery

branches off the right coronary artery delivers blood to the lateral right side of the heart

posterior interventricular artery

branches off the right coronary artery supplies the heart's apex and posterior ventricular walls

causes of heart valve disorders

can be present at birth (congenital) or appear later (acquired) due to certain infections, high blood pressure, and/or calcifications that occur with aging

coronary sinus

cardiac vein a collection of veins come together to form a large one vessel, the coronary sinus

great cardiac vein

cardiac vein drains the anterior surface of the heart into the coronary sinus

middle cardiac vein

cardiac vein drains the posterior surface of the heart into the coronary sinus

anterior cardiac veins

cardiac vein example of exception to the coronary sinus rule as these veins drain directly into the right atrium

symptoms of cardiac tamponade

chest pressure, cough, and dizziness these symptoms occur because the heart can not expand and contract forcibly which decrease blood flow to the lungs and the rest of the body

Major coronary veins

coronary sinus, great cardiac vein-> middle cardiac vein-> small cardiac vein

serous pericardium

deep to the fibrous pericardium thin, slippery, two-layer serous membrane that forms a closed sac around the heart

coronary circulation- Veins

do not encircle the heart like the coronary arteries when blood leaves the coronary arteries it flows into capillaries where gas exchange occurs, then it flows out of the capillaries and into the veins, the veins then drain into the coronary sinus, and lastly, into the right atrium Note: most, but not all, cardiac veins drain into the coronary sinus

pericardium

double-walled sac that encloses the heart

Circular muscle fiber arrangement

found in the atria myocardium which contracts to force blood into ventricles below

Spiral muscle fiber arrangement

found in the ventricles result in a contraction from apex to base in a wringing-like motion forcing the blood into the great vessels in the upper region of the ventricles (pulmonary trunk and aorta)

function of the heart

generates the pressure needed to propel blood forward continuously into the blood vessels it's a double-sided, 4 chamber muscular pump that functions to simultaneously move blood into the blood vessels of two circulatory pathways

Describe the amount of force that is generated during one hear beat.

give a tennis ball a good, hard squeeze. that's about the same amount of force your heart uses to pump blood out to the body.

incompetent valve

heart valve disorder the valve does not close comletely so blood can move backward (blood flow is no longer one-way) depending on the specific tepye of back flow this condition is not always a bad thing.. many successful competitive runners have aortic valve incompetence

Stenosis

heart valve disorder the valve narrows so blood cannon move across the valve the heart has to work harder to accomplish normal flow, harder work will require additional muscle mass

atrial natriuertic peptide (ANP)

hormone released for the left and right atriums to lower blood pressure and to control electrolyte homeostatsis

myocarditis

inflammation of the myocardium may be caused by a virus or bacteria (untreated strep throat that results in rheumatic fever may weaken the heart's pumping ability

mitral value prolapse (MVP)

is a heart valve discorder, where the leaflets of the valve and/or the chordae tendineae are anatomically different which results in the parachute like leaflets billowing into the atrium above, there may or may not be back flow strong hereditary tendency, although the exact cause is unknown, affected family members are often tall, thin, with long arms and finers, and straight backs most commonly in women from 20-40 years old, but also occurs in men often no symptoms.. symptoms occur when the mitral valve become increasing incompetent

pericardial cavity

located between the parietal and visceral layers, filled with serous fluid function: lubricate the serous membranes to allow heart to work in relatively friction-free environment

location and orientation of the heart

located in the between lungs, covered by sternum and rib cage. The bottom of the heart sits above the diaphragm. the heart is positioned more towards the left side, so the left lung is smaller in size.

aortic semilunar valve

located on the left side within the aorta

Pulmonary semilunar valve

located on the right side within the pulmonary trunk

Cardiac tamponade

meaning: heart plug a condition that resuls when the heart is compressed by fluid within the sac this is a serious condition because compression the heart limits its ability to pump blood if a great deal of serious fluid or blood is in the sac a syringe needle will be inserted into it so the fluid can be withdrawn

fibrous pericardium

most superficial layer of the pericardium made up of dense connective tissue

semilunar (SL) valves

named for their shape and are located within the great vessels just as they leave the heart from the ventricles after blood leaves the heart, ventricular pressure decrease so blood flows backwards (from high pressure in the great vessels to low pressure in the ventricles) when the blood reaches the semilunar valves leaflets, they fill with blood and expand to close off the ventricles

Murmurs

occur when the valve does not coapt together tightly resulting in blood moving backward (regurgitation) or there are physical changes such as narrowing (stenosis) can creat characteristic abnormal sounds that can be described as swishing, crakling, and /or rattling noises and are caused by turbulent flow of blood across the valve

Too much fluid or Pericardial effusion (wet pericarditis)

overproduction of serous fluid resulting from an infection or autoimmune disorder it can also result from a broken blood vessel or tear in the heart wall which results in the release blood into the sac

visceral layer, or epicardium

part of the serous pericardium that lines the heart

parietal layer

part of the serous pericardium that lines the internal surface of the fibrous pericardium

interatrial septum

physically separates the atria from one another

left atrioventricular valve= bicuspid valve= mitral valve

positioned between the left atrium and left ventricle, has 2 flexible cusps

Right atrioventricular valve= Tricuspid valve

positioned between the right atrium and right ventricle, it has 3 flexible cusps.

Base

positioned superiorly, posteriorly and to the right

atrioventricular (AV) valves- function

prevent backflow of blood into the atria when the ventricles contract

function of the fibrous pericardium

protects the heart, anchors it to surrounding structures, and prevents overfilling of the heart with blood

the two coronary arteries- function/location

provides blood to the heart muscle branch off the aorta on the left and right side

right atrium (RA)

receives deoxygenated blood from the systemic circulation via the superior vena cava, inferior vena cava, and coronary sinus

function of the left side of the heart

receives oxygenated blood from the lungs and sends it to the body, including the heart itself

left atrium (LA)

receives oxygenated blood from the pulmonary circulation via the 4 pulmonary veins

function of the right side of heart

receives the oxygen poor blood from the body and pumps it to the lungs to be oxygenated

interventricular septum

separates the left and right ventricles

heart valves

simple mechanical devices that ensure the one-way flow of blood through the heart, function passively and open and close due to pressure differences 2 types: atrioventricular and semilunar

endocardium

squamous epithelium that lines the heart chambers it's important that its smooth because its in direct contact with blood cells. The smooth surface allows the blood cells to flow

characteristics of cardiac muscle fibers

striated and contracts, like skeletal muscle, via the sliding filament mechanism short, fat, and brached fibers has one centrally located nucleus (occasionally, you'll see a fiber with two nuclei) the plasma membrane of adjacent fibers are linked via intercalated discs ( unique to cardiac muscles) -- contacts desmosomes: cell junctions that prevent cells from pulling apart during contractions, and gap junctions: cell junctions that allow movement of ions and other small molecules from one cardiac fiber to the next, allow all the cardiac fibers to contract as a unit rather than individually

systemic circuit

the left side of the heart receives the oxygenated blood returning from the lungs and pumps this blood throughout the body to supply oxygen and nutrients to body tissues

Cardiac muscle fiber arrangement

the myocardium pattern difference reflects pumping properties 2 types: circular and spiral

pulmonary circuit

the right side of the heart that receives oxygen-poor blood from the body tissues and then pumps this blood to the lungs to pick up oxygen and dispels carbon dioxide

why is the wall mass between the left and right ventricles different?

the right ventricle's wall mass is approximately 1/3 that of the left's due to the left ventricle's need to pump against higher pressure found in the aorta

why is the myocardium in the ventricles much thicker than the atria's myocardium?

the ventricles have to pump blood further than the atriums

a person's heart is approximately the size of

their clenched fist

What's the shape of the heart?

tipped over 3 sided pyramid.

coronary circulation- function

to provide nutrients, oxygen, and eliminate waste from the heart muscle the blood contained within the chambers does not provide these things to the heart

What similarities are found in both ventricles?

trabeculae carneae, papillary muscles/Chordae tendineae, and blood outflow tracts. they pump the same volume of blood, and pump at the same time.