Cardiovascular System Pennix

How much does the heart weigh?

250-350 g

How much blood does the heart pump and beat daily?

700L and beats over 100,000 times daily

Location of heart

Between lungs, part of mediastinum, and 2/3 of mass lies left of midline

Apex

tip of left ventricle and points slightly anteriorly

Diaphragmatic surface

formed mostly by left ventricle and main muscle for respiration

Pericardium

covering that surrounds the heart

Fibrous Pericardium

resembles a bag that sits on the diaphragm and provides tough protection/anchors heart in mediastinum

Serous Pericardium

thinner and delicate layers (2)

Parietal Layer (Serous Pericardium)

Attached to fibrous pericardium

Visceral Layer (serous pericardium)

attached to myocardium

Myocardium function

generates and circulates blood throughout the body

Endocardium

barrier between blood and myocardium

Endocardium

thin layer of epithelial tissue that is continuous

2 Chambers of the heart are?

Atria and Ventricles

Atria

receives blood, each atria has an auricle and separated by interatrial septum.

Left atrium gathers blood from?

lungs

Right atrium gathers blood from?

rest of body

Ventricles

pump blood, has interventricular septum and has sulci

Sulci

separates chambers of heart

Coronary Sulcus

separates atria from ventricles and stores fat/blood vessels

Blood flows from what pressure?

high to low

Coronary Sinus

drains blood from myocardium

Sequence for blood flow

Vena cava, right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary artery, lungs, pulmonary veins, left atrium, mitral valve, left ventricle, aortic valve, and body

Valves

keep blood from going backwards

How many atrioventricular valves are there?

2: Tricuspid Valve and Mitral Valve

Tricuspid Valve

Has 3 cusps, right side, assists in blood flow to the lungs, and uses chordeae tendinae to prevent backflow, manages deoxygenated blood flow, open during diastole to fill ventricles

Mitral Valve

2 cusps, left side, manages oxygenated blood from the lungs, uses chordae tendineae to prevent backflow, open during diastole to fill ventricles

Chordae tendineae

fibrous cord connects cusps to papillary muscles in the mitral valve

Papillary Muscles

located by the mitral valve and anchors tendineae to ventricle walls

How many semilunar valves are there?

2 valves (Pulmonary and Aortic valves)

Semilunar Valves

prevent back flow of blood, arteries that leave the heart have these

Blood supply of myocardium

left and right coronary arteries from the ascending aorta (1st branch)

Carotid and Vertebral Arteries

2 different arteries supplying area with blood flow, throughout the body, and provides collateral circulation for blood to reach an organ

Angina Pectoris

reduced oxygen supply weakens cardiac cells

Symptoms of Angina Pectoris

tightness and choking sensation for short periods

Cause of Angina Pectoris

stress, hypertension, and exertion

Myocardial infarction

heart attack, myocardial tissue behind the blocked arteries die and the dead tissue may disturb conduction system of heart which can lead to sudden death

Infarction

tissue death from lack of blood supply

Sinoatrial node (SA)

right atrial wall and inferior to opening of vena cava, impulse travels over atria which stims av node, natural pacemaker

Atrioventricular (AV) node

The inferior portion of the interatrial septum, is the electrical gatekeeper between the atria and ventricles, and sends signal through bundle

AV bundle (bundle of his)

has two bundles and transmits electrical impulses from AV node to the ventricles to coordinate heart contraction

Purkinje Fibers

pass from bundle branches into myocardium and stims the contraction of ventricles

EKG

records electricity changes that happen in a heart cycle

P Wave

Atrial depolarization and a fraction of a second after atria contraction, small first spike

Q wave

small first downward spike, ventricle depolarization

R Wave

Big spike up, ventricle depolarization

S Wave

large downward spike, ventricle depolarization

T Wave

ventricular repolarization

QRS Wave hides what?

atrial repolarization

physiology of cardiac cycle

2 atria contract while 2 ventricles relax. opp is true

Systole

phase of contraction, top number

diastole

phase of relaxation, bottom number

Cardiac cycle

complete heartbeat, consists of systole, diastole of atria and ventricles

Atria Systole

continuous blood flow into right atrium, pulmonary veins bring blood into left atrium, SA node triggers atrial contraction, and increased atrial pressure forces AV valves to open

Ventricular Filling

ventricles fill with blood

Ventricular Systole

increased pressure slams AV valves shut (1st sound lubb+longer of 2 sounds), pressure builds until ventricular pressure exceeds atrial pressure, and semilunar valves open and blood leaves via arteries

Ventricular Diastole

arterial pressure stays high and forces blood back to heart and semilunar valves close (2nd sound, quieter)

heart murmur

any condition that causes unusual sounds to be heard and caused by turbulent blood flow

Mitral and Aortic stenosis

narrowing of valves by scar formation or congenital defect

Mitral and aortic insufficiencies

backflow of blood because the cusp doesn’t close properly

Mitral Valve Prolapse (MVP)

inherited, mitral valve is pushed back too far during contraction, asymptomatic

elastic conducting arteries

large diameters/thin walls, tunica media has more elastic fibers and less smooth muscle

muscular distributing arteries

distribute blood to rest of body, more smooth muscle in tunica media, regulates blood needs of structures they serve

capillaries

permit exchange of nutrients and waste, walls are 1 epithelial layer thick, diameter is 1 RBC, higher the tissues activity the more capillaries

Veins

tunica interna and media are thinner, externa thicker, some contain valves to prevent backflow of blood, named correspondingly to arteries

Varicose veins

weak valves, allows gravity to force blood in distal part of vein, pressure stretches vein and causes loss of elasticity

shock

failure of cardiovascular system to deliver adequate nutrients

Blood Flow is determined by?

Blood Pressure and Resistance

Blood Pressure

pressure on artery wall due to left ventricle contraction

Resistance

Friction in a liquid

B.V Length

longer vessel means higher resistance

B.V. Radius

bigger radius means less resistance

Cardiac Output

volume is ejected by left ventricle into aorta each minute and is the main factor in B.P

Blood Volume

5 L, directly proportional to blood pressure

Peripheral Resistance

arterioles vasoconstriction/vasodilation controls this

capillary exchange

slowest to aid in exchange of nutrients and gases, depends on concentration differences of surrounding tissues

Aid in venous return

velocity of blood, skeletal muscle and valves in veins, and breathing

venous milking

muscle contraction and squeezes blood up, valves prevent backflow

Breathing

decreased pressure in thoracic cavity

capillary

smallest and most abundant blood vessel