Anatomy Cardiovascular, Respiratory, and Urinary Systems

Functions of the heart

generate blood pressure

route blood

ensure one way blood flow

regulate blood supply

location of the heart

mediastinum

in middle of chest

shape of the heart

an inverted cone

apex of the heart

blunted rounded point of cone

at the bottom of the heart

tilted to the left

base of heart

flat part at opposite end of cone

at top of heart

size of the heart

size of a closed fist

function of the pericardium

anchors the heart

prevents overdistension

reduces friction

makes up the pericardium

fibrous pericardium

serous pericardium

makes up the serous pericardium

parietal pericardium

visceral pericardium

makes up heart wall

epicardium

myocardium

endocardium

epicardium

the visceral pericardium

provides smooth outer-surface for heart

most superficial heart wall layer

myocardium

composed of cardiac muscle cell

responsible for heart contracting

middle layer of heart wall

endocardium

provides smooth inner surface

deepest layer of heart wall

pectinate muscles

muscular ridges in auricles and right atrial wall

increases surface area of myocardium

trabeculae carneae

muscular ridges and columns on inside walls of ventricles

increases efficiency of myocardium

right atrium

superior to right ventricle

receives deoxygenated blood from, superior vena cava, inferior vena cava, coronary sinus

left atrium

superior to left ventricle

receives oxygenated blood from pulmonary veins

right ventricle

inferior to right atrium

sends deoxygenated blood through pulmonary trunk/arteries

left ventricle

inferior to left atrium

sends oxygenated blood through aorta

interatrial septum

wall between the atria

interventricular septum

wall between the ventricles

papillary muscles and chordae tendineae

work together to control the valves

atrioventricular valves

between the atria and ventricles

prevents backflow into atria when ventricles contract

chordae tendineae attach cusps to papillary muscles

tricuspid valves

an AV valve

separates right atrium and right ventricle

3 cusps

bicuspid valve

aka mitral valve

an AV valve

separates left atrium and left ventricle

2 cusps

semilunar valves

separate ventricles and major arteries

prevents backflow from major arteries back into ventricles

pulmonary semilunar valves

separates the right ventricle and pulmonary artery

aortic semilunar valve

separates the left ventricle and aorta

atria

receiving chambers

superior to ventricles

ventricles

sending chambers

inferior to atria

what sits in the coronary sulcus

great cardiac vein

what sits in the anterior interventricular sulcus

anterior interventricular artery

great cardiac vein

what sits in the posterior interventricular sulcus

posterior interventricular artery

middle cardiac vein

blood flow through the heart

superior & inferior vena cava, coronary sinus → right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary trunk → pulmonary arteries → lungs → pulmonary veins → left atrium → bicuspid valve → left ventricle → aortic valve → aorta → body/coronary arteries → superior & inferior vena cava, coronary sinus

blood flow through coronary circulation

right and left coronary artery → interventricular arteries → marginal arteries → circumflex arteries → great, small, and middle cardiac veins → coronary sinus

mean arterial pressure (MAP)

average pressure in arteries during a complete cardiac cycle

mean arterial pressure equation

CO x TPR

cardiac output (CO)

the amount of blood leaving the heart per minute

Cardiac output equation

HR x SV

stroke volume (SV)

volume of blood leaving the heart per beat

stroke volume equation

EDV - ESV

end diastolic volume (EDV)

amount of blood in the ventricle before contraction

end systolic volume (ESV)

amount of blood in the ventricle after contraction

total peripheral resistance (TPR)

resistance in the blood vessels

Structural characteristics of cardiac muscle cells

striated

elongated, branched

actin & myosin

sarcoplasmic reticulum

intercalated disks

functional characteristics of cardiac muscle cell

wringing contraction

each cell produces its own AP

depolarization from Ca2+

autorythmic

involuntary control

similarities between skeletal and cardiac muscles

striated, actin & myosin, sarcoplasmic reticulum, resting membrane potential, repolarization from outflow of K+

difference between cardiac muscle and skeletal muscle

cardiac muscle:

branched and elongated, intercalated disks, longer and prolonged onset of contraction, depolarization from Ca2+

AP production in cardiac muscle

depolarization, early-repolarization, plateau, final repolarization

causes depolarization in cardiac cells

opening of voltage gated Na+ and Ca2+ channels, closing of voltage gated K+ channels

causes early repolarization phase

voltage gated Na+ and some Ca2+ channels close, small number of voltage gated K+ channels open

causes plateau phase

voltage gated Ca2+ channels remain open - Ca2+ and some Na+ move into cell, this cancels out the K+ moving out of the cell

causes final repolarization phase

voltage gated Ca2+ channels close, lots more voltage gated K+ channels open

importance of the refractory period

it ensures that contraction and most of relaxation is complete before another AP can be initiated.

responsible for the rhythmic contractions and prevents tetanic contraction

autorhythmicity

the ability to stimulate itself and contract at regular intervals

How the SA node is a pacemaker

pacemaker cells in the SA node depolarize, causing an AP in the SA node. These AP’s spread through the conducting system of the heart to other cardiac muscle cells

conducting system of the heart

SA node → AV node → AV bundle (bundle of His) → R. & L. bundle branches → purkinje fibers

P wave

first wave in ekg

represents atrial depolarization

QRS complex

the big wave

represents ventricular depolarization

T wave

last wave

represents ventricular repolarization

cardiac cycle

one beat

contraction to contraction

systole

heart contracting

diastole

heart relaxed

makes the 1st heart sound

the AV valves closing

makes the 2nd heart sound

the semilunar valves closing

aortic pressure

the pressure within the aorta

when the 1st heart sound happens

at the beginning of ventricular systole

when the 2nd heart sound happens

at the beginning of ventricular diastole

things affecting MAP

changes in CO (changes in HR or SV) or PR

phases of the cardiac cycle

atrial systole: active ventricular filling

ventricular systole: period of isovolumetric contraction

ventricular systole: period of ejection

ventricular diastole: period of isometric relaxation

heart relaxed: passive ventricular filling

active ventricular filling

actively forces blood into the ventricles

begins with depolarization of SA node

chambers during active ventricular filling

atria contract, ventricles fill

valves during active ventricular filling

SV valves closed, AV valves opened

pressure during active ventricular filling

pressure in atria higher than ventricles

phase of ekg during active ventricular filling

p wave

heart sound during active ventricular filling

no heart sound

period of isovolumetric contraction

starts at the completion of atrial contraction

action potential travels to AV node and down to purkinje fibers

no blood flows from the ventricles during contraction

chambers during period of isovolumetric contraction

ventricles start to contract, atria relax

valves during period of isovolumetric contraction

AV valves close, semilunar valves remain closed

pressure during period of isovolumetric contraction

pressure in ventricles higher than atria but lower than pulmonary trunk and aorta

phase of ekg during period of isovolumetric contraction

QRS complex

heart sound during the period of isovolumetric contraction

the 1st heart sound

period of ejection

ventricular contraction continues

blood flows to pulmonary trunk or aorta

chambers during period of ejection

ventricles have contracted

valves during period of ejection

semilunar valves open, AV valves remain closed

pressure during period of ejection

pressure in ventricles overcome pressure in aorta and pulmonary trunk

phase of ekg during period of ejection

the ST interval

heart sounds during period of ejection

no heart sounds

period of isovolumetric relaxation

ventricular repolarization

blood begins to flow back to ventricles

chambers during period of isovolumetric relaxation

ventricles relax, atria relaxed

valves during period of isovolumetric relaxation

semilunar valves close, AV valves remain closed

pressure during period of isovolumetric relaxation

ventricular pressure falls below pressure in aorta and pulmonary trunk

phase of ekg during period of isovolumetric relaxation

end of t wave

heart sound during period of isovolumetric relaxation

the second heart sound

passive ventricular filling

blood passively moving into ventricles

accounts for most of ventricular filling

chambers during passive ventricular filling

ventricles and atria relaxed

valves during passive ventricular filling

AV valves open, semilunar valves remain closed

pressure during passive ventricular filling

ventricular pressure falls below atrial pressure

phase of ekg during passive ventricular filling

TP interval

heart sound during passive ventricular filling

possible third heart sound