-between the lungs and diaphragm
left of the body's midline
-size of a person's fist
connective tissue sac that surrounds the heart and keeps it in place
Pericardium - 2 layers
parietal layer and visceral layer
outer layer of pericardium
-inner layer of pericardium
-attached to the heart wall
Pericardial cavity location
space between parietal and visceral layers of the pericardium
Pericardial cavity contains...
Pericardial Fluid function
lubricant by reducing friction within the pericardium as the heart beats
Cardiac muscle that makes up the heart wall
contraction of the heart
Two superior chambers of the heart
partition between the right and left atria
appendage on the external surface of each atrium
increases atrial volume
Two inferior chambers of the heart
partition between right and left ventricle
Atria wall thickness and function
-transport blood to the nearby ventricles
Ventricles wall thickness and function
-pump blood over a longer distance to organs outside the heart
Right Ventricle pumps blood to...
alveoli of lungs
Left Ventricle pumps blood to...
rest of the organs in the body
Which ventricle is thicker?
Left Ventricle - larger workload
Heart valves purpose
prevent backflow of blood
Heart valves - tissue?
Heart valves open and close due to...
changes in blood pressure that occur in the chambers as the heart contracts and releases
2 major groups of heart valves
-atrioventricular (AV) valves
atrioventricular (AV) valves
separate the atria from the ventricles
2 types of AV valves
4 chambers of the heart
-two superior atria
-two inferior ventricles
Tricuspid valve location
right AV valve
Tricuspid valve - how many cusps (flaps)?
Bicuspid valve - AKA
Bicuspid valve location
left AV valve
Bicuspid valve - how many cusps (flaps)?
Atrioventricular (AV) valves structure
-consists of cusps
-attached by strings of connective tissue (chordae tendineae) to papillary muscles
strings of connective tissue that attach to papillary muscles
ventricular muscle fibers that project out from each ventricle
Atrioventricular (AV) valves function
permit unidirectional flow of blood from the atria into the ventricles
AV valves: Ventricles are relaxed...what is happening?
-the papillary muscle are relaxed and the chordae tendineae are slack
-blood in the atria pushes the AV valve open and moves into the ventricles
AV valves: Ventricles are contracted...what is happening?
-the papillary muscle also contracts and the chordae tendineae are taut
-chordae tendineae pull on the cusps of the AV valves which closes the valves preventing backflow from the ventricles to the atria
Semilunar valves location
located at the junction between the ventricles and the arteries
2 types of semilunar valves
-pulmonary semilunar valve
-aortic semilunar valve
pulmonary semilunar valve location
junction between the right ventricle and the pulmonary trunk
large artery that branches to give rise to the smaller pulmonary arteries
aortic semilunar valve location
junction between the left ventricle and aorta
semilunar valve structure - how many cusps?
3 - half moon shaped
semilunar valve structure - cusps attached to..
inner walls of the pulmonary trunk and aorta and project into the lumen of these arteries
semilunar valve function
permit unidirectional flow from ventricles to pulmonary artery and aorta
Semilunar valves:Ventricles are contracted...what is happening?
blood in ventricles forces semilunar valves to open and move into pulmonary artery/aorta
Semilunar valves: Ventricles are relaxed...what is happening?
any blood that moves back towards the heart fills the pockets of the cups of the semilunar valves...this causes the valves to close which prevents back flow from the pulmonary trunk and aorta
pump that is responsible for the circulation of blood through the blood vessels
Superior Vena Cava
brings deoxygenated blood from blood vessels in the upper region of the body to the right atrium
Inferior Vena Cava
brings deoxygenated blood from the lower region of the body to the right atrium
brings deoxygenated blood from blood vessels in the heart wall to the right atrium
3 veins that bring blood back to the heart
-Superior vena cava
- Inferior vena cava
- Coronary sinus
Pathway of blood (start with veins)
right atrium-tricuspid valve-right ventricle-pulmonary semilunar valve-pulmonary trunk-right/left pulmonary artery-alveoli (blood then becomes oxygenated)-pulmonary veins-left atrium-bicuspid (mitral) valve-left ventricle-aortic semilunar valve-aorta-branches into smaller arteries
2 groups of blood vessels
pulmonary circulation + examples
-blood vessels that transport blood to and from the alveoli of the lungs
-pulmonary arteries and pulmonary veins
systemic circulation + examples
-blood vessels that transport blood to and from the rest of the organs of the body (except alveoli)
-aorta and inferior vena cava
Why does the heart have its own blood vessels?
the heart wall is thick and nutrients cannot diffuse from the blood in the heart to the cardiac muscle
Coronary (cardiac) circulation + examples
-blood vessels that supply the heart
-coronary arteries, cardiac veins, coronary sinus
conduction system of the heart
causes the heart to undergo self-excitation (generate own action potential) followed by coordination contraction
5 parts of the conduction system
-atrioventricular (AV) node
-bundle of His
-bundle branches (right/left)
-sinoatrial (SA) node
sinoatrial (SA) node location
located within the wall of the right atrium between the atrial muscle fibers
atrioventricular (AV) node location
bundle of His...AKA
bundle of His location
bundle branches (right/left) location
Purkinje fibers location
within the walls of the ventricles between the ventricular muscle fibers
Components of conduction system - characteristics
-specialized cardiac muscle fibers that lack actin and myosin and therefore do not contract
Components of conduction system - function
initiating an action potential and then conducting the action potential to one another and to those muscle fibers in the chambers
Mechanisms of conduction system: Start?
SA node generates an action potential
Mechanisms of conduction system: SA node sends action potential...then?
spreads through the atria, causing atrial muscle fibers to contract as a unit (this allows blood to move from atria to ventricle)
Mechanisms of conduction system: as atrial fibers contract...what is happening?
action potential is moving from the atria to the AV node
Mechanisms of conduction system: AV node receives action potential...then?
action potential sequentially proceeds through the bundle of His, the right/left bundle branches, and Purkinje fibers
Mechanisms of conduction system: Purkinje fibers have received action potential...then?
the action potential spread through the ventricles, which causes them to contract and blood moves into the pulmonary trunk/aorta
Which chamber receives action potential first and why?
-this allows the ventricles to fill up with blood before ejecting into the pulmonary/systemic circulations
Functions as a pacemaker?
regulates the SA node (pacemaker)
autonomic nerves that supply the heart
SA node - normal resting conditions
parasympathetic nerves slow down the SA node to where it releases 75 action potentials per minute
Normal heart rate
75 beats per minute
-any site outside the SA node that become the pacemaker of the heart
-heart rate is usually slower
Which node usually takes over if the SA node is not producing action potentials?
-surgical implant (with batteries) underneath the skin with wires running to the atria and/or ventricles
-sends electrical activity to stimulate the heart to contract
Supplies nerves to the heart
both divisions of the autonomic nervous system (ANS) - parasympathetic nervous system and sympathetic nervous system
Vagus (X) nerves
-innervate the SA node of the heart
Parasympathetic nerves release the neurotransmitter...
stimulation of the parasympathetic nerves to the heart has one major effect...
decrease in heart rate
Vagus (X) nerves function
slow down the release of action potentials from the SA node
slow heart rate (falls below 60 bpm)
Bradycardia is caused by...
overactive parasympathetic (Vagal) stimulation of the hear
cardiac accelerator nerves
-innervate SA node and ventricular myocardium
Sympathetic nerves release the neurotransmitter....
stimulation of the sympathetic nerves to the heart has two major effects...
-increased heart rate
-increased ventricular contraction
cardiac accelerator nerves function
speed up the release of action potentials from the SA node
-rapid heart rate (over 100 bpm)
-caused by excessive exercise or stress on the body
adrenal glands release two hormones under sympathetic conditions
-recording of the electrical activity (action potentials) that passes through the heart
-AKA - EKG
used in ECGs by placing on the skin of the limbs or skin of chest
detect the action potentials that pass through the heart as it beats
ECG - 3 waves
-represents atrial depolarization (atria become excited)
-shortly after the atria contract
-represents ventricular depolarization (ventricles become excited)
-shortly after the ventricles contract
-represents ventricular repolarization (revert back to unexcited state)
-shortly after the ventricles relax
SA node is nonfunctional (junctional rhythm)...ECG pattern?
-P waves are absent
-AV node takes over as the pacemaker and set the HR to 40-60 bpm
AV node is partially blocked or damaged (2nd degree heart block)...ECG pattern?
P waves outnumber QRS waves b/c some action potentials are not conducted through the AV node
ventricles contract too quickly and out of sequence (ventricular fibrillation)...ECG pattern?
-distorted QRS waves that are numerous and outnumber the P waves
-defibrillating ventricles do not pump blood well and defibrillation paddles must be used to reset the SA node as the pacemaker
events that occur in the heart with each heartbeat - lubb/dupp
Cardiac cycle - muscle fibers undergo?
3 stages of cardiac cycle
-atrial and ventricular diastole
atrial and ventricular diastole process
-muscle fibers of the atria/ventricles are relaxed - both AV and semilunar valves are closed
-blood flows into atria from the vena cavae/pulmonary veins
-blood then forces the AV valves to open to move into ventricles
Atrial systole process
-SA node generates an action potential which spreads to atrial muscle fibers
-atrial muscle fibers contracts which pushes blood into ventricles
Ventricular systole process
-action potential moves through the AV node, bundle of His, right/left bundle branches, Purkinje fibers and then ventricles
-ventricular muscle fibers contract; AV valves close in response to prevent back flow; close of AV valves causes the first heart sound: "lubb"
-ventricles contract; blood forces semilunar valves to open and move into pulmonary trunk/aorta; semilunar valves close to prevent back flow; close of semilunar valves causes 2nd hear sound: "dupp"
AV valves close - first heart sound?
Semilunar valves close - second heart sound?
amount of blood pumped out of each ventricle of the heart per minute
cardiac output is equal to the product of...
stroke volume (SV) and heart rate (HR)
cardiac output equation
amount of blood ejected from each ventricle with each heart beat
stroke volume - normal ranges
cardiac output - normal ranges
How long does it take the blood to move through the entire circulatory system?
Maximal sympathetic stimulation...cardiac output can increase to...
as much as 25 L
cardiopulmonary resuscitation (CPR)
cardiac compression performed with artificial ventilation of the lungs, however the norm is just doing chest compressions until help arrives
inflammation of the pericardium
-begins suddenly and has no known cause, however sometimes linked to a viral infection
-often mistaken for a heart attack
-last for 1 week and treat with drugs that reduce inflammation
gradual and long lasting inflammation
condition where a high amount of fluid in the pericardium compresses the heartstenosis
narrowing of a heart valve opening that restricts blood flow
failure of a valve to close...AKA
insufficiency or incompetence
scar formation or a congenital defect that causes narrowing of the mitral valve
mitral valve prolapse (MVP)
back flow of blood from the left ventricle into the left atrium
most common valvular disorder
mitral valve prolapse (MVP) - 30% of the population
aortic valve is narrowed
backflow of blood from the aorta into the left ventricle
-damages mitral and aortic valves
-bacterial disease that triggers the bodies antibodies to attack heart valves, etc.
most commonly replaced heart valve
condition of reduced blood flow to the myocardium
-severe pain that accompanies myocardial ischemia
silent myocardial ischemia
ischemic episodes without pain - very dangerous
myocardial infarction (MI)
complete obstruction to blood flow in a coronary artery