Chapter 20: The Cardiovascular System Flashcards
what does the heart lie between?
between the lungs and the mediastinum (space between the thoracic cavity)
what makes up the mediastinum?
heart, thymus gland, aorta, superior vena cava, inferior vena cava, pulmonary trunk
what does the pericardium do and what are its parts?
holds the heart in place
consists of outer fibrous pericardium and inner serous pericardium (epicardium)
parts of the serous pericardium
parietal layer
visceral layer
where is the paricardial cavity found? what does it house?
between the visceral and parietal layers of the serous pericardium
filled with pericardial fluid which reduces friction
what is pericarditis?
inflammation of the pericardium
what are the 3 layers of the heart wall?
epicardium, myocardium, endocardium
what is myocardium made of?
muscular wall; cardiac tissue
what is endocardium made of?
simple squamous epithelium
areolar CT covers valves and lines chambers
what is myocarditis?
inflammation of the heart muscle (myocardium)
what is endocarditis?
inflammation of the endocardium which involves the heart valves
what are the chambers of the heart?
2 upper atria (thin walls)
2 lower ventricles (thick wall)
*thickness of chamber depends on muscle
what’s on the external surface of the heart and their structure?
auricles: small extensions of atriums
sulci: grooves containing blood vessels and fat
function of the right atrium
recieves deoxygenated blood from 3 major blood vessels
- superior vena cava
- inferior vena cava
- coronary sinus
what is the fossa ovalis (right atrium)?
remnant of the foramen ovale
structure of pectinate muscles
raised ridges of the myocardium in the walls of the right atrium
how does blood enter the tricuspid valve (atrioventricular valve)
blood passes from the right atrium into the right ventricle through this valve
what does the right ventricle form?
forms most of the anterior surface of the heart
function and structure of the trabeculae carne
raised ridges of myocardium located in the walls of the ventricle
part of the hearts conduction system
function of the pulmonary semilunar valve
valve through which blood is pumped from right ventricles into the pulmonary trunk
structure of the moderator band of muscles
stretches across the lumen of the right ventricle and attaches to the interventricular septum
what does the left atrium do?
recieves oxygenated blood from 4 veins
how does blood pass through the mitral/bicuspid valve (atrioventricular valve?
valve through which blood passes from the left atrium to the left ventricle
structure of pectinate muscles
raised ridges of myocardium located in the walls of the left atrium
what does the left ventricle form?
the apex of the heart
structure of trebeculae carne
raised ridges of myocardium located in the walls of the left ventricle
how does blood pass through the aortic semilunar valve?
valve through which blood is pumped from the left ventricle into the aorta
how does blood pass through ductus anteriosus
shunts blood from the puplmonary trunk into the aorta
what controls the thickness of the chambers in the mycardium ?
the function of each chamber
why are the wall of the right ventricle thinner than the left ventricle?
they pump blood into the lungs (pulmonary circulation)
why are the walls of the left ventricle thickest?
they pump blood to the body (systemic circulation)
what causes the valves to open/close?
pressure changes as the heart contracts and relaxes
what do the 2 atrioventricular valves do?
prevent back flow from the ventricles to the atria by contracting papillary muscles that tighten chordae tendinae
what are chordae tendinae
anchor cusps of the papillary muscle valves that keep valves closed
when do atrioventricular valves open?
when pressure in the atria exceeds the pressure in the ventricles
what do the 2 semilunar valves do?
prevent backflow from major arteries in heart to ventricles
when do semilunar valves open?
when pressure in the ventricles exceeds the pressure in the major arteries
what is stenosis?
narrowing of the a valve which restricts blood flow since the valve cant open completely
what is insufficiency or incompetence of a valve?
failure of valve to close completely which causes heart murmers (backflow of blood through valve that doesnt close)
what is mitral valve prolapse?
bulging of leaflets of the mitral valve into the left atrium during ventricular systole
symptoms: fatigue, dizzy, palpitation, dystinia, chest pain
what is a heart murmur?
abnormal sound caused by backflow through valve that is partially closed
left side of heart pumps ___
right side of heart pumps ___
systemic circulation
pulmonary circulation
what is coronary circulation?
flow of blood the vessels that go through the myocardium
what is the key vein in coronary circulation?
coronary sinus
structure of cardiac muscle fibers
elongate branching cells with a large nucleus
irregular contouored fibers at junctions
connected by intercalcated discs (gap junctions and desmosomes)
how do cardiac muscles compare to skeletal muscles?
they have the same arrangement of actin & myosin and the same bands, zones and Z discs
how are heart cells (cardiocytes) replaced?
stem cells in blood migrate to heart then differentiate
what do autorhythmic cells capable of?
generating their own electrical activity
why are cardiac muscle cells autorhythmic?
they are self-excitable and act as pacemaker to set rhythm
they form the conduction system that is the route for action potentials to go through the heart
Has but doesnt NEED nerve supply
what are the 5 structures of the conduction system?
- sinotrial node (right atrium)
- atrioventriculaar node (right atrium)
- atrioventricular bundle (interventricular septum)
- R&L bundle branches (interventricular septum)
- conduction myofibers (ventricular myocardium)
what does stimulation from the ANS by way of the cardiac acceleration/inhibitory center do?
modifies the heartbeat for rate and strength of contraction
what system is stimulated by the cardiac accelerator center?
sympathetic (increase heart rate)
what system is stimulated by the cardiac inhibitory center?
parasympathetic (decrease heart rate)
what is tachycardia?
a resting heart rate over 100
what is bradycardia?
resting heart rate under 60
what fixes abnormal heart rhythm?
pacemaker
what actions make up the cardiac cycle?
systole (contraction) and diastole (relaxation) of both atria followed by systole and diastole of ventricles
how does the cardiac cycle force blood
high pressure to low pressure
what are the phases of the cardiac cycle?
diastasis, atrial systole, ventricular systole, ventricular diastole
what are the steps of diastasis?
- atrial systole during ventricular diastole forces blood into ventricles
- atria diastoles as ventricular systole begins which ejects blood from ventricle into pulmonary trunk and ascending aorta
- during diastole, the atria fills with blood and then the ventricles begin diastole
- causing both atria and ventricles to be diastoled (diastesis)
what does diastesis force the AV valves to do?
open
ventricular systole causes
ventricles to contract and increase pressure that forces AV valves to close which is the 1st heart sound
ventricular diastole causes
ventricles to relax
as pressure in ventricles decrease the SL valves close which is 2nd heart sound
what is auscultation?
listening to body sounds with stethescope
what is the 3rd heart sound?
vibration of ventricular walls as blood rushes into ventricles
what is the 4th heart sound?
contraction of the atrial pectinate muscles in the wall of the atrium
muscles ensure all blood drains
why is electrical activity detected at the surface of the body?
electricity travels from nodes through the myocardium
muscle membranes depolarize/repolarize
electrical current spreads to tissues surrounding heart where it can be detected
what does EKG do?
determines if conduction pathway is abnormal, if heart is enlarged, damaged, measures amount, direction, and speed of electrical movement
what must occure before the heart muscle contracts?
depolarization
what types of waves/complex does the EKG measure?
P wave: atrial depolarization (SA node)
T wave: ventricular repolarization
QRS complex: ventricular depolarization (SA node)
what is fibrilation?
electrical activity becomes becomes chaotic and coordinated systole ends as multiple foci in the atria fire
what are atrial fibrilation?
when AV node stimulated by random activity in atria (non fatal)
what are ventricular fibrilation?
when ventricles fail (fatal)
why must a hearts ability to dischaarge oxygen-carrying blood be variable?
because body cells need specific amounts of blood each minute to maintain health
what is cardiac output?
volume of blood pumped from ventricles into the aorta/pulmonary trunk each minute
what is diastolic volume?
200 mls of blood
how do the right and left ventricles compare ?
how do pulmonary and systemic circulations compare?
r&l: they pump the same amount of blood per minute
p&s: they pump the same volume of blood per minute
what is the stroke volume?
volume of blood ejected by the ventricles with each contraction
what is heart rate?
of beats per minute
how do you find cardiac output?
stroke volume x heart rate
approx 5 liters of blood per min goes through cardiovascuar system
what is the residual volume?
amount of blood remaining in the ventricles after systole (130 ml)
sympathetic stimulation causes what 5 events?
- stimulation of SA node & tachycardia
- increased speed of electrical conduction
- increase force of systole and greater stroke volume
- decrease length of refractory period
location: cardiovascular center of medulla
parasympathetic stimulation causes what 5 events?
- inhibits stimulation of SA node and stimulate bradycardia
- decrease speed of electrical conduction
- decrease force of systole
- increase length of refractory period
- decrease size of cardiac output
location: cranial nerve 10
what are fetal lungs incapable of?
dont oxygenate fetal blood, no pulmonary circulation
structure of foramen ovale
becomes fossa ovalis and limbus of the fossa ovalis 1 year after birth
structure of ligamentum arteriosum
ductus arteriosus interconnects the pulmonary artery with the aorta, degenerates into a fibrous ligament called the ligamentum arteriosum after birth
what is angina pectoris?
temporary chest pain that occurs when heart isnt recieveing enough oxygen
caused by narrowing arteries, ischemia