Exam 2: Chap 20 Flashcards
what does the cardiovascular system consist of?
blood, heart, blood vessels
heart
a double pump that circulates the blood through an estimated 100,000 miles of blood vessels
where is the heart situated?
between the lungs in the mediastinum (space within the thoracic cavity)
mediastinum includes what
includes: heart, thymus gland, aorta, superior vena cava, inferior vena cava, and pulmonary trunk
pericardium
encloses and holds the heart in place; consists of an outer fibrous pericardium, and an inner serous pericardium (epicardium)
serous pericardium
composed of a parietal layer and a visceral layer
pericardial cavity
between the parietal and visceral layers of the serous pericardium; potential space filled with pericardial fluid - reduces friction
pericardial fluid
reduces friction
pericarditis
inflammation of the pericardium
3 layers of the heart wall
epicardium, myocardium, endocardium
myocardium
muscular wall; cardiac tissue
endocardium
composed of simple squamous epithelium; areolar CT; covers valves and lines chambers
myocarditis
inflammation of the heart muscle (myocardium)
endocarditis
an inflammation of the endocardium and usually involves the heart valves
chambers of the heart
2 upper atria
2 lower ventricles (thicker wall)
*thickness of chamber depends on muscle
what is on the external surface of the heart?
auricles and sulci
auricles
small extensions of each atrium
sulci
grooves that contain blood vessels and fat
right atrium receives what
receives deoxygenated blood from 4 major blood vessels:
- superior vena cava
- inferior vena cava
- coronary sinus
- anterior cardiac veins
fossa ovalis (right atrium)
the remnant of the foramen ovale
pectinate muscles
raised ridges of the myocardium in the walls of the left and right atrium
tricuspid valve (atrioventricular valve)
blood passes from the right atrium into the right ventricle through this valve.
right ventricle forms what part of the heart
forms most of the anterior surface of the heart
trabeculae carnae
raised ridges of myocardium located in the walls of the left and right ventricle
function: part of the heart’s conduction system
pulmonary semilunar valve
valve through which blood is pumped from the right ventricles into the pulmonary trunk
moderator band of muscle
stretches across the lumen of the right ventricle and attaches to the interventricular septum
left atrium receives what
receives oxygenated blood from four veins
mitral / bicuspid valve (atrioventricular valve)
valve through which blood passes from the left atrium to the left ventricle
left ventricle forms what part of the heart
forms the apex of the heart
aortic semilunar valve
valve through which blood is pumped from the left ventricle into the aorta.
ductus arteriosus
shunts blood from the pulmonary trunk into the aorta
what does the thickness of the myocardium of each chamber vary according to?
the function of each chamber
are atrial walls thicker or thinner than ventricle walls?
thinner.
why are the walls of the right ventricle thinner than the left ventricle?
they pump blood into the lungs (pulmonary circulation)
why are the walls of the left ventricles thickest?
they pump blood into the systemic circulation
what do valves open close in response to?
pressure changes as the heart contracts and relaxes
what to the 2 atrioventricular valves do?
prevent blood flow from the ventricles back to the atria
what is back flow prevented by?
the contraction of cone like papillary muscles that tighten fibrous cords called chordae tendineae
chordae tendineae
anchor cusps of the valve to the papillary muscles; DO NOT open valves … keeps valves closed
when do atrioventricular valves open?
when pressure in the atria exceeds the pressure in the ventricles
what do the 2 semilunar valves prevent?
blood flow from the major arteries of the heart back into the ventricles
when do semilunar valves open?
when pressure in the ventricles exceeds the pressures in the major arteries
stenosis
a narrowing of a heart valve which restricts blood flow because the valve cannot completely open
insufficiency or incompetence
a failure of a valve to close completely; causes heart murmurs - back flow of blood through a valve that doesn’t completely close.
mitral valve prolapse
a bulging of one or both leaflets of the mitral valve into the left atrium during ventricular systole: need an EKG. doesn’t cause a problem, can grow out of it, more common in women.
NO: coffee, chocolate, soda, nicotine, or nasal spray
symptoms: fatigue, dizziness, palpitation, dyspnea, non-cardiac related chest pain
heart murmur
an abnormal sound that is caused by the turbulent backward flow of blood through a valve that is only partially closed. not all murmurs are abnormal or symptomatic, but most indicate a valve disorder
the left side of the heart is the pump for _________
systemic circulation
the right side of the heart is the pump for the ____
pulmonary circulation
coronary (cardiac) circulation
the flow of blood through the many vessels that traverse through the myocardium of the heart
principal arteries in the coronary circulation
right and left coronary arteries
principal vein in the coronary circulation
coronary sinus
cardiac muscle fibers
elongated, branching cells, with a single, large and centrally located nucleus; their fibers have irregular contours at their junctions and are connected by intercalated discs (gap junctions and desmosomes)
cardiac muscles have the ____ arrangement of actin and myosin, and the same bands, zones, and Z discs as skeletal muscles
same
replacement of heart cells (cardiomyocytes)
stem cells in the blood can migrate to the heart and differentiate
autorhythmic cells
generate their own electrical activity
why are cardiac muscle cells autorhythmic?
they are self-excitable; act as a pacemaker to set the rhythm for the entire heart; form the conduction system which is the route for propagating action potentials through the heart muscle.
DOES NOT need a nerve supply to beat (but it still has one)
components of the conduction system
1.sinoatrial node (right atrium)
- atrioventricular node (right atrium)
- atrioventricular bundle [bundle of His] (interventricular septum)
- R&L bundle branches (interventricular septum)
- conduction myofibers [Purkinje fibers] (ventricular myocardium)
what will stimulation from the autonomic nervous system by way of the cardiac acceleration center or cardiac inhibitory center do?
modify the heartbeat in terms of rate and strength of contraction
cardiac accelerator center
sympathetic (increase heart rate)
cardiac inhibitory center
parasympathetic (decreases heart rate)
tachycardia
resting heart rate over 100
bradycardia
resting heart rate less than 60
what can be done to fix an abnormal heart rhythm?
insert a pacemaker.
cardiac cycle
consists of the systole (contraction) and diastole (relaxation) of both atria, rapidly followed by the systole and diastole of both ventricles
systole
contraction
diastole
relaxation
during a cardiac cycle, which way is blood forced?
high pressure to low pressure
phases of the cardiac cycle
diastasis, atrial systole, ventricular systole, and ventricular diastole.
diastasis
atrial systole begins during ventricular diastole and forces blood into the ventricles. atria start diastole as ventricular systole begins. During ventricular systole, blood is ejected from ventricles into pulmonary trunk and ascending aorta. The atria (diastole) begin to fill with blood. The ventricles now enter diastole; for a very short time, both atria and ventricles are in diastole (diastasis).
diastasis forces the AV valves to _____
open
atrial systole
the atria contract and force blood into the ventricles stretching the ventricular walls
ventricular systole
the ventricles contract and increased pressure forces the AV valves to close. this closure of AV produces the first heart sound.
ventricular diastole
the ventricles are relaxed and commence diastole; as the pressure in the ventricles decrease the SL valves close. (2nd heart sound)
auscultation
the act of listening to sounds within the body with a stethoscope
where does the sound of a heartbeat come from?
primarily, the turbulence in blood flow caused by the closure of the valves, not from the contraction of the heart muscle.
first heart sound
lub; created by the closure of the AV valves
second heart sound
dub; represents the closure of the SL valves
third heart sound
inaudible with stethoscope; caused by the vibration of the ventricular walls as blood rushes into ventricles.
fourth heart sound
inaudible with stethoscope; caused by the contraction of the atrial pectinate muscles in the wall of atrium; muscles ensure all blood drains from atrium
why is electrical activity detected at the surface of the body?
as electrical activity sweeps from the nodes through the myocardium, muscle membranes depolarize and re-polarize and electrical current spread into the tissues surrounding the heart and can be detected.
Electrocardiogram (EKG or ECG)
helps to determine if the conduction pathway is abnormal, if the heart is enlarged, and if certain regions of the heart are damaged. measures amount, direction, and speed of electrical movement through the heart. Therefore, waves of depolarization and repolarization sweep through the heart. before the heart muscle contracts, depolarization must occur
EKG waves/complex
P wave, T wave, QRS complex
P wave
represents atrial depolarization by firing of SA node (right and left atrium)
QRS complex
ventricular depolarization by firing of SA nose. spreads through bundle of His, Purkinje fibers, and ventricular muscle. BEFORE ventricular systole.
T wave
ventricular repolarization
fibrillation
electrical activity becomes chaotic and coordinated systole ends as multiple foci in the atria fire.
atrial fibrillation
dangerous but not fatal; the AV node is stimulated by random activity in the atria
ventricular fibrillation
rapidly fatal; the ventricles have failed.
the heart’s ability to discharge oxygen-carrying blood must be _____. why?
variable. because body cells need specific amounts of blood each minute to maintain health and life.
cardiac output
the volume of blood pumped from the left ventricle (or right ventricle) into the aorta (or pulmonary trunk) each minute.
diastolic volume
200 mls of blood
right and left ventricles each pump _____ amount of blood per min and _____ volume of blood is pumped through the pulmonary and systemic circulations each min
same. same.
stroke volume
the volume of blood ejected by the ventricles with each contraction.
heart rate
number of beats per minute
cardiac output equation
stroke volume (mL/min) X heart rate (beats/min)
about 5 liters of blood per min goes through cardiovascular system.
what happens to cardiac output during exercise/stress?
considerably increased.
can go from 5ml/min to either 15/20ml or 35-40ml in a trained athlete.
residual volume
the amount of blood remaining in the ventricles after systole (130mL).
increase in heart rate and/or stroke volume will _____ cardiac output
increase
the more forceful the systole, the _____ the cardiac output
greater
autonomic nervous system: sympathetic stimulation
causes 5 events:
1. stimulation of the SA node and tachycardia
2. increased speed of electrical conduction
3. increase force of systole and greater stroke volume
4. decrease in length of refractory period.
located in : cardiovascular center of medulla
autonomic nervous system: parasympathetic
causes 5 events (opposite of sympathetic)
- inhibits the stimulation of the SA node and causes bradycardia
- decrease speed of electrical conduction
- decrease force of systole and lesser stroke volume
- increase in length of refractory period
- decrease in the size of the cardiac output
found in cranial nerve 10
fetal lungs
do not oxygenate fetal blood. fetal pulmonary circulation is unnecessary.
foramen ovale
becomes the fossa ovalis and the limbus of the fossa ovalis at about 1 year after birth.
ligamentum arteriosum
ductus arteriosus interconnects the pulmonary artery with the aorta, degenerates into a fibrous ligament called the ligamentum arteriosum shortly after birth.
angina pectoris
temporary chest pain or a sensation of pressure that occurs while the heart muscle is not receiving enough oxygen.
cause:
narrowing of arteries
decreased oxygenation to heart muscles (ischemia)
evident upon exercise and stress
symptoms:
discomfort over chest (pain/pressure)
