Lecture 4: Internal Anatomy of the Heart Flashcards
The heart is a muscular organ divided into…
right and left pumps
Under normal circumstances, do the right and left pumps of the heart communicate directly?
no
What is each pump further divided into?
two communicating chambers: atrium and ventricle
What does the atrium do?
collects blood
What does the ventricle do?
discharges blood (pumps)
What kind of circulation is the right pump involved in?
pulmonary circulation
Where does the right pump move blood?
from the heart to the lungs for gas exchange
What kind of circulation is the left pump involved in?
systemic circulation
Where does the left pump move blood?
from the heart to all tissues of the body
What is the first step of cardiac blood flow?
deoxygenated blood from systemic circulation collects into right atrium and passes into the right ventricle
How does deoxygenated blood enter the right atrium?
from vena cavae, coronary sinus or directly
What is the second step of cardiac blood flow?
deoxygenated blood is pumped from the right ventricle into the pulmonary trunk/arteries and into the pulmonary circulation
What is the third step of cardiac blood flow?
oxygenated blood from pulmonary circulation collects in the left atrium and pass into the left ventricle
Where does the oxygenated blood from the pulmonary circulation that collects in the left atrium come from?
the pulmonary veins
What is the fourth step of cardiac blood flow?
oxygenated blood is pumped from the left ventricle and into the systemic circulation
Where does blood leave after entering the left ventricle to get pumped into the systemic circulation?
the aorta
What kind of surface is the posterior atrial wall (right atrium)?
smooth
What do the anterior/lateral walls of the right atrium contain?
parallel folds of pectinate muscles
Where does the parallel folds of pectinate muscles extend into?
the right auricle
What is the function of pectinate muscles?
they help expand atrial volume while minimizing atrial wall stress
Blood passes into the right ventricle through…
the right atrioventricular valve
Where is the fossa ovalis located?
between the two atria
What is the crista terminalis?
crest at transition between smooth wall and pectinate muscle
What are the 7 parts of the right atrium?
- fossa ovalis
- valve of IVC
- opening and valve of coronary sinus
- right atrioventricular valve
- crista terminalis
- pectinate muscles
- right auricle
What is the function of the foreman ovale?
it allows oxygenated blood from the IVC to bypass right ventricle and go to the left atrium instead
What becomes after birth when the foreman ovale seals?
the fossa ovalis
How are fetal lungs and pulmonary circulation in utero?
“offline”
How does gas exchange occur in utero?
through the yolk sac and placenta
What does prenatal circulation include?
shunts
What is the function of shunts in utero?
they allow the pulmonary circulation to be bypassed
What is left when the FO fails to seal completely?
a patent foreamen ovale
How does deoxygenated blood enter the right ventricle?
through the right atrioventricular valve (tricuspid)
How many cusps does the atrioventricular valve?
3
What are the cusps of the atrioventricular valve linked by?
chordae tendineae
What are the 3 cusps of the atrioventricular valve linked to?
3 sets of papillary muscles
What are the names of the 3 papillary muscles?
anterior, posterior, septal
What is the function of the papillary muscles and chordae?
they ‘hold on’ to the cusps to keep them from prolapsing into the right atrium during ventricular contraction (systole)
What assists the ventricle walls?
the trabeculae carnae
What do the right ventricle walls do?
pump deoxygenated blood out the pulmonary valve into the pulmonary trunk
What are the 6 parts of the right ventricle?
- right atrioventricular valve
- papillary muscles
- trabeculae carnae
- chordae tendineae
- cusps
- pulmonary (semilunar) valve
What is another name for the pulmonary valve?
semilunar valve
How many pulmonary veins enter the left atrium?
4
Which auricle has less pectinate muscle?
the left auricle
What is another name for the atrioventricular valve in the left atrium/ventricle?
bicuspid
Why is the left atrioventricular valve called bicuspid and not tricuspid?
because it has only 2 sets of cusps/chordae/papillary muscles
What is the difference in ventricular walls between the left and right ventricles?
the left ventricular wall is much thicker
What is the ductus arteriosus?
a second shunt to bypass pulmonary circulation
What does the ductus arteriosus turn into in the first few months of postnatal life?
ligamentum arteriosum
What are the two phases of the cardiac cycle?
the ventricular diastole and systole
Which phase of the cardiac cycle is the longest?
the ventricular diastole
What happens during ventricular diastole?
both ventricles relax and blood refills both chambers via open atrioventricular valves
What is going on between the atrioventricular and semilunar valves during diastole?
atrioventricular: open
semilunar: closed
Which phase of the cardiac cycle is the shortest?
the ventricular systole
What happens during ventricular systole?
both ventricles contract and blood is pumped out of them via open semilunar valves
What is going on between the atrioventricular and semilunar valves during systole?
atrioventricular: closed
semilunar: open
What is the direction of flow through the heart chambers?
unidirectional
What is the function of heart valves in the chambers?
prevents back flow into the chambers the blood just left
Which valves are open and closed during ventricular diastole?
AV: open
semilunar: closed (to prevent back flow)
Which valves are open and closed during ventricular systole?
AV: closed (to prevent back flow)
semilunar: open
What causes auschultation?
the valves snap shut and make an audible sound that can be heard
How can we hear auscultations?
by placing a stethoscope in the right place
Which line do you read the L and R semilunar (aortic) valve at?
at the parasternal line
Where do you read the left semilunar valve?
at the right second intercostal space
Where do you read the right semilunar valve?
at the left second intercostal space
Where do you read the right and left tricuspid valve?
at the left fifth intercostal space
Which line do you read the right tricuspid valve?
the parasternal line
Which line do you read the left tricuspid valve?
the midclavicular line
What is the classification of the efferent control of the heart function?
autonomic
What do sympathetic fibers from spinal cord levels T1-T4 and the cervical ganglia arise as?
sympathetic cardiac nerves
How do parasympathetic fibers come from the vagus nerves as?
cardiac branches
What do the parasympathetic fibers cause the heart rate to do?
decrease
What do the sympathetic fibers cause the heart rate to do?
increase
What do the SNS and PSNS fibers mesh to form?
a cardiac plexus
What is the function of the cardiac plexus?
it provides branches to conduction system of the heart, coronary vasculature and myocardium
What is included in the heart’s conduction system? (6)
- sinoatrial node
- atrioventricular node
- atrioventricular bundle
- right bundle branch
- left bundle branch
- Purkinje fibres
What is the septomarginal band?
‘bridge’ across inferior right ventricle for better conductance to right anterior papillary m.
Where does the septomarginal band cross?
the inferior right ventricle
What is the natural pacemaker of the body?
the sinoatrial node
The ANS is only…
efferent
What is sensory input provided by in the ANS?
general visceral afferent fibers
What do general visceral afferent fibers run with?
the ANS fibers
Which two fibres share circuitry in the posterior horn of the spinal cord?
the general visceral afferent fibres and somatic fibres
What is referred pain?
when somatic and visceral signals get misinterpreted by the brain
