Anatomy of the Heart Flashcards
heart
cone-shaped muscular pump
where is the heart located
in the thorax between the lungs
what is the heart protected by
the ribs and sternum
between which ribs does the heart lie
ribs 2-5 to the left of the midline
where is the apex of the heart found
in the 5th intercostal space in the midclavicular line
pericardium
the coverings of the heart- composed of an outer fibrous layer and an inner serous pericardium
fibrous pericardium
-inelastic, made of dense connective tissue
-fuses inferiorly with the diaphragm and superiorly with the great vessels.
function of fibrous pericardium
prevents overfilling of the heart and anchors it in position
serous pericardium
Fuses inferiorly with the diaphragm and superiorly with the great vessels
serous pericardium: parietal layer
-outer layer
-lines the inner surface of the fibrous pericardium
serous pericardium: visceral layer
-epicardium
-inner layer
-adheres to the surface of the heart
coronary vessels runs through which pericardium of the heart
visceral layer
serous pericardium: pericardial cavity
potential space between the parietal and visceral layers containing pericardial fluid
-allows smooth movement
function of the serous pericardium
prevents friction
what are the 3 layers of the heart wall
Endocardium: inner layer – endothelium
Myocardium: middle layer - cardiac muscle (thick layer of muscle)
Epicardium: outer layer - visceral pericardium
trabeculae carnae
meaty ridges found inside the heart
look at internal diameter of the heart diagram
fibrous skeleton of the heart
bands of fibrous connective tissue between the atria and ventricles
what does the fibrous skeleton of the heart electrically separate
the atria from the ventricles preventing the chambers from contracting at the same time
what does the fibrous skeleton of the heart surround
the pulmonary trunk and aorta
does the fibrous skeleton of the heart contain heart valves
yes
what are heart valves
one way valves that prevent the backflow of blood
what are the two different heart valves
atrioventricular valves (AV)
semilunar valves
tricuspid valve
right AV valve (3 cusps)
bicuspid/ mitral valve
left AV valve (2 cusps)
what are the different semilunar valves
pulmonary
aortic
view diagram on heart valves
where are the atrioventricular valves located
between the atria and ventricles
how are the AV valves opened
by the blood flowing from atria to the ventricles
what are the AV valves anchored by
chordae tendinae to papillary muscles (form part of the heart wall)
what does contraction of the papillary muscles prevent
eversion of the valves and therefore backflow of blood into the atria
when do AV valves open
when ventricular pressure is less than atrial pressure
when do AV valves close
when ventricular pressure is greater than atrial pressure
functions of the semilunar valves
guard the entrance of the aorta and pulmonary trunk
prevents backflow of blood into the ventricles
how do the semilunar valves open
by the force of blood as the ventricles contract
what causes the semilunar valves to close
blood flows backwards in the aorta and pulmonary trunk during ventricular relaxation, this pools in the cusps and pushes them shut
how much blood does the heart receive
250 ml/min
during ventricular relaxation, where is the blood delivered to
myocardium
what does the left coronary artery split into
-anterior interventricular (runs anteriorly down between the ventricles and descends at the front of the vessel)
-circumflex
what does the right coronary artery split into
marginal artery
posterior interventricular
which veins drain into the coronary sinus
the great, middle and small cardiac veins
the coronary sinus empties into which atrium
right atrium
the patency of coronary vessels are examined by?
angiography (x-ray used to check blood vessels and how blood flows through them)
what is heart contraction coordinated by
the cardiac conducting system
what type of cells initiate electrical impulses in heart contraction
non-contractile cells
what cells are involved in the cardiac conducting system
-Sinoatrial (SA) node
- Atrioventricular (AV) node
- AV bundle (bundle of His)
- Right & left bundle branches
- Purkinje fibres
what measures the activity of the heart
electrocardiogram
why is foetal circulation different from usual circulation
- oxygen and nutrients are received from
the placenta via the umbilical vein - Need to bypass non functional lungs
foetal circulation: foramen ovale
connects the right to the left atria-bypassing right ventricle and pulmonary system
foetal circulation: ductus arteriosus
connects the pulmonary trunk to the arch of the aorta bypassing pulmonary system and the left side of the heart
-rather than going to the lungs, it goes directly to the aorta
foetal circulation: ductus venosus
connects the umbilical vein to inferior vena cava bypassing the liver
why is here limited need for the liver in fetal circulation
nutrients are being produced by the mother so limited need
what valve does the foramen ovale contain
shutter valve
foetal circulation: shutter valve
pressure in the heart forces the valve to be open
-pressure in the right side of the heart is greater than the left so the blood goes directly from the right to the left atrium
when the newborn takes the first breath, what happens after the lungs expand
blood rushes into the pulmonary circulation increasing oxygen levels and constricting the ductus arteriosus
when a newborn takes their first breath and the left atrium pressure increases, what happens
the foramen ovale closes to become fossa ovalis
-pressure in the left atrium will now be higher than pressure in the right atrium and pressure in the lungs have dropped
when the umbilical cord is tied, what happens
the umbilical vessels close leading to the ductus venosus fibroses
once a foetus changes to an adult, the ductus venosus changes to
the ligamentum venosum
when the foetus becomes an adult, the foramen ovale becomes the
fossa ovalisw
when the foetus becomes an adult, the ductus arteriosus becomes what
the ligamentum arteriosum
