Lab 3 - The Heart Flashcards
sheep and human hearts differ mainly by the shape of their…
atria
how does the vena cava in a sheep differ to that of a human
3 major branches - L anterior, R anterior and a posterior vena cava
head-end of a human/sheep =
cranial
bottom end of a human/sheep =
caudal
the caudal end of a sheep is also known as the…
posterior
how do you know that you are looking at the ventral view of the heart?
- auricles will be pointed towards you
- ligamentum arteriosum visible
- curved
the interventricular sulcus marks the position of…
the septum and the course of one of the coronary arteries and a cardiac vein
apex formed by which ventricle?
left ventricle
which great artery is visible with no disection
the pulmonary trunk
how do you know that you are looking at the dorsal view of the heart?
- flat surface
- vena cava clearly visible
name of the fibrous bridge between the pulmonary trunk and the aorta
ligamentum arteriosum
name of the first branch of the aorta
brachiocephalic artery
if you removed the atria and large arteries and you looked down at the four openings, which opening would be the most ventral? what would emerge in the centre? would the ventricles be more ventral or dorsal?
Pulmonary trunk is the most ventral.
Aorta would arise in the centre.
The ventricles are towards the dorsal side
How can you differentiate the auricle from the atrium?
auricle has an irregular internal surface of trabeculae whereas the main atrium is smooth. Different origins in the developing embryo.
trabeculae
rods of muscle fibres which cross over and weave around each other
moderator band
- slender, muscular bridge which traverses the right ventricle.
- no mechanical function.
- contains purkinje fibres for conduction.
chordae tendineae when mitral valve is open and closed
loose when mitral valve is opened
tight when mitral valve is closed
how many coronary artery openings? where are they found?
2 openings found in the aorta, just inside the aortic valve flaps
where do the cardiac veins return their blood
via tiny perforations in the wall of the small left anterior vena cava
coronary ostia
openings to the coronary arteries
which structure allows blood to cross from the right to the left atrium in the sheep fetus?
foramen ovale
fossa ovalis
- translucent membrane ,which covers the hole in the atrial septum, in the the adult sheep
- found in the posterior vena cava
relative wall thickness: RV LV RA LA
relative wall thickness: RV = MEDIUM LV = THICK RA = THIN LA = THIN
when do the atria fill with blood?
during ventricular systole and isovolumetric relaxation
closure of the ________ and _________ valves causes the first heart sound (“____”).
closure of the ________ and _________ valves causes the second heart sound (“____”)
closure of the mitral and tricuspid valves causes the first heart sound (“lub”).
closure of the aortic and pulmonary valves causes the second heart sound (“dub”)
when are all four heart valves closed
- isovolumetric contraction
- isovolumetric relaxation
max and min pressure in the left ventricle
max = 120mmHg min = 5mmHg
rupture of papillary muscle
- caused by myocardial infarction
- valve collapses and blood leaks onto atrium
which side of the heart is the flap covering the foramen ovale
left
the ligamentum arteriosum is a remnant of a large fetal vessel called the _____ _______. This vessel carried blood from the ________ ______ to the ______.
the ligamentum arteriosum is a remnant of a large fetal vessel called the ductus arteriosus. This vessel carried blood from the pulmonary trunk to the aorta.
before birth (prenatal) th luns are filled with ______ ____ which ________ their resistance. This is why only ___ of blood from the RV travels to the lungs.
before birth (prenatal) th luns are filled with amniotic fluid which increases their resistance. This is why only 10% of blood from the RV travels to the lungs.
prenatal aorta carries ________ blood.
mixed.
deoxygenated returning from the lungs and oxygenated coming from the RA (via the foramen ovale)
at birth the foramen ovale closes because… (5 steps)
- resistance in the lungs decrease when they fill with air
- leads to increased volume returning to the LA
- pressure in LA becomes greater than RA
- flap valve closes
- becomes sealed in place by growth of connective tissue = FOSSA OVALIS
postnatal, the ductus arteriosus closes because…
an increase in oxygen causes smooth muscle to contract and close the vessel, forming the LIGAMNETUM ARTERIOSUM
If the ductus arteriosus remained open (“______”) after birth the result would be a larger shunt of blood from ______ to _______ ______. In that case, the volume of blood reaching the lungs would be ________ than normal.
If the ductus arteriosus remained open (“patent”) after birth the result would be a larger shunt of blood from aorta to pulmonary trunk. In that case, the volume of blood reaching the lungs would be larger than normal.
