Lab - Sheep's Heart Flashcards
Choose the CORRECT option. The moderator band:
a) prevents blood from pushing the valve cusps into the atrium.
b) provides tension to the cords of the valve during ventricular contraction.
c) is designed to increase the structural strength of the ventricular wall.
d) prevents over-expansion of the ventricle.
e) is part of the heart’s conduction system.
e)
is part of the heart’s conduction system.
Yes, it consists of Purkinje fibres which are conductive and part of the heart’s conduction system.
Which of the following statements is correct about the left ventricle?
a) contains oxygenated blood.
b) pumps blood into the pulmonary trunk.
c) has an atrioventricular valve with 3 cusps.
d) has a ‘C’ shaped lumen when cut in cross section.
e) generates low pressure.
Contains oxygenated blood. Yes it ejects oxygenated blood that it receives from the left atrium through the aorta so tissues can be bathed in O2.
Which one of the following structures can be found in the sheep heart?
a) inferior vena cava
b) right posterior vena cava
c) superior vena cava
d) left anterior vena cava
e) anterior interventricular sulcus
left anterior vena cava
Yes, this is a structure found in the sheep as it drains blood from the left front side into the right atrium
In the sheep heart, blood which enters the coronary arteries has just passed through the:
a) pulmonary valve
b) aortic valve
c) bicuspid valve
d) mitral valve
e) tricuspid valve
aortic valve. yes, the aortic valve is found between the LV and aorta. The entrance to the coronary arteries is called the coronary ostia and is found at the base of the aortic valve.
During your dissection of the sheep heart you used scissors to remove the apex of the heart. Among the structures cut with the scissors at that moment were the:
a) fossa ovalis
b) interatrial septum
c) papillary muscles
d) aortic valve cusps
e) left and right auricles
papillary muscles
Yes, these papillary muscles would likely be cut during the apex removal seen as the larger protrusions enveloping the lumen of the left ventricle.
Occasionally after the birth of a lamb the ductus arteriosus fails to close. In that case the expected consequence would be:
a) greater blood flow to the lungs than to the systemic circuit
b) a shunt from the pulmonary trunk to the aorta
c) a shunt from the left ventricle to the right ventricle
d) cyanosis (blue discolouration of the skin)
e) continued blood flow through the foramen ovale
Yes, as if the ductus arteriosus fails to close, since there is a higher pressure in the systemic circuit, blood may be shunted back through pulmonary trunk and with lower resistance in pulmonary circuit favours greater blood flow to the lung capillaries.
In the sheep heart one of the four heart valves has only two flaps or cusps. When closed this valve prevents blood from flowing:
a)
from the left ventricle to the left atrium
A chamber of the sheep heart is entered by three thin-walled vessels of unequal size. The chamber has a valve at its outlet but no inlet valves. The wall of the chamber is partly smooth, and partly trabeculate. In life, the blood in the chamber would be dark red/blue in colour. The chamber is the:
a) left atrium
b) left ventricle
c) right atrium
d) right ventricle
e) coronary sinus
the right atrium
yes. The three thin-walled vessels refer to the venae cavae which deliver deoxygenated blood to the right atrium. There are no inlet valves because blood collects in the RA.
The following pairs of terms compare the left side of the sheep heart with the right side. Which pair is INCORRECT?
a) ventricle crescent-shaped in cross section – ventricle circular in cross-section
b) thick-walled ventricle – thin-walled ventricle
c) left and right pulmonary veins – right anterior, left anterior and posterior vena cavae
d) aortic valve – pulmonary valve
e) mitral valve – tricuspid valve
a) ventricle crescent-shaped in cross section – ventricle circular in cross-section
. yes - this is incorrect as the left ventricle cross-section is circular while the right ventricle cross-section is a crescent shape(like a pocket attached to the left ventricle).
In relation to the sheep heart, the following pairs describe first a chamber or vessel of the heart, and then the source of the blood which enters it. Which pair is INCORRECT?
a) aorta – left ventricle
b) left atrium – cardiac veins
c) right atrium – three vena cavas
d) pulmonary trunk – right ventricle
e) coronary arteries – aorta
left atrium - cardiac veins . yes, this is incorrect as cardiac veins carry deoxygenated blood and all deoxygenated blood returns to the right atrium not the left atrium.
During a dissection of the sheep heart, most structures encountered are made of either cardiac muscle or connective tissue. Which of the following is made of white fibrous connective tissue?
a) interventricular septum
b) moderator band
c) chordae tendineae
d) auricles
e) visceral pericardium
chordae tendineae
yes - this is correct as these structures consist of avascular collagen fibres which facilitates the closure of the atrioventricular valves
The options below each list three structures from the sheep heart in a particular order. Choose the option which, when entered into the following statement would make it correct. “After blood has passed through the ………………………. it returns to the ……………………………… through ……..………………… .”
a) coronary arteries / left anterior vena cava / cardiac veins
b) lungs / right atrium / pulmonary veins
c) left ventricle / pulmonary circuit / the pulmonary arteries
d) foramen ovale / systemic circuit / the ductus arteriosus
e) aorta / right atrium / pulmonary veins
a) coronary arteries / left anterior vena cava / cardiac veins
the blood from coronary arteries are collected by the cardiac veins which open up in the entrance of the left anterior vena cava, just upstream of the right atrium
