Lecture 7 - The Heart Flashcards
The heart: what is it and where is it located?
Cone-shaped, muscular pump
Located in the thorax between the lungs (in the cardiac notch of the left lung) and is located between ribs 2-5 and is protected by the sternum and ribs
Pericardium: what is it and what does it do?
Covers the heart and is composed of an outer fibrous layer and an inner serous pericardium
Protects the heart, anchors it in place, and prevents friction with other tissues and organs
The fibrous layer of the pericardium: what is it made of and what does it connect to?
Inelastic, made of dense connective tissue
Fused inferiorly with the diaphragm and superiorly with the great vessels
The serous layer of the pericardium: what is it made of and what does it do?
Made of visceral, pericardial, and parietal pericardium.
Prevents friction in the heart
Visceral pericardium
Adheres to the heart
Pericardium cavity
Lines the inner surface of the
fibrous pericardium
Pericardial cavity: what is it?
The potential space between the parietal and visceral layers
Contains fluid
Heart wall
Endocardium, myocardium, and epicardium.
Endocardium
The inner layer of the heart wall
Myocardium
Cardiac muscle positioned between endocardium and epicardium
Epicardium
Visceral pericardium
Fibrous skeletal of the heart
The heart has bands of fibrous tissue that separate the atria and ventricles electrically
Types of valves in the heart
Atrioventricular valves - Prevents backflow from the ventricles to the aorta
Semilunar valves - Prevents backflow back into the pulmonary vein/aorta
Atrioventricular valves: what do they do, how does contraction work, and examples of the valves?
Each valve opens/closes when the pressure in the atrium is higher/lower than the ventricle it is connected to.
The contraction of the papillary muscle controls valves.
Tricuspid (R) and bicuspid/matrial (L) valves
Semilunar valves: when are they open/closed and what examples?
It opens when the ventricles pump blood as the pressure forces it open
As ventricular pressure falls, blood begins to backflow but the blood first pools in cusps which makes the valves close
Aortic and pulmonary valve
Tricuspid valve
Between the right atrium and ventricle, prevents backflow from the right ventricle into the right atrium
Bicuspid/matrial valve
Between the left atrium and ventricle, prevents backflow from the left ventricle into the left atrium
Aortic valve
prevents backflow from the aorta into the left ventricle
Pulmonary valve
Prevents backflow from the pulmonary artery into the right ventricle
The heart receiving blood: how much, when, and from what?
250 ml/m
Supplied to the myocardium during the relaxation of the ventricles
The left side of the heart is supplied from the left coronary artery (circumflex, anterior interventricular)
The right side of the heart is supplied from the right coronary artery (marginal, posterior interventricular)
Right atrium blood supply from the cardiac vessels
The great, middle, and small cardiac veins drain into the coronary sinus which supplies blood to the right atrium
The anterior cardiac veins drain directly into the right atrium
Cardiac conducting system: what does it do, how does it do it, and what are examples?
Controls heart contraction
Initiates electrical impulses that cause the heart to contract
SA and AV node, AV bundle (of His), bundle branches, Purkinje fibres
Foetal circulation: the differences with normal circulation
Since nutrients and oxygen are received from the placenta, there is no need for the lungs so the blood circulation is averted from the lungs and the liver
Foetal circulation: the three blood shortcuts
Foramen ovale - connects the right atrium to the left atrium so that less blood is sent to the right ventricle (which would pump to the lungs)
Ductus arteriosus - connects the pulmonary trunk to the aorta so that less blood is sent to the lungs
Ductus venosus - connects the inferior vena cava and umbilical vein and this sends less blood through the liver
Foetal circulation: how it changes after birth?
Foramen ovale - closes because of the increased pressure in the LA, it then becomes the fossa ovalis
Ductus arteriosus - as the baby takes its first breaths, the lungs expand and oxygen levels rise and this constricts it, closing it and making it now the Ligamentum arteriosum
Ductus venosus - umbilical cord dries and the vessels close, making the DV become the Ligamentum venosum
