Lecture 1 Flashcards
Basic internal and external features of heart, characteristics of each chamber
What are the characteristics of the right atrium?
Forms right border of the heart. Receives blood from 3 veins: superior vena cava, inferior vena cava and coronary sinus. Smooth posterior wall, anterior wall rough with pectinate muscles which extend into auricle. Blood passes from RA to RV via tricuspid/right atrioventricular valve.
What are the characteristics of the left atrium?
Forms the base of the heart, same thickness as right atrium. Receives blood from lungs through 4 pulmonary veins. Has smooth posterior and anterior wall, pectinate muscles in auricle only. Blood passes from left atrium to left ventricle via bicuspid/mitral valve.
Which valve does blood pass through to go from the left atrium to the left ventricle?
Mitral/bicuspid valve
What are the characteristics of the right ventricle?
Forms most of the anterior surface of heart. Inside walls contain ridges called trabeculae carneae.
Tricuspid valve/right atrioventricular valve characteristics
Between RA and RV. Consists of 3 cusps composed of dense connective tissue covered by endocardium. Connected to chordae tendineae which are connected to papillary muscles.
Papillary muscles are
cone shaped trabeculae carneae
RV separated from LV by partition called
interventricular septum
Blood flows from RV through the
pulmonary semilunar valve into pulmonary trunk, which divided into left and right pulmonary arteries which take blood away from heart.
What are the characteristics of the left ventricle?
thickest chamber, forms apex of heart. Has trabeculae carneae on walls and chordae tendineae anchoring cusps of bicuspid valve to pap muscles. Blood goes from LV through aortic semilunar valve to ascending aorta, to coronary arteries which supply blood to heart wall and rest goes to arch of aorta and descending aorta, branches of which take blood to rest of body.
During fetal life, ductus arteriosus shunts blood from
pulmonary trunk into aorta, reduced blood flow in not working fetal lungs
Ligamentum arteriosum
remnant or ductus arteriosus which connects arch of aorta to pulmonary trunk
Prominent feature of interatrial septum
oval depression called fossa ovalis
Fossa ovalis, remnant of
foramen ovale, opening in interatrial septum of fetal heart closes soon after birth.
coronary sulcus
marks external boundary between superior atria and inferior ventricles
anterior interventricular sulcus
shallow groove on anterior surface of heart marking external boundary between right and left ventricles
Posterior interventricular sulcus
continuous with anterior; marks external boundary between ventricles on Posterior aspect
Heart is directed
anterior, inferior and to the left
Base of heart is
its posterior surface
pericardium function
Membrane that surrounds and protects the heart. Confines heart to position in mediastinum, allows enough freedom for vigorous and rapid contraction.
Main parts of pericardium
Fibrous pericardium and serous pericardium.
Order of pericardium from outside in
Fibrous pericardium, parietal layer of serous pericardium, pericardial cavity, visceral layer of serous pericardium/epicardium, myocardium, endocardium
Pericardial fluid
reduces friction between layers of serous pericardium as heart moves. In pericardial cavity. Secreted by pericardial cells.
fibrous pericardium
Composed of tough, inelastic, dense irregular connective tissue. Prevents overstretching of heart, provides protection, anchors heart in mediastinum.
Layers of the heart wall
epicardium, myocardium and endocardium.
Fibrous skeleton of heart
dense connective tissue, surrounds valves of heart, fuse with each other and merge with interventricular septum.
Peak pressure in RA
5 mmHg
Peak pressure in RV
27 mmHg
Peak pressure in LA
8 mmHg
Peak pressure in LV
120 mmHg
Improvements in heart
- atrium is reservoir upstream of pump. 2. Inlet and outlet valve of pump close together, walls of chamber can shorten in length and width. 3. Auricle increases capacity of atrium.
Fibrous skeleton of heart functions
- Form structural foundation for heart valves 2. Prevent overstretching of valves 3.Point of insertion for bundles of cardiac muscle fibres 4. electrical insulator between atria and ventricles.
Fibrous skeleton of the heart has complete rings around
mitral valve and aortic semilunar valve.
Fibrous skeleton of the heart has no ring around the
pulmonary semilunar valve
Fibrous skeleton of heart has incomplete ring around
tricuspid valve.
Conduction system of heart. AP conduction order
- S.A. node spontaneously depolarises, AP goes to atria via gap junctions 2. AP reaches AV node 3. AP propagates to AV bundle/bundle of His ONLY SITE APS CAN CONDUCT FROM ATRIA TO VENTRICLES - fibrous skeleton insulates everywhere else. 4. AP enters right and left bundle branches 5. Purkinje fibres rapidly propagate AP to rest of ventricular myocardium leading to ventricular ejection
Speed of SA node through atrial muscle
0.5 m/s slow
Speed of AP through AV node
0.05 m/s very slow
Speed of AP through AV bundle through to Purkinje fibres
5 m/s fast
Result of SA node through atrial muscle AP conduction
atrial contraction
Result of AP moving through AP node
100 millisecond delay
Results of AP moving through AV bundle through to Purkinje stores
even ventricular ejection = systole
What part of conduction system is “in” the fibrous skeleton?
AV node
Rank speed of conduction from fastest to slowest for the S.A. node, AV node and Purkinje fibres
Purkinje fibres, SA Node, AV node
Why heart does not require nervous impulse to beat
S.A. node repolarises and depolarises on own (spontaneously
