Lecture 5 Flashcards
Anatomy of the heart - II
What is the function of the AV valves?
To prevent blood from returning to atria during ventricular contraction
What is the right side AV valve called?
Tricuspid valve
What is the left side AV valve called?
Bicuspid (mitral) valve
What are the semilunar valves?
The aortic valves, separating the ventricles from the aorta
What are the antiventricular (AV) valves?
Bi/tricuspid valves that seperate the atriums from the ventricles
What is diastole?
Blood is arriving in the receiving chambers to fill the ventricular chambers. AV valves open, semilunar valves closed
What is Systole?
Ventricles are contracting and pressure is increasing within the chambers. Pressure opens the semilunar valves, AV valves closed.
What are the papillary muscles?
5 muscles originating from the ventricular walls, attached to the bi and tricuspid valve leaflets via the chordae tendineae and functionally prevent regurgitation of ventricular blood via tensile strength by preventing inversion of valve leaflets during systole
What is the anatomical positioning of the right coronary artery?
Runs in the epicardial groove between right atria and ventricle and around to the right lateral margin towards the posterior aspect of the heart.
What is the anatomical positioning of the anterior interventricular artery?
On the anterior surface of the heart and runs over the interventricular septum
What is the anatomical positioning of the left coronary artery?
Originates as a branch from the aorta and travels between the pulmonary trunk and the left atrial appendage. Under the appendage, the artery divides
What is the anatomical positioning of the circumflex artery?
Runs in left coronary groove between the left atrium and ventricle around to the lateral margin on the posterior
What are the arteries of the supply path of the heart?
coronary arteries x2, circumflex and anterior interventricular arteries
What are the veins of the drainage path of the heart?
Coronary sinus, great and small cardiac vein
What is the function of the supply path of the heart?
To supply the heart with oxygen and nutrients
What is the function of the drainage path of the heart?
To remove the deoxygenated blood and send through the right to go to the lungs
What is the anatomical positioning of the Coronary sinus?
Sits toward the posterior of the heart, between the left atrium and the left ventricle.
What is the function of the coronary sinus?
Drain the deoxygenated blood directly back into the right atrium
What is the anatomical positioning of the small cardiac vein?
Along the base of the right ventricle and courses parallel to the right coronary artery. Runs to the posterior, connecting with the coronary sinus.
What is the anatomical positioning of the great cardiac vein?
Runs in the anterior interventricular groove around to the posterior, connecting with the coronary sinus.
What is the function of the small cardiac vein?
Drains the anterior surface of the right side of the heart
What is the function of the great cardiac vein?
Drains the anterior surface of majority of the left side of the heart
What is the function of the small diameter of the capillaries?
Thin to only allow one red blood cell to pass as a time. This is because O2 and nutrients in RBC need to be as close to capillary walls as possible for highest efficiency.
Whats is the myocardium?
Cardiac muscle tissue that contains features of both smooth and skeletal muscle as well as specialised specialisations for heat function. Function is to beat the heart.
What is the structure of cardiac muscle cells?
Striated. Short and branched. Generally single nuclei / cell. Central, oval nucleus. Cytoplasmic organelles packed at poles of nucleus. Very high mitochondrial supply (~20%)
How does cardiac muscle cell structure compare to skeletal muscle structure (respectively)?
Short and branched vs long unbranched
Single nuclei vs multinucleated
Central, oval nucleus vs peripheral nucleus
Sarcomeres not parallel vs sarcomeres parallel
What are the ICD’s
Intercollated disks, which are unique to ONLY cardiac muscle
What are the three units that make an ICD
Adhesion belt, desmosome, gap junction
What is an adhesion belt?
An intercellular junction that links actin - actin in adjacent cells via a series of trans-membranous proteins that cross between the two. Tethered together so if one contracts it stimulated the contraction of the other.
What is a desmosome?
An intercellular junction that links the internal cytokeratins to each other via trans-membranous membranes. Protein rich, darker appearance
What is a gap junction?
A gap between the cells which allows electrochemical communication. Ca++ from one cell is able to leak through to neighbouring cell to stimulate contraction
What is the conduction system of the heart?
A network of nodes, cells and signals that controls the heartbeat
What is the function of the conduction system of the heart?
To increase the efficiency of ventricular contractions and antiventricular valve action. Controlled by autonomic nerves which can alter the rate of impulse (PNS & SNS)
Where does the conduction pathways begin?
At the sinoatrial (SA) node
What is the atrioventricular node?
The connection point between the atria and ventricles
What is the function of the atrioventricular node?
To control the passage of the heart’s electrical signal from the atria to the ventricles, ensuring only one is carrying an electrical impulse at a time
What is the SA and AV node connected by?
The internodal pathway
Where does the electrical impulse end?
The purkinje fibres
What connects the AV node and purkinje fibres?
The AV bundle which separates into the R&L bundle branches
Conduction cells were originally…?
Cardiac muscle cells which differentiated
What is the evidence suggesting the differentiation of cardiac muscle cells to conduction cells?
Peripheral myofibrils, central nucleus, mitochondria and glycogen, gap junctions, desmosomes and adhesion belts
Conduction cells make up __ of cardiac cells?
1%
