Lecture 5: ANATOMY OF THE HEAT, PART 2 Flashcards
What valves does each side of the heart have?
A semilunar valve and an atrioventricular valve
Where is the atrioventricular valve found?
Between the atrium and the ventricle
Where is the semilunar valve found?
Between the ventricle and the outflow artery
What is the function of atrioventricular valves?
To prevent blood returning to the atria during ventricular contraction
What is the AV valve on the right side?
The tricuspid valve
How many leaflets/cusps does the tricuspid valve have?
3
What is the AV valve on the left side?
The bicuspid (mitral) valve
How many leaflets/cusps does the bicuspid valve have?
2
What is the filling phase called?
Diastole
What is the squeezing phase called?
(ventricular) systole
How is theAV valve during diastole?
Open to allow blood to drain into the ventricle
How is the semilunar valve during diastole?
Closed to prevent blood from leaving the ventricle
How is the AV valve in (ventricular) systole?
Closed to prevent blood flowing back into the atrium
How is the semilunar valve during (ventricular) systole?
Open to allow blood to exit the ventricle
What is the function of semilunar valves?
To prevent blood returning to ventricles during filling (diastole)
What is the semilunar valve on the right side?
The pulmonary (semilunar) valve
How many cusps does the pulmonary (semilunar) valve have?
3
What does the pulmonary (semilunar) valve control?
Flow into the pulmonary circulation
What is the semilunar valve on the left side?
The aortic (semilunar) valve
How many cusps does the aortic (semilunar) valve have?
3
What does the aortic (semilunar) valve control?
Flow from the left ventricle to the aorta
When are semilunar valves pushed open?
As blood flows out of the heart
When do semilunar valves close?
As the blood starts to backflow
What is the size comparison of AV and semilunar valves?
Semilunar valves are much smaller than AV valves
How is the AV leaflet described?
Large and flappy
What would the AV leaflet do if there was nothing preventing it shutting?
It would slam shut
What are papillary muscles?
Finger-like projections of the ventricular wall
What do papillary muscles do?
Tension early in systole
What are chordous tendineae?
Tendonous chords which are attached to the tip of the papillary muscle and the AV leaflet
Where is the tension in the papillary muscle transferred to?
The chord tneidneae
What do the papillary muscles and chordous tendineae do?
Allow the AV leaflet to slowly move into place when closing
Where does the first branch of the systemic circulation form the aorta go?
Straight to the heart (oxygenated blood)
Where is the right coronary artery found?
Running in a groove in the epicardium between the right atrium and ventricle (oxygenated blood)
Where does the left coronary artery run?
It runs a small distance and then branches into the circumflex artery and anterior inter ventricular artery (oxygenated blood)
What is the right side of the heart drained by?
The small cardiac vein (deoxygenated blood)
What is the left side of the heart drained by?
The great cardiac vein (deoxygenated blood)
Where do the small cardiac vein and great cardiac vein join?
At the coronary sinus at the posterior of the heart
What does the coronary sinus do?
Drain deoxygenated blood into the right atrium
What is the width of a capillary?
About the width of a red blood cell so the distance for diffusing substances to travel is minimised
What features does cardiac muscle have?
It has features of smooth and skeletal muscle as well as cardiac muscle specific specialisations
What is the function of cardiac muscle?
Beating of the heart
Is cardiac muscle striated?
Yes, just like skeletal muscle but not smooth muscle
How are the cells of cardiac muscle described?
Short, branced
How wide are cardiac muscle cells?
Approximately 25 micrometres
How many nuclei in cardiac muscle cells?
One (or occasionally 2) which is the same as smooth muscle but not skeletal
How is the nucleus in cardiac muscle described?
Centrally positioned and oval shaped (in skeletal muscle the nucleus is pushed to the outsides)
Where are cytoplasmic organelles in cardiac muscle?
Packed at the poles of the nucleus
How are cardiac muscle cells connected?
By intercalated discs which are only found in cardiac muscle
What volume of a cardiac muscle cell is mitochondria?
20%
How are the sarcomeres arranged in cardiac muscle?
Irregular and branched (not linearly arranged as in skeletal)
What are intercalated discs?
Regions between cardiomyocytes (cardiac muscle cells)
What are the 3 junctions in intercalated discs?
Adhesion belts, desmosomes and gap junctions
What do adhesion belts link?
Actin to actin via trasnmembrane proteins
Where are adhesion belts found?
In the vertical portion and transfer force between cells
What do desmosomes link?
Cytokeratin with cytokeratin
What do gap junctions allow?
Electrochemical communication
Where are gap junctions placed?
Parallel to the force of contraction because they are delicate junctions
What does the conduction system of the heart actions do?
Greatly increase the efficiency of heart pumping
What is the conduction system of the heart responsible for?
The co-ordination of heart contraction and atrioventricular valve action
What alters the rate of conduction impulse generation?
Autonomic nerves
What type of tissue is the conduction system of the heart?
Modified cardiac tissue, not nervous tissue
Where does the conduction pathway of the heart begin?
At the superior aspect of the right atrium where there is a cluster of cells called the sinoatrial node
Where does the conduction pathway go after the sinoatrial node?
Through the atrial chamber by internodal pathways
Where do the internodal pathways reunite?
At the AV node which is the gateway into the ventricular chambers
What comes after the AV node?
The AV bundle which goes down the inter ventricular septum into the tight snd left bundle branches
What is the last part of the conduction system?
Purkinje fibres
Where do purkinje fibres go?
They run up into the papillary muscles
What do purkinje cells have?
Some peripheral myofibrils, mitochondria and glycogen
Where is the nucleus of purkinje cells?
Central
What junctions are found in purkinje cells?
Lots of gap junctions because involved in communication, some desmosomes and a few adhesion belts
What portion of cardiac cells are purkinje cells?
1%
