Lecture 3 Flashcards
What valves are there? How many cusps?
right atrioventricular valve: tricuspid valve
left atrioventricular valve: bicuspid (mitral) valve
aortic semilunar valve: three cusps
pulmonary semilunar valve: three cusps
How are the two types of valve opened and closed? What are their functions?
The atrioventricular valves are shut by the chordae tendinae (which are pulled on by the papillary muscles, one for each cusp). They are opened to allow blood to flow into the ventricles and closed to prevent blood flowing back into the atrium during diastole.
The semilunar valves are opened to allow blood to flow out of the heart (into the arteries, both pulmonary and aorta), this occurs due to being pushed open by the high pressure in the ventricles, they close as the blood starts to backflow.
Which valves are open during diastole? Which during systole?
Diastole: atrioventricular open, semilunar closed
Systole: atrioventricular closed, semilunar open.
What is the main circulation path of the heart?
The right and left coronary artery branch off from the aorta before the aortic valve, this allows it to fill with blood when the valve is closed due to pressure, the left coronary artery then flows into the circumflex (around the diameter) artery and anterior interventricular artery (around the apex).
The main coronary veins are the small cardiac vein and great cardiac vein, these both flow into the coronary sinus, this returns the blood to the right atrium.
Which layer seperates the atrium and the ventricles?
The fibroseptum.
What important features are there of cardiac muscle? What do they look like?
Must be very unexhaustable, they are short and wide branched cells, striated and with normally 1 but sometimes two centralised nuclei with cytoplasmic organelles packed at the poles of the nucleus, they are interconnected via intercalated disks with roughly 25% mitochondria volume, sarcomeres are also irrefular due to the branched structure.
What structures make up an intercalated disk and what are the orientations and functions?
Adhesion belts link actin to actin and are normally found on the verical portion, desmosomes like cytokeratin with cytokeration and are found anywhere, gap junctions are for electrochemical communication and are found in the horizontal portions.
Why is a conduction system of the heart important, what can affect it? What does it involve?
The conduction system greatly increases the efficiency of heart pumping, it is responsible for the co-ordination of heart contraction and of atrioventricular valve action. It can be affected by autonomic nerves. The pathway is sinoatrial node (upper right of right atrium, the signal also travels to the left atrium via the interatrial node), to the atrioventricular node (lower left of right atrium), to the septal branches (septum), to the purkinje fibers found around the apex of the heart.
What type of cell does the conduction in the heart?
Modified cardiac muscle cells.
Which nerves increase the heart rate? Which slow it?
parasympathetic slows, sympathetic speeds up.
What do purkinje cells contain in abundance?
Mithocondria, glycogen, intercalated disks and lots of gap junctions, also some peripheral myofibrils.
