Lecture 5 Flashcards
What is the role of the Atrioventricular (AV) Valve?
Controls flow from the Atrium to the ventricle and prevents blood from returning to the Atrium during ventricular contraction
What is the role of the semilunar valve?
Control flow from the ventricle to the outflow arteries and prevent blood from flowing backwards.
What is the AV valve on the right side of the heart called?
Tricuspid valve
3 leaflets
What is the AV valve on the left side of the heart called?
Bicuspid (mitral) valve.
2 leaflets
What happens during the Diastole phase of the cardiac cycle?
Filling phase, the heart is relaxed as blood fills the ventricular chambers from the atrial chamber
What are the AV valve doing during the diastole phase?
The tricuspid and mitral valves are open during thi phase to allow blood to flow through from the atrium into the ventricle.
What are the semilunar valves doing during the diastole phase?
They are shut in order to prevent blood from flowing back ventricles.
What happens during the ventricular Systole phase of the cardiac cycle?
The Ventricles are contracting, this exerts pressure on the blood inside the ventricle to push the. blood out.
What are the AV valves doing during the systole phase ?
They are closed so that the pressure resulting from contraction isn’t able to push blood back into the atrium.
What are the semilunar valves doing during the systole phase ?
They are open so that the pressure resulting from contraction is able to push the blood out into the outflow artery
What is the role of semilunar valves?
Determine the passage of blood between the ventricles and main arteries
What is the semilunar valve on the right side of the heart called?
Pulmonary semilunar vale
three cusps
What Is the semilunar valve on the left side of the heart called?
Aortic semilunar valve (3 cusps)
How are AV valves and SL valves different structurally?
SL valves are much smaller because they are passing pressurised blood whereas the AV valves are larger because they are passing blood that under of a lower pressure and moving slower.
What is a papillary muscle?
A fingerlike projection of the ventricular wall, the tip of the muscle has little tendinous cords which are attached to the free edge of the AV leaflets. When pressure increases in ventricular chambers, the papillary muscles develop tension on the chordae tendineae which prevents the leaflets from slamming shut.
What are coronary arteries?
Branches that come off the root of the aorta and branch back straight onto the heart. Their role is to supply oxygenated blood to the heart.
Location of the right coronary artery?
On the right side of the aorta, just above the aortic valve\ve. Runs in the epicardium in a grove between the right atrium and right ventricle
Location of the left coronary artery?
On the left side of the aorta, goes a short distance then branches into the interventricular artery.
Location of the interventricular artery?
Branches off the left coronary artery and runs over the interventricular septum
Location of the circumflex artery?
Runs in left coronary groove in the epicardium between left atrium and left ventricle, runs around to the margin and posterior.
What is the role of cardiac veins?
Drains blood back
What side of the heart is drained by the small cardiac veins?
Right side
What side of the heart is drained by the great cardiac vein?
Left side
What is the coronary sinus?
Receives the deoxygenated blood that is being drained back by the cardiac veins and drains into the right atrium so that it can be sent back into the pulmonary circuit for reoxygenation
Explain why capillaries have such a specific structure?
They are roughly the diameter of one blood cell so that red blood cells have to travel single file and as close to the wall s possible to make gas exchange easier
What is the function of cardiac muscle?
Beating of the heart
Characteristics of a cardiac muscle cell?
Striated
Short, branched cells
1-2 nuclei per cell
Central oval shaped nucleus
Cytoplasmic organelles ast at the poles of nucleus
Interconnected with neighbouring cells via intercalated discs
What are intercollated discs?
Connect neighbouring discs. Consist of three intercellular junctions; Adhesion belts, desmosomes and gap junctions.
What are adhesion belts?
Intercellular junction that links the contractile actin in one cell via membranous proteins to the actin in a neighbouring cell.
What are desomosomes?
Intercellular junction that links the cytokeratin (cytoskeleton) to the neighboring cells cytokeratin.
What are Gap junctions
Intercellular junction that fuses the cells plasma membranes together through electrochemical communication.
What is the conduction system of the heart?
Specialised system that coordinates the contraction of the muscle.
Increases efficiency and contribute to the function of Av cells by telling the hert when to contract.
Autonomic nervous input to this pathway that increases/decreases heart rate.
What is the SA node?
A cluster of cells where the conduction pathway begins. It spontaneously generates contraction potentials which pass through the atrial chambers through a series of pathways called the internodal branches.
What is the AV node?
The gateway down into the ventricular chambers
What do conduction pathways consist of?
Modified cardiac muscle cells
What are pekingie cells?
Cardiac muscle cells that no longer contract and have become modified for this role carrying conduction potentials.
Structure of pekingie cells?
Redundant Myofibrils that have been pushed to the periphery of the cell , centrally located nuclei, cytoplasm that is full of mitochondria and glycogen stores and gap junctions as the main intercellular junction.
