CV system: Cardiac structure and function Flashcards
How does the heart receive its blood supply?
Via coronary arteries
What is myocardial infarction (MI)?
- Blockage in coronary blood flow results in cell damage.
- Exercise training protects against heart damage during an MI.
The Heart Wall: What are the characteristics and function of the endocardium?
Characteristics: endothelial tissue and a thick subendothelial layer of elastic and collagenous fibres.
Function: Serves as protective inner lining of the chambers and valves.
The Heart Wall: What are the characteristics and function of the myocardium?
Characteristics: Cardiac muscle tissue separated by CT and including blood capillaries, lymph capillaries, and nerve fibres.
Function: Provides muscular contractions that eject blood from the heart chambers
The Heart Wall: What are the characteristics and function of the epicardium (visceral pericardium)?
Characteristics: Serous membrane including blood capillaries, lymph capillaries, and nerve fibres.
Function: Serves as lubricating outer covering.
What is pericarditis?
The pericardial cavity is filled with pericardial fluid which lubricates. Pericarditis is when there is not enough fluid. It is the inflammation of the lining around your heart.
Describe how an AP travels through the heart.
- APs originate in the SA node and travel across the atrium wall from SA to AV node.
- APs pass through AV node and along AV bundle (extends from AV node) through fibrous skeleton, into the interventricular septum.
- The AV bundle divides into right and left bundle branches, and APs descend to the apex of each ventricle along the bundle branches
- APs area carried by the Purkinje fibres from the bundle branches to the ventricular walls.
What does the P wave show?
Atrial depolarization
What does the QRS complex show?
Ventricular depolarization and atrial repolarisation
What does the T wave show
Ventricular repolarization
What is end diastolic volume?
The maximum amount of blood in the ventricles
What is systolic volume?
Amount of blood remaining in heart after ventricular contraction
In exercise, O2 extraction can increase but increased O2 delivery relies mainly on what?
An increase in coronary blood flow.
What is heart O2 consumption principally required for?
Contraction, with requirements for maintaining basal metabolism comprising only 10-20% of total O2 consumption
Coronary blood flow is closely related to cardiac work. What are coronary blood vessels mainly controlled by?
Control of coronary blood flow is mainly metabolic - main metabolic vasodilator is ADENOSINE.
-Also β-adrenergic vasodilation (via ANS)