Chapter 9: Cardiac Physiology Flashcards
What are the layers of the heart?
Endocardium, Myocardium, Epicardium, Pericardium
The heart consists of four main layers, each with specific functions.
What is the function of the myocardium?
Thick for contractions
The myocardium is responsible for the heart’s pumping action due to its muscular structure.
Which layer of the heart has large T-tubules?
Myocardium
The presence of large T-tubules facilitates rapid depolarization and contraction.
What structures are found in the endocardium?
No intermediate filaments, Troponin, Tropomyosin
These proteins play crucial roles in muscle contraction.
What is the purpose of the pericardium?
Attaches heart to sternum and keeps it in place
The pericardium protects the heart and anchors it within the thoracic cavity.
What are intercalated disks?
Desmosomes and gap junctions
These structures facilitate communication and mechanical attachment between cardiac muscle cells.
What are chordae tendineae?
Projections called papillary muscles
Chordae tendineae connect the papillary muscles to the heart valves, preventing valve inversion.
Fill in the blank: The _______ layer of the heart is responsible for the pumping action.
Myocardium
True or False: The epicardium is the outermost layer of the heart.
True
What are the two main functions of the epicardium?
Protects the heart, provides a smooth surface for the heart
The epicardium is also involved in the formation of the pericardial cavity.
What is the role of the endocardium?
Lines the heart chambers and covers the heart valves
It helps to prevent blood from clotting and reduces friction during heartbeats.
What does the SA Node set in cardiac physiology?
BIM
BIM stands for Basic Intrinsic Mechanism.
What is the intrinsic rate of the SA Node?
60-100 bpm
What is the intrinsic rate of the AV Node?
40-60 bpm
What is the intrinsic rate of the Bundle of His?
20-40 bpm
What happens when the SA Node fails?
AV Node takes over at 40-60 bpm
Fill in the blank: The SA Node sets the _______ of the heart.
rhythm
True or False: The SA Node is the primary pacemaker of the heart.
True
What does the term ‘ectopic focus’ refer to?
Abnormal pacemaker activity outside the SA Node
What are the two main types of conduction pathways in the heart?
Internodal pathways and interatrial pathways
What is the normal heart rate range set by the SA Node?
60-100 bpm
What happens to the heart rate if both the SA Node and AV Node fail?
Ventricles may take over at 20-40 bpm
Fill in the blank: The Bundle of His connects the _______ to the ventricles.
atria
What is the significance of latent pacemakers?
They can take over pacing if the primary pacemaker fails
What is the term for the heart’s ability to generate its own rhythm?
Automaticity
How does the heart rate change in response to increased vagal tone?
Decreases
