Functional Structure Of Heart Flashcards
Mention importance of inelastic nature of percardium
Prevent sudden heart dilatation, but it allows for physiological variation in cardiac size.
Pericardium can adapt to slow stretch during ….
Growth or cariac hypertrophy
Functions of A-V ring
- Cardiac skeleton for origin & insertion for cardiac muscles with atrial above & ventricular below.
- Electric insulator between atria & ventricles. It is pierced by A-V bundle.
Describe the left venticular aid, is the opposite true?
When there is failure of right ventricle, healthy left ventricle can give an aid to RV, where its contraction will pull upon the free trangular RV wall & compress blood within its chamber against thick IV septum, thus raising pressure inside RV.
There is no RV aid.
Mention important of junction of cardiac muscle fibers
Gap junctions
Desmosomes
Mention important proteins in skeletal msucles
Myosin, actin, tropomyosin & troponin
T tubeles contain …., which are …..
Dihydropyridine receptors
Voltage-gated Ca++ channels
Terminal cisternae has …., which is ….
Ryandodine receptors
Ca++ release channels
Function of T-tubule
Rapid spread of excitation wave from surface membrane deep into interior of the muscle fiber.
Describe Ca++ indiced Ca++ release
When DHP receptors are activated, the Ca++ entered though it from the ECF triggers the release of Ca++ from cisterns of SR via ryanodine receptors.
What is meant by: the heart is a functional syncytium?
Acts as a single unit & doesn’t have multiple units unlike skeletal muscle motor units, thus to a thershold stimulus it responds fully, but with subthershold there is no response. All or none rule.
Mention structures that allow heart to act AS IF it is a true syncytium & their functions
Gap junction: allow high electric conduction with low resistance (1/400 of the normal) (electric syncytium)
Desmosomes: strong mechanical attachments between adjacent cell membranes. (Mechanical syncytium)
Mention cardiac characteristics which allow aerobic metabolism dominance.
Abundant blood supply
Hight content of myoglobin
Numerous and large elongated mitochondria
GR: Cardiac action potential is not initiated by the neural activity
There is specialized muscle tissue which initiates its own action potential (autorhythmic tissue cells) which then spreads by the conductive tissue cells to contractile cells.
Write a short note on nodal tissue
SAN & AVN
Specialized in initiation of the excitation wave at a regular rhythm