SECRETS WITHIN THE HEART

SECRETS WITHIN THE HEART

1. What is law of heart muscle?

It states that the size of the fibers, glycogen content and rate of conduction increases from nodal to purkinje, while length of systole, duration of refractory period and rhythm city increases in reverse order.

2. Which part of the conducting system of heart has longest refractory period at normal heart rate?
Right bundle branch has the longest and bundle of his has the shortest period.

3. What is the normal refractory period in children?

Oneyear-0.11 sec
6years-0.13sec
12years-0.14sec

4. What is Hill’s sign?

In aortic regurgitation, the blood pressure in the leg is higher than the arm. BP increases that is goes “uphill” as the examiner goes down the body.

5. What are neurohemal organs?

Some of the circumventricular organs function as neurohemal organs. (similar to glands but they store their secretary products in a special chamber until stimulated to release it by a signal from the nervous system or another hormone in to the circulation.eg.oxytocin and vasopressin enter the circulation in posterior pituitary and hypothalamic hypophysiotropic hormones enter the portal hypophysial circulation in the median eminence.

6. What is vagal tone?

Impulses from the vagal nerve producing inhibition of the heart beat.SA node displays intrinsic automacity –spontaneous pacemaker activity at a rate of 100-110 action potentials (beats) per minute.(SAnode is predominantly innervated by right vagus)this vagal tone reduces the resting heart rate down to 60-80 beats per minute.

7. What is vasomotor tone?

Under normal condition, C1 area of the VMC transmits signals to sympathetic vasoconstrictor fibers at a rate of half to two impulses per second called sympathetic vasoconstrictor tone. These impulses maintain a partial state of constriction in the blood vessel called vasomotor tone.

8. What is J point?

The point marking the end of QRS complex and the beginning of ST segment .at this point all parts of the ventricles have become depolarized .so no current is flowing around the heart. Therefore, the potential of ECG at this point is zero voltage.

9. What is J wave?

This is rounded rather narrow ‘hump’ like wave usually superimposed on the distal limb of QRS complex and it is due to the early repolarization.Also known as Osborne’s wave occurs in hypothermia.

10. What is central venous pressure?

Pressure in the right atrium is called CVP because all the systemic veins open into the right atrium.