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.

RAYS OF LIGHT

RAYS OF LIGHT

HEART

*The divine is always seated in your heart, consciously living in you.

*It is the heart that has wings, not the head.

*For the mind-knowledge
  For the heart –love and joy
  For the life-power
  For the matter –beauty.

  RAYS OF LIGHT
  Sayings of 
  THE MOTHER

RESPIRATORY SYSTEM-SECRETS

RESPIRATORY SYSTEM-(SECRETS)

1. Explain the voluntary control of respiration

Voluntary control of respiratory muscles by the motor cortex can override the medullary respiratory centre. This allows us either to speed up ventilation or to hold our breath at will. However, voluntary control is only partial, because if we stop breathing for more than a minute or so, arterial pco2 rises and po2 falls providing a chemoreceptor –driven stimulus to ventilation.

2. What is air hunger?

Increased activity in the vasomotor centre is primarily responsible for cardiovascular adjustments to low blood pressure but also stimulates ventilation. This explains the increased breathing, known as air hunger, which is seen in surgically shocked patients.

3. What is smokers cough?

Individuals who smoke create a constant irritation to the trachea. Overtime, the irritation from smoke can cause the epithelium of trachea to change from a pseudo stratified ciliated columnar to stratified, squamous epithelium. Without cilia, the epithelium cannot clear the mucus and debris. This provides an environment for the growth of microorganism leading to respiratory infections. This trigger the cough reflex commonly called smokers cough.

4. What are the effects of ageing on the respiratory system?

With advancing age, the airways and tissues of the respiratory tract, including the alveoli, become less elastic and more rigid; the chest wall also becomes more rigid. the result is a decrease in lungcapacity.moreover ,a decrease in blood level of o2,decreased activity of alveolar macrophages and diminished ciliary action of the epithelial lining .owing to all these age related factors ,elderly people are more susceptible to pneumonia, bronchitis and other pulmonary disorders.

5. What is the significance of residual volume?

Some amount of air is always present in the lung because of RV or FRC, and therefore continuous exchange of gases is made possible and thereby concentrations of o2 and co2 in blood are maintained constant.

6. Why are venous RBCs more fragile than arterial RBCs?

When blood passes through tissue capillaries, co2 enters into blood and causes chloride shift. (Chloride ions diffuse from plasma into the RBCs).as a result, osmotic pressure inside the RBCs becomes higher than that of plasma. this causes osmotic absorption of fluid into the RBCs.venous RBCs contain therefore the greater quantity of fluid as compared to arterial RBCs .when placed in hypotonic solutions they can take lesser amount of fluid and hence more fragile than arterial RBCs.

PHYSIOLOGY SECRET

PHYSIOLOGY SECRET

Comment on fatigue in diaphragm
Diaphragm is a striated skeletal muscle innervated by phrenic nerve. (C3-C5).Like the heart it must contract in repetitive rhythmical fashion for life. The muscle composition of diaphragm is well suited to the task. Though diaphragm is a skeletal muscle, it is not fatigued.
55% of diaphragm fibers are slow twitch oxidative type: Highly resistant to fatigue.

25% are fasttwitch, oxidative, glycolytic type: Relatively resistant to fatigue.

The remaining 20% are fast twitch glycolytic: susceptible to fatigue.

In general, slow twitch oxidative fibers are arranged with more capillaries, myoglobin, mitochondria and isoenzymes that favors aerobic metabolism. In addition, fast twitch with less capillaries, myoglobin, mitochondria, and isoenzymes that favors anaerobic metabolism.75percentageof muscle fibers have good to excellent endurance characteristics.