Facts about cardiac activity

Hyderabad: This article is in continuation to the previous article that focused on double circulation of blood. In this article we will discuss regulation of cardiac activity, disorders of circulatory system, Coronary Artery Diseases (CADs). REGULATION OF CARDIAC ACTIVITY: Normal activities of the heart are regulated intrinsically, i.e., auto regulated by specialised muscles (nodal tissue), […]

Hyderabad: This article is in continuation to the previous article that focused on double circulation of blood. In this article we will discuss regulation of cardiac activity, disorders of circulatory system, Coronary Artery Diseases (CADs).

REGULATION OF CARDIAC ACTIVITY:

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Normal activities of the heart are regulated intrinsically, i.e., auto regulated by specialised muscles (nodal tissue), hence the heart is called myogenic.
A special neural centre in the medulla oblangata can moderate the cardiac function through autonomic nervous system (ANS).

Neural signals through the sympathetic nerves (part of ANS) can increase the rate of heart beat, the strength of ventricular contraction and thereby the cardiac output.
On the other hand, parasympathetic neural signals (another component of ANS) decrease the rate of heart beat, speed of conduction of action potential and thereby the cardiac output.
Adrenal medullary hormones can also increase the cardiac output.

DISORDERS OF CIRCULATORY SYSTEM
High Blood Pressure (Hypertension): Hypertension is the term for blood pressure that is higher than normal (120/80).

In this measurement 120 mm Hg (millimetres of mercury pressure) is the systolic, or pumping, pressure and 80 mm Hg is the diastolic, or resting, pressure.
If repeated checks of blood pressure of an individual are 140/90 (140 over 90) or higher, it shows hypertension.

High blood pressure leads to heart diseases and also affects vital organs like brain and kidney.

Coronary Artery Disease (CAD):

Coronary artery disease, often referred to as atherosclerosis, affects the vessels that supply blood to the heart muscle.
It is caused by deposits of calcium, fat, cholesterol and fibrous tissues, which makes the lumen of arteries narrower.
Angina: It is also called ‘angina pectoris’.

A symptom of acute chest pain appears when no enough oxygen is reaching the heart muscle.
Angina can occur in men and women of any age but it is more common among the middle-aged and elderly. It occurs due to conditions that affect the blood flow.
Heart Failure: Heart failure means the state of heart when it is not pumping blood effectively enough to meet the needs of the body.

It is sometimes called congestive heart failure because congestion of the lungs is one of the main symptoms of this disease.
Heart failure is not the same as cardiac arrest (when the heart stops beating) or a heart attack (when the heart muscle is suddenly damaged by an inadequate blood supply).