The heart lung machine is used so that surgeons can oprate on the arteries supplying heart muscle.the arteries may be diseased.

(a) Name these arteries and explain how they may become diseased
(b) suggest why a patient is put on a heart lung machine during such an operation.

(a) The arteries supplying the heart muscle are called the coronary arteries. These arteries may become diseased due to a condition called coronary artery disease (CAD). CAD occurs when plaque, which is made up of cholesterol, fatty substances, calcium, and other cellular waste products, builds up inside the walls of the coronary arteries. Over time, this plaque can harden and narrow the arteries, a condition known as atherosclerosis. The narrowing of the arteries restricts blood flow to the heart muscle, leading to various symptoms like chest pain (angina), shortness of breath, and in severe cases, even heart attacks.

(b) During an operation on the arteries supplying the heart muscle, a patient may be put on a heart-lung machine (also known as a cardiopulmonary bypass machine). This machine temporarily takes over the functions of the heart and lungs while allowing the surgeon to operate on the heart in a bloodless and motionless environment. Here's how the heart-lung machine works:

1. Blood is diverted from the patient's body into the heart-lung machine through plastic tubes called cannulas.
2. The blood passes through a pump, an oxygenator, and a heat exchanger in the machine.
3. The pump simulates the action of the heart, circulating the blood through the machine.
4. The oxygenator adds oxygen to the blood, removing carbon dioxide, just like the lungs do.
5. The heat exchanger regulates the temperature of the blood, maintaining normal body temperature.
6. The oxygenated and temperature-regulated blood is then returned to the patient's body through another set of cannulas, bypassing the heart and lungs.

By using a heart-lung machine, the surgeon can stop the patient's heart momentarily, allowing them to operate on the arteries without the risk of excessive bleeding or potential damage from the heart's movements. Additionally, the heart-lung machine ensures adequate oxygenation and perfusion of the patient's organs and tissues while the heart is non-functional.

(a) The arteries supplying the heart muscle are known as the coronary arteries. They may become diseased due to a condition called coronary artery disease (CAD). CAD is primarily caused by a buildup of plaque inside the arteries. Plaque consists of cholesterol, fat, calcium, and other substances that can accumulate over time and narrow the coronary arteries. This narrowing, called atherosclerosis, reduces blood flow to the heart muscle, leading to various complications such as angina (chest pain) or even a heart attack.

(b) During an operation on the coronary arteries, a patient may be put on a heart lung machine for several reasons. First, it allows the surgeon to temporarily bypass the heart and lungs, enabling them to operate on the heart without blood flowing through it. This is important for procedures such as coronary artery bypass grafting (CABG), where the surgeon needs to create new pathways for blood to reach the heart muscle by using segments of healthy blood vessels from elsewhere in the body.

Secondly, the heart lung machine takes over the functions of the heart and lungs during the procedure. It circulates oxygenated blood throughout the body, providing a steady supply of oxygen and nutrients to vital organs and tissues. Additionally, the heart lung machine removes carbon dioxide and waste products from the blood, maintaining the body's normal metabolic balance.

Overall, the heart lung machine allows the surgeon to operate on the coronary arteries while maintaining vital organ perfusion and oxygenation, ensuring the patient's safety and providing optimum conditions for successful surgery.