Circulatory System

Why do people have redder faces after exercise?

During exercise, the heart would pump harder and more frequently to meet the body’s increase in oxygen and nutrient demands. This harder and more frequently pumping would increase the rate at which oxygen and nutrients are transported to other parts of the body as a faster rate. The increase in rate of respiration increases the amount of heat produced. The blood vessels at the skin surface would dilate to allow more heat to be loss into the environment. This dilatation of the blood vessels at the skin surface provides more space for the blood to flow. This would lead to an increase the amount of blood flowing through, thus giving someone a flushed look.  

The heart pumps harder so as to meet the body's increase demand for oxygen and nutrients to produce more energy through respiration. The harder the heart pumps, the harder the ventricular contractions to increase the rate of oxygen and nutrients being transported around the body. The blood vessels at the skin surface will dilate due to the increased frequency of blood flow. This increases frequency produces heat which is lost to the environment, causing flushed cheeks.

How does smoking affect the circulatory system?

The smoke from the cigarettes causes the platelets to become sticky and therefore more likely form blood clots. These blood clots will prevent blood from flowing through, thus diminishing the blood flow to the heart and various body parts. This results in a decreased amount of nutrients and oxygen reaching the different parts of the body, leading to potential heart attack. Also, the carbon monoxide in the smoke will bind irreversibly with the red blood cells, decreasing its oxygen carrying-capacity. This results in a decreased supply of oxygen being transported around the body and to the heart, thus also leading to potential heart failure.