is the movement of molecules from an area of high concentration to an area of low concentration.
Interactions of the circulatory system The circulatory system interacts with the digestive system to transport food molecules around the body. Simple food molecules are absorbed through the wall of the small intestine into the bloodstream and transported around the body. The circulatory system interacts with the respiratory system to transport gases around
the body. Oxygen diffuses from the lungs into the bloodstream. Oxygen is picked up by haemoglobin in the red blood cells and transported around the body for respiration in the cells. Carbon dioxide is produced by the cells as a waste product of respiration. It is dissolved in the plasma and transported back to the lungs. It diffuses out of the capillaries and into the lungs where it is expelled from the body when we exhale. The digestive system, circulatory system and respiratory system work together to provide the body with the materials required for energy, growth and repair.
Fig. 11 The circulatory system interacts with the digestive and respiratory systems. 9.5 The circulatory system and health
Heart disease is the leading cause of death in Ireland today. It accounts for about one third of deaths each year. Heart health is affected by many factors, including diet, lifestyle and inherited factors.
Heart disease An unhealthy lifestyle and a diet that is high in salt and animal fats can lead to a condition called atherosclerosis (narrowing of the arteries). The arteries become hard and a fatty substance builds up on the inside making them narrower. The amount of blood that can flow through
the clogged arteries is reduced and the heart has to work much harder to pump blood. Sometimes a clot will form, completely blocking the flow of blood in the artery.
94 Healthy artery
Blood clot
Build-up of fatty substance
Blocked artery
Fig. 12 Atherosclerosis is the narrowing of the arteries.
