The Digestive System

Part C
Digestion is the procedure of breaking down food into smaller parts. Most of the food humans consume should be digested into more basic parts, in order for it to be absorbed into the body and used within the body. Additionally, nutrients are the most important substances that allow the body to perform daily activities. Furthermore, carbohydrates, fats and proteins are the chief nutrients that the human body needs, in order to grow, repair, move, and maintain homeostasis. These nutrients are broken down and absorbed into the body at different rates, and into precise arrangements, as they travel through the organs throughout the digestive system.

• Carbohydrates are the body's preferred energy source, and are found in the forms of starch, sugar and fibre. Additionally, carbohydrates move into the small intestine, where enzymes released by the pancreas break those carbohydrates into simple forms, so they can be absorbed into the bloodstream.
• Lipids that are consumed, are mainly fats.
Bile is produced in the liver, stored and released in the gall bladder, and combines fat bubbles into smaller particles. The combined particles are broken down, into fatty acids. Furthermore, those fatty acids combine with cholesterol and bile, and move into the cells. Then, most of them pass into vessels, near the intestine. These vessels, transference lipids to the veins, and the blood in the body carries lipids to be stored in tissue throughout the human body.
• Proteins are mainly found in meat, eggs, dairy products, fish, and nuts. Protein must be digested by enzymes into small molecules called amino acids, before protein can be used to build and repair tissues. Amino acids are absorbed into the bloodstream and then transported throughout the body.

Carbohydrates (Amylase) – produced in the stomach, small intestine, and pancreas.
Protein – Amino Acids

Lipids (Gastric lipase) – produced in the small intestine, and pancreas. Starch – Glucose

Protein (Pepsin) – produced in the stomach, pancreas, and small intestine.
Fats (lipids) – Fatty acids and glycerol

Part D

The cardiovascular system, the respiratory system, and the digestive system, are the three systems that interrelate for the complete function of the human body.
The respiratory and cardiovascular systems work together to perform the gas exchange. Without gas exchange, the cells would die. Therefore, it is vital for these systems to work together. Through the respiratory system, oxygen enters the body, and then it is transported as oxyhaemoglobin to the cells, and this is with the help of the cardiovascular system. Additionally, the cardiovascular system also transports the waste. For example, carbon dioxide. The waste is transported to the respiratory system, which gets rid of unwanted substances. Furthermore, without the respiratory system, oxygen will not be able to enter the body, and it could not release the carbon dioxide waste. Therefore, without the cardiovascular system, the oxygen and carbon dioxide could not travel throughout the body, in order for us to
breathe.

Moreover, the cardiovascular system connects with the digestive system for a peak heart rate. The digestive system produces nutrients, and with help from the cardiovascular system, transports the nutrients where it is needed throughout the body. The digestive toxins are also discharged from system with the help of the cardiovascular system, which transports them to kidneys. Furthermore, the digestive system breaks down large molecules, into simple molecules, such as glucose. These are then transported to cells of the body via the circulatory system.