The small intestine is over 6 metres long and is the place where most of the nutrients are absorbed. There are three parts to the small intestine. They are the duodenum, the jejunum and the ileum. The inside of the small intestine is covered by millions of tiny finger like projections called villi. The shape of the villi ensures a large surface area so that the digested food can be absorbed quickly.
What is peristalsis and where does it occur?
Peristalsis is the process of food being propelled downwards, this takes place in the oesophagus. Peristalsis is muscular contractions that squeeze and relax the walls of the oesophagus.
Briefly describe the process of digestion from ingestion of food to the elimination of waste
The mouth takes in the food and uses the teeth and salivary glands to break down the food so it could move onto the next phase. The pharynx pushes the food down into the oesophagus also known as the food pipe. The oesophagus uses the process of peristalsis to propel the food down towards the stomach. The stomach uses hydrochloric acid and pepsin to help with the break down of food the stomach churns the food for the process of breaking down the food and then leaves the stomach in the form of chyme. This then enters the small intestine, this is where all the nutrients in the food are absorbed. Also in the digestive process the pancreas and the liver also play a part. The pancreas releases hormone in the body via the blood steam as well as that it also produces enzymes such as, Trysin- which digests proteins and breaks them down into amino acids,
Amylase- which continues the digestion of starch,
Lipase- which breaks down the fats into fatty acids and glycerol,
The pancreas also keeps a check on the amount of glucose in the blood. If the levels of glucose are too high or too low, it produces hormones that stimulate the liver to adjust the balance. The liver has a number of functions such as,
Storing and filtering blood,
Secreting bile to help break down fat,
Detoxification of harmful substances such as alcohol, paracetomol and other chemicals into safer form,
Storage of vitamins A,D,E and K,
Storage of glycogen, which can be broken down into glucose and used for energy by the body when required,
The large intestine is also known as the colon. Here any undigested food is now waste (roughage) this passes from the small intestine to the large intestine in liquid form. Any remaining nutrients and water are removed from the waste matter and are reabsorbed back into the body. The result is solid faeces being formed. From here the waste is emptied into the rectum. The rectum has two sphincter muscles at the end and this is known as the anus, waste matter is expelled through the anus, this is known as elimination.
State four functions of the liver as part of the digestive system
The liver has a number of functions such as,
* Storing and filtering blood,
* Secreting bile to help break down fat,
* Detoxification of harmful substances such as alcohol, paracetomol and other
chemicals into safer form,
* Storage of vitamins A,D,E and K,
* Storage of glycogen, which can be broken down into glucose and used for energy by
the body when required.
Give three metabolic functions of the liver as part of the excretory system
* Stored fat is broken down to provide energy.
* Excess amino acids are broken down and converted into urea
* Drugs and poisons are broken down
* Antibodies and antitoxins are made
What organs make up the urinary system?
The urinary system are made up of the following organs,
* The kidneys/renal organs
* The ureter
* The bladder
* The urethra
What is the difference between a male and female urethra?
The male urethra is a common canal for the urinary system and reproductive system and is 18-20cms long. The female urethra. In the female it serves as the urinary system only and is 4cm long.
What is the main function of the urinary system?
The main function of the urinary system is to keep the body in homeostasis (balanced body). The system also helps to control the PH of the blood and regulate blood pressure.
