When breathing out the intercostals and diaphragm relaxes. Thorax volume decreases and the air is forced out of the lungs. Air is forced in the rib cage and sternum drop in and down, then the air is forced out the thorax and finally to force the air out of the thorax the diaphragm moves up.
Describe the jobs of red and white blood cells and explain how these are carried out.
The job of the red blood cell is to carry oxygen to all the cells in the body. They have a flying doughnut shape to give maximum surface area for absorbing oxygen. In the lungs, haemoglobin absorbs oxyhaemoglobin. In body tissues the reverse happens to release oxygen to the cells. They have no nucleus to make more room for haemoglobin.
The white blood cells jobs are to be defence against disease. They have a large nucleus. They absorb unwelcome microbes (bacteria). They also produce anti bodies to fight bacteria and antitoxins to neutralise the toxins produced by bacteria.
Draw an alveoli to show its structure and explain how its structure is adapted to its function.
The bronchioles finally end at small bags called alveoli where the gas exchange takes place.
An alveoli are an ideal exchange surface, they have and enormous surface area. A moist lining for dissolving gases. Very thin walls and a copious blood supply.
Describe the events occurring during digestion, and the enzymes and juices involved, until the digested food enters the villi.
The event that occurs during digestion, saliva moistens the food. Contains amylase, which begins the digestion of starch in the mouth. The pits in the stomach wall produce gastric juice, which contains hydrochloric acid and the enzymes pepsin and rennin. The bile, which is produced in the liver, neutralises acid from the stomach and breaks fats into small droplets, which are easier for the enzymes to digest. Pancreatic juice contains four different enzymes, which digest carbohydrate, fat and protein. Absorption occurs when nutrients pass through its cells and into the blood and lymph vessels.
