A) describe the process of digestion of food in human beings with diagram.
b) describe the respiraton process in human being with diagram.
Answers
Answer:
A) The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). In this system, the process of digestion has many stages, the first of which starts in the mouth (oral cavity). Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body. The secretion of saliva helps to produce a bolus which can be swallowed to pass down the oesophagus and into the stomach.
Saliva also contains a catalytic enzyme called amylase which starts to act on food in the mouth. Another digestive enzyme called lingual lipase is secreted by some of the lingual papillae on the tongue and also from serous glands in the main salivary glands. Digestion is helped by the mastication of food by the teeth and also by the muscular actions of peristalsis and segmentation contractions. Gastric juice in the stomach is essential for the continuation of digestion as is the production of mucus in the stomach.
Peristalsis is the rhythmic contraction of muscles that begins in the oesophagus and continues along the wall of the stomach and the rest of the gastrointestinal tract. This initially results in the production of chyme which when fully broken down in the small intestine is absorbed as chyle into the lymphatic system. Most of the digestion of food takes place in the small intestine. Water and some minerals are reabsorbed back into the blood in the colon of the large intestine. The waste products of digestion (faeces) are defecated from the anus via the rectum.
B) Air is drawn into the body through the nostrils.
ii. The air from the nasal cavity passes to the pharynx, which leads to the trachea, through a slit called glottis.
iii. The trachea runs down the neck and divides into two bronchi, which lead into the lungs and further divide into smaller bronchioles. The smallest bronchioles terminate into alveoli.
iv. The walls of the alveoli are thin and covered by blood capillaries to facilitate the exchange of gases in the lungs.
v. In the alveoli, the exchange of gases takes place, CO 2 from the blood is replaced with O 2 and CO 2 is removed out of the body.
vi. In humans, for the process of respiration, air is drawn into the lungs by the process of breathing.
When an individual inhales, the diaphragm moves down, and the chest cavity expands and the oxygen rich air is drawn into the lungs. When the individual exhales, the diaphragm relaxes and the chest cavity moves back to its relaxed position and the carbon dioxide rich air is expelled out of the body.
October 15, 2019
