1) During inhalation, the ribcage expands as the intercostal muscles contract, and the diaphragm contracts and moves downward. This expansion increases the volume of the thoracic cavity, creating a lower pressure inside the lungs. As a result, air rushes into the lungs.
During exhalation, the ribcage relaxes as the intercostal muscles relax, and the diaphragm relaxes and moves upward. This reduces the volume of the thoracic cavity, increasing the pressure inside the lungs. This increased pressure forces air out of the lungs.
2) a) The walls of the stomach are protected against corrosion by hydrochloric acid through the presence of a layer of mucus. Mucus is secreted by specialized cells in the stomach lining and forms a thick protective barrier that prevents direct contact between the hydrochloric acid and the stomach wall.
b) The walls of the stomach are protected against digestion by protein enzymes through several mechanisms. First, protein enzymes in the stomach, such as pepsin, are secreted in an inactive form called pepsinogen. This prevents them from digesting the stomach's own proteins. Once in the stomach, the low pH environment activates pepsinogen, converting it into the active enzyme pepsin. Secondly, the stomach lining has a thick layer of mucus that prevents the enzymes from coming into contact with the stomach wall.
3) The alkalinity of the duodenum is maintained through the secretion of bicarbonate ions by cells in the duodenum and the pancreas. Bicarbonate ions neutralize the acidic chyme that enters the duodenum from the stomach, raising its pH level. This is important because the enzymes in the small intestine that digest food work optimally at a neutral or slightly alkaline pH.
4) Ugali is a staple food in East Africa, particularly in countries like Kenya and Tanzania. The process of ingestion, digestion, absorption, and assimilation for ugali is as follows:
Ingestion: Ugali is typically made from maize flour and water, which are combined to form a thick, stiff dough-like consistency. It is ingested by eating it.
Digestion: The digestion of ugali primarily occurs in the stomach and small intestine. In the stomach, the mechanical action of chewing and the release of salivary amylase begin breaking down the carbohydrate in the maize flour. In the small intestine, pancreatic enzymes and enzymes produced by the small intestine break down the carbohydrates, proteins, and fats in ugali into smaller molecules.
Absorption: The small intestine is responsible for absorbing the breakdown products of carbohydrates (glucose), proteins (amino acids), and fats (fatty acids and glycerol). These molecules are then absorbed into the bloodstream and transported to various cells in the body.
Assimilation: Once absorbed, the glucose, amino acids, and fatty acids are transported to cells throughout the body. They are then utilized for energy production, building new molecules, and other cellular processes.
5) The enzyme that digests maltose to glucose is called maltase. Maltase is produced by cells lining the small intestine, particularly in the duodenum. It catalyzes the hydrolysis reaction, breaking down maltose (a disaccharide composed of two glucose molecules) into two glucose molecules.
1)Describe changes that occur in the ribcage and diaphragm during;
a)Inhalation
b)Exhalation
2)Explain how the walls of the stomach are protected against;
a)Corrosion by hydrochloric acid
b)Digestion by the protein enzymes
3)Explain how the alkalinity of the duodenum is maintained.
4)Describe the ingestion digestion,absorption and assimilation of ugali
5)Name the enzymes that digest maltose to glucose
1 answer