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) 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) Changes that occur in the ribcage and diaphragm during inhalation:
a) During inhalation, the ribcage expands. The intercostal muscles between the ribs contract, pulling the ribs upward and outward. This movement increases the volume of the thoracic cavity, creating negative pressure in the lungs. The diaphragm, which is a dome-shaped muscle located below the lungs, contracts and flattens out. This further increases the volume of the thoracic cavity and allows the lungs to expand. As a result, air rushes into the lungs through the nose or mouth.
b) During exhalation, the ribcage and diaphragm return to their resting positions. The intercostal muscles relax, allowing the ribs to move downward and inward. This reduces the volume of the thoracic cavity, causing an increase in pressure in the lungs. The diaphragm relaxes and moves back up into its dome-shaped position. This decrease in volume and increase in pressure in the lungs cause air to be expelled out of the lungs.
2) How the walls of the stomach are protected against corrosion by hydrochloric acid and digestion by protein enzymes:
a) The walls of the stomach are protected against corrosion by hydrochloric acid through several mechanisms. The stomach lining has a layer of mucus that covers its inner surface, forming a protective barrier. This mucus layer acts as a physical barrier, preventing the acid from coming into direct contact with the stomach tissue. Additionally, the mucus contains bicarbonate ions, which help neutralize the acid and maintain a relatively neutral pH close to the lining of the stomach.
b) The walls of the stomach are protected against digestion by protein enzymes by the same layer of mucus. The mucus not only acts as a physical barrier against the enzymes but also contains substances called mucoproteins that inhibit the activity of these enzymes. This prevents the enzymes from attacking and breaking down the proteins within the stomach wall.
3) How the alkalinity of the duodenum is maintained:
The alkalinity of the duodenum, the first part of the small intestine, is maintained through a combination of secretions from various glands and organs:
- Bile, produced by the liver and stored in the gallbladder, is released into the duodenum. Bile contains bile salts, which emulsify fats and create an alkaline environment.
- Pancreatic juice, produced by the pancreas, is also released into the duodenum. This juice contains bicarbonate ions, which neutralize the acidic chyme (partially digested food) coming from the stomach, thereby raising the pH and maintaining alkalinity.
- Secretions from the Brunner's glands, located in the duodenum's submucosa, also contribute to its alkalinity. These secretions contain bicarbonate ions as well.
The collective action of these secretions helps maintain the alkaline environment necessary for the proper functioning of digestive enzymes and protects the duodenal lining from the acidic chyme.
4) Ingestion, digestion, absorption, and assimilation of ugali:
Ugali is a type of food common in Eastern Africa, particularly in countries like Kenya and Tanzania. Here's a step-by-step breakdown of its ingestion, digestion, absorption, and assimilation:
Ingestion: Ugali is typically made by mixing maize flour with water and cooking it to form a thick paste-like consistency. It is then consumed directly as a staple food.
Digestion: Digestion of ugali primarily occurs in the stomach and small intestine. In the stomach, mechanical digestion begins as the food is churned and mixed with gastric juices, including hydrochloric acid and protein-digesting enzymes (such as pepsin). Enzymes break down the proteins present in the maize flour. In the small intestine, further digestion takes place through the action of pancreatic enzymes, which break down complex carbohydrates (such as starch) in the ugali into smaller sugar molecules.
Absorption: The end products of digestion, such as simple sugars, amino acids, and other nutrients, are absorbed through the walls of the small intestine into the bloodstream. This absorption is facilitated by specialized cells in the lining of the small intestine called villi and microvilli, which increase the surface area for absorption.
Assimilation: Once absorbed into the bloodstream, the nutrients are transported to various organs and tissues of the body. In the case of ugali, the sugars are converted into glucose, which can be used by cells for energy. The amino acids are used for protein synthesis in the body. Other nutrients are also utilized for various metabolic processes and to support bodily functions.
5) The enzyme that digests maltose to glucose is called maltase. Maltase is produced by the cells lining the small intestine. It breaks down maltose, a disaccharide consisting of two glucose molecules, into individual glucose molecules. These glucose molecules can then be absorbed into the bloodstream for further use in the body's energy production and other metabolic processes.