a) Saliva: Saliva is a digestive fluid produced by salivary glands in the mouth. Its main function is to initiate the process of digestion. Saliva contains enzymes, such as amylase, which begins the breakdown of carbohydrates into simpler sugars. It also moistens the food, making it easier to chew and swallow. Additionally, saliva contains antibacterial agents that help to maintain oral hygiene.
b) Bile Juice: Bile juice is a greenish-yellow fluid produced by the liver and stored in the gallbladder. It plays a crucial role in the digestion and absorption of fats. Bile contains bile salts that emulsify large fat globules into smaller droplets, increasing the surface area for the action of lipase, an enzyme that breaks down fats into fatty acids and glycerol. Bile is released into the small intestine when fatty foods are ingested.
c) HCl (Hydrochloric Acid): HCl is a strong acid produced by the gastric glands in the stomach. Its main function is to create an acidic environment in the stomach, which is essential for the activation of the enzyme pepsin. Pepsin plays a key role in breaking down proteins into smaller peptides, starting the process of protein digestion.
d) Villi: Villi are tiny, finger-like projections found in the small intestine. They increase the surface area for nutrient absorption. Inside the villi, there are even smaller microscopic structures called microvilli, which further increase the absorptive surface area. The absorption of nutrients, such as carbohydrates, proteins, and fats, takes place through the walls of the small intestine and is facilitated by the presence of villi and microvilli.
