Digestion in Amoeba and Hydra

Digestion in Amoeba

• Digestion process in Amoeba includes ingestion, digestion, absorption, assimilation, and egestion.
• Heterotrophic nutrition is achieved through phagocytosis, allowing Amoeba to engulf food particles like bacteria, algae, and protozoans using pseudopodia.
• Intracellular digestion occurs within food vacuoles formed from engulfed food, which fuse with lysosomes containing enzymes.
• Enzymes such as proteases, nucleases, and lipases break down food particles during digestion.
• Nutrients from digested food are absorbed to support cellular growth and energy; excess is stored as glycogen or lipids.
• Egestion involves expelling undigested material through the vacuole.

Digestion in Hydra

• Hydra exhibits both intracellular and extracellular digestion; fragments of food are engulfed by nutritive-muscle cells.
• Gastrovascular cavity serves for digestion and nutrient circulation; proteins, fats, and carbohydrates can be digested, with starch being indigestible.
• Absorption occurs as nutrients diffuse from the gastrodermal cells post-digestion.
• Egestion of indigestible residues is achieved through muscular contractions, with the mouth also functioning as an anus.

Nutrition in Ruminants

• Ruminants belong to the suborder Ruminantia and order Artiodactyla, including giraffes, deer, cattle, sheep, and goats.
• They possess a four-chambered stomach that facilitates complex digestion, mixing food with hydrochloric acid and pepsinogen to form chyme.

Human Alimentary Canal

• Small Intestine: Once food reaches the duodenum, it mixes with pancreatic enzymes and bile, leading to nutrient absorption via villi, which connect to capillaries for nutrient uptake.
• Large Intestine: Absorbs remaining water and nutrients; transforms waste into stool, stored in the rectum until egestion through the anus.

Associated Digestive Glands

• Salivary Glands: Produce saliva containing salivary amylase, facilitating starch digestion.
• Stomach Glands: Secrete hydrochloric acid, creating an acidic environment for pepsin to digest proteins.
• Liver: Breaks down fats, processes nutrients, filters impurities, and generates glucose from non-carbohydrate sources.
• Pancreas: Secretes pancreatic enzymes for digestion, with peristalsis aiding bolus movement through the esophagus to the stomach.

Digestive Process in the Stomach

• Gastric juice, consisting of water, hydrochloric acid, and enzymes, facilitates protein breakdown into polypeptides.
• Churning movements mix food with digestive juices, and peristaltic waves propel the mixture towards the duodenum.

Digestive Process in the Small Intestine

• Pancreatic juice raises pH for optimal enzyme activity; trypsin and chymotrypsin digest proteins, while amylase and lipase target carbohydrates and fats, respectively.
• Bile emulsifies fats into smaller droplets, enhancing fat digestion.
• Intestinal juice further breaks down emulsified fats and carbohydrates, helping absorb nutrients through enterocytes.

Enzymatic Actions

• Pancreatic Juice: Activates with alkaline pH; involved in protein (trypsin, chymotrypsin), carbohydrate (amylase), and fat (lipase) digestion.
• Bile: Contains bile salts that emulsify fats for better enzyme action.
• Intestinal Juice: Completes digestion of fats and carbohydrates; contains enzymes like sucrase, maltase, and lactase for monosaccharide production.