Human Nutrition

Parietal cells

Step 1: Gastric glands contain three main types of cells with different functions. Step 2: Parietal cells (also called oxyntic cells) specifically secrete hydrochloric acid (HCl) and intrinsic factor. Step 3: HCl creates the acidic environment needed for pepsin activation and kills harmful bacteria. Step 4: Mucus cells secrete protective mucus, while peptic/chief cells secrete pepsinogen enzyme. Step 5: The intrinsic factor from parietal cells is essential for vitamin B12 absorption in the small intestine.

Ileum

Step 1: The small intestine has three parts with different lengths. Step 2: Duodenum is about 26 cm long and U-shaped. Step 3: Jejunum is about 2.5 meters long and forms the middle portion. Step 4: Ileum is about 3.5 meters long, making it the longest part of the small intestine. Step 5: Caecum is part of the large intestine, not the small intestine. The ileum's length provides maximum surface area for nutrient absorption.

Vitamin B12

Step 1: The liver plays a crucial role in storing and processing various vitamins. Step 2: Vitamin B12 is specifically stored in large quantities in the liver (about 2-5 mg). Step 3: The liver synthesizes and stores vitamin B12, and liver damage can severely affect B12 metabolism. Step 4: While the liver also processes other vitamins, B12 deficiency is most directly linked to liver dysfunction. Step 5: Liver damage can also affect the production of intrinsic factor needed for B12 absorption, leading to deficiency.

Proteins

Step 1: Kwashiorkor is a form of Protein Energy Malnutrition (PEM). Step 2: It specifically results from severe protein deficiency in the diet. Step 3: Children with kwashiorkor show symptoms like protruding belly, oedema, stunted growth, and poor brain development. Step 4: While calories may be adequate, the lack of proteins prevents proper growth and development. Step 5: This differs from marasmus, which involves both protein and calorie deficiency. The protein deficiency affects enzyme production and tissue maintenance.