Human and Social Biology Notes PDF

Human and Social Biology Notes on Macronutrients and Micronutrients 1. Functions of Macronutrients **1.1 Carbohydrates** **Types**: Starch, reducing sugars, and non-reducing sugars **Starch**: A complex carbohydrate that serves as a primary energy source. **Reducing sugars**: simple sugars like...

Human and Social Biology Notes on Macronutrients and Micronutrients 1. Functions of Macronutrients **1.1 Carbohydrates** **Types**: Starch, reducing sugars, and non-reducing sugars **Starch**: A complex carbohydrate that serves as a primary energy source. **Reducing sugars**: simple sugars like glucose and fructose that can reduce other compounds. **Non-reducing sugars**: sugars like sucrose, which do not participate in redox reactions due to their structure. - **Functions**: Provide energy (4 kcal per gram). Spare protein is used for energy, allowing for muscle repair and growth. - Support digestive health (fiber). **Sources of carbohydrates**: Starch: rice, potatoes, corn. - Reducing sugars: fruits, honey, milk. Non-reducing sugars: table sugar, some syrups. **1.2 Lipids** **Types**: fats, oils, and phospholipids. - **Functions**: - Supply energy (9 kcal per gram). Make up cellular membranes (phospholipids). Store fat-soluble vitamins (A, D, E, K). Provide insulation and protect organs. **Sources of Lipids**: Saturated fats: butter, cheese. Unsaturated fats: olive oil, nuts, avocados. **1.3 Proteins** - **Building blocks**: Composed of amino acids. - **Functions**: - Build and repair tissues. - Act as enzymes and hormones. - Support immune function. - Maintain pH and fluid balance. - **Sources of Proteins**: - Animal sources: Meat, eggs, dairy. - Plant sources: Beans, lentils, tofu. **Chemical and Physical Properties**: - **Carbohydrates**: - Composed of carbon, hydrogen, and oxygen (C, H, O). - Soluble in water; sweet taste. - **Lipids**: - Composed mainly of carbon and hydrogen (C, H). - Insoluble in water; hydrophobic. - **Proteins**: - Composed of amino acids containing carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur (C, H, O, N, S). - Complex structures with distinct folding. **Hidden Sources of Sugars**: - Processed foods, sauces, snacks, and even savory items often contain added sugars. - Common hidden sugars: High-fructose corn syrup, sucrose, and glucose. **Effects of Sugar-Sweetened Beverages on Health**: - Increased risk of obesity, type 2 diabetes, and dental caries. - Can lead to increased triglycerides, impacting heart health. **Benefits of Fresh Fruits and Vegetables** (Specific to Caribbean): - Rich in vitamins, minerals, fiber, and antioxidants. - Tropical fruits like mango, papaya, and guava offer vital nutrients and hydration. - Vegetables such as callaloo and yams provide essential vitamins like A, C, and potassium. 2. Functions of Micronutrients **2.1 Vitamins** - **Vitamin A**: Essential for vision and immune function. Sources: Carrots, spinach, liver. - **Vitamin B1 (Thiamine)**: Important for energy metabolism and nerve function. Sources: Whole grains, legumes, nuts. - **Vitamin C**: Antioxidant; aids in tissue repair and immune function. Sources: Citrus fruits, strawberries, broccoli. - **Vitamin D**: Essential for calcium absorption and bone health. Sources: Fortified milk, sunlight exposure. - **Vitamin E**: Antioxidant; protects cell membranes. Sources: Nuts, seeds, vegetable oils. - **Vitamin K**: Important for blood clotting and bone health. Sources: Leafy greens, broccoli. **2.2 Minerals** - **Calcium**: Needed for strong bones and teeth. Sources: Dairy products, leafy greens. - **Magnesium**: Involved in over 300 biochemical reactions, including muscle and nerve function. Sources: Nuts, whole grains, green leafy vegetables. - **Fluoride**: Enhances dental health and prevents cavities. Sources: Fluoridated water, tea. - **Iodine**: Essential for thyroid function and metabolism. Sources: Iodized salt, seafood. - **Phosphorus**: Important for bone health and energy production. Sources: Meat, dairy, nuts. - **Sodium**: Critical for maintaining fluid balance. Sources: Table salt, processed foods. - *Iron*: Necessary for oxygen transport in red blood cells. Sources: Red meat, beans, fortified cereals. **Hidden Sources of Salt**: - Processed and packaged foods, condiments (ketchup, soy sauce), snacks, and ready-to-eat meals often contain high levels of hidden salt. Deficiency Diseases: Causes, Symptoms, and Treatment 1. Night Blindness (Vitamin A Deficiency) **Cause**: - **Deficiency of Vitamin A**: This vitamin is essential for the production of visual pigments in the retina and maintaining overall eye health. Common causes include inadequate dietary intake, malabsorption, or certain medical conditions that affect fat absorption. **Symptoms**: - Difficulty seeing in low light or darkness (nyctalopia). - Dryness of the eyes (xerophthalmia). - In severe cases, it can lead to complete blindness. **Treatment**: - **Dietary Changes**: Increase intake of vitamin A-rich foods such as carrots, sweet potatoes, spinach, and liver. - **Supplements**: Oral vitamin A supplements may be recommended, especially in severe cases or in populations at risk. - **Public health interventions**: Vitamin A supplementation programs in areas where deficiency is prevalent. 2. Iron-Deficiency Anaemia **Cause**: - **Deficiency of Iron**: This can occur due to insufficient iron intake, poor absorption, blood loss (e.g., menstruation or gastrointestinal bleeding), or increased demand (e.g., during pregnancy). **Symptoms**: - Fatigue and weakness. - Pale skin and mucous membranes. - Shortness of breath and dizziness. - Cold hands and feet. - Brittle nails and headaches. **Treatment**: - **Dietary Changes**: Increase intake of iron-rich foods such as red meat, beans, lentils, fortified cereals, and spinach. - **Supplements**: Oral iron supplements (ferrous sulfate) may be prescribed. - **Addressing Underlying Causes**: Treatment of any underlying conditions causing blood loss or malabsorption. 3. Rickets (Vitamin D Deficiency) **Cause**: - **Deficiency of Vitamin D**: This can occur due to lack of sunlight exposure, poor dietary intake of vitamin D (found in fatty fish, fortified dairy, and eggs), or malabsorption issues. **Symptoms**: - Bone pain or tenderness. - Delayed growth and development in children. - Weakening of bones, leading to deformities such as bowed legs or curvature of the spine. - Muscle weakness. **Treatment**: - **Dietary Changes**: Increase intake of vitamin D-rich foods and foods fortified with vitamin D. - **Sunlight Exposure**: Encourage safe exposure to sunlight. - **Supplements**: Vitamin D supplements may be given, especially for at-risk populations (infants, children, and those with limited sun exposure). - **Physical Activity**: Promote weight-bearing exercises for bone health. 4. Goitre (Iodine Deficiency) **Cause**: - **Deficiency of Iodine**: Iodine is crucial for the synthesis of thyroid hormones. Deficiency can occur due to a lack of iodine in the diet, especially in areas where iodine is not present in the soil. **Symptoms**: - Enlargement of the thyroid gland (visible swelling in the neck). - Difficulty swallowing or breathing in severe cases. - Fatigue and weight changes (this may result from associated thyroid dysfunction). **Treatment**: - **Dietary Changes**: Increase intake of iodine-rich foods such as iodized salt, seafood, dairy products, and certain grains. - **Supplements**: Iodine supplementation may be provided in regions with known deficiencies. - **Public Health Measures**: Implementation of iodization programs for salt to prevent deficiency in populations. **1. Functions of Water**: - **Solvent for Hydrolysis**: Water acts as a solvent, facilitating hydrolysis reactions—where complex molecules are broken down into simpler molecules by the addition of water. This is essential for digestion, metabolism, and the cellular breakdown of nutrients. - **Transport Medium**: Water is the primary component of blood and lymph, providing a medium for transporting oxygen, nutrients, hormones, and waste products throughout the body. It ensures efficient circulation and nutrient delivery. - **Regulation of Body Temperature**: Water helps maintain body temperature through sweating and respiration, allowing the body to dissipate excess heat. - **Lubrication**: Water provides lubrication in joints and acts as a cushion for organs, protecting them from shock. - **Participation in Biochemical Reactions**: Water is involved in various biochemical processes, including chemical reactions and enzymatic activities. Role of Dietary Fiber in the Body **1.8 Role of Dietary Fiber**: - **Digestive Health**: Dietary fiber aids in regulating bowel movements by adding bulk to stool and promoting peristalsis, which helps prevent constipation. - **Prevention of Obesity**: Fiber contributes to satiety (feeling full) by slowing down digestion and prolonging stomach emptying. High-fiber foods generally have lower energy density, which can help control caloric intake and reduce the risk of obesity. - **Blood Sugar Control**: Soluble fiber can slow the absorption of sugar, helping to regulate blood sugar levels, which is beneficial for individuals with diabetes. - **Cholesterol Management**: Soluble fiber can help lower cholesterol levels by binding to bile acids, preventing their reabsorption in the intestine. - **Gut Health**: Certain fibers act as prebiotics, promoting the growth of beneficial gut bacteria, which contributes to overall gut health and can enhance the immune system. Causes and Effects of Constipation and Diarrhea **1.9 Causes and Effects of Constipation and Diarrhea**: **Constipation**: - **Causes**: Insufficient dietary fiber, inadequate fluid intake, sedentary lifestyle, certain medications, or underlying health conditions. - **Effects**: Infrequent bowel movements, hard and dry stools, abdominal discomfort, bloating, and straining during bowel movements. - **Diarrhea**: - **Causes**: Infections (viral, bacterial, or parasitic), food intolerances, inflammatory bowel diseases, stress, or medications. - **Effects**: Frequent watery stools, abdominal cramps, dehydration, and electrolyte imbalances. **Proper Hygiene in Food Preparation**: - Proper hygiene is crucial in food preparation to prevent foodborne illnesses that can lead to diarrhea (e.g., cholera, gastroenteritis). This includes: - Washing hands before handling food. - Properly cooking and storing food. - Avoiding cross-contamination between raw and cooked foods. - Ensuring safe water sources. Importance of a Balanced Diet **1.10 Importance of a Balanced Diet**: - **Definition**: A balanced diet provides all the essential nutrients the body needs in the right proportions, supporting overall health and well-being. - **Food Groups**: - **Carbohydrates**: Provide energy. - **Proteins**: Essential for growth and repair. - **Fats**: Important for energy storage and cell structure. - **Vitamins and Minerals**: Necessary for biochemical reactions and maintaining health. - **Water**: Crucial for hydration and physiological processes. **Effects of Age, sex, and occupation on Dietary Needs**: **Age**: Nutritional needs change throughout life (e.g., increased calcium and vitamin D for children and older adults). - **Sex**: Men and women have different dietary requirements (e.g., women may require more iron due to menstruation). **Occupation**: Physically active individuals generally require more calories and nutrients, whereas sedentary jobs may require fewer calories. Effects of Malnutrition on the Human Body **1.11 Effects of Malnutrition**: **Definition**: Malnutrition refers to both undernutrition (deficiency in nutrient intake) and overnutrition (excess intake of nutrients). - **Obesity**: **Adult Obesity**: Increased body weight due to excess fat, leading to health issues (e.g., heart disease, diabetes). **Childhood Obesity**: Similar effects in children, linked to sedentary lifestyles and high-calorie diets. **Eating Disorders**: **Anorexia**: characterised by an intense fear of gaining weight and severe restriction of calorie intake. - **Bulimia**: Involves cycles of binge eating followed by compensatory behaviours (e.g., vomiting, excessive exercise). **Protein and Energy Malnutrition**: **Kwashiorkor**: Caused by a deficiency of protein despite adequate calorie intake, leading to oedema, irritability, and liver enlargement. **Marasmus**: A severe deficiency of both protein and calories, resulting in significant weight loss and muscle wasting. **Sources and Effects of Hidden Salt**: **Sources**: Processed foods, presevatives, canned soups, sauces (soy sauce, ketchup), and snack foods often contain high levels of hidden salt. **Effects**: Excess salt intake can lead to hypertension (high blood pressure), increased strain on the cardiovascular system, and other health issues.  Teeth 1. Types of Teeth in Infants vs. Adults **Infant Teeth (Deciduous Teeth):** - **Total**: 20 primary teeth (baby teeth) - **Incisors**: 8 (4 upper, 4 lower) - **Canines**: 4 (2 upper, 2 lower) - **Molars**: 8 (4 upper, 4 lower) **Adult Teeth (Permanent Teeth):** - **Total**: 32 permanent teeth - **Incisors**: 8 (4 upper, 4 lower) - **Canines**: 4 (2 upper, 2 lower) - **Premolars**: 8 (4 upper, 4 lower) - **Molars**: 12 (6 upper, 6 lower, including wisdom teeth) Roles of Different Teeth - **Incisors**: Sharp edges for cutting food. Present in both infants and adults. - **Canines**: Pointed teeth for tearing food. Present in both groups. - **Molars**: Flat surfaces for grinding food. More prominent in adults (including premolars). 1.15 Importance of Teeth in Digestion - **Mechanical Breakdown**: Teeth aid in breaking down food into smaller pieces, increasing surface area for digestive enzymes. - **Mixing**: Teeth help mix food with saliva, which begins the digestive process. 1.16 Structures of the Tooth and Their Functions External Structures: - **Enamel**: Hard outer layer protecting the tooth from decay. - **Dentine**: Supports the enamel and contains microscopic tubes leading to nerve endings, sensitive to temperature and pain. - **Cement**: Covers the root of the tooth, helping anchor the tooth in the jawbone. Internal Structure: - **Pulp Cavity**: Contains blood vessels and nerves that supply nutrients and sensory function to the tooth. 1.17 Causes of Tooth Decay - **Bacteria**: Accumulation of bacteria forms plaque. - **Sugar**: Consumption of sugary foods and drinks increases bacteria that produce acids harmful to tooth enamel. - **Acidic Beverages**: Sugar-sweetened beverages and carbonation contribute to the erosion of enamel. 1.18 Process of Tooth Decay 1. **Bacterial Action**: Food particles, particularly sugars, are broken down by bacteria in the mouth. 2. **Acid Production**: Bacteria produce acids that dissolve enamel and dentine, leading to decay. 3. **Cavity Formation**: If untreated, decay progresses through the layers of the tooth. 1.19 Guidelines for the Care of Teeth - **Flossing**: Daily flossing removes food particles and prevents plaque buildup. - **Brushing**: Brush teeth at least twice daily with fluoride toothpaste. - **Fluoridation**: Use of fluoride helps strengthen enamel and prevent decay. - **Dental Check-Ups**: Regular check-ups (at least bi-annually) for professional cleaning and examination. - **Diet**: Limit sugary foods and beverages while choosing a balanced diet rich in nutrients. 1.20 Properties, Role, and Importance of Enzymes in Digestion - **Amylase**: - **Source**: Produced in saliva (salivary amylase) and pancreas (pancreatic amylase). - **Role**: Breaks down carbohydrates into simple sugars. - **Catalase**: - **Source**: Produced in liver cells. - **Role**: Converts hydrogen peroxide into water and oxygen. Major Structures of the Digestive System: - **Mouth**: Begins digestion (teeth and saliva). - **Esophagus**: Tube connecting mouth to stomach. - **Stomach**: Enzymatic breakdown of food. - **Small Intestine**: Primary site for digestion and absorption of nutrients. - **Large Intestine**: Absorption of water and formation of feces. - **Anus**: Ejection of waste. 1. **Mouth** - **Structure**: Contains the teeth, tongue, and salivary glands. - **Function**: - **Teeth**: Mechanically break down food into smaller pieces to increase surface area. - **Tongue**: Aids in manipulating food, mixing it with saliva, and pushing it toward the pharynx for swallowing. - **Salivary Glands**: Produce saliva, which contains enzymes like amylase that begin the breakdown of carbohydrates. 2. **Esophagus** - **Structure**: A muscular tube that connects the throat (pharynx) to the stomach. - **Function**: - Transports food from the mouth to the stomach via a series of muscular contractions known as peristalsis. 3. **Stomach** - **Structure**: A muscular, expandable pouch located between the esophagus and the small intestine. - **Function**: - **Mechanical Digestion**: Churns and mixes food with gastric juices. - **Chemical Digestion**: Secretes hydrochloric acid (HCl) and digestive enzymes (like pepsin) that help break down proteins. - **Storage**: Acts as a temporary storage site for food before it moves to the small intestine. 4. **Small Intestine** - **Structure**: A long, coiled tube (about 6 meters) with three main sections: duodenum, jejunum, and ileum. - **Function**: - **Digestion**: The duodenum receives bile from the liver and pancreatic juices that neutralize stomach acid and continue the digestion of carbohydrates, proteins, and fats. - **Absorption**: The walls of the jejunum and ileum are lined with villi and microvilli, which increase surface area and allow for efficient absorption of nutrients into the bloodstream. 5. **Pancreas** - **Structure**: A glandular organ located behind the stomach. - **Function**: - Produces digestive enzymes (such as proteases, lipases, and amylase) and bicarbonate to neutralize stomach acid. These are secreted into the small intestine. - Also functions as an endocrine organ by producing insulin and glucagon, which regulate blood sugar levels. 6. **Liver** - **Structure**: A large, reddish-brown organ located in the upper right abdomen. - **Function**: - Produces bile, which is important for the emulsification of fats, aiding their digestion and absorption. - Processes nutrients absorbed by the small intestine and detoxifies harmful substances. 7. **Gallbladder** - **Structure**: A small pear-shaped pouch under the liver. - **Function**: - Stores and concentrates bile produced by the liver until it is needed in the small intestine for the digestion of fats. 8. **Large Intestine (Colon)** - **Structure**: A wider, shorter tube than the small intestine that extends from the small intestine to the rectum. - **Function**:  - Absorbs water and electrolytes from the remaining indigestible food matter. - Ferments unabsorbed material, and compacts waste into feces. - Store feces until it is ready to be expelled. 9. **Rectum** - **Structure**: The final section of the large intestine. - **Function**: - Stores feces before excretion. 10. **Anus** - **Structure**: The opening at the end of the digestive tract. - **Function**: - Controls the expulsion of feces from the body through the anal sphincter. Digestion and Absorption of Food in the Alimentary Canal **1. Digestion Processes:** Mechanical Digestion (Mastication) - **Mastication**: The process of chewing, which occurs in the mouth. Teeth break down food into smaller pieces, increasing the surface area for enzymes to act upon. - **Mixing**: The tongue helps mix food with saliva, forming a bolus that can be easily swallowed. Chemical Digestion - **Saliva**: Contains enzymes like salivary amylase, which begins the breakdown of carbohydrates into simple sugars. - **Stomach**: Gastric juice (HCl and pepsin) further digests proteins. The acidic environment also kills bacteria and activates digestive enzymes. - **Small Intestine**: - **Pancreatic Juices**: Contain enzymes like pancreatic amylase, lipase, and proteases, which digest carbohydrates, fats, and proteins, respectively. - **Bile**: Emulsifies fats, making them more accessible for lipases to digest. **2. Absorption Processes:** Mechanisms of Absorption - **Osmosis**: The passive movement of water molecules across a semipermeable membrane. In the intestines, water is absorbed from the digested food into the blood. - **Diffusion**: The passive movement of molecules from an area of higher concentration to an area of lower concentration. Nutrients like monosaccharides (e.g., glucose) and amino acids enter the bloodstream through the intestinal wall via diffusion. - **Active Transport**: The process by which nutrients (such as glucose and amino acids) are absorbed against their concentration gradient, requiring energy. This occurs through specific transporter proteins in the intestinal epithelial cells. Fate of the Products of Digestion After Their Absorption 1. **Glucose**: - After absorption, glucose is transported via the hepatic portal vein to the liver. It can be used immediately for energy or stored as glycogen for later use. 2. **Amino Acids**: - Similar to glucose, amino acids are sent through the hepatic portal vein to the liver, where they can be used to synthesize proteins, converted into energy, or transformed into other compounds. 3. **Fatty Acids and Glycerol**: - Absorbed into epithelial cells in the small intestine, fatty acids and glycerol are reassembled into triglycerides, packaged into chylomicrons, and released into the lymphatic system before eventually entering the bloodstream. The liver processes these lipids as needed. 4. **Role of the Hepatic Portal Vein**: - The hepatic portal vein carries nutrient-rich blood from the gastrointestinal tract to the liver. This allows the liver to metabolize and store nutrients before they enter systemic circulation. 5. **Role of the Liver**: - The liver regulates blood sugar levels, synthesizes proteins, detoxifies harmful substances, and stores vitamins and minerals. It plays a crucial role in the metabolism of glucose, amino acids, and fats. 6. **Assimilation**: - After the liver processes the absorbed nutrients, they are distributed to various tissues in the body to be utilized for growth, energy, and repair. This process is known as assimilation. Structure of a Villus and Its Function in Absorption A villus is a small, finger-like projection found in the lining of the small intestine. - **Structure**: - **Microvilli**: Small hair-like structures on the surface of each villus that further increase surface area. - **Intestinal Epithelial Cells**: Specialized cells that contain transport proteins for nutrient absorption. - **Lacteal**: Lymphatic vessel within each villus that transports absorbed fats. - **Capillaries**: Small blood vessels that transport absorbed nutrients directly to the bloodstream. - **Function in Absorption**: - The extensive surface area created by the villi and microvilli allows for maximum absorption of nutrients. The close proximity of capillaries and lacteals allows for efficient transfer of glucose, amino acids, fatty acids, and glycerol into the blood and lymphatic system. Distinction Between Egestion and Excretion - **Egestion**:  - The process of expelling undigested waste material from the body. It occurs primarily through the rectum and anus as feces. Egestion involves the removal of substances that the body cannot utilize. - **Excretion**: - The process of removing metabolic waste products produced by the body's cells. This includes the elimination of nitrogenous wastes (like urea) and excess substances (like salts) through urine produced by the kidneys. Excretion is crucial for maintaining metabolic homeostasis.