Nutrition and the Human Body (Summary) PDF

# Nutrition and the Human Body (Summary) ## Unicellular vs. Multicellular Organisms - Unicellular organisms directly incorporate nutrients into their bodies. - Multicellular organisms have complex systems (digestive, respiratory, circulatory, and excretory) to obtain and transport nutrients to cell...

# Nutrition and the Human Body (Summary) ## Unicellular vs. Multicellular Organisms - Unicellular organisms directly incorporate nutrients into their bodies. - Multicellular organisms have complex systems (digestive, respiratory, circulatory, and excretory) to obtain and transport nutrients to cells. ## Main Functions of Nutrition - **Provide Nutrients:** Fuel vital processes like growth, repair, and energy production. - **Eliminate Waste:** Removal of substances like CO2 and metabolic by-products to prevent toxicity. # Systems Involved in Nutrition 1. **Digestive System:** - Breaks down food into nutrients. - Nutrients are absorbed into the bloodstream and transported to cells. 2. **Respiratory System:** - Supplies oxygen for metabolism. - Expels carbon dioxide produced during metabolic activities. 3. **Circulatory System:** - Transports oxygen, nutrients, and waste products throughout the body. 4. **Excretory System:** - Removes waste products like urea and CO2 from the body. # Interconnection of Systems - **Digestive System:** Extracts nutrients from food. - **Circulatory System:** Delivers nutrients and oxygen from the digestive and respiratory systems to cells. - **Respiratory System:** Provides oxygen for energy production and removes CO2. - **Excretory System:** Filters and eliminates waste products. # Digestive System ## Function The digestive system processes food, extracts nutrients for the body, and eliminates waste. It includes the digestive tract (a continuous tube) and associated glands that secrete digestive juices. ## Structure 1. **Digestive Tract:** - **Mouth:** Food enters here. Teeth (incisors, canines, molars) cut, tear, and grind food. Saliva from salivary glands moistens food to form a bolus. - **Pharynx and Esophagus:** Food is swallowed and moves via peristaltic movements. - **Stomach:** Secretes gastric juice containing: - **Pepsin:** Breaks down proteins. - **Hydrochloric Acid:** Activates pepsin and destroys bacteria. - **Rennin:** Coagulates milk. The bolus turns into chyme. - **Small Intestine:** Absorbs most nutrients through villi and microvilli. Digestive juices mix with chyme here: - **Pancreatic Juice:** Neutralizes stomach acid and breaks down fats, proteins, and carbs. - **Bile:** Emulsifies fats. - **Intestinal Juice:** Completes digestion of nutrients. - **Large Intestine:** Absorbs water and forms feces. Contains microbiota producing vitamins (e.g., B12, K). - **Rectum and Anus:** Expel waste. 2. **Digestive Glands:** - **Salivary Glands:** Produce saliva, which starts carbohydrate digestion. - **Liver:** Produces bile, detoxifies substances, and stores nutrients. - **Pancreas:** Produces enzymes and hormones like insulin. # Diseases of the Digestive System | Organ | Disease | Description | |---|---|---| | Teeth | Cavities | Destruction of enamel by bacteria feeding on food residues, leading to decay. | | Stomach | Gastritis | Inflammation of the stomach lining, causing pain and heartburn. | | | Ulcers | Erosion of the stomach lining, often caused by *H. pylori* or excess acid. | | Intestines | Gastroenteritis | Inflammation due to bacteria or viruses, leading to diarrhea and vomiting. | | | Diarrhea | Rapid movement of food, preventing water absorption, causing dehydration. | | | Coeliac Disease | Autoimmune reaction to gluten, damaging intestinal lining. | | Liver | Hepatitis | Inflammation caused by viruses, alcohol, or medication. Can lead to liver damage. | | | Cirrhosis | Scarring of liver tissue, impairing function, often due to alcohol abuse. | # Respiratory System ## Function The respiratory system supplies oxygen for cellular energy and removes carbon dioxide, a waste product of metabolism. Oxygen is essential for cell respiration, and cell respiration is what allows the body to oxidise nutrients. ## Structure 1. **Airways:** - **Nostrils:** Filter, warm, and humidify air. - **Pharynx:** Shared with the digestive system; directs air to the larynx. - **Larynx:** Contains vocal cords; protects airways during swallowing. - **Trachea:** A cartilage-supported tube that branches into bronchi. - **Bronchi and Bronchioles:** Lead air into the lungs and terminate in alveoli. 2. **Lungs:** - Oxygen is absorbed and carbon dioxide is expelled in alveoli. - Alveoli have thin walls surrounded by capillaries, facilitating gas exchange. - **Right Lung:** Three lobes; **Left Lung:** Two lobes (smaller to accommodate the heart). 3. **Pulmonary Ventilation:** - **Inhalation:** Diaphragm contracts, air enters as lungs expand. - **Exhalation:** Diaphragm relaxes, air is expelled as lungs deflate. ## Diseases of the Respiratory System | Disease | Description | |---|---| | Chronic Bronchitis | Persistent inflammation of bronchi due to smoking or pollution. Symptoms: coughing, chest pain. | | Asthma | Bronchial constriction and excess mucus production triggered by allergens or irritants. | | Flu | Viral infection causing fever, fatigue, and respiratory discomfort. | | Pneumonia | Infection that inflames alveoli, filling them with fluid. Often caused by bacteria or viruses. | | Emphysema | Alveoli lose elasticity, reducing oxygen exchange. Often linked to smoking. | | COVID-19 | Viral infection affecting respiratory function, causing symptoms from mild (fever, cough) to severe (breathing issues). | # Tips for Respiratory Health - Avoid smoking to reduce lung damage and disease risk. - Exercise regularly to improve lung capacity. - Minimize exposure to pollutants. - Practice good hygiene to reduce infection risks.