Human Respiratory System Overview

Organ System

• An organ system is a group of organs working together for essential functions like digestion, circulation, or respiration.
• Cells are the basic units of life, performing processes.
• Tissues are groups of similar cells performing specific tasks, for example, lining organs.
• Organs are structures made of tissues, performing specific functions like the stomach or heart.

Respiratory System

• Main Function: supply oxygen to blood for cellular respiration and remove carbon dioxide.
• Nose: filters, warms, and moistens incoming air.
• Pharynx: connects nasal cavity to larynx.
• Trachea: reinforced tube for air passage to Bronchi.
• Bronchi: splits into smaller tubes to lead air into each lung.
• Alveoli: tiny sacs where gas exchange happens through diffusion in the lungs.
• Lungs: provide space for gas exchange.
• Diaphragm: muscle that contracts for inhalation.
• Exercise increases body's need for oxygen and carbon dioxide production, causing faster, deeper breathing.

Circulatory System

• Differences between blood vessels:
  • Arteries: thick, muscular walls, carrying oxygenated blood away from the heart (except pulmonary artery).
  • Veins: thinner walls, carrying deoxygenated blood back to the heart, often with valves to prevent backflow.
  • Capillaries: one-cell thick walls, responsible for nutrient and gas exchange between blood and tissues.
• Main Function: transports oxygen, nutrients, hormones, and waste products to ensure all body cells receive what they need and remove waste.

Digestive System

• Digestion: Breaking down food into smaller, absorbable molecules for energy and nutrients.
• Mechanical digestion: Physical breakdown of food (e.g. chewing, churning in the stomach).
• Chemical digestion: Enzymatic breakdown of macronutrients into smaller molecules.
• Key concepts: Teeth (incisors, canines, molars), Bolus, Oesophagus (peristalsis), Gastric juice, Small intestine (main absorption site with villi), Large intestine (absorb water, form feces).
• Liver: produces bile for fat digestion and absorption, detoxifies substances, and processes nutrients.
• Villi: tiny projections in the small intestines for nutrient absorption into the bloodstream.
• Macronutrients (Proteins, Fats, Carbohydrates): broken down by enzymes into smaller components (amino acids, fatty acids + glycerol, glucose)