Science

• Respiratory system


  Biological system consisting of specific organs and structures used for gas exchange in animals and plants
• Primary components of the respiratory system in humans and other mammals

  • Nose
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi
  • Lungs
• Air enters through the nose

  1. Filtered

  2. Warmed

  3. Humidified
• Nasal cavity


  • Contains hair and mucus that trap dust and pathogens
• Pharynx


  Also known as the throat, a muscular tube that serves as a pathway for both air and food
• Larynx


  Commonly called the voice box, located below the pharynx, contains the vocal cords and is responsible for sound production
• Larynx


  • The epiglottis, a flap of tissue, prevents food from entering the trachea
• Trachea


  Also known as the windpipe, a tube that connects the larynx to the bronchi
• Trachea


  • Reinforced with cartilage rings to keep it open
  • Lined with cilia and mucus to trap particles and pathogens
• Bronchi


  The trachea splits into two main bronchi (right and left), each entering a lung, and further divide into smaller bronchi and bronchioles
• Bronchioles


  Smaller branches of the bronchi that continue to subdivide, becoming progressively narrower and leading to the alveolar ducts
• Alveoli


  Tiny air sacs at the end of bronchioles, where oxygen diffuses into the blood and carbon dioxide diffuses out
• Lungs


  • The right lung has three lobes, and the left lung has two lobes
  • Each lung is encased in a pleural membrane that reduces friction during breathing
• Diaphragm


  A dome-shaped muscle located below the lungs, contraction creates negative pressure in the chest cavity, drawing air into the lungs
• Intercostal muscles


  Located between the ribs, help expand and contract the chest cavity to facilitate breathing
• Pleura


  A double-layered membrane surrounding each lung, the pleural cavity between the layers contains a small amount of fluid to reduce friction during breathing movements
• Mucous membranes and cilia

  • Line the respiratory tract, producing mucus to trap dust, pathogens, and other particles, cilia move the mucus toward the pharynx to be swallowed or expelled
• Inhalation (Inspiration)


  1. Diaphragm and intercostal muscles contract

  2. Thoracic cavity expands, creating negative pressure

  3. Air is drawn into the lungs
• Exhalation (Expiration)


  1. Diaphragm and intercostal muscles relax

  2. Thoracic cavity reduces in size

  3. Air is expelled from the lungs
• Common respiratory conditions


  • Asthma
  • Bronchitis
  • Pneumonia
  • COPD
  • Lung cancer
• Preventive measures for respiratory health

  • Avoid smoking
  • Reduce exposure to pollutants
  • Practice good respiratory hygiene
• Circulatory system


  Also known as the cardiovascular system, a complex network that plays a vital role in maintaining homeostasis in the body, responsible for the transportation of blood, nutrients, oxygen, carbon dioxide, hormones, and other essential substances throughout the body
• Primary function of the circulatory system

  • Transports oxygen, nutrients, hormones, and waste products throughout the body
• Main components of the circulatory system

  • Heart
  • Blood vessels
  • Blood
• Heart


  Pumps blood throughout the body
• Heart structure


  • Four chambers (two atria, two ventricles)
  • Valves prevent backflow of blood (tricuspid, pulmonary, mitral, aortic)
  • Pathway: Right atrium -> right ventricle -> lungs -> left atrium -> left ventricle -> body
  • Electrical system controls heart rate (SA node, AV node, Bundle of His, Purkinje fibers)
• Arteries


  Carry blood away from the heart, have thick, elastic walls (e.g., aorta)
• Veins


  Carry blood toward the heart, have thinner walls, valves to prevent backflow (e.g., vena cava)
• Capillaries


  Microscopic vessels where exchange of substances occurs between blood and tissues
• Blood components


  • Red blood cells (erythrocytes) - carry oxygen via hemoglobin
  • White blood cells (leukocytes) - fight infection
  • Platelets (thrombocytes) - aid in blood clotting
  • Plasma - liquid component, carries nutrients, hormones, and waste products
• Systemic circulation


  Delivers oxygenated blood to the body and returns deoxygenated blood to the heart
• Pulmonary circulation


  Exchanges carbon dioxide for oxygen in the lungs
• Coronary circulation


  Supplies blood to the heart muscle itself
• Blood pressure


  Force of blood against arterial walls
• Blood pressure measurements


  • Systolic pressure - pressure during heart contraction
  • Diastolic pressure - pressure during heart relaxation
  • Normal range: typically around 120/80 mmHg
• Blood flow regulation


  • Autonomic nervous system controls heart rate and vessel diameter
  • Hormones influence blood pressure and volume (e.g., adrenaline, antidiuretic hormone)
  • Local factors - tissue needs can cause local vasodilation or vasoconstriction
• Functions of the circulatory system

  • Transport - oxygen, carbon dioxide, nutrients, hormones, waste products
  • Protection - immune response (white blood cells), clotting (platelets)
  • Regulation - body temperature, pH balance, fluid balance
• Common circulatory conditions


  • Hypertension
  • Atherosclerosis
  • Heart attack
  • Stroke
  • Anemia
  • Hemophilia
• Preventive measures for circulatory health

  • Healthy diet
  • Regular exercise
  • Avoiding smoking
  • Managing stress
• Genetics


  The branch of biology that studies genes, genetic variation, and heredity in living organisms