Lesson 4 - 11.1 Structure and Function of the Respiratory System

Chapter Overview

  • Chapter 11: The Respiratory System

  • Focus on structure and function.

Learning Goals

  • Identify components of respiratory tract and lung structures.

  • Explain inhalation and exhalation processes.

  • Describe gas exchange function in alveoli.

  • Explain hemoglobin's role in oxygen transport.

Importance of Breathing

  • We breathe approximately 17,000 times daily.

  • Oxygen is essential for cellular activities.

Main Functions of the Respiratory System

  1. Transport air to/from the lungs.

  2. Protect against inhaled particles.

  3. Exchange oxygen for carbon dioxide.

Structure of the Human Respiratory System

  • Components: Nasal cavity, oral cavity, nostrils, pharynx, larynx, trachea, bronchi, lungs, diaphragm.

  • Differentiation between upper and lower respiratory tract.

Upper Respiratory Tract

  • Mouth: Passage for air and food.

  • Nose: Filters air using hairs and mucus; warms and moistens air.

  • Pharynx: Shared by digestive and respiratory systems; epiglottis prevents food entry into trachea during swallowing.

  • Larynx: Voice box; produces sound via vibrating vocal cords.

Lower Respiratory Tract

  • Trachea: Windpipe with C-shaped cartilage rings.

  • **Lungs: ** Internal sacs for gas exchange; right lung (3 lobes), left lung (2 lobes, space for the heart).

  • Bronchi: Fork from trachea into lungs; branch into smaller bronchioles.

  • Alveoli: Tiny air sacs at bronchiole ends; site of gas exchange.

Diaphragm and Breathing

  • Diaphragm: Dome-shaped muscle aiding in inhalation/exhalation.

  • Inhalation Process: Diaphragm & intercostal muscles contract, increasing lung volume, air rushes in.

  • Exhalation Process: Relaxation of diaphragm & intercostal muscles, decreasing lung volume, air is expelled.

Gas Exchange in Lungs

  • Alveoli Function: Lined with moist cells for oxygen diffusion into capillaries.

  • Oxygen binds to hemoglobin in red blood cells for transport.

  • Carbon dioxide diffuses out via the same pathway during exhalation.

Gas Transport and Diffusion

  • Oxygen travels from alveoli (higher pressure) to bloodstream (lower pressure) mainly bound to hemoglobin (98.5% of transport).

  • Carbon dioxide exits tissues (higher pressure) into bloodstream (lower pressure) and is transported in three ways: dissolved in plasma, bound to hemoglobin, or converted to bicarbonate.

Respiratory Diseases

  • Asthma: Inflammation/swelling of bronchi and bronchioles; obstruction due to excessive mucus.

  • Chronic Obstructive Pulmonary Disease (COPD): Includes bronchitis and emphysema from smoking/pollution.

  • Respiratory Infections: Influenza, tuberculosis, pneumonia; can severely impact lung function.

Effects of Smoking and Vaping

  • Nicotine: Stimulates reward pathways; leads to continued smoking.

  • Carbon Monoxide: Compromises oxygen delivery; binds more strongly to hemoglobin than oxygen.

  • TAR: Accumulates in alveoli; irritates airways and inhibits cilia function.

  • Vaping Risks: Associated with respiratory issues, chemicals like diacetyl (causing popcorn lung) and others have been linked to serious lung damage.