PSIO120 Respiratory System Revision Slides T2 2024.pdf

PSIO120 Module 1 Revision The Respiratory System James Dries [email protected]  IMPORTANT These revision slides are designed to assist you with your final exam revision by focusing on important broad concepts, however, they should not be solely re...

PSIO120 Module 1 Revision The Respiratory System James Dries [email protected]  IMPORTANT These revision slides are designed to assist you with your final exam revision by focusing on important broad concepts, however, they should not be solely relied upon. All material covered in PSIO120 is examinable, including textbook readings, information presented in lecture slides, information spoken during lectures, and presented/spoken in tutorials. Refer to the textbook and lectures for a more thorough explanation of concepts if required.  Respiratory System Overview Contributes to homeostasis by facilitating exchange of gases (O2 and CO2) between the atmospheric air, blood, and tissue cells. Also helps to adjust the pH of the body fluids Is an interface between external and internal environments  Respiration Involves both the respiratory and the circulatory systems Four processes that supply the body with O2 and dispose of CO2 Pulmonary ventilation (breathing): movement of air into and out of the lungs Respiratory system External respiration: O2 and CO2 exchange between the lungs and the blood Transport: O2 and CO2 in the blood Circulatory Internal respiration: O2 and CO2 exchange system between systemic blood vessels and tissues  Respiratory System Structure Major organs: Upper respiratory system – Nose, nasal cavity, and paranasal sinuses – Pharynx Lower respiratory system – Larynx – Trachea – Bronchi and their branches – Lungs and alveoli  Respiratory System Structure Conducting zone: conduits to gas exchange sites ▪ Nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles Respiratory zone: site of gas exchange ▪ Microscopic structures: respiratory bronchioles, alveolar ducts, alveolar sacs and alveoli Respiratory muscles: control of pressure gradient ▪ Diagphram and other muscles that facilitate respiration Upper Respiratory System  The Nose Two regions: external nose and nasal cavity 1. External nose: root, apex, bridge, and external nares Philtrum: a shallow vertical groove inferior to the apex Alar cartilage: lateral boundary of nostrils (external nares) 2. Nasal cavity: within and posterior to the external nose Divided by a midline nasal septum Posterior nasal apertures (choanae; internal nares) open into the nasal pharynx Roof: ethmoid and sphenoid bones Floor: hard and soft palates  The Nose Functions: Provides an airway for respiration Moistens and warms the entering air Filters and cleans inspired air Serves as a resonating chamber for speech Houses olfactory receptors  Nasal Cavity Superior, middle, and inferior nasal conchae (turbinates) – Protrude from the lateral walls – Increase mucosal area – Enhance air turbulence Meatuses (superior, middle and inferior) – Air passages – Assist conchae increase nasal cavity surface area – Both structures warm and moisten air  Functions of the Nasal Mucosa and Conchae During inhalation, the conchae and nasal mucosa filter, heat, and moisten air During exhalation, these structures reclaim heat and moisture  Paranasal Sinuses Located in frontal, sphenoid, ethmoid, and maxillary bones Lighten the skull and help to warm and moisten air Contain mucous membranes continuous with the nasal cavity Resonating chambers for speech  Pharynx Muscular tube that connects to the: – Nasal cavity and mouth superiorly – Larynx and oesophagus inferiorly – Known commonly as the throat Nasopharynx Pharynx Oropharynx Laryngopharynx Spans from the base of the skull to the level of the sixth cervical vertebrae  Larynx Attaches to the hyoid bone and opens into the laryngopharynx Continuous with the trachea Functions: 1. Provides a patent airway 2. Routes air and food into proper channels 3. Voice production (voice box) Larynx  Trachea Windpipe - from the larynx into the mediastinum Wall composed of four layers: 1. Mucosa: ciliated pseudostratified epithelium with goblet cells 2. Submucosa: areolar connective tissue with seromucous glands 3. Hyaline cartilage (C-shaped rings) 4. Adventitia: areolar connective tissue  Bronchi and Subdivisions Air passages undergo 23 orders of branching Branching pattern called the bronchial (respiratory) tree Trachea bifurcates at the carina to form left and right main (primary) bronchi Bronchi and Subdivisions  Conducting Zone Structures Each lobar bronchus branches into segmental (tertiary) bronchi Segmental bronchi divide repeatedly Bronchioles are less than 1 mm in diameter Terminal bronchioles are the smallest - less than 0.5 mm diameter  Respiratory Zone Respiratory bronchioles, alveolar ducts, alveolar sacs (clusters of alveoli) ~300 million alveoli account for most of the lungs’ volume and are the main site for gas exchange  Alveoli Surrounded by fine elastic fibers Contain open pores (pores of Kohn) that connect adjacent alveoli Allow air pressure throughout the lung to be equalized House alveolar macrophages that keep alveolar surfaces sterile Contains lysozymes and antibodies (Ig-G) Type I alveolar cells (95%) responsible for gas exchange Type II alveolar cells (5%) produce lung Alveoli: plural of alveolus surfactant Lungs Right lung – 3 lobes Left lung – 2 lobes  Blood Supply Pulmonary circulation (low pressure, high volume) Pulmonary arteries deliver systemic venous blood to the lungs ̶ Branch profusely, along with bronchi ̶ Feed into the pulmonary capillary networks Pulmonary veins carry oxygenated blood from respiratory zones to the heart  Pleurae Thin, double-layered serosa Parietal pleura on thoracic wall and superior face of diaphragm Visceral pleura on external lung surface Pleural fluid fills the slitlike pleural cavity Provides lubrication and surface tension  Boyle’s Law The relationship between the pressure and volume of a gas (at a constant temperature) Pressure (P) varies inversely with volume (V): P1V1 = P2V2 i.e., as the volume in a chamber decreases, the pressure increases proportionally, and vice-versa  Lung Pressures Intrapulmonary (intra-alveolar) pressure (Ppul) Pressure in the alveoli Fluctuates with breathing Always eventually equalizes with Patm Intrapleural pressure (Pip): Pressure in the pleural cavity Fluctuates with breathing Always a negative pressure (