HUBS192 Tutorial L14-16 2024-10-04 PDF

Summary

This document provides detailed anatomical lectures on the respiratory system. It covers structures, functions, and epithelium of the upper and lower respiratory tracts, the larynx, and breathing mechanisms. Additional details regarding the thorax and pleura are covered.

Full Transcript

HUBS192 TUTORIAL With Analina Lecture 14 – The Upper Respiratory Tract Lecture 15 – The Lower Respiratory Tract Lecture 16 – Anatomy of The Thorax and Breathing If you were an organ, which ICE BREAKER one would you be? LECTURE 14 The Upper Respiratory Structure L14 LEARNIN...

HUBS192 TUTORIAL With Analina Lecture 14 – The Upper Respiratory Tract Lecture 15 – The Lower Respiratory Tract Lecture 16 – Anatomy of The Thorax and Breathing If you were an organ, which ICE BREAKER one would you be? LECTURE 14 The Upper Respiratory Structure L14 LEARNING OBJECTIVES 1. Describe the structures of the respiratory system and state their functions 2. Describe the structures of the upper respiratory tract 3. Describe the epithelia of the upper respiratory tract The respiratory system Consists of connected organs and structures which function to conduct clean, warm and moist air into the alveoli so that gas exchange can occur with blood circulating in the capillaries. Also responsible for: Sound production (voice) Sense of smell (olfaction) Epithelia in the respiratory system The respiratory tract is lined with mucosa: a sheet of epithelia attached via. the basement membrane to lamella propria (connective tissue beneath) “Form follows function” Conducting region: respiratory epithelium Pharynx: stratified squamous epithelium Alveoli: simple squamous epithelium Olfaction: olfactory mucosa (top 1/3 of nasal cavity) Epithelia in the respiratory system Respiratory epithelium is more accurately called pseudostratified ciliated columnar epithelium with goblet cells Found everywhere except the bronchioles and alveoli Goblet cells: Produce mucus which traps debris (dust, pathogens, etc.). Also moistens the air Ciliated cells: Cilia beat to move mucous up towards the pharynx, where it will be swallowed and digested or expelled via. Coughing Basal cells: stem cells for more columnar cells The nose - structure The nose is the primary passageway for air, so it requires clear airways. The borders of the nasal cavity are: Roof: ethmoid + sphenoid bones Floor: hard + soft palates Walls: medial = nasal septum, lateral = conchae Surrounding the nose are paranasal sinuses. These are cavities which: Lighten the skull Increase surface area to clean, warm and moisten the air Aid in sound resonance The nose - surfaces The nasal cavity is mostly covered in respiratory epithelium, but the top 1/3 contains olfactory receptors for smell. The nasal vestibules are the spaces just inside the external nares (nostrils) They have: Sweat and sebaceous glands Vibrissae: small, coarse hairs which filter dust, sand, etc. Lined with stratified squamous epithelia for protection Conchae The three conchae are bony projections into the nasal cavity: Covered with respiratory epithelium Act as ‘turbinates’, swirling inspired air → allows for more contact time → maximizes warming and moistening the air, as well as olfactory detection Pharynx structures Pharynx (throat) Muscular, funnel-shaped tube shared by the respiratory and digestive system. Nasopharynx Oropharynx Laryngopharynx (air) (air, food) (air, food) Resp. mucosa Stratified Stratified squamous Posterior nares → squamous Hyoid bone → soft palate Soft palate → opening of larynx Soft palate blocks hyoid bone Ensures food has food moving back Contains palatine “right of way” up during and lingual during swallowing swallowing tonsils Where auditory tubes drain LECTURE 15 The Lower Respiratory Tract L11 LEARNING OBJECTIVES 1. Describe the structures of the lower respiratory tract (LRT) 2. Describe the key anatomical features of the lungs 3. Describe how the structure of the LRT varies along its length 4. Describe the structure of the alveoli where gas exchange occurs, including the structure of the alveolar wall and the gas exchange barrier Larynx Larynx The larynx is only for the passage of air. It is found anterior to the oesophagus and surrounded by different cartilages. When swallowing, the epiglottis closes over the airway to prevent food from entering the airways. Vocal folds: Vestibular folds: “True” vocal folds “False” vocal cords Air passing causes Found superior to vibrations → sound vocal cords waves Prevent foreign Testosterone affects the object entry into cartilage/ muscle → the glottis longer, thicker folds = deeper voice Trachea The trachea is found anterior to the oesophagus, between the larynx and bronchi Maintains a patent airway – C-shaped cartilages Trachealis muscle at posterior – aids in coughing Lined with resp. epithelium → warms, humidifies air The mucociliary escalator moves debris to the pharynx Goblet cells secrete mucous which traps dust and debris The lungs The lungs are a pair of respiratory organs. They contain alveoli with facilitate gas exchange. Right – 3 lobes, left – 2 lobes. Bronchi and vessels enter at the hilum. They contain the bronchial tree: 1° bronchi 2° (lobar) and 3° (segmental) bronchi Bronchioles Terminal bronchioles Bronchial tree Alveoli Terminal bronchioles open into alveoli: Alveoli are arranged into “bunches of grapes” which are open at one end. They are covered in a dense capillary network layer. Type 1 pneumocyte: Type 2 pneumocyte: Most abundant Less abundant Squamous Cuboidal Form the blood-air Secrete surfactant barrier Phospholipid that decreases the surface tension of alveolar fluid Stops alveoli “sticking together” Blood-air barrier The blood-air barrier is the site of has exchange in the lungs. It has three key layers: 1. Alveolar cell 2. Fused basement membranes of alveolar endothelial cells 3. Endothelial cell The basement membranes of the alveolar cell and the endothelial cell are fused together. LECTURE 16 Anatomy of The Thorax and Breathing L16 LEARNING OBJECTIVES 1. Describe the key anatomical features of the thoracic cavity, including the joints, muscles and pleural membranes 2. Explain the relationship between pressure and volume for a gas and how this relates to breathing 3. Describe how the anatomical features facilitate changes of volume of the thorax 4. Describe the anatomical mechanism of breathing Thoracic cavity The thoracic cavity contains the: Mediastinum (heart and pericardium) Two pleural cavities (lungs) → if one cavity is punctured, the other lung will be unaffected The diaphragm separates the thorax from the abdomen Both spaces are lined by a double layer of serous membranes Visceral adheres to the organ Parietal adheres to the body wall Thoracic joints - anterior 1. Sternocostal Synovial (1st = cartilaginous) Sternum to costal cartilage 2. Costochondral Cartilaginous Rib to costal cartilage 3. Interchondral Synovial Costal cartilage to costal cartilage Thoracic joints – posterior 1. Costovertebral Synovial Rib to vertebral body 2. Costotransverse Synovial Rib to transverse process Respiratory muscles Diaphragm Intercostals Accessory muscles Skeletal muscle Externals: expand cavity Some increase cavity volume Relaxed = dome shape during quiet and forced Some decrease cavity volume inspiration Contracted = flattened Internals: decrease cavity Separates thorax from for forced expiration only abdomen Boyle’s law: P = 1/V Ventilation (AKA breathing) is driven by pressure changes in the thoracic cavity Breathing in expands the thoracic cavity (volume increases) Increase in volume = decrease in pressure → air moves down pressure gradient and into the lungs Decrease in volume = increase in pressure → air flows out Inspiration vs. Expiration Inspiration: increase in Expiration: decrease in thoracic cavity volume thoracic cavity volume Quiet inspiration Quiet expiration Diaphragm contracts (flattens) Diaphragm relaxes (dome shape) External intercostals contract (lifts External intercostals relax (lowers ribs) ribs) Forced inspiration Forced expiration The above + contraction of Internal intercostals contract accessory muscles (depresses ribs) Other accessory muscles contract Thoracic movement The lungs stick to the visceral pleura and the parietal pleura sticks to the thoracic wall Between the visceral and parietal pleura, the pleural cavity is filled with fluid This fluid creates surface tension, causing the layers to stay together and move as one Therefore expansion of the thoracic wall causes the lungs to also expand!

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