BSC 2086 1st Edition Lecture 16 Outline of Last Lecture I. Nonspecific DefensesII. Specific Defenses III. Cells and Immunity IV. Immunity Disorders V. Effects of Aging on Immune System Outline of Current Lecture I. Introduction to Respiratory SystemII. Components of Respiratory SystemIII. Upper Respiratory TractIV. Larynx V. TracheaVI. Lungs Current LectureI. Introduction to Respiratory Systema. Provides O2 to cells and removes CO2 that they producedb. Oxygeni. Obtained from air by diffusion across sensitive exchange surfaces of the lungsii. Carried by cells to cardiovascular system which brings back CO2 to the lungsc. Cells make energy through mechanisms that use up the O2 and have a by-productof CO2i. Energy produced is used for maintenance, growth, defense and divisionII. Components of Respiratory System a. Functions:i. Makes available extensive gas exchange surface area between the circulating blood and airii. Moves air to and from the exchange surfaces of the lungsiii. Provides protection of the respiratory surfaces from the outside environmentiv. Makes soundsv. Plays a role in olfactory senseb. Organizations i. Divided into:1. Upper respiratory system – above larynx 2. Lower respiratory system - below larynx c. Respiratory tracti. Conducting portion: from nasal cavity to terminal bronchioles1. Involved in ONLY moving air into and out of the lungs2. No gas exchange occurs in this portion 3. Lined by the respiratory mucosa a. Consists of an epithelial layer and an areolar layer known as the lamina propria ii. Respiratory portion: respiratory bronchioles and alveoli 1. Alveoli are air filled pockets found within the lungsa. Gas exchange takes place hered. Respiratory epitheliumi. In order for gases to exchange efficiently:1. Alveoli walls must be < 1 µm (very thin)a. Allows for movement of gases through the walls 2. Surface are must be very big, about 35 times the surface area of the body e. Lamina Propriai. Underlying layer of areolar tissue which supports the respiratory epitheliumii. Part of respiratory mucosa in the conducting portion of respiratory tractiii. Contains mucous glands that secrete onto the epithelial surface in the upper respiratory tract, trachea and bronchiiv. Contains smooth muscle cells that encircle lumen of bronchioles in the conducting portion of the lower respiratory systemf. Alveolar Epithelium i. Delicate simple squamous epithelium because it is a single later of flat epithelial cellsii. Mixture of scattered and specialized cells that line exchange surfaces of alveolig. Respiratory Defense Systemi. Removes particles and pathogens through the use of filtration mechanisms 1. Mucous cells and mucous lands make the mucus that bathes exposed surfaces2. Cilia can be described as a mucus escalator, which sweeps debris trapped in the mucus towards the pharynx 3. Large particles removed through filtration in nasal cavity4. Small particles that arrive to the lungs are engulfed by alveolar macrophages III. Upper Respiratory Tracta. Nose i. Location where air enters the respiratory systemii. Nasal hairs are the first filters for entering particlesb. Nasal cavityi. Provides olfaction (sense of smell)ii. Secretes mucousiii. Tears clean and moisten nasal cavityiv. Warms and humidifies air entering respiratory system1. This step is skipped when breathing through the mouthc. Pharynx i. Chamber shared by respiratory and digestive systemii. Extends from internal nares to the entrance of the larynx and esophagusiii. Divided into:1. Nasopharynx – superior portion2. Oropharynx – middle portion3. Laryngopharynx – inferior portion IV. Larynxa. Air enters larynx from the pharynx b. A cartilaginous structure that surrounds the glottis i. Glottis: Narrow opening connecting pharynx and larynx c. Cartilages:i. Thyroid cartilage – anterior surface called laryngeal prominence (aka. Adam’s apple)1. Largest in males due to release of testosteroneii. Cricoid cartilageiii. Epiglottisd. Functions of the cartilagei. Thyroid and cricoid cartilage support and protect the glottis and the entrance to the tracheaii. During swallowing the epiglottis folds back over the glottis in order to prevent the entry of food and liquids into the trachea (windpipe)1. While swallowing the larynx is elevatede. Ligamentsi. Vestibular ligaments lie within the vestibular folds1. Protect the delicate vocal foldsii. Sound is produced by the air passing through the glottis 1. Vocal folds (those involved with sound are known as vocal cords) vibratea. Higher pitches come from slender, short foldsb. Low pitches come from thicker, long foldsV. Tracheaa. Structure:i. Aka. windpipeii. Extends from cricoid cartilage into mediastinum where it branches into right and left pulmonary bronchi iii. Submucosa1. Under mucosa of trachea, which contains mucous glands b. Cartilages i. 15-20 tracheal cartilages which strengthen and protect airway1. Not continuous in the area where the trachea and esophagus are in contact 2. The C-shape that it forms allows distortion in the tracheal wall for food passage into the esophagusii. The ends of the tracheal cartilage are connected by an elastic ligament and trachealis muscle1. Diameter is reduced when trachealis muscle contracts2. Sympathetic stimulation causes relaxation of trachealis musclec. Primary Bronchii. Right and left primary bronchi are separated by an internal ridge known as the carina ii. Differences:1. Right primary bronchus is larger in diameter2. Right primary bronchus descends at a steeper angle which is the reason for which most foreign objects entering the trachea enter the right primary bronchus VI. Lungsa. Right and left lungs are in right and left pleural cavity b. The base, or inferior portion of each lung, rests on the top portion of the diaphragmc. Lobes of the lungs are separated by deep fissuresi. Right lung has 3 lobes ii. Left lung has 2 lobes because it makes room for the heart, whose apex points towards itd. Primary Bronchusi. Branches, forming secondary bronchi (lobar bronchi)ii. Each lobe has one secondary bronchuse. Secondary Bronchii. Branch, forming tertiary bronchi (segmental bronchi)f. Structure of Bronchii. Walls of primary, secondary and tertiary bronchi contain progressively more smooth muscle but less cartilageii. An increase in smooth muscle tension will affect constriction and resistance of airways g. Bronchitisi. Inflammation of the bronchial walls which results in constriction and difficulty breathingh. The Bronchiolesi.
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