2Respiration Ventilation: Movement of air into and out of lungs External respiration: Gas exchange between air in lungs and bloodTransport of oxygen and carbon dioxide in the bloodInternal respiration: Gas exchange between the blood and tissues
3Respiratory System Functions Gas exchange: Oxygen enters blood and carbon dioxide leavesRegulation of blood pH: Altered by changing blood carbon dioxide levels (increase C O2 = decrease pH)Voice production: Movement of air past vocal folds makes sound and speechOlfaction: Smell occurs when airborne molecules are drawn into nasal cavityProtection: Against microorganisms by preventing entry and removing them from respiratory surfaces.
4Respiratory System Divisions Upper tract: nose, pharynx and associated structuresLower tract: larynx, trachea, bronchi, lungs and the tubing within the lungs
5Nose (Nasus) and Nasal Cavities External nose (visible part – includes hyaline cartilage plates & nasal bones )Nasal cavityFrom nares (nostrils) to choanae (openings into the pharynx)Vestibule: just inside nares – lined with stratified squamous epithelium – continuous with skinHard palate: floor of nasal cavity – separates nasal cavity from oral cavity – covered by mucous membraneN asal septum: partition dividing cavity. Anterior cartilage; posterior vomer and perpendicular plate of ethmoid (divides nasal cavity into right & left parts)C hoanae: bony ridges on lateral walls with meatuses (passageways) between. Openings to paranasal sinuses and to nasolacrimal duct
6Functions of Nasal Cavity: Passageway for air (open even if mouth full of food)Cleans the air [vestibule lined with hair & this traps particles / mucous membrane consists of pseudostratified ciliated columnar epithelium with goblet cells (mucus)]Humidifies( moisture from mucous membranes & from excess tears that drains into nasal cavity through nasolacrimal duct), warms air ( warm blood flowing through mucous membranes - this prevents damage to respiratory passages caused by cold air)Smell [superior part of nasal cavity consists of olfactory epithelium (sensory receptors)]Along with paranasal sinuses are resonating chambers for speech
7Pharynx:Common opening for digestive and respiratory systems (connected to respiratory at larynx & to digestive at esophagus)Three regionsNasopharynx:a. Pseudostratified columnar epithelium with goblet cells.b. Mucous and debris from nasal cavity is swallowed.c. Openings of Eustachian (auditory) tubes – air that passes through them to equalize air pressure between atmosphere & middle ear.d. Floor is soft palate (separates nasopharynx from oropharynx), uvula is posterior extension of the soft palate – prevents swallowed materials from entering nasopharynx & nasal cavityOropharynx: shared with digestive system (extends from soft palate to epiglottis). Lined with moist stratified squamous epithelium – air, food, & drink passes through.Laryngopharynx: epiglottis to esophagus. Lined with moist stratified squamous epithelium – food & drink pass through here to esophagus (very little air passes /too much air = gas)
9Larynx - base of tongue to trachea / passageway for air Unpaired cartilagesThyroid: largest, Adam’s appleCricoid: most inferior, base of larynx (other cartilages rest here)Epiglottis: attached to thyroid and has a flap near base of tongue. Elastic rather than hyaline cartilagePairedArytenoids: attached to cricoidConiculate: attached to arytenoidsCuneiform: contained in mucous membraneLigaments extend from arytenoids to thyroid cartilageVestibular folds or false vocal foldsTrue vocal cords or vocal folds: sound production. Opening between is glottis - laryngitis is an inflammation of mucosal epithelium of vocal folds
10Functions of LarynxMaintain an open passageway for air movement: thyroid and cricoid cartilagesEpiglottis and vestibular folds prevent swallowed material from moving into larynx – during swallowing, epiglottis covers the opening of larynx so, food & liquid slide over epiglottis toward esophagus. Also, closure of vestibular folds can also prevent the passage of air----when person holds breath.Vocal folds are primary source of sound production. Greater the amplitude of vibration, louder the sound (force of air moving past vocal cords determines amplitude). - Frequency of vibration determines pitch. Also, length of vibrating segments of vocal folds affect ex: when only anterior parts of folds vibrate, higher pitched tones are produced & when longer sections of vibrate, lower tones result.- Arytenoid cartilages and skeletal muscles determine length of vocal folds and also abduct the folds when not speaking (only breathing) to pull them out of the way making glottis larger (allows greater movement of air).The pseudostratified ciliated columnar epithelium (lines larynx) traps debris, preventing their entry into the lower respiratory tract.
12Trachea - windpipeMembranous tube of dense regular connective tissue and smooth muscle; supported by hyaline cartilage C-shaped rings (protects & maintains open passageway for air) . Posterior surface is devoid of cartilage & contains elastic ligamentous membrane and bundles of smooth muscle called the trachealis.Contracts during coughing-----this causes air to move more rapidly through trachea, which helps expel mucus & foreign objects.Inner lining: pseudostratified ciliated columnar epithelium with goblet cells. Mucus traps debris, cilia push it superiorly toward larynx and pharynx.Divides to formLeft and right primary bronchi (each extends to a lung)Carina: cartilage at bifurcation (forms ridge). Membrane of carina especially sensitive to irritation and inhaled objects initiate the cough reflex
13Tracheobronchial Tree and Conducting Zone Trachea to terminal bronchioles which is ciliated for removal of debris.Trachea divides into two primary bronchi. (right is larger in diameter & more in line with trachea than left)Primary bronchi divide into secondary (lobar) bronchi (one/lobe) which then divide into tertiary (segmental) bronchi.Bronchopulmonary segments: defined by tertiary bronchi.Tertiary bronchi further subdivide into smaller and smaller bronchi then into bronchioles (less than 1 mm in diameter), then finally into terminal bronchioles.Cartilage: holds tube system open; smooth muscle controls tube diameter-----ex: during exercise, diameter increases, decreases resistance to airflow, increases volume of air movedduring asthma attack, diameter decreases, increases resistance to airflow, decreases volume of air flowAs tubes become smaller, amount of cartilage decreases, amount of smooth muscle increases------ex: terminal bronchioles have no cartilage & only have smooth muscle.
14Respiratory Z one: Respiratory Bronchioles to Alveoli Respiratory zone: site for gas exchangeRespiratory bronchioles branch from terminal bronchioles. Respiratory bronchioles have very few alveoli (small, air filled chambers where gas exchange between air & blood takes place). Give rise to alveolar ducts which have more alveoli. Alveolar ducts end as alveolar sacs that have 2 or 3 alveoli at their terminus.Tissue surrounding alveoli contains elastic fibers (alveoli expand during inspiration & recoil during expiration)No cilia, but debris removed by macrophages. Macrophages then move into nearby lymphatics or into terminal bronchioles.
15The Respiratory Membrane Three types of cells in membrane.Type I pneumocytes. Thin squamous epithelial cells, form 90% of surface of alveolus. Gas exchange.Type II pneumocytes. Round to cube-shaped secretory cells. Produce surfactant (makes it easier for alveoli to expand during inspiration).Dust cells (phagocytes)Layers of the respiratory membraneThin layer of fluid lining the alveolusAlveolar epithelium (simple squamous epitheliumBasement membrane of the alveolar epitheliumThin interstitial spaceBasement membrane of the capillary endotheliumCapillary endothelium composed of simple squamous epitheliumTissue surrounding alveoli contains elastic fibers that contribute to recoil.
16Lungs Two lungs: Principal organs of respiration Base sits on diaphragm, apex at the top, hilus (hilum) on medial surface where bronchi and blood vessels enter the lung. All the structures in hilus called root of the lung.Right lung: three lobes. Lobes separated by fissures (deep & prominent)Left lung: Two lobesRight lung is larger & heavier than leftDivisionsLobes (supplied by secondary bronchi), each lobe is subdivided into bronchopulmonary segments (supplied by tertiary bronchi and separated from one another by connective tissue partitions), bronchopulmonary segments are subdivided into lobules (supplied by bronchioles and separated by incomplete partitions).Note: 9 bronchopulmonary segments present in left lung & 10 present right lungNote: Individual diseased bronchopulmonary segments can be surgically removed, leaving the rest of lung intact, because major blood vessels & bronchi do not cross connective tissue partitions.
18Thoracic WallThoracic vertebrae, ribs, costal cartilages, sternum and associated musclesThoracic cavity: space enclosed by thoracic wall and diaphragmDiaphragm separates thoracic cavity from abdominal cavity
19Inspiration and Expiration Inspiration: diaphragm, external intercostals, pectoralis minor, scalenesDiaphragm: dome-shaped with base of dome attached to inner circumference of inferior thoracic cage. Central tendon: top of dome which is a flat sheet of connective tissue.Quiet inspiration: accounts for 2/3 of increase in size of thoracic volume. Inferior movement of central tendon and flattening of dome. Abdominal muscles relaxOther muscles: elevate ribs and costal cartilages allow lateral rib movementExpiration: muscles that depress the ribs and sternum: such as the abdominal muscles and internal intercostals.Quiet expiration: relaxation of diaphragm and external intercostals with contraction of abdominal musclesLabored breathing: all inspiratory muscles are active and contract more forcefully. Expiration is rapid
21PleuraPleural cavity surrounds each lung and is formed by the pleural membranes. Filled with pleural fluid.Visceral pleura: adherent to lung. Simple squamous epithelium, serous.Parietal pleura: adherent to internal thoracic wall.Pleural fluid: acts as a lubricant and helps hold the two membranes close together (adhesion).Mediastinum: central region, contains contents of thoracic cavity except for lungs.
22Blood and Lymphatic Supply Two sources of blood to lungs: Pulmonary & BronchialPulmonary artery brings deoxygenated blood to lungs from right side of heart to be oxygenated in capillary beds that surround the alveoli. Blood leaves via the pulmonary veins and returns to the left side of the heart.Bronchial arteries provide oxygenated systemic blood to lung tissue. They arise from the aorta & run along the branching bronchi. Part of this now deoxygenated blood exits through the bronchial veins to the azygous (drains chest muscles); part merges with blood of alveolar capillaries and returns to left side of heart.Blood going to left side of heart via pulmonary veins carries primarily oxygenated blood, but also some deoxygenated blood from the supply of the walls of the conducting and respiratory zone.Two lymphatic supplies: superficial and deep lymphatic vessels. Exit from hilusSuperficial drain superficial lung tissue and visceral pleuraDeep drain bronchi and associated C.T.No lymphatics drain alveoliPhagocytic cells within lungs phagocytize carbon particles & other debris from inspired air & move them to lymphatic vesselsOlder people & smokers lungs appear gray to black because accumulation of these particlesC ancer cells from lungs can spread to other parts of body through lymphatic vessels.
23Ventilation Movement of air into and out of lungs Air moves from area of higher pressure to area of lower pressure (requires a pressure gradient)If barometric pressure (atmospheric pressure) is greater than alveolar pressure, then air flows into the alveoli.Boyle’s La w : P = k/V, where P = gas pressure,V = volume, k = constant at a given temperatureIf diaphragm contracts, then size of alveoli increases. Remember P is inversely proportionate to V; so as V gets larger (when diaphragm contracts), then P in alveoli gets smaller.
24Alveolar Pressure Changes: (Note: Barometric air pressure is Alveolar Pressure Changes: (Note: Barometric air pressure is always assigned a value of zero)