2 RespirationEntire process of exchanging gases between the atmosphere and body cells is called respiration.Breathing or ventilation – moving air in and out of the lungsExternal respiration – exchange of gases between the air in the lungs and the blood.Internal respiration – exchange of gases between the blood and body cells.Cellular respiration – use of O2and production of CO2 by cells of the body
3 Organs of the Respiratory System: Two parts or tracts:Upper respiratory tract (URT) – nose, nasal cavity, sinuses and pharynxLower respiratory tract – larynx, trachea, bronchial tree, and lungs
10 Thyroid cartilage “Adam’s Apple” In female more rounded – shorter front to back – shorter vocal cordsIn male more “V” shaped – longer front to back – longer vocal cords
11 Cricoid cartilage – inferior to thyroid cartilage. Marks end of larynx Epiglottic cartilage – elastic cartilageAttaches to thyroid cartilage and supports epiglottisArytenoid cartilages andCorniculate cartilages serve as sites for muscles that regulate tension on vocal cords and aid in closing larynx during swallowingCuneiform cartilages in mucous membrane – stiffen soft tissue
12 Vocal cordsTwo sets of muscle and connective tissue covered by mucous membraneUpper are “false vocal cords” –close off glottis to keep food outLower are true vocal cords – sound produced when air forced across them.Pitch changed by amount of tension – modified by resonating chambers, and position of lips, mouth and tongue
15 Trachea “windpipe” Extends from larynx to primary bronchi (T5) Smooth muscle – trachealis muscle20 – “C” shaped rings of hyaline cartilageOpen end of C posterior to allow esophagus to expand inLined with pseudostratifed ciliated columnar epitheliumRidge – carina – most sensitive areas for triggering cough reflex
21 Bronchial Tree Right and left primary bronchi Right bronchus shorter, wider, more verticalSecondary or lobar bronchi3 branches on right ; 2 on leftTertiary or segmental bronchi10 branches on right; 8 on leftBronchi lined with pseudostratified ciliated columnar epitheliumHeld open by complete rings of cartilage
27 Pulmonary ventilation Air moves depending on a pressure gradientBefore inspiration, pressure in lungs = pressure of atmosphere = 760 mm HgInspiration increases the size of the thoracic cavity and ↓ pressure .Diaphragm is the most important muscle of inspiration.- 75 % of air
32 Diaphragm is innervated by the phrenic nerve. Decreases pressure 1-3 mm HgMoves 500 ml of airExternal intercostals also contract – move ribs up and sternum forwardStrenuous breathing – sternocleidomastoid, scalenes, and pectoralis minor
33 ExpirationPassive process – the diaphragm and external intercostals relax. Elastic recoil of stretched elastic fibers and surface tension of the liquid in the lungs decreases the lung volume and increases the pressure, forcing air out of the lungs.Forced expiration involves contraction of the internal intercostal and abdominal muscles.
37 Lung volumesTidal volume – air moved by one respiration, about 500 ml.Inspiratory reserve volume – additional air taken in during maximal inhalationExpiratory reserve volume – additional air expired during forced exhalation.Residual volume – amount of air left in alveoli after forced expiration that keeps them inflated.
40 Other lung volumesAnatomic dead space – due to conducting parts of system
41 Regulation of the Respiratory Center Respirations can be modified by factors from inside and outside the brain.Chemical influences:Central chemoreceptors in medulla oblongataSensitive to changes in conc. of CO2 and pHCO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-carbon + water carbonic hydrogen bicarbonate dioxide acid ion ion
42 Peripheral Chemoreceptors Carotid bodies and aortic bodiesStimulated by oxygen concentration decreaseSend impulses to respiratory centers, and breathing increasesNot triggered until O2 is very low (50 mm Hg)