Respiratory System Respiration Respiration has three meanings o Ventilation of the lungs breathing o The exchange of gases between the air and blood and between blood and the tissue fluid o The use of oxygen in cellular metabolism Respiratory system is an organ system that mechanically brings air in and out of the body Functions include o Produces oxygen and carbon dioxide exchanges between blood and air o Produces speech and other vocalizations o Allows for the sense of smell Organs of Respiratory System Nose pharynx larynx trachea bronchi lungs General Aspects of System Air flows along a dead end pathway in the lungs Upper respiratory tract o Nose through larynx organs in head and neck Lower respiratory tract o Trachea through lungs organs in thorax Conducting division Respiratory Division o Passages for airflow nostrils to bronchioles o Alveoli and other distal gas exchange regions Nose Functions o Warms cleanses humidifies inhaled air o Detects odors o Resonating chamber that amplifies the voice External Anatomy o Two upper nasal bones o Several pieces of hyaline cartilage and dense connective tissue in lower half Nasal Cavity called nasal fossae Nasal septum divides internal chamber or nasal cavity into right and left chambers Hard palate forms floor separates the nasal cavity from the oral cavity and allows one to breathe while you chew food Just inside nostril find stratified squamous epithelium and vibrissae guard hairs Three folds of tissue or conchae on lateral wall o Narrow air passage beneath each conchae called meatus o Narrowness of passages and turbulence ensures air contacts mucous membranes Nasal Cavity Mucosa Olfactory epithelium o Lines roof of nasal fossa o Catch odor molecules with immobile cilia in ciliated pseudostratified columnar epithelium Respiratory Epithelium mucosa epithelium Defensive role of mucosa o Lines rest of nasal cavity with ciliated pseudostratified columnar o Mucus from goblet cells and mucous glands traps inhaled particles Function of cilia of mucosa o Sweep debris laden mucus into pharynx to be swallowed Regions of Pharynx Muscular funnel with three regions Nasopharynx houses the pharyngeal tonsils Larynx Voice box is a cartilaginous chamber Epiglottis o Flap of tissue that guards glottis superior opening of larynx direct food o The folds of the larynx are even more important for keeping food and and drink to esophagus drink out of the airway The inferior vocal cords on both sides of glottis produce sound when air passes between them vibrating them o Loudness is based on the force of the air passing through the cords Trachea Rigid tube anterior to esophagus Supported by C shaped hyaline cartilage rings o Opening in rings faces posteriorly towards esophagus o Trachealis spans opening in rings adjusts airflow by expanding or contracting Trachea and larynx lines with ciliated pseudostratified columnar epithelium The mucus traps inhaled particles and the upward beating of the cilia moves mucus up and out mucociliary escalator Lungs Surface Anatomy Conical with a broad concave base resting on the diaphragm A blunt peak called the apex projecting slightly above the clavicle Much of the space within the rib cage is occupied by the liver spleen and stomach inferior to the lungs and diaphragm The right lung has three lobes while left lung has two lobes Bronchial Tree Primary bronchi Secondary lobar brinchi o One secondary bronchus for each lobe of lung Tertiary segmental bronchi All bronchi are lines with pseudostratified columnar epithelium and contain lymphocyte nodules All bronchi contain elastic connective tissue to provide recoil to expel air Smooth muscle which contracts or relaxes to constrict or dilate the airway Bronchioles o No cartilage but layer of smooth muscle in wall o Divides into many terminal bronchioles End of conducting division o Respiratory bronchioles Divide into alveolar ducts end in alveolar sacs Alveoli bud from respiratory bronchioles alveolar ducts and alveolar sacs o Main site for gas exchange Path of Air Flow Nasal cavity pharynx larynx trachea main bronchus lobar bronchus segmental bronchus bronchiole terminal bronchiole respiratory bronchiole alveolar ducts alveolus Alveoli An alveolus is a tiny sac Cells of the alveolus o Squamous alveolar cell Thin broad cells that allow for rapid gas diffusion between alveolus and bloodstream o Great alveolar cells Cuboidal cells that cover the remaining 5 of alveolar surface Repair the alveolar epithelium when the sqaumous cells are damaged Secrete pulmonary surfactant o Alveolar macrophages Most numerous lung cells Wander the lumen and the connective tissue between alveoli Alveolar Fluid The alveolar wall has a thin film of moisture and any excess liquid is absorbed by The mean blood pressure of the capillaries I lungs is very low as compared to The osmotic uptake of water overrides filtration and have new re absorption Fluid must be kept form accumulating in the alveoli because it interferes with gas the blood capillaries capillaries in rest of body diffusion Pleurae and Pleural Fluid pleurae Visceral on outer surface of lungs and parietal on inner surface of rub cage Pleural Cavity space between pleurae filled with lubricating pleural fluid Functions o Reduce friction for fluid acts as a lubricant that eases lung expansion and contraction o Create pressure gradient Lower pressure than atmosphere assists lung inflation o Compartmentalization by pleurae mediastinum and pericardium prevents spread of infection Pulmonary Ventilation Breathing pulmonary ventilation repetitive cycle of inspiration and expiration The lungs fill with air and empty of air as their volume expands and decreases due to action of the respiratory muscles No muscles are directly attached to lungs Quiet respiration at rest while forced respiration deep or rapid breathing is for example during exercise Respiratory Muscles Diaphragm o Prime mover of pulmonary ventilation o Relaxation allows diaphragm to bulge upward o Contraction flattens diaphram enlarging thoracic cavity o The diaphragm alone accounts for about two thirds of pulmonary airflow Internal and External intercostal muscles o Aid diaphragm o Stiffen the thoracic cage during respiration prevents it from caving inward o Contribute to enlargement and contraction of thoracic cage o During quiet breathing scalenes hold ribs 1 an 2 stationary while external intercostals muscles pull the other rubs upward o Increases both transverse and