Respiratory system

Enduring understanding: The structure of organs affect their function.

Essential Question: How do we breathe?

Functions of respiratory system: Gas exchange- oxygen to the blood carbon dioxide out of the blood

organs involved in respiratory system

Nose: -external nares = nostrils -nasal cavity -nasal septum - divides right and left half -conchae - three lobes - increase surface area -increase air turbulence -mucous covered -trap particles so don't go to lungs palate - partition between nasal and oral cavity - hard palate - bone -soft palate - tissue conchae

problem with nose: -rhinitis - inflammation of nasal mucosa -cause - cold viruses, allergens - sinusitis - sinus inflammation -passageways to sinuses are blocked or infected

Pharynx (throat): -passageway for food and air -auditory tubes drain into nasopharynx -tonsils located here (immune sys) -pharyngeal tonsil (adenoid) -palatine tonsil -lingual tonsil problem: tonsillitis - inflammation of tonsils (remove pharyngeal and palatine tonsils) pharyngeal tonsil nasopharynx oropharynx laryghgopharynx palatine tonsil lingual tonsil

Larynx (voice box): glottis -air and food go through -inferior to pharynx -thyroid cartilage = Adam's apple -epiglottis at top -covers trachea when swallowing food -cough reflex -doesn't work when unconscious glottis http://www.yorku.ca/earmstro/journey/images/larynx.gif vocal folds http://www.aic.cuhk.edu.hk/web8/Hi%20res/Larynx%201.jpg looking down from top

Trachea (windpipe): -lined with ciliated mucosa -propels mucus -catches dust particled -inhibited by smoking -C rings of hyaline cartilage -support -allow food to be swallowed in esophagus -Heimlich maneuver http://www.fotosearch.com/LIF116/trachea/

Tracheostomy - provides alternate route for air if trachea blocked http://www.fotosearch.com/LIF139/nu120015/

Primary Bronchi: -branches at end of trachea -run obliquely -right = wider, shorter and straighter, food usually gets lodged here -air entering this area is warm, cleansed and moist -goes to smaller subdivisions http://www.medidoktor.hu/images/bronchi-bronchioles-alveoli.jpg

Lungs: -paired -in thoracic cavity -visceral pleura - covering on lungs -parietal pleura - walls of thoracic cavity -pleural fluid in between -Pleurisy = inflammation of pleura -due to decreased fluid -painful - or increased fluid -creates pressure on lungs -less painful http://www.lungusa.org/atf/cf/%7B7A8D42C2-FCCA -4604-8ADE-7F5D5E762256%7D/clean_lung_hr.jpg

Bronchioles: Alveoli: -smallest branches, farthest from bronchi -have cartilage in walls Alveoli: -air sacs -site of gas exchange -millions of these in lungs -rest of tissue = stroma -elastic connective -give "sponginess" http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f25-9a_bronchioles_and__c.jpg

SEM of Human lung tissue

-surface area of lung tissue of healthy man = 50-70 square meters -in alveoli - have macrophages that pick up bacteria, carbon particles and debris -have surfactant = lipid material produced by alveolar cells -lower surface tension of water lining the cells so that the alveoli do not collapse between breaths -premie babies (before 28-30 weeks) do not make this yet -called infant respiratory distress syndrome

Alveolar membrane

Mechanics of breathing: -"Volume changes lead to pressure changes which lead to flow of gases to equalize pressure" Inspiration: -diaphragm and external intercostals contract -diaphragm moves inferiorly and flattens -thoracic cavity increases in size -lungs attached to thoracic cavity stretch -gases in lungs spread to fill space, decreases gas pressure -creates a vacuum to suck air in -when internal pressure = external pressure inspiration stops

Expiration: -depends on elasticity lungs rather than muscles -inspiratory muscles relax -ribcage retracts -lungs recoil -volume decreases and gas pressure increases above atmospheric pressure -gases flow out

nonrespiratory movements: -due to reflexes 1. cough- clears lower passageways 2. sneeze-clears upper respiratory passageways 3. crying-emotion mechanism 4. laughing-emotion mechanism 5. hiccups-spasms of diaphragm, irritation of diaphragm or phrenic nerve 6. yawn-ventilates all alveoli

Respiratory volumes: Normal breathing ~ 500 ml. = tidal volume (TV) inspiratory reserve volume (IRV) = amount of air taken in forcilby over the tidal volume ~ 2100-3200 ml. expiratory reserve volume (ERV) = amount of air forcibly exhales after tidal volume ~ 1200 ml residual volume = air left in lungs after ERV blown out -keeps alveoli inflated -allows continued gas exchange vital capacity = total amount of exchangable air = TV + IRV + ERV

Dead space volume - air that never reaches alveoli, is in conducting pathways measure respiratory volumes with respirometer

Problems with respiratory system: 1. hypoxia - lack of oxygen to tissues -bluish tinge to skin -due to anemia, pulmonary disease or impaired blood circulation 2. carbon monoxide poisoning -if present hemoglobin prefers this over oxygen to carry -due to fires, faulty furnaces -kills victims quietly, no signs

3. emphysema: -walls of alveoli break becoming larger and larger chambers -decreased gas exchange -fibrosis of tissue -barrel shaped chest due to overinflation of lungs 4. Bronchitis: - inflammation of bronchi (mucosa inflamed) -produce large quantities of mucus -can lead to pneumonia 5. cystic fibrosis: -lethal genetic disease (1 in 2400 children) -faulty CFTR protein - impairs regulation of Cl channels -oversecretion of thick mucus - clogs passageways -can lead to infections

7. Asthma: -chronic inflammation of bronchial passageways -can be triggered by allegies, stress, exercise -leads to constriction of airways and increase mucus production -can cause death if not treated -symptoms: coughing, wheezing 8. Lung cancer: -1/3 of all deaths in U.S. -aggressive, metastasizes quickly -low survival rate because diagnosed so late -cause - smoking, exposure to asbestos -treatment - removal of diseased lung radiation/chemotherapy

nonsmoker smoker