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 bloodcarbon 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

lungspalate - 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)

nasopharynx

oropharynx

laryghgopharynx

pharyngeal tonsil

palatine tonsil

lingual tonsil

Larynx (voice box):-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

http://www.yorku.ca/earmstro/journey/images/larynx.gif

looking down from tophttp://www.aic.cuhk.edu.hk/web8/Hi%20res/Larynx%201.jpg

vocal folds

glottis

Trachea (windpipe):

http://www.fotosearch.com/LIF116/trachea/

-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

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:

http://www.lungusa.org/atf/cf/%7B7A8D42C2-FCCA-4604-8ADE-7F5D5E762256%7D/clean_lung_hr.jpg

-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

Bronchioles:

-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

nonsmokersmoker