Respiratory SystemRespiratory System

OrgansOrgansControl of RespirationControl of Respiration

HomeostasisHomeostasis

Path of Air through the Respiratory SystemPath of Air through the Respiratory System

pharynxnose

larynx

lung bronchiole

mouth

nasal cavity

trachea bronchus(pl: bronchi)

glottis

Made of alveoli

(air sacs)

Functions of Respiratory Tract OrgansFunctions of Respiratory Tract Organs

• Nasal Cavities: warm, moisten and filter airNasal Cavities: warm, moisten and filter air

• Larynx: vocal cords produce soundLarynx: vocal cords produce sound

• Trachea (windpipe): permits passage of Trachea (windpipe): permits passage of air, ciliated cells move mucus and debris air, ciliated cells move mucus and debris toward pharynxtoward pharynx

• Bronchial Tree: bronchi and bronchioles Bronchial Tree: bronchi and bronchioles permit passage of airpermit passage of air

• Lungs: gas exchangeLungs: gas exchangeglottis

vocalcords

Applying Your KnowledgeApplying Your Knowledge

A.A. Where are the vocal cords located? Where are the vocal cords located? B.B. Which leads to an alveolus?Which leads to an alveolus?C.C. Where does gas exchange take place?Where does gas exchange take place?D.D. Which is shared between the respiratory and Which is shared between the respiratory and

digestive systems? digestive systems?

1.1. PharynxPharynx2.2. LungLung3.3. LarynxLarynx4.4. BronchusBronchus5.5. BronchioleBronchiole

Gas Exchange in Lungs: External RespirationGas Exchange in Lungs: External Respiration

Exchange occurs between air in the alveolus and blood in the surrounding capillaries:

Oxygen from alveolus enters bloodstream,Carbon dioxide from blood enters alveolus

Returns oxygenated

blood to heart

Carries deoxygenated

blood from heart

Sites of gas exchange

Ventilation: Inspiration and ExpirationVentilation: Inspiration and Expiration

Action of intercostal muscles between ribs

Dome-shaped muscle

below lungs

Control of VentilationControl of Ventilation

• Respiratory Center in Brain Respiratory Center in Brain stimulates rhythmic inspiration, stimulates rhythmic inspiration, responding to levels of carbon responding to levels of carbon dioxide and hydrogen ionsdioxide and hydrogen ions

• Chemoreceptors in arteries send Chemoreceptors in arteries send signals to respiratory center in signals to respiratory center in response to changing oxygen levelsresponse to changing oxygen levels

Diffusion Controls Gas Exchanges in the BodyDiffusion Controls Gas Exchanges in the Body

• External RespirationExternal Respiration– gas exchange between air in alveoli and blood gas exchange between air in alveoli and blood

in pulmonary capillariesin pulmonary capillaries

– pOpO22 is higher in air, pCO is higher in air, pCO22 is higher in blood is higher in blood

– OO22 diffuses into blood, CO diffuses into blood, CO2 2 diffuses into lung airdiffuses into lung air

• Internal RespirationInternal Respiration– gas exchange between blood in systemic gas exchange between blood in systemic

capillaries and tissue fluidcapillaries and tissue fluid

– pOpO22 is higher in blood, pCO is higher in blood, pCO22 is higher in tissues is higher in tissues

– OO22 diffuses into tissues, CO diffuses into tissues, CO2 2 diffuses into blooddiffuses into blood

Specialized ComponentsSpecialized Components• Carbonic Anhydrase: enzyme involved in release of Carbonic Anhydrase: enzyme involved in release of

carbon dioxidecarbon dioxide

• Hemoglobin: oxygen-carrying molecule on surface Hemoglobin: oxygen-carrying molecule on surface of red blood cellsof red blood cells

• Surfactant: layer of lipoprotein that lowers surface Surfactant: layer of lipoprotein that lowers surface tension and prevents alveoli from closingtension and prevents alveoli from closing

Tissue StructureTissue Structure• Trachea: Trachea:

pseudostratified pseudostratified ciliated columnar ciliated columnar epitheliumepithelium

• Alveoli: simple Alveoli: simple squamous squamous epithelium epithelium

HomeostasisHomeostasis• Gas ExchangeGas Exchange

– oxygen is needed for energy release through oxygen is needed for energy release through cellular respirationcellular respiration

• Regulation of Blood pHRegulation of Blood pH– When COWhen CO22 is released by tissues, levels of H is released by tissues, levels of H++

increase and pH is loweredincrease and pH is lowered

– When COWhen CO22 is released from lungs, H is released from lungs, H++ has has

been used to produce water, increasing pH to been used to produce water, increasing pH to neutral level (7.4)neutral level (7.4)

bicarbonate ion

hydrogen ion

carbonic acid

carbon dioxide

water

Bicarbonate Buffering System of BloodBicarbonate Buffering System of Blood

Carbonic anhydrase

Applying Your KnowledgeApplying Your Knowledge

A.A. Which enzyme assists in controlling blood Which enzyme assists in controlling blood pH? (Choices on left)pH? (Choices on left)

B.B. For internal respiration, where is pCOFor internal respiration, where is pCO2 2

greater? (Choices on left)greater? (Choices on left)C.C. Which one represents a muscle located Which one represents a muscle located

below the lungs? (Choices on right)below the lungs? (Choices on right)

1.1. Tissue FluidTissue Fluid

2.2. HemoglobinHemoglobin

3.3. Carbonic AnhydraseCarbonic Anhydrase

4.4. BloodBlood

5.5. AlveolusAlveolus

1.1. SurfactantSurfactant

2.2. DiaphragmDiaphragm

3.3. Columnar EpitheliumColumnar Epithelium

4.4. Intercostal MuscleIntercostal Muscle

5.5. Squamous EpitheliumSquamous Epithelium