respiratory system notes std 3 2011

Respiratory System

• Functions

– Large area for gas exchange

– Move air to & from lungs

– Protect respiratory surfaces

– Produce sounds

– Aiding sense of smell

Internal nares

Nasal cavity

Pharynx

Sphenoidal sinus

Esophagus

Frontal sinus

Nasal conchae

Nose

Hyoid bone

Larynx

Tongue

Bronchioles

Bronchus

Trachea

Diaphragm

LEFTLUNG

RIGHTLUNG

Stem cell

Mucous cell

Mucus layer

Laminapropria

Movementof mucus

to pharynx

Ciliated columnarepithelial cell

Respiratory Anatomy

• Respiratory Tract– Upper

• Conducting portion– External nares to larger bronchioles– Warms, moistens, filters

» Respiratory mucosa• Respiratory epithelium

• Ciliated columnar• Mucous (goblet) cells• Loose connective tissue

– Lower• Respiratory portion

– Smallest bronchioles & alveoli

Nasal cavity

Internal nares

Soft palate

Frontal sinus

Mandible

Nasal conchae

Nasal vestibule

External nares

Hard palate

Oral cavity

Tongue

Respiratory Anatomy

• Nose– External nares– Nasal cavity

• Flushed by– Mucus from …– Tears from …

– Nasal vestibule• Hairs

– What for?

– Nasal septum– Nasal conchae

• Folds – useful?• Turbulent air flow - useful?

– Hard palate• Floor of nasal cavity

– Soft palate• Floor of nasopharynx

Internal nares

Nasopharynx

Oropharynx

Soft palate

Laryngopharynx

Esophagus

Frontal sinus

Mandible

Hard palate

Tongue

Hyoid bone

Internal nares

Nasopharynx

Pharyngeal tonsil

Soft palate

Entrance toauditory tube

Frontal sinus

Hard palate

Oral cavity

Oropharynx

Soft palate

Palatine tonsil

Hyoid bone

Epiglottis

Laryngopharynx

Esophagus

Hyoid bone

Trachea

Respiratory Anatomy

• Pharynx– Internal nares to esophagus/larynx– 3 parts

• Nasopharynx (nose pharynx)– Internal naresedge of soft palate– Pharyngeal tonsil– Opening to auditory tube

» Which goes where?– Normal respiratory epithelium

• Oropharynx (mouth pharynx)– Soft palate edge of tongue (hyoid bone level)– Palantine tonsils

» Say ‘aaaaahhhhhh’

• Laryngopharynx (larynx pharynx)– Hyoid bone entrance to esophagus

• What about food?

Glottis

Vocal fold

Esophagus

Hyoid bone

Cricoid cartilage

Thyroid cartilage

Trachea

Vocal cords

Hyoid bone

Cricoid cartilage

Thyroid cartilage

Trachealcartilages

Epiglottis

Ligament

Extrinsic (thyrohyoid)

ligament

Ligament

Trachea

Larynx

Arytenoid cartilages

False vocal cords

Cuneiform cartilage

Corniculate cartilage

Anterior view Posterior view

Figure 15.4ce

Vocal cord

Epiglottis

False vocal cord

ANTERIOR

POSTERIOR

Root of tongue

Glottis(open)

Vocal cord

Epiglottis

False vocal cord

Root of tongue

Glottis (closed)

Respiratory Anatomy

• Larynx (voice box)– Starts at the glottis– What’s it made of

• 9 cartilages with associated ligaments & skeletal muscles

– The largest 3 cartilages• Epiglottis

– Projects above glottis– During swallowing covers glottis

» Why is this rather important?

• Thyroid cartilage– Forms much of lateral & frontal portions– Adam’s apple

» Yes, women can have them

• Cricoid cartilage– Posterior portion

Respiratory Anatomy

• Larynx (voice box)– 2 pairs of ligaments

• False vocal cords (top pair)– Rather inelastic

– Prevent stuff from entering glottis

• True vocal cords (bottom pair)– Elastic ligaments

– Small muscles change position & tension

» For what?

– Coughing reflex• Triggered by stuff on vocal cords

• Keep glottis closed while chest & abdomen contract

Respiratory Anatomy

• Vocal cords & sound production– Air passing over glottis vibrates vocal cords

– Pitch depends on …• Diameter & Length

– Kids small

– MEN! PUBERTY! LARGER!

• Tension– Only one you can control

– Higher tension = higher pitch

– Voice NOT only vocal cords• Amplification & resonance in pharynx, oral cavity, nasal

cavity, sinuses

Trachea

Larynx

Hyoid bone

Tracheal cartilage

Primary bronchi

Secondary bronchi

RIGHT LUNGLEFT LUNG

Mucous gland

Tracheal cartilage

Respiratoryepithelium

Tracheal ligament

Trachealis muscle(smooth muscle)

Esophagus

Respiratory Anatomy

• Trachea– Tough, flexible tube– Begins @ C6 attached to cricoid cartilage– Ends in mediastinum @ L5

• Branches into rt & lt primary bronchi

– 15-20 tracheal cartilages• Prevent collapse/overexpansion• C shaped – posterior open portion

– Why?» Allow expansion of esophagus

– Trachealis muscle• Changes diameter – autonomic control

Trachea

Cartilage plates

Tertiary bronchi

Left primarybronchus

Secondarybronchus

Smaller bronchi

Visceral pleura

Respiratorybronchiole

Terminalbronchiole

Bronchioles

Bronchopulmonarysegment

Alveoli in apulmonary

lobule

Respiratory Anatomy

• Bronchi– Right & left primary bronchi

• Walls resemble trachea– Ciliated epithelium, C shaped cartilage

• Right is steeper

– Bronchial tree• Primary secondary tertiary smaller bronchi

bronchioles

• Cartilage gets smaller, then disappears

• Bronchiole walls - smooth muscle– Why?

» Bronchodilation & bronchoconstriction

Lymphaticvessel

Alveoli

Interlobularseptum

Alveolar sac

Parietal pleura

Pleural cavity

Visceral pleura

Arteriole

Alveolarduct

Smooth musclearound terminalbronchiole

Branch ofpulmonaryartery

Respiratoryepithelium

Bronchiole

Bronchial artery (red),vein (blue), and

nerve (yellow)

Respiratorybronchiole

Terminalbronchiole

Branch ofpulmonary

vein

Capillarybeds

Elastic fibers

Respiratory Anatomy

• Bronchioles

– Terminal bronchioles (.3-.5 mm)

• Supplies air to lobule of lung– Lobule

» segment bounded by connective tissue

» fed by single bronchiole

– Terminal bronchiole branches into respiratory bronchioles

» Deliver gas to exchange surfaces

Alveolar epithelialcell

Capillary

Alveolar structure

Alveolar macrophage

Endothelial cell of capillary

Alveolar macrophage

Septic cell (secretes

surfactant)

Elasticfibers

Respiratory Anatomy

• Alveoli– Respiratory bronchioles alveolar ducts alveolar sacs

• Alveolar sacs– Connected to multiple alveoli

– Each lung has about 150 million alveoli– About 140 m2 of surface area– Function?

• What type of tissue necessary?– Simple squamous

– Other cells• Alveolar macrophages• Septal cells

– Surfactant» Reduces surface tension of water

• Why necessary?

Alveolar epithelium

Red blood cell

Capillary lumen

EndotheliumNucleus of

endothelial cell

Fused basement

membranes

Surfactant

Alveolar air space

The respiratory membrane

0.5 m

Respiratory Anatomy

• Respiratory membrane– Gas exchange– 3 layers

• Squamous epithelium• Fused basement membrane• Endothelium in capillary

– About 1m thick– Diffusion muy rapidamente– O2 & CO2 diffuse

• Both lipid soluble

– Receive blood from …• Pulmonary arteries branch along bronchi• 1 lobule; 1 arteriole

– Each alveolus surrounded by capillary bed

– Blood pressure• Rather low – about 30 mm Hg• Easily blocked

– Pulmonary embolism

Apex

Superiorlobe

Middlelobe

Inferiorlobe

Superior lobe(costal surface)

Base

RIGHT LUNG

LEFT LUNG

Anterior view

Cardiac notch (inmediastinal surface)

Inferior lobe

Respiratory Anatomy

• Lungs– Right -3 lobes/Left – 2 lobes– Light, spongy consistency

• Like a twinkie before the filling … mmmmm• Why?

– Lots of elastic fibers• Why?

• Pleural cavities– 2 – one for each lung

• Parietal & visceral– Separated by pleural cavity

» Which is filled with …• Which does what?

– Separated by mediastinum– Pnuemothorax

• Air in pleural cavity – bad?

Respiration

• Internal Respiration– exchange of CO2 & O2 between IF & cells

• External Respiration– All activities in exchange of CO2 & O2 between IF &

outside • Pulmonary respiration

– Movin’ air in & out of lungs

• Gas diffusion– Respiratory membrane & capillary cell membrane

• Transport of CO2 & O2– Between alveoli & capillary

– Hypoxia & anoxia

Respiration

• Pulmonary ventilation– Physical movement of air into & out of lungs

• Respiratory cycle– A single breath

• Respiratory rate– Breaths per minute

• 12-18 adults/18-20 kids

• Alveolar ventilation– In & out of alveoli

• Prevent CO2 buildup

Ribs andsternumelevate

Diaphragmcontracts

MediastinumPleuralspace

Diaphragm

Pressure outside andinside are equal, so no

movement occurs.

Po Pi

AT REST

Diaphragm

Volume increases;Pressure inside falls,

and air flows in.

Po Pi

INHALATION

Externalintercostal

Serratusanterior

Pectoralisminor

Scalenemuscles

Sternocleido-mastoid

Volume decreases;Pressure inside rises,

so air flows out.

Po Pi

EXHALATION

Rectusabdominis(otherabdominalmusclesnot shown)

Internalintercostals

Transversusthoracis

Respiration

• Pressure & airflow

– Air flows from … to …

– If you increase volume, then pressure …

– Inhalation

• The volume of the thoracic & pleural cavities …

• Therefore the pressure …

• Therefore the external pressure is …

• Therefore air moves …

Respiration

• Pressure & air flow– Diaphragm

• Relaxed – dome up into thoracic cavity– Lungs compressed

• Contracted – flattens out– Lungs expanded

– Rib cage• Elevation of rib cage

– External intercostals

• Lowers rib cage– Internal intercostals

Respiration

• Compliance– Resilience & ability to expand

• Lower compliance = greater force to ventilate

• Modes of Breathing– Quiet breathing

• Muscular inhalation– 75% diaphragm, 25% ext. intercostals

• Passive exhalation

– Forced breathing• Both inhalation & exhalation require muscular contraction

– Which muscles?

Inspiratoryreserve volume

(IRV)

Pulmonary volumes

Inspiratorycapacity

Restingtidal volume (VT 500 mL)

Functionalresidual capacity

Expiratoryreserve volume(ERV)

Volume(mL)

Residualvolume

Minimal volume(30–120 mL)

Totallung

capacity

Vitalcapacity

Time

Residual volume

Vitalcapacity

Inspiratorycapacity

Functionalresidualcapacity

IRVVT

ERV

3300500

10001200

1900500700

1100

6000 mL 4200 mL

Males Females

Respiration

• Lung Volume & Capacities

– Tidal volume

• Amt of air moved in/out during single cycle

• Can be increased/decreased– How?

• Resting tidal volume (VT)– About 500 mL

– Expiratory reserve volume (ERV)

• Amt of air that could be expelled at end of cycle– About 1000 mL

Respiration

• Lung Volume & Capacities

– Inspiratory Reserve Volume (IRV)

• Amt of air inhaled above VT

– Vital Capacity

• Max amt of air moved in/out in one cycle

– Residual volume

• Amt of air left after max exhale

– Minimal volume

• Amt of air left after lungs punctured

Alveolus

Systemiccircuit

Interstitial fluid

Pulmonarycircuit

Systemiccircuit

Externalrespiration

Internalrespiration

Alveolarcapillary

Respiratorymembrane

PO2 40PCO2 45

PCO2 40PO2 100

PCO2 40PO2 100

PO2 40PCO2 45

Systemiccapillary

PCO2 45

PCO2 40PO2 95

PO2 40

PO2 159

PCO2 30.4

Gas Exchange

• Partial Pressure– Air is mixture of gases

• 78% N2; 21% O2; wee bit of H2O & CO2

– Total pressure equal to the sum of the pressures of each gas separately• PN + PO2

+ PH2O + PCO2= 760 mmHg

– PO2= (.209)760 mmHg = 159 mmHg

– Oxygen will go down its own partial pressure gradient• Outside air = 159 mmHg

• Alveolar air = 100 mmHg

• Blood = 40 mmHg

Red blood cells

Systemiccapillary

Alveolar

capillary

Plasma

Alveolar

air space

O2 pickup

Cells in

peripheral

tissues

O2 delivery

O2

O2O2

O2

Hb

Hb O2

O2

O2O2

Hb

Hb

Gas Transport

• Oxygen transport

– 1.5% dissolved in plasma

– 98.5% hemoglobin

• Bind to iron ion in heme group

– Amt O2 bound/released depends on

• PO2 of surroundings– Normal conditions (PO2 = 40 mmHg) only about 25% released

– Active tissue (PO2=15 mmHg)

– What are the conditions of active tissue?

– Temp? pH?

23% binds toHb, forming

carbaminohemoglobin,

HbCO2

CO2 diffusesinto bloodstream

H removedby buffers, especially

Hb

93% diffusesinto RBCs

7% remains dissolvedin plasma (as CO2)

H2CO3 dissociates into H and HCO3

–

70% convertedto H2CO3 by

carbonic anhydrase

HCO3– moves out of RBC

in exchange for CI–

(chloride shift)

CI–

Systemiccapillary

Alveolar

capillary

CO2 pickupCO2 delivery

CO2

CO2CO2

CO2

Hb

Hb

H

Hb

Hb

H HCO3–

H2CO3

H2O

HCO3–

CI–

H HCO3–

Hb

Hb H

CO2Hb

HCO3–

CI–

CO2Hb

H2O

H2CO3

Chloride

shift

CO2

Gas Transport

• Carbon dioxide transport– 7% Plasma– 23% Carbaminohemoglobin

– CO2 binds to amino acids in globulins of hemoglobin

– 70% Bicarbonate ions– Carbonic anhydrase

– CO2 + H2O H2CO3 H+ + HCO3-

– In peripheral tissue, moves to the right

– Chloride shift– H + binds to hemoglobin– HCO3

- leaves RBC, Cl- enters

– What happens in the lungs?

Control of Respiration

• Local Control

– In active tissues

• PO2? PCO2

?– Greater differences in partial pressure …

• Rising PCO2relaxes smooth muscles in arterioles

– In lungs

• Blood directed to alveoli with lots ‘o oxygen– Low O2 constricts alveolar capillary sphincters

» Is this the same response in peripheral tissues?

– Rising CO2 relaxes smooth muscle in walls of bronchioles


• Respiratory Centers– Medulla oblongata

• Respiratory rhythmicity centers– Dorsal respiratory group (DRG)

» Inspiratory centers• Functions EVERY cycle• What muscles does it control?• Quiet breathing

• Increasing stimulation for 2 sec• Silent for 3 sec

– Ventral respiratory group» Forced breathing only» Has both inspiratory & expiratory centers

• What muscles does it control?


• Reflex control– Mechanoreceptor reflexes

• Respond to changes in lung volume OR arterial pressure

• Inflation reflex– Prevent overexpansion of lungs

» Inspiratory center inhibited

» Expiratory center stimulated

• Deflation reflex– Prevents lungs from collapsing

» Inspiratory center stimulated

• NEITHER involved in quiet breathing– Why?


• Reflex control

– Chemoreceptor reflexes

• Respond to chemical changes in blood or CSF

• CO2 more effective than O2– Why?

• Free divers– 3 or 4 quick deep breaths

» What happens to CO2 levels in blood?

respiratory system notes std 3 2011

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