The Respiratory Sys (pgs 829-873)


Ventilation – moving air

Respiration – exchanging gases


v     Respiratory Sys

Ø      Function

§        Supply O2 to body

§        Dispose of CO2 from body


v     4 phases of respiration

Ø      Pulmonary Ventilation (Breathing)

§        Moving air into/out of lungs

Ø      External Respiration

§        Movement of O2 from lungs to blood

§        Movement of CO2 from blood to lungs

§        Exchanging gases w/ air in lungs

§        Called “external” b/c it is soon exhaled

Ø      Transportation of Respiratory gases

§        Transport of O2 from lungs to tissue cells

§        Transport of CO2 from tissue cells to lungs

§        Blood = transport fluid

Ø      Internal Respiration

§        Movement of O2 from blood to tissue cells

§        Movement of CO2 from tissue cells to blood

§        Exchange of gases inside body


v     Respiratory/Circulatory Sys

Ø      If either fails = O2 starvation


v     Functional Anatomy of Respiratory Sys

Ø      Nose, nasal cavity, pharynx, larynx, trachea, bronchi (& subdivisions), lungs (alveoli)

Ø      2 zones

§        Respiratory zone

·        Actual site of gas exchange

·        Composed of respiratory bronchioles, alveolar ducts, alveoli

§        Conducting zone

·        Carries air to lungs

¨      Cleanses

Ø      Mucus = fly paper (sticky)

§        Traps dust

¨      Humidifies/Moistens

Ø      Air passes over mucosa

¨      Warms

Ø      B.v. in nose vasodilate

§        ↑ blood = ↑ heat of air to prevent shock to lungs

·        Doesn’t do respiration

·        Composed of nose, pharynx, trachea, larynx, bronchi, bronchioles


v     The Nose and Paranasal Sinuses

Ø      Functions of Nose

§        Provides an airway for respiration

§        Moistens and warms entering air

§        Filters and cleans inspired air

§        Serves as a resonating chamber for speech

§        Houses olfactory (smell) receptors

Ø      Structures

§        External: external nose

·        External openings

¨      Nostrils (external nares)

§        Internal: internal nasal cavity

·        Nasal septum

¨      Cartilage

¨      Vomer bone

¨      ┴ plate ethmoid bone

·        Roof

¨      Ethmoid & sphenoid bones

·        Floor

¨      Palate

Ø      Hard

§        Separates nasal & oral cavities

§        Supported by maxillary process & palatine bones

Ø      Soft

§        Muscular

·        Vestibule

¨      Chamber above nostrils

¨      Lined w/ skin containing sebaceous (oil) & sweat glands

Ø      Lined w/ vibrissae (nose hairs)

§        Trap dust & pollen

·        Mucosa

¨      Lining on sides of nose

¨      Olfactory mucosa

Ø      Lines slit-like superior region of nasal cav.

Ø      Contains smell receptors

¨      Respiratory mucosa

Ø      Pseudostratified ciliated columnar

§        Cilia           

·        Moves contaminated mucus to throat where it is swallowed and later digested by stomach juices

Ø      Contains goblet cells

§        Mucous glands (secretes mucus) & serous glands (secretes H2O & enzymes)

·        1 qt/day

·        Defensins – antimicrobial

·        Lysozomes – antibacterial

¨      Nasal mucosa

Ø      Rich supply of nerve endings

§        Contact w/ dust & particles triggers sneeze reflex

·        Nasal conchae (see diag 22.3 pg 832)

¨      Scroll like projections of nasal wall

¨      Superior, middle, inferior

¨      Meatus

Ø      Groove below e@ (each) conchae

¨      Enhance air turbulence in cavity

Ø      Allows nongaseous particle to get trapped

¨      Functions

Ø      During inhalation

§        Filter

§        Heat

§        Moisten

Ø      During exhalation

§        Reclaims heat & moisture    

·        Minimizes moisture & heat loss from body thru breathing

·        Paranasal sinuses (spaces next to nose)

¨      Located in frontal, sphenoid, ethmoid, maxillary bones

¨      Lined w/ mucosa

¨      Lighten skull

¨      Warm & moisten air


v     The Pharynx

Ø      Connects nasal & oral cavities

Ø      “Throat”

Ø      3 regions

§        Nasopharynx

·        Behind nasal cavity

·        Above soft palate

·        Air passageway only

·        Uvula

¨      Keeps food & liquids OUT

¨      Ciliated pseudostratified columnar epithelium

¨      Pharyngeal tonsil

Ø      Destroys pathogens entering nasopharynx in air

§        Oropharynx

·        Behind oral cavity

·        Connected by archway called “fauces”

·        Passageway for food/liquid & air

·        Stratified squamous epithelium

¨      Protective, resist abrasion

·        Palatine tonsils

¨      Sides of fauces

·        Lingual tonsil

¨      Base of tongue

§        Laryngopharynx

·        Food & air passageway

·        Stratified squamous epithelium

·        Behind epiglottis


v     The Larynx

Ø      Voice box (switching box)

Ø      3 main functions

§        Provide open airway

§        Switching mechanism to route air (trachea) & food (esophagus)

§        Voice production

Ø      Cartilage in larynx (diag 22.4 pg 834)

§        2 arytenoid – anchors vocal cords

§        2 corniculate – looks like kernel of corn

§        2 cuneiform

§        1 thyroid

·        Laryngeal prominence (Adam’s apple)

§        1cricoid

§        1 epiglottis (guardian of airways)

·        Mucosa-containing taste buds

Ø      Swallowing

§        Entire larynx up

§        Epiglottis mushes against tongue & is forced downward at unattached end

§        Epiglottis covers opening of trachea

§        Food/liquid slides down epiglottis into esophagus

Ø      Vocal ligaments

§        Attached to arytenoid cartilage

§        Composed of elastic fibers

§        Form core of mucosal folds

·        Vocal folds (true vocal cords)

¨      Strings of CT

¨      Pearly white (no b.v.)

¨      Vibrate producing sounds

¨      ∆ pitch = ∆ length or tension of cord

¨      ↑ pitch =  tighten or shorten ( musc attached to arytenoids)

¨      Slow = low tension = low pitch

¨      Fast = high tension = high pitch

·        Glottis  

¨      Space between true vocal cords

Ø      Sphincter functions of larynx

§        Valsalva’s maneuver

·        Vocal folds acting as sphincter that prevents air passage

¨      Prevents exhalation during abdominal straining

Ø      Associated w/ defecation

Ø      Associated w/ lifting a heavy load


The Trachea – around 4 inches long

            “Windpipe” – from neck to chest, ends at division (bronchii)



                                    Goblet cells (make mucous) - microvilli

Cilia to move mucous to pharynx

                                    Lamina propria - elastic


                                    Connective tissue layer

                                    Contains Seromucous glands – help to make mucous


Connective Tissue with 16-20 partial rings of cartilage

                                    Trachealis muscle

                                                Across the posterior part of the “rings” (closes the ring)

                                                Smooth muscle – contracts to narrow trachea

                                                            Faster air flow – coughing


Bronchi and bronchial tree

            Primary Bronchi – one per lung

                        Right is shorter, wider, more vertical

            Secondary Bronchi

                        One per lobe of lung

                                    3 on right, 2 on left

            Tertiary (“segmental”) Bronchi

One for each segment (segment is a part of lobe)

            “Bronchial Tree”

Keeps dividing (23 divisions)

Bronchioles (little bronchi)

            Smaller than 1 mm

Terminal Bronchioles

            Smaller than ½ mm


Composition of Bronchi changes as they divide


Cartilage type



Large Bronchi

Cartilage rings

Psuedostratified, ciliated

Many goblet cells for mucous


Very little

Small Bronchi

Reduced rings

Columnar (less production/move)

More muscle


Cartilage “plates”

Cuboidal (very little mucous/cilia)

Macrophages present

Muscle ring


Most of bronchial tree is part of conducting zone

            No gas exchange in conducting zone

Respiratory zone

            Anywhere gas exchange happens

            (anywhere there are alveoli)



            Little round chambers (hollow) where gas exchange happens

            Around 300 million in the lungs

            May be attached directly to “respiratory broncholes”

                        Named because they have alveoli for gas exchange

            May occur in clusters (“Alveolar Sac”)

                        Alveolar Sac – like a bunch of grapes

                        Alveoli – like a grape


Cell types

            Type 1 cells

                        Main component of wall

                        Make angiotensin converting enzyme (urinary/circulatory system)

                        Sit on a basal lamina

                                    Shared with the capillaries

Respiratory Membrane (see pg. 841)

                                                            Type 1 | basal lamina | tunica intima


Type II cells

            Less common

            Make surfactant

                        Fluid that reduces surface tension in lung (more below)


Other features of Alveoli

            Alveolar pores

                        Tubes connecting adjacent alveoli

                                    Equalize pressure

                                    Alternate route

                                                Still use alveoli if disease blocks alveoli


            Eat any microbes that get inhaled

            Crawl up bronchial tree until they encounter cilia

                        Carried to throat and swallowed

                                    2 million/hour

            Elastic Fibers

                        Surround alveoli (see pg. 841)



            All of thorax except mediastinum


                        Hilus – notch where root attaches

                        Root – bronchi and vessels that attach at hilus

                        Apex – tip at top

                        Base – surface against diaphragm

                        Fissures – separations between lobes

                                    Right lung

                                                Oblique fissure – diagonal between middle & lower

                                                Horizontal fissure – between middle & upper

                                    Left lung

                                                Oblique fissure

                        Cardiac notch

                                    Notch in left lung to accommodate the heart

                        Costal (“rib”) surface

                                    Surface of lung resting against ribs


            Subdivisions of lung


                                    Bronchiopulmonary segment

                                                Lobe (penny size or smaller)



                        Mostly air

                        Tissue of lungs = “stroma”


            Bronchial Arteries

                        High pressure, systemic circuit

                                    All of lungs except alveoli

                        BLOOD DRAINS VIA PULMONARY VEINS!!!!



            Serous membranes

                        Visceral and parietal layers

                        Serous fluid between



Lungs stick to ribs from surface

tension of serous fluid



            Pulmonary ventilation (moving air in and out of lungs)

            Inspiration = breath In

            Expiration = air Exits


Respiratory pressure

            “Air always flows from high pressure to low pressure”

Patm = atmospheric pressure (~760 mm Hg / 15 lbs/square inch)

Ppul = pressure inside alveoli  (“intrapulmonary pressure” – bad name)


If Ppul > Patm the air flows out of lungs

If Ppul < Patm the air flows into lungs


Intrapleural pressure

pressure of serous fluid between pleura layers

            Should ALWAYS be negative (below Ppul & Patm ) 

                        Usually –4 mm Hg

                        Why surface of lungs are stuck to ribs


            If positive, the lung will collapse


                                    McSwain Dart or Chest Tube



            Elasticity of alveolar wall

            Surface tension of alveolar fluid


            Boyle’s Law: if amount is constant and pressure goes up

                                    The volume will go down



               Quiet (tidal)

                              Diaphram – drops

                              External Intercostals – pull ribs up and out

               Deep (inspiratory reserve)

                              Diaphram – drops

                              External Intercostals – pull ribs up and out

                              Sternocleidomastoid – pull ribs up and out

                              Pectoralis minor – pull ribs up and out



                              Muscle movement causes lung volume to increase

                                             Ppul drops

                                                            Air rushes in to compensate



               Quiet (tidal)

                              Muscles relax

                              lungs return to normal size


                                             surface tension

               Deep (expiratory reserve)

                              Abdominal muscles (oblique and transverse)

                                             Push organs up against diaphragm

                              Internal intercostals

                                             Pull ribs inward



                              Lungs volume reduced

                                             Ppul rises

                                                            Air leaves lungs to compensate


F = delta P / R  (just like blood)


Surfactant (type II cells) lowers surface tension

               Water surface tension is so strong it would collapse lungs


Lung compliance

               How stretchy the lungs are

                              Healthy lungs are very compliant (stretchy)

                                             Very little effort to stretch them and breath



Respiratory volumes

               Tidal volumes (TV) – the amount you normally breath in and out at rest

                              (half a liter) KNOW THIS

               Reserve volumes – the extra space in your lungs that could be used

                              Inspiratory reserve volume (IRV) – the extra you could breath in

                              Expiratory reserve volume (ERV) – the extra you could breath out

               Residual volume (RV) – the amount you never get out of lungs (residue)



Respiratory Capacities

               Inspiratory Capacity – amount you can breath in after TIDAL exhale

                              Normal amount you breath in + Extra you could

                              IC = TV + IRV

               Functional Residual Capacity – amount left in lungs after TIDAL exhale

                              Amount you still could breath out + amount you’ll never get out

                              FRC = ERV + RV

               Vital Capacity = amount of air you could breath out after breathing in as much as possible

                              Normal amount in + extra in + extra you can breath out

                              VC = TV + IRV + ERV

               Total Lung Capacity = all the air that can be in the lungs

                              TLC = TV + IRV + ERV + RV


Dalton’s law

               What partial pressure is

                              % of total air pressure due to a gas

                                             Nitrogen = 79%

                                             Oxygen = 21%

                                             Carbon Dioxide = 0.04 %



               “When a mixture of gases is in contact with a liquid,


each gas will dissolve in the liquid in proportion to its partial pressure.”


Do all gasses have the same solubility?  NO

                              Carbon Dioxide = very soluble

                              Oxygen = not so soluble (1/20th of carbon dioxide’s solubility)

                              Nitrogen = almost no solubility in fluids (more soluble in fats)


               We exchange about the same amount of oxygen and carbon dioxide


                                             Low solubility

                                                            Still dissolve a lot because it has fairly high partial pressure

                                                                           We can breath :)

                              Carbon Dioxide

                                             Very little in air (low partial pressure)

                                             Very soluble

                                                            Still dissolve as easily as oxygen


                                             Almost insoluble

                                             Doesn’t go into blood unless it is at very high pressure


                                                                           More soluble in fats

                                                                                          Nitrogen narcosis

                                                                           Won’t go into blood easily when leaving body



Pg. 855

Ventilation perfusion coupling

               Low oxygen area of lungs (e.g. disease)

                              Bronchioles constrict – less air to bad area

                              Arterioles constrict – less blood to bad area

               High oxygen area of lungs

                              Broncholes relax – more air to that area

                              Arterioles relax – more blood to that area

               Result – we send air and blood to the parts of the lungs

                              That are best able to do gas exchange.  We ignore

                              The parts that can’t do their job well


P. 856

Internal respiration

               Exchange of gases at body tissues

               Depends on pressure gradients just like at lungs


Oxygen transport

               Dissolved in blood (1.5%)

               On RBC (98.5%)


                                             4 globins, 4 hemes

                                                            carries 4 O2 molecules


               Oxygen Affinity

                              The more oxygen, the more affinity for oxygen

                              No oxygen                           “might be nice to have”

                              One oxygen                         “that’s good, let’s have another”

                              Two oxygen                         “wow, this is really good stuff,

                                                                           I need to keep some of it around”

                              Three oxygens                    “This is a stickup.  Give me a fourth oxygen”


                              Things that lower hemoglobin’s affinity for oxygen

                                             High temperature

                                             Acidic conditions

                                             Lots of CO2 in the area



               “Saturated” = full


                              Full of oxygen (98% saturated)


                              Less oxygen( 75% saturated)

                              Still more than half full




               Breathing deeper and harder


                              Already 98% full, can’t add much more


                              Breathing faster removes CO2 from blood

               Can remove so much CO2 that you can black out before

               Needing to breath (pg. 865)



P. 859

Hypoxia – low oxygen to tissues


               Anemic Hypoxia – few RBC or little Hb to carry Oxygen

               Ischemic hypoxia – blood doesn’t flow  well, can’t deliver oxygen

               Histotoxic hypoxia – cells can’t take oxygen to use (cyanide)

               Hypoxemic hypoxia – low oxygen levels


p. 859

CO2 Transport (3 ways)

               As a gas dissolved in plasma (7-10%)

               Bound to hemoglobin (20%)

               As bicarbonate ions (70%)


CO2 + H20 <==> H2CO3 <==> H+  + HCO3-

Carbon Dioxide + Water <==> Carbonic Acid <==> Hydrogen Ions + Bicarbonate


This happens inside red blood cells

Hydrogen ions bind to hemoglobin, bicarbonate ions go into blood plasma


Pg. 861

“Acid” = more H+ ions than OH- ions

“Base” = more OH- ions than H+ ions


Bicarbonate Ions are one type of blood buffer

If the blood is too acidic (has too many H+ ions) they will bind with bicarbonate

If blood is too basic, the carbonic acid will break down to release H+ ions


Control of Respiration

               Medulla: (2 centers)

                              Dorsal Respiratory Group (inspiratory center)

                                             Pacemaker for breathing

                              Controls diaphragm and external intercostals

                                                            (stuff that causes inspiration)

                              Ventral Respiratory Group

                                             Controls internal intercostals, abdominals

                                                            (stuff that causes forced exhalation)

                                             Controls sternocleidomastoid

                                                            (forced inhalation)



               Emotions that affect breathing


Factors affecting breathing (pg. 864)

               Pulmonary irritation – vagal afferent nerves

                              Fumes – constrict broncholes

                              Sneeze – expel irritant


               Chemical factors

                              “Of all the chemicals influencing respiration, CO2 is the most potent and

                              the most closely controlled”


                              CO2 levels up = need to breath

                                             Chemoreceptors in medulla

                                             Sensors in carotid sinus and aortic arch


                              Influence of pH (pg. 866)

                                             Too Acid = breath faster/deeper = less CO2 in blood = less carbonic acid

                                             Too basic = breath slow/shallow = more CO2 = more carbonic acid