Chapter 14 Respiration1

7/18/2019 Chapter 14 Respiration1

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Respiratory System

The link between metabolism and

respiration



Respiration

• Defined as the exchange of gasses between theatmosphere, lungs and tissues.

• Respiration supports aerobic metabolism by providing both an electron acceptor (O2) and aroute of elimination for the byproducts ofmetabolism CO2 + H2O

• C6H12O6 + 6O2 --> 6CO2 + 6H20• Aerobic metabolism is required in complex

organisms of our size



3 Steps of Respiration

• Pulmonary Ventilation - gas exchange

between the atmosphere and lungs

• External Respiration - gas exchange

between the lungs and blood

• Internal respiration - gas exchange between

the blood and tissues



Components of Respiration

• Upper respiratory system

nose, turbinate bones,

sinuses and pharynx• Lower respiratory system

larynx, trachea, bronchi

and lungs



Upper Respiratory System



Nose• Composed of both

cartilage and bone

• External nares - nostrils

• Olfactory nerve enters at

the cribiform plate

• Internal nares - opening

into the nasopharynx

• Contains the nasal

conchae and the openings

to the paranasal sinuses



Turbinate/Sinuses• The function of the nose is

to warm, clean andmoisten the air

• The turbinate bonesmaximize surface area andair contact with a hair-lined, highly vascularmucus membrane

• The SNC contains theolfactory region

• The sinuses lighten theskull and act as resonancechambers for the voice.Sinuses frequently becomeinfected



Pharynx• Respiratory/digestive

system pathway

• Nasopharynx

-posterior to nose

-eustachian tubes

-pharyngeal tonsil

• Oropharynx

-posterior to mouth

-contains palatine and

lingual tonsil• Laryngopharynx

-posterior to larynx

-continuous with

esophagus



Lower

RespiratorySystem



Larynx• Responsible for

voice

production

• The glottis is

the opening in

the larynx

through which

air passes.

• The glottis iscovered by the

epiglottis

during

swallowing to prevent food

entry into the

trachea



Vocal folds/voice production• The Ventricular Folds

- uppermost folds

- false vocal chords

- They close to preventthe passage of foreignobjects into the trachea

• The vocal folds- lowermost folds

- true vocal folds

involved in sound

production Note: sound production

requires the vocalfolds (larynx),

pharynx, mouth,

tongue, nasal cavityand sinuses



Trachea• Composed of hyaline

cartilage rings that keepthe airway open

• 4.5 inches long

• Divides into right and left primary bronchi

• The mucosa is lined withciliated pseudostratifiedcolumnar ep. with lots ofmucous cells. This traps

dust and allows it to bemoved into thelaryngopharynx

• Carina - tracheal/bronchi junction - cough reflex-



Bronchi

• Primary bronchi branch from the trachea and go tothe right and left lungs

• The right primary bronchus is nearly vertical,shorter, wider, thus more likely to receive foreign

objects• The primary bronchi split into secondary bronchi

with each going to separate lobes of the lung

• Right Lung - 3 secondary bronchi going to the

superior, middle and inferior lobes

• Left Lung - 2 secondary bronchi going to thesuperior and inferior lobes



Lungs• The right lung has three lobes and the left lung has

two lobes and a cardiac notch

• The lungs do no attach directly to the thoraciccavity

• Each lung is enclosed by two thin membranescalled pleurae which form the pleural sac

• The parietal layer covers the thoracic cavity

• The visceral layer covers the lungs

• The intrapleural space occurs between these layers

and contains a lubricating fluid• Pleurisy - inflammation/scarring of the pleural sac

leading to pain and a friction rub on inspiration

• A collapsed lung occurs when the vacuum

between layers is disrupted



Lungs Continued

• The base of the lungs sits on the diaphram

• The lung apices rise above the clavicles

• The hilus is where all the bronchi and blood vessels enter the lungs

• The cardiac notch is the indentation in the

left lung where the heart fits



Alveolar Sacs

• The common space intowhich alveoli empty

• Composed of many

alveoli• Each alveolus is an air sac

composed of simplesquamous epithelium linedheavily with capillaries

• Alveoli provide a hugesurface area for gasexchange



Alveolus Continued• Gas exchange occurs

across the

alveolar/capillarymembranes

• Total surface area is 750square feet

• Septal Cells are locatedhere and secretesurfactant that lowers thesurface tension so themoist walls of the alveoli

do not stick together• Dust Cells (alveolar

macrophages) phagocytesthat remove debris





Respiration

• Boyle’s law - The pressure of gas inside acontainer is inversely proportional to the volumeof the container

• The relevance of this law is demonstrated in the

expansion or compression of lung tissue• When the chest expands the intrapulmonary

pressure drops (relative to atmospheric pressure)creating a negative pressure that pulls air into the

lungs• When the chest relaxes or is compressed the

intrapulmonary pressure increases (relative toatmospheric pressure) creating a positive pressure

that expels air from the lungs







Pulmonary Volumes

• Tidal Volume - amount breathed in and out duringnormal respiration (500ml)

• Anatomic Dead Space - amount of air in therespiratory tract that does not reach the lungs

• Inspiratory reserve - the amount of air the lungscan take in after normal inhalation

• Expiratory reserve - the amount of air the lungscan expel after a normal exhalation

• Residual Volume - the amount of air left in thelungs after expiratory reserve

P l C it



Pulmonary Capacity

• Inspiratory capacity - tidal volume plusinspiratory reserve = maximum amount of air a

person can breath in following a restingexpiration.

• Vital Capacity - inspiratory reserve + tidalvolume + expiratory reserve. This capacity is themaximum amount of air a person can expel aftertaking the deepest breath possible

• Total Lung Capacity - the vital capacity + theresidual volume

• Spirometry - measures these volumes todetermine different types of lung disease



Respiratory Cycle

• Inspiration

Diaphragmatic and external intercostal

contraction- contraction of the diaphram pulls thelungs down and increase the volume of thethoracic cavity

Accessory muscles of respiration raise the sternum

and the first two ribs for deep breaths• Expiration

Diaphragmatic/external intercostal relaxationcombined with internal intercostal contraction that

pulls the ribs down in forced expiration

esp ratory yc e



esp ratory yc e



External/internal respiration

• External respiration - gas exchange between thealveoli and alveolar capillary beds

Alveoli Blood

PO2 105 mmHg ------------> PO2 40 mmHg

PCO2 40 mmHg <----------- PCO2 45 mmHGBlood is oxygenated and CO2 is lost

• Internal respiration - gas exchange between the blood and tissues

Blood Tissues

PO2 105 mmHg ------------> PO2 40 mmHg

PCO2 40 mmHg <----------- PCO2 45 mmHG







Transportation of Respiratory Gasses

• O2 - transported bound to Fe in hemoglobin

(oxyhemoglobin). Hemoglobin O2 binding isdependant on O2 concentration, temperature, pHand DPG (Glycolysis intermediate-metabolism)

• CO2 - transported in plasma as a dissolved gas

(7%), bound to hemoglobin (23% ascarbaminohemoglobin) and transported in the

plasma as bicarbonate ions

• RBC contain carbonic anhydrase

• CO2 + H2O <---> H+ + HCO3-

• Respiratory alkalosis - hyperventilation

• Respiratory acidosis - hypoventilation



Control of Respiration

• The rate of air flow is modified to meet metabolicdemand

• The medullary rhythmicity center contains twosets of neurons known as the dorsal and ventralrespiratory groups.

• The dorsal group is responsible for the basicrhythm of breathing. Impulses from this areatrigger the diaphram and other inspiratory muscles

to contract and expand the thoracic cavity. Thelack of impulses from this area leads to relaxationof the contractile muscles and subsequentexhalation

• Inspiration is active and expiration is passive

• The ventral respiratory group is inactive during



• The ventral respiratory group is inactive duringnormal respiration

• The ventral group becomes active during periodsof forceful inspiration or expiration by activatingaccessory muscles of respiration

• The pneumotaxic area located in the pons, justabove the medulla, continuously transmits

impulses to the dorsal respiratory group to fine-tune the rate of respiration

• The pneumotaxic area controls the rate ofrespiration

• Strong pneumotaxic activity = shorter inspiratory bursts from the dorsal respiratory = increased rateof respiration

• Weak pneumotaxic activity = longer inspiratory

bursts and the rate of breathing decreases







The Inflation Reflex

• Regulates the depth of respiration

• Stretch receptors located in the visceral pleura,

bronchioles and alveoli send sensory impulses to

the pneumotaxic area via the vagus nerve.• Increased activity of the stretch receptors activates

the pneumotaxic area to shorten the duration of

inspiration and prevent overinflation of the lungs

during forceful breathing



Central Chemoreceptors

• Central Chemoreceptors - located inchemosensitive areas of the respiratory center(ventral portion)

-sensitive to changes in CO2 and blood pH

-increased CO2 or H+ ion conc. Trigger increasedrespiratory rate

H+ + HCO3 ----> H2O + CO2

increased respiration decreases CO2 + H ionconcentration

• Note central receptors are not sensitive to O2conc.



Peripheral Chemoreceptors

• Peripheral chemoreceptors exist in specializedstructures called the aortic and carotid bodies

• The aortic body is located in the walls of the aorticarch

• The carotid body is located in the walls of thecarotid sinuses

• An extreme drop in O2 concentration stimulatesthese receptors to trigger an increase in respiratory

rate and and tidal volume.• These receptors are also sensitive to changes in

CO2 and H conc., though not as sensitive ascentral receptors







Baroreceptors

• These receptors monitor blood pressure

changes and can cause an alteration in the

rate of respiration



Lungs/Emotions

• The emotion associated with the lungs is

grief

• The lungs are highly sensitive to emotionalupset

• Conscious deep diaphragmatic breathing

can be used to calm oneself or to distractoneself from pain



Terms

• Upper respiratory infection-

pharyngitis/bronchitis/peumonia

• Tuberculosis - mycobacterium• Pneumothorax

• Pulmonary embolism

• RDS - surfactant• Emphysema

• Hypo/hyperventilation - CO2 levels



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Chapter 14 Respiration1