Respiratory System

A. Functions1. respiration2. smell3. filtration/defense4. sound & speech production5. eliminate waste

Respiratory SystemB. Anatomy of the Respiratory System

1. Nose/Nasal CavityA) functions

1) provide airway for respiration2) filter incoming air3) warm and moisten incoming air4) aids in speech5) location of olfactory receptors

Respiratory SystemB) has external and internal portionsC) external

1) root2) bridge3) apex4) external nares or nostrils

D) internal1) nasal cavity – divided into 2 sections by the

nasal septum

Respiratory System

a) roof is composed of ethmoid and sphenoid bonesb) floor is composed of the hard and soft palatesc) each side is further divided into sections by the

superior, middle, and inferior conchai) these cause air to swirl causing particles to

become trapped in mucus2) internal nares – openings between the nasal cavity

and pharynx

Respiratory System

2. Pharynx – throatA) composed of 3 regions

1) nasopharynxa) is continuous with nasal cavityb) normally serves as a passageway for air

only c) blocked by soft palate and uvula during

swallowing

Respiratory System

2) oropharynxa) lies posterior to oral cavity – from soft palate

to tip of the upright epiglottisb) passageway for both food and air

3) laryngopharynxa) lies posterior to the upright epiglottis and

extends to esophagusb) passageway for both food and air

Respiratory System

3. Larynx – voice box A) extends from hyoid bone to the tracheaB) has 3 functions

1) provide open airway2) acts as a switching mechanism to route

food and air down correct paths3) is location of vocal folds (cords) – speech

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C) is composed on nine pieces of cartilage1) largest piece is the thyroid cartilage – causes

protrusion = laryngeal prominence (Adam’s apple)2) epiglottis – blocks trachea during swallowing3) 3 paired cartilages – arytenoid, cuneiform &

corniculate4) cricoid cartilage is the inferior-most piece

D) the cough reflex is initiated here – caused when something other than air enters the trachea

Respiratory System

E) glottis – opening between the vocal folds within the larynx

4. Trachea – windpipeA) extends from larynx until it branchesB) is ciliated and produces mucus to help trap

particles in inspired airC) tracheal rings – rings of hyaline cartilage that

provide strength and support

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5. The Respiratory Tree – structures serve as a conduit for airA) right and left primary bronchi

1) initial branches of the tracheaB) secondary bronchiC) tertiary bronchiD) continues branching (up to 23 times)

Respiratory System

E) bronchioles – 1mm diameterF) terminal bronchioles – < 0.5mm

6. The Respiratory Zone – structures where gas exchange occursA) respiratory bronchioles (contain alveoli)B) alveolar sacs – cluster of alveoli

1) alveolar ducts

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C) alveoli1) actual site of gas exchange2) about 300 million per lung3) coated in surfactant

a) detergent-like lipoprotein chemicalb) reduces surface tension of the water in the

alveoli and prevents the alveoli from collapsing upon themselves

Respiratory System

C. Respiration – Breathing, Exchange, Transport 1. Inspiration (Inhalation)

A) result of a pressure difference between:1) atmospheric pressure2) intrapulmonary pressure

B) Boyle’s Law – the pressure exerted by a gas varies inversely to its volume

C) Mechanism1) diaphragm & external intercostals

Respiratory System2. Expiration (Exhalation)

A) normal/restful expirationB) exercise or forced expiration

1) abdominals & internal intercostals 3. Gas exchange (O2 & CO2)

A) dictated by Dalton’s Law – the total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gas in the mixture1) partial pressure

Respiratory System

B) a partial pressure difference is necessary at locations where gases are exchanged1) alveoli & blood2) blood & cells

C) pO2 is highest in the alveoli and lowest in the cells

D) pCO2 is highest in the cells and lowest in the alveoli

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E) rate of gas exchange is affected by:1) partial pressure difference2) gas solubility3) surface area4) diffusion distance

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4. Transport of GasesA) O2 transport

1) 2 main formsa) dissolved in plasma – 1.5%b) bound to hemoglobin (Hb) – 98.5%

i) Hb + O2 = HbO2 (oxyhemoglobin)

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2) affinity affected by:a) pH – decreased pH causes decreased affinityb) temperature – increased temp causes

decreased affinityc) pCO2 – increased pCO2 causes decreased

affinity

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B) CO2 transport – 3 basic forms 1) dissolved in plasma – 7%2) bound to hemoglobin – 23%

a) Hb + CO2 = HbCO2 (carbaminohemoglobin)

3) bicarbonate ions – 70%

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a) forms in RBCCO2 + H2O H2CO3 H+ + HCO3

-

i) HCO3- leaves the RBC

ii) H+ binds with hemoglobiniii) chloride shift – Cl- moves into RBC

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b) process reverses in the lungsCO2 + H2O H2CO3 H+ + HCO3

-

i) HCO3- enters the RBC

ii) H+ breaks from hemoglobin and binds with HCO3

-

iii) reverse chloride shift – Cl- moves out of the RBC

Respiratory System5. Control of Respiration

A) Respiratory Center – 4 areas1) Dorsal Respiratory Group (DRG)

a) dominatesb) sets normal rhythm

i) 2 sec. on/3 sec. offii) 12-15 breaths/min

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2) Ventral Respiratory Group (VRG)a) usually inactiveb) activated by DRG

3) pneumotaxic areaa) helps coordinate transition from inspiration to

expirationb) inactivates DRG

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4) apneustic areaa) helps coordinate transition from expiration

to inspiration b) activates DRGc) overridden by pneumotaxic

B) the respiratory center is influenced by:1) higher brain centers (conscious control)

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2) stretch receptors in lungs3) irritant receptors in trachea & lungs4) chemoreceptors in brain

a) detect CO2 & H+ 5) chemoreceptors in aortic arch and common

carotid arteriesa) detect O2, CO2 & H+

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6. Respiratory Air VolumesA) Respiratory Volumes

1) Tidal volume (TV) – the amount of air inhaled or exhaled with each breath under resting conditions

(males – 500ml/females – 500ml)2) Inspiratory reserve volume (IRV) – the

amount of air that can be forcefully inhaled after a normal tidal volume inhalation

Respiratory System3) Expiratory reserve volume (ERV) – the amount

of air that can be forcefully exhaled after a normal tidal volume exhalation

4) Residual volume (RV) – amount of air remaining in the lungs after a forced exhalation (1200ml/1100ml)

5) Dead Space Volume (DSV) – amount of air in the respiratory pathway not involved in gas exchange (150ml/150ml)

Respiratory SystemB) Respiratory capacities

1) Total lung capacity (TLC) – the sum of all respiratory volumes. (6000ml/4200ml)

2) Vital capacity (VC) – the total amount of exchangeable air (4300ml/3100ml)

Respiratory System

7. Breathing PatternsA) Eupnea – normal breathing B) Apnea – transient cessation of breathingC) Dyspnea – difficult, labored, or painful

breathing1) often indicates lung infection/injury

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D) Hyperventilation1) can result in respiratory alkalosis

E) Hypoventilation1) can result in respiratory acidosis

Respiratory System8. Respiratory Disorders

A) Sinusitis – inflamed sinuses from a nasal cavity infection

B) Laryngitis – inflammation of the vocal cordsC) Pharyngitis (strep throat) – inflammation of the

pharynx; caused by Streptococcus bacteriaD) Pleurisy – inflammation of the pleural

membranesE) Pneumothorax – air in the intrapleural spacesF) Atelectasis – lung collapse

Respiratory SystemG) Carbon Monoxide Poisoning – CO binds with

Hb in place of O2

H) Pneumonia – infectious inflammation of the lungs (usually bacterial but can also be viral or fungal)

I) Emphysema – permanent enlargement of the alveoli due to destruction of the alveolar walls

J) Chronic bronchitis – inhaled irritants lead to chronic excessive mucus production as well as inflammation and fibrosis of the mucosa

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K) Asthma – bronchoconstriction prevents airflow into the alveoli

L) Tuberculosis – an infectious disease caused by the bacterium Mycobacterium tuberculosis resulting in fibroid masses in the lungs

M) Cystic Fibrosis – genetic disorder that causes an increase in mucus production resulting in clogged respiratory passages

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N) Infant Respiratory Distress Syndrome (IRDS) – alveoli collapse between breaths causing labored breathing and sometimes inadequate respiration1) seen in premature infants