BI 233 Pulmonary Test

Exchange of gas between the atmosphere and the lungs is termed what?

Pulmonary ventilation: The mechanical process of moving air into (inspiration) and out of (expiration) the lungs. Exchange of air between atmosphere and lungs. One of the three key processes of respiration

What are the cells that secrete surfactant?

Type 2 - cuboidal cells, secrete surfactant to reduce surface tension and prevent alveolar collapse, part of the alveoli

What are the normal diastolic and systolic pressures in the pulmonary arteries?

Systolic = 15-30 mmHg / diastolic = 4-12 mmHg

Avg = 26/8

What is the normal capillary pressure of the bronchial capillaries; pulmonary capillaries?

Bronchial capillaries: 100 mmHg

Pulmonary capillaries: 8 mmHg

At what pulmonary capillary pressure would you begin to observe fluid in the interstitium?

When the pulmonary capillary HPc exceeds plasma colloid OPc, so when the capillary pressure reaches >20-25 mmHg

What are the factors that tend to collapse the lungs?

• Pleural cavity contains lubricating fluid and maintains a negative intrapleural pressure (~754 mmHg or −6 mmHg relative to atmospheric pressure) to prevent lung collapse

• Elastic recoil of lung tissue: Elastic basement membranes of the alveoli and elastic fibers in the bronchioles and alveolar ducts tend to assume the smallest size possible at any given time

• Surface tension of fluid in alveoli: Exerts a force directed toward the center of the alveoli Tends draw them to their smallest possible dimensions as H2O forms hydrogen bonds The Law of LaPlace is an expression of this force or attraction

  • Note: Water molecules have a greater attraction for each other than for air, and pull close together. The alveoli would collapse between breaths if surfactant wasn’t present to reduce surface tension by interfering with the cohesiveness of the water molecules (minimizes surface tension)

  • The concentration of surfactant is higher in the smaller alveoli than in the larger -> thus, surface tension is equalized among the different sized alveoli

What are the factors that hold the lungs open?

• Pleural fluid adhesive forces: Created by pleural fluid in pleural cavity which secures the pleura together As the diaphragm contracts and thoracic cavity increases (expands) the parietal pleura lining the cavity is pulled outward in all directions and the visceral pleura and lungs are pulled along with it

• Positive pressure within lungs

  • Intrapulmonary pressure (Ppul): Relatively positive in relation to intrapleural pressure, Ppul > Pip à presses lungs against thoracic wall. Rises and falls with inspiration and expiration with a 0 net pressure difference. Equal to atmospheric pressure

  • Intrapleural pressure (Pip): Always below atmospheric pressure during normal breathing

    • Before inspiration about 756 (-4) mmHg

    • During inspiration about 754 (-6) mmHg which pulls walls of lungs outward

      • A pneumothorax is the presence of air in the intrapleural space

How much is the normal tidal volume?

Tidal volume: amount of air inhaled and exhaled with each breath under resting conditions; about 500 ml Only ~350 ml of the tidal volume reaches the alveoli; ~150ml remain in anatomical dead space (nose, pharynx, larynx, trachea, bronchi, and bronchioles)

Aka air moved per breath

Avg volume: ~500 mL

The amount of air left in the lungs after a normal tidal volume respiration is the:

Functional residual capacity = ERV + RV - amt of air remaining in lungs after normal tidal expiration, ~2400 mL

How do you calculate alveolar ventilation?

• = (Tidal volume − Dead space) × Respiratory rate 

• V̇a = tidal volume (Vt) - anatomic dead space volume (Vd) x respiratory rate (RR) per minute 

  • Alveolar ventilation V̇(a) = (Vt − Vd) × RR 

    • V̇a = (500 -150) x 12 = 4200 ml/min; or 4.2L/min 

• Deep, slow breathing is more efficient than shallow, rapid breathing for gas exchange

  • An individual breathing 22 times/minute at a Vt of 300 ml would have an alveolar ventilation of: (300 ml − 150 ml) × 22 breaths/minute = 3300 ml

  • An individual breathing 12 times/minute at a Vt of 600 ml would have an alveolar ventilation of: (600 ml − 150 ml) × 12 = 5400 ml

What muscles are used for inspiration?

• Diaphragm: Contraction increases superior-inferior dimensions of the thoracic cavity

  • Accounts for 65 – 75% of the inspiratory volume changes during normal breathing 

• External intercostals: Increase the diameter of the thorax in the anterior-posterior, and lateral planes

• Accessory muscles used during deep or labored inspiration 

  • Sternocleidomastoid: elevates the sternum

  • Scalene: elevates the superior two ribs

  • Pectoralis minor: elevates the 3rd - 5th ribs

What muscles can be recruited for expiration?

• Muscles of forced expiration contract to increase intra-abdominal pressure and force diaphragm upward

  • External and internal obliques and transversus abdominis: Muscle contraction increases intraabdominal pressure which pushes organs against diaphragm. Decreases superior-inferior volume

  • Internal intercostals: Extend downward and backward between adjacent ribs; pulling them down

  • Rectus abdominus: Pull the substernal ribs inferiorly

What chemical factors can result in smooth muscle mediated changes in airway radius?

• Bronchiole diameter changes -> resistance

• Luminal Occlusion

  • Airway narrowing can also occur from intraluminal obstruction:

    • Edema: Inflammatory mediators (e.g., histamine, leukotrienes) cause endothelial cell contraction and increased vascular permeability → airway wall swelling

    • Mucus:

      • Histamine stimulates mucus secretion

      • Leukotrienes trigger exocytosis of mucins from goblet cells and submucosal glands

    • Excess mucus contributes to airflow limitation in asthma and chronic bronchitis.

What chemical factors can result in changes in luminal bronchial diameter (not mediated by smooth muscle)

• Parasympathetic (vagal) stimulation → acetylcholine release → muscarinic M3 receptors → bronchoconstriction

• Sympathetic influence (via circulating epinephrine from the adrenal medulla) → activation of β -adrenergic receptors → ₂ bronchodilation

  • Note: direct sympathetic innervation of bronchioles is minimal

• Histamine (via H1 receptors) → bronchoconstriction

• Leukotrienes (e.g., LTC₄, LTD₄, LTE₄) → potent, sustained bronchoconstriction; stronger effect than histamine and central to asthma pathophysiology

How does Charles Law apply to respiration?

Charles’ Law: The volume of a gas is directly proportional to its absolute temperature if pressure remains constant. 

As inspired air enters the warmer lungs and warms from ambient to core body temperature, it expands, contributing slightly to lung volume.

How does Henry’s law apply to respiration?

Henry’s Law: The amount of gas dissolved in a liquid at a given temperature is proportional to the gas’s partial pressure and its solubility coefficient.  

• Thus, the amount of gas that dissolves into blood from alveolar air depends on:

  • Solubility Coefficient (a physical constant describing how easily a gas diffuses through liquid): 

    • CO₂ = 0.57 → highly soluble; diffuses ~20× faster than O₂ 

    • O₂ = 0.024 → poorly soluble

    • N₂ = 0.012 → nearly insoluble

  • Temperature of the Liquid: Gas solubility decreases as temperature increases

    • Example: more O₂ dissolves in cold water than in warm

  • Partial Pressure of the Gas: Higher partial pressures increase gas solubility in liquid

• Oxygen diffuses into the blood when its alveolar partial pressure is high, and CO2 diffuses out when its blood partial pressure is high

How does Dalton’s law apply to respiration?

Dalton's law: Total pressure = sum of partial pressures 

• The total pressure of a gas is equal to the sum of the pressures that each gas in the mixture exerts independent of each other. Atmospheric pressure = 760 mmHg (PO2 + PCO2 + PN2 + PH20 + p other gases) 

  • Partial Pressures of Inhaled Air 

    • PN2 = 0.786 x 760 mmHg = 597.4 mmHg 

    • PO2 = 0.209 x 760 mmHg = 158.8 mmHg 

    • PH2O = 0.004 x 760 mmHg = 3.0 mmHg 

    • PCO2 = 0.0004 x 760 mmHg = 0.3 mmHg 

    • p other gases = 0.0006 x 760 mmHg = 0.5 mmHg 

    • Total = 760 mmHg 

  • Atmospheric Pressure  

    • At sea level, atmospheric pressure (Patm) is sufficient to support a column of mercury 760 mm high (760 mmHg).  

    • As altitude increases, total atmospheric pressure decreases.  

      • Example: Denver (~5,000 ft) → Patm ≈ 619 mmHg, so PO ≈ ₂ 129 mmHg (619 × 0.209). 

    • Each gas in a mixture exerts a pressure independent of other gases, called its partial pressure.  

    • To calculate partial pressure: multiply the fractional concentration of the gas by total atmospheric pressure.  

      • O₂ : 20.9% of air → 0.209 × 760 = 159 mmHg (rounded)

      • CO₂ : 0.04% of air → 0.0004 × 760 = 0.3 mmHg

• Determines the pressure gradients required for oxygen and carbon dioxide to diffuse between the lungs and the bloodstream

At sea level what is normal PATM O2, PA O2, Pa O2, PV O2?

• P_{ATM O2} = 158.8 mmHg

• P_{A O2} = 100 mmHg

• P_{a O2} = 100 mgHg

• P_{V O2} = 40 mmHg

What would be considered a normal SaO2?

100% (95-100%)

What effect would emphysema have on P A 02; P a 02; P V 02 and SaO2

Emphysema = progressive lung disease where the alveoli are damaged and rupture, creating one large air space instead of many small ones. Reduces surface area for oxygen absorption and causes lunges to lose elasticity, making it hard to exhale

It causes ventilation-perfusion mismatch and limited gas exchange -> lower PaO2, PvO2, SaO2, while PAO2 remains relatively stable

COPD

What is ventilation perfusion coupling?

• Ventilation: the amount of air reaching the alveoli

• Perfusion: the blood flow in pulmonary capillaries

• Coupling: autoregulatory mechanisms that synchronize perfusion with ventilation

  • Pulmonary arterioles dilate when alveolar ventilation and PAO2 are high

  • Pulmonary arterioles constrict when alveolar ventilation and PAO2 are low

    • Marked vasoconstriction occurs when PAO2 < 60 mmHg

• Chronic or widespread hypoxia can lead to pulmonary hypertension and right-sided heart failure

• Perfusion is uneven and influenced by body position:

  • Zone 1 (apex): Minimal perfusion; alveolar pressure > capillary pressure

    • In an upright position there is less perfusion the apex of the lungs (zone 1) and the alveolar pressure is higher than the capillary pressure

  • Zone 2 (mid-lung): Intermittent perfusion (systolic > alveolar pressure, diastolic < alveolar pressure)

  • Zone 3 (base): Continuous perfusion throughout the cardiac cycle; alveolar pressure < capillary pressure

    • Pulmonary circulation pressure averages about 25/8 mmHg

• The matching of air flow with blood flow in the lungs, maximizes the exchange of oxygen and CO2 between the tiny alveoli and bloodstream

When standing, what lung zone exhibits the greatest perfusion?

Zone 3 - because low pressure, gravity pulls majority of blood downward, causing capillaries at the lung bases to be maximally dilated and full of blood

How are ventilation-perfusion ratios calculated? What is the ideal Va/Q?

• (V̇a/Q̇) 

• To match a sufficient volume of air in the alveoli to sufficient pulmonary blood flow an ideal alveolar ventilation-toperfusion ratio (V̇a/Q̇) would be: 

  • 4 L/min of alveolar ventilation (V̇a) to 5 L/min of pulmonary blood flow (Q̇) in the lungs, thus V̇a/Q̇ = 0.8

    • Base of the lungs - blood flow exceeds ventilation. 

      • V̇a/Q̇ = ~ 2 L/min of alveolar ventilation (V̇a) to 5 L/min of capillary blood flow (Q̇)  

        • V̇a/Q̇ = 0.4  

    • Apex of the lungs - Ventilation exceeds perfusion 

      • V̇a/Q̇ = ~ 4 L/min of alveolar ventilation (V̇a) to 2 L/min of capillary blood flow (Q̇)  

        • V̇a/Q̇ = 2 (represents under perfusion and is 2.5 times the ideal value)  

          • The high V̇a/Q̇ is conceptually similar to dead space air

How is the majority of CO2 carried back to the lungs in the blood?

• Bicarbonate Ions (~70%)  

  • CO₂ diffuses into RBCs and reacts with H₂O (catalyzed by carbonic anhydrase) to form carbonic acid (H₂CO₃) 

  • H₂CO₃ dissociates into H⁺ and HCO₃⁻ :

    • H⁺ binds to Hb, facilitating O₂ release (Bohr effect)  

    • HCO₃⁻ exits RBCs in exchange for Cl⁻ (the chloride shift) to maintain ionic balance

  • In pulmonary capillaries, the reverse occurs:  

    • HCO₃⁻ re-enters RBCs, combines with H⁺ to form H₂CO₃  

    • H₂CO₃ dissociates into CO₂ and H₂O

    • CO₂ then diffuses into alveoli, along concentration gradient, for exhalation

Whose law would apply to what occurs to intrapleural pressure during inspiration?

BOYLE'S LAW: At constant temperature, gas pressure is inversely proportional to volume (P ∝ 1/V)

• Gas always fills its container. If the size of the container decreases the pressure of the gas increases

• When thoracic volume increases (inspiration), intrapulmonary pressure drops, and air enters

• During expiration, volume decreases, pressure increases, and air exits.

How would an increase in temperature affect the O2-Hb dissociation curve?

• As temperature rises, Hb affinity for O decreases, facilitating O unloading in ₂ ₂ metabolically active tissues

  • Heat shifts the dissociation curve to the right; requires higher PO2 for same % saturation of Hb

• Cooling shifts it to the left

• Clinical example: hyperthermia or exercising muscle, increased temp shifts the curve rightward, improving O delivery. In hypothermia, a leftward shift impairs tissue O release.

How would a decrease in pH affect the O2-Hb dissociation curve?

• Normal blood pH = 7.4

• A decrease in pH (↑ H⁺) weakens the Hb–O₂ bond, promoting O₂ release  

  • This occurs when tissue CO₂ levels rise, there is an increase in H⁺.  

• ↓ pH shifts the curve to the right; ↑ pH shifts it to the left

• Clinical example: Lactic acidosis or respiratory acidosis (↑ CO₂) shifts the curve rightward, enhancing O₂ delivery to hypoxic tissues. In alkalosis (e.g., hyperventilation), Hb holds O₂ more tightly, reducing release.

Under normal circumstances what is the percent saturation of Hb at a pO2 of 20? 40? 60? 90?

• Hb saturation is primarily determined by PO₂.  

• Alveoli (P_O2 ~100 mmHg): Hb nearly fully saturated HbO2  

• Tissues at rest (P_O2 ~40 mmHg): Hb ~75% saturated → ~25% of O₂ released into tissue cells

  • 40 -> 75%

• Tissues during vigorous exercise (P_O2 ~20 mmHg): Much more O₂ released due to steep slope of curve.  

  • 20 -> 35%

• P_O2 between 60–100 mmHg: Hb is ≥90% saturated, providing a buffer against moderate hypoxemia

  • At a low P_O2 of 60 mmHg Hb ~ 90% saturated  

  • 60 -> 90%

• Clinical implication: Patients with chronic lung disease may maintain adequate Hb saturation (>90%) despite reduced PO2, but once PO2 drops below ~60 mmHg, saturation falls steeply, causing hypoxemia.

• 90 -> 95%

What is the difference between alveolar ventilation rate and minute volume of respiration?

• Alveolar ventilation = (tidal volume - dead space) x respiratory rate

• Minute volume of respiration = respiratory rate (breaths/minute) x tidal volume

• Minute volume is the total volume of air inhaled or exhaled in one minute. Alveolar ventilation rate is the specific volume of fresh air that reaches the alveoli per minute, excluding the air trapped in "dead space" that cannot participate in gas exchange

Describe the Bohr effect?

Describes how an increase in carbon dioxide (CO₂) and hydrogen ions (lower pH) decreases hemoglobin's affinity for oxygen. This causes the oxygen-hemoglobin dissociation curve to shift to the right, prompting red blood cells to actively release oxygen where your body needs it most

When given a total atmospheric pressure and the partial pressure of a gas, how do you calculate the percent of gas in the atmostphere?

Divide (partial pressure/total pressure) * 100

What percent of O2 is in the atmospheric air? CO2?

O2: 20.9%

CO2: .04

At atmospheric pressure of 500 mmHg, what is the PATM O2? PATM CO2?

O2 = .209 * 500 = 104.5 mmHg

CO2 = .0004 * 500 = .2 mmHg

What percent of O2 is transported dissolved in plasma? What is arterial and venule PO2?

O2 = 1.5%

PaO2 = 100 mmHg

PvO2 = 40 mmHg

What percent of CO2 is transported dissolved in plasma? What is arterial and venule pCO2?

CO2 = 5-7% in plasma

PaCO2 = 40 mmHg

PvCO2 = 45 mmHg

Name the center that prolongs inspiration? Name the center that shortens inspiration?

Apneustic Center:

Provides excitatory input to the medullary inspiratory neurons, prolonging inspiration

Its precise physiological role in humans is debated; pontine integration is now often emphasized rather than discrete “centers.”

What respiratory center is responsible for producing the “ramp” signals?

• Medullary Respiratory Centers

  • Ventral Respiratory Group (VRG)

    • Primary inspiratory center: Neurons (Pre-Botzinger complex) capable of intrinsic depolarization produce spontaneous rhythmic firing

      • Inspiratory impulses are generated in a gradually increasing fashion, described as a ramp signal:

        • Signals begin weakly and increase steadily for ~2 seconds

      • They are transmitted via the phrenic nerve to the diaphragm and via the intercostal nerves to the external intercostal muscles

        • Signal cessation (~3 seconds) allows passive expiration

      • This cycle repeats continuously at ~12–18 breaths per minute (inspiration ~2 sec, expiration ~3 sec)

What is the primary stimulus affecting the peripheral chemoreceptors? Central chemoreceptors?

• Peripheral Chemoreceptors

  • Located in the carotid bodies (bifurcation of the common carotids) and aortic bodies (aortic arch).

  • Stimulate ventilation strongly when PaO₂ < 60 mmHg

  • Glomus cells in the carotid body sense hypoxemia and release neurotransmitters (ATP, acetylcholine, and dopamine) to activate afferent fibers of the glossopharyngeal nerve, relaying signals to medullary centers

  • Carotid bodies are also implicated in sensing lactate, linking metabolism to ventilatory control

• Central Chemoreceptors

  • Located bilaterally in the medulla

  • Highly sensitive to PaCO₂, which diffuses across the blood–brain barrier and forms H⁺ in CSF

  • Small changes strongly affect ventilation:

    • Arterial PaCO₂ is normally maintained within ±3 mmHg of ~40 mmHg

    • A rise of just 5 mmHg can nearly double alveolar ventilation, even if PaO₂ and pH remain unchanged

  • Hyperventilation decreases PaCO₂ and reduces the stimulus for central chemoreceptors

  • Chronic Hypercapnia: In chronic pulmonary disease (e.g., COPD), persistently high PaCO₂ desensitizes central chemoreceptors

    • Hypoxemia (PaO₂ < 60 mmHg) becomes the primary ventilatory drive (“hypoxic drive”)

    • Caution with oxygen therapy:

      • Increasing PaO₂ above ~60 mmHg can reduce hypoxic drive

      • Worsening hypercapnia during O₂ therapy is also due to:

        • Increased V/Q mismatch

        • Reduced hemoglobin buffering of CO (Haldane effect)

Exchange of gas between the blood and lungs is: 

external respiration

What is the middle portion of the pharynx?

Oropharynx

What structure elevates to close off the windpipe?

Larynx

Which forms the anterior wall of the larynx?

Thyroid cartilage

How many lobar bronchi are in the right lung

3

Which cells comprise the walls of the alveoli

Type 1 squamous

Which of the following is not found in the left lung: 

horizontal fissure

Which of the following is the primary muscle of respiration? 

diaphragm

Which pressure prevents the lungs from collapsing: 

transpulmonary pressure

Air moves out of the lungs when the pressure inside the lungs is: 

greater than the pressure in the atmosphere

Intrapulmonary pressure is the: 

pressure within the alveoli of the lungs

During normal pulmonary ventilation, intrapleural pressure (Pip) changes from ___ during inspiration: 

-4 -> -6 mmHg

During respiration air enters into the lungs because: 

atmospheric pressure is greater than the pressure inside the lungs

Which of the following is false: 

intrapleural pressure (Pip) increases during inspiration

Which best describes the forces that act to pull the lungs away from the thorax wall and thus collapse the lungs: 

the natural tendency for the lungs to recoil and the surface tension of the alveolar fluid

Which of the following forces prevent the lungs from collapsing: 

an intrapulmonary pressure greater than the intrapleural pressure

Inspiratory capacity is ___: 

total amount of air that can be inspired after a tidal expiration

The air moved in and out with each normal breath is termed the: 

tidal volume

ERV + RV = 

FRC

Spirometry results reveal a vital capacity of 2 liters. This is well below the predicted value of 5.5 L. What disorder might this finding suggest: 

fibrosis of the lungs

The lung volume that represents the total volume of exchangeable air is: 

vital capacity

tidal volume is air: 

exchanged during normal breathing

TV + IRV + ERV + RV = 

TLC

What is the percent of oxygen in the atmosphere: 

20.9%

Which of the following gases makes up the highest percentage of atmospheric gas: 

nitrogen

pCOs of the systemic arteries: 

40 mmHg

For inspiration of air, which of the following happens first: 

diaphragm contracts and thoracic volume begins to increase

In plasma, the quantity of oxygen in solution is: 

only about 1.5% of the oxygen carried in blood

How is the bulk of carbon dioxide transported in blood: 

as bicarbonate ions in plasma, after first entering the RBCs

What is the normal partial pressure of O2 in arterial blood: 

100 mmHg

What is the normal partial pressure of CO2 in venous blood:

45 mmHg

The Bohr effect describes the tendency for hemoglobin to more readily unload oxygen under which conditions: 

a decrease in serum pH

What is the approximate SaO2 at a pO2 of 20 mmHg if blood pH were 7.4 (normal) and blood temp were 98.6 (normal): 

35%

What is the approximate SaO2 at a pO2 of 40mmHg if blood pH were 7.4 (normal) and blood temp were 986 (normal) : 

75%

Activation of which of the following would increase the respiratory rate:

pneumotaxic center

Which of the following is responsible for generating the spontaneous action potentials that set your basic respiratory rate:

medulla

These chemoreceptors stimulate an increase in respiration if oxygen levels drop below 60 mmHg: 

Peripheral chemoreceptors 

Typically how long does the inspiratory phase, generated by the medulla last: 

2 seconds

Your patient has a diagnosis of emphysema. They are currently afebrile (not feverish) and have normal blood pH. When you place the pulse oximeter on their finger it reads 90% at rest. What is their PaO2 in mmHg: 

60 mmHg

glucose + O2 →

6CO2 + 6H2O + ~36 ATP - in cell, why we breathe

CO2 + H2O in blood → H2CO3 (CA) →

H+ + HCO3- → CO2 + HHb - from Bohr effect → HbCO2

H+ and Cl- from chloride shift → HbO2 → O2 + HHb → O2 to cell

lungs reverse of this?

PA O2

normal: 100

pulmonary edema: 100

COPD/emphysema: 60

Pa O2

normal: 100

pulmonary edema: 50

COPD/emphysema: 60

Sa O2

normal: 100

pulmonary edema: 90

COPD/emphysema: 90

PA CO2

normal: 40

pulmonary edema: 40

COPD/emphysema: higher

Pa CO2

normal: 40

pulmonary edema: 40

COPD/emphysema: higher

Pv O2

normal: 40

pulmonary edema: 30

COPD/emphysema: 35

Pv CO2

normal: 45

pulmonary edema: 45

COPD/emphysema: higher

Sv O2

normal: 75

pulmonary edema: 60

COPD/emphysema: 65

respiration

3 processes:

1. pulmonary ventilation

2. external respiration

3. internal respiration

pulmonary ventilation

The mechanical process of moving air into (inspiration) and out of (expiration) the lungs. Exchange of air between atmosphere and lungs

external respiration

Gas exchange between alveoli and blood (pulmonary capillaries)

O2 enters blood, CO2 exits

internal respiration

Gas exchange between blood (systemic capillaries) and cells

O2 diffuses into cells, CO2 into the blood

Trachea and bronchi are lined with what kind of cell

pseudostratified ciliated columnar epithelium containing goblet cells that secrete mucus for trapping particles

Cilia move the mucus toward the pharynx to be swallowed or expectorated

As airway branches into bronchioles, epithelium transitions to what kind of cell, and cartilage becomes what

the epithelium transitions to simple cuboidal, and cartilage is replaced by smooth muscle to allow regulation of airway diameter

Pharynx

Begins at the internal nares and extends to the level of the cricoid cartilage

Three regions:

1. Nasopharynx

2. Oropharynx

3. Laryngopharynx

Nasopharynx

internal nares to inferior boarder of soft palate Lined with pseudo-stratified columnar epithelium and serves only as an air passage. closed off by the uvula during swallowing.

Eustachian (pharyngotympanic) tubes open into nasopharynx

Oropharynx

soft palate to superior border of the epiglottis

air and food passageway

Laryngopharynx

Superior border of epiglottis to inferior border of cricoid cartilage lies posterior to the upright epiglottis and extends from the superior border of the epiglottis to the inferior border of the cricoid cartilage, where it continues as the esophagus posteriorly and opens into the larynx anteriorly

Both the Oropharynx and Laryngopharynx are lined with nonkeratinized stratified squamous epithelium, suited for protection against abrasion from ingested material

Larynx

structure anterior to the distal portion of the pharynx and contains the vocal folds, contains epiglottis, thyroid cartilage, cricoid, vocal folds, vestibular fold, arytenoid cartilage, glottis, rima glottidis

Epiglottis

During swallowing the larynx elevates and the epiglottis closes off the trachea

Thyroid cartilage

Fused plates of hyaline cartilage that form the anterior wall of the larynx