AP 2, CH 22: Respiratory System

What is the most important function of the respiratory system?

Supply tissues with oxygen and remove carbon dioxide

Define the four processes of respiration including pulmonary ventilation

1. Pulmonary Ventilation

   1. Breathing (air moves in and out of lungs)

2. External Respiration

   1. Gas exchanged between alveoli and blood

3. Transport

   1. Oxygen and carbon dioxide transported in blood

4. Internal Respiration

   1. Gas exchange between blood and tissues

What are five major functions of the nose

1. Provides airway for respiration

2. Moistens air and warms air

3. Serves are chamber for speech

4. Filters inhaled air

5. Contains receptors for smell

What are the two functions of the paranasal sinuses

Lighten the skull, enhance voice resonsane

What are the four paranasal sinuses

1. Frontal

2. Maxillary

3. Ethmoid

4. Sphenoid

Three regions of the pharynx (top to bottom)

1. Nasopharynx

2. Oropharynx

3. Laryngopharynx

What type of epithelium lines the nasopharynx? How does this relate to the function of the nasopharynx?

Pseudostratified ciliated columnar epithelium; helps filter and move mucus.

Why is it important for the lining of the oropharynx to transition to stratified squamous epithelium?

Because food passes through and this epithelium protects against abrasion.

Which type of epithelium lines the laryngopharynx? How does it relate to the function of the laryngopharynx?

Stratified squamous epithelium; protects from food abrasion during swallowing.

What respiratory structures make up the conducting zone of the airway?

• nose

• nasal cavity

• pharynx

• larynx

• trachea

• bronchi

• bronchioles

• terminal bronchioles

Function: transport air, no gas exchange

Which respiratory structure make up the respiratory zone of the airway?

• Respiratory Bronchioles

• Alveolar ducts

• Alveolar sacs

• Alveoli

• Function: Gas exchange

Where does gas exchange occur?

Only in the respiratory zone

What are the three main functions of the larynx?

1. Keep airways open

2. Routes air and food

3. Voice production

Of which type of cartilage are the thyroid cartilage and cricoid cartilage made?

Hyaline cartilage

Of which type of cartilage is the epiglottis made?

Elastic cartilage

What is the function of the glottis?

Opening that allows air to pass through the larynx

What is the function of the epiglottis?

Prevents food from entering the trachea during swallowing

To what bone does the larynx attach?

Hyoid bone

What is the function of the vocal folds (true vocal cords)?

Produce sound; voice

What is the function of the vestibular folds (false vocal cords)?

Helps close the glottis during swallowing

Name the four layers of trachea

1. Mucosa

2. Submucosa

3. Hyaline cartilage layer

4. Adventitia

What role does hyaline cartilage play in the structure and function of the trachea?

Keeps airway open and prevents collapse

Why is it useful for the esophagus that the cartilage rings around the trachea leave a gap at the posterior side of the trachea?

Allows esophagus to expand when swallowing food

What is the carina?

The ridge where the trachea splits into the primary bronchi

Name the three divisions of the bronchi that connect the carina to the bronchioles

1. Primary bronchi

2. Secondary bronchi

3. Tertiary bronchi

What is the diameter at which a bronchus is considered a bronchiole?

1 mm diameter

What is the diameter at which a bronchiole is considered a terminal bronchiole?

0.5mm diameter

Of what two layers is the thin respiratory membrane composed?

1. Alveolar epithelium

2. Capillary endothelium

Name the main cell type in the epithelial layer of the respiratory membrane

Type I alveolar cells

Why is it important that the respiratory membrane be incredibly thin?

Allows rapid gas diffusion

What are the main gasses being exchanged at the respiratory membrane?

Oxygen and carbon dioxide

Name the secretion of type II alveolar cells that prevents the alveoli from collapsing during exhalation

Surfactant (produced by type II alveolar cells)

Be able to place in order the airway structures from the nasal passages to the alveoli

• Nose / nasal cavity

• Pharynx

• Larynx

• Trachea

• Primary Bronchi

• Secondary Bronchi

• Tertiary Bronchi

• Bronchioles

• Terminal bronchioles

• Respiratory bronchioles

• Alveolar ducts

• Alveoli

The base of the lung rests on the _____

diaphragm

The apex of the lung is located deep to the _____

Clavicle

What is the name of the space provided for the heart by the smaller size of the left lung

Cardiac notch

What is the name for the structure (curvature) at which the bronchi and blood vessels enter the lung?

Hilum

Of what type of membrane are the pleura an example?

Serous membrane

Which layer of the pleura covers the thoracic wall? Which layer covers the external surface to the lung?

Parietal pleura: covers thoracic wall

Visceral pleura: covers lungs

What are two functions of the pleura related to lung function?

1. Reduce friction

2. Helps lung adhere to thoracic wall

The relationship between pressures in which three locations determines the flow of air into and out of the lungs?

1. Atmospheric pressure

2. Intrapulmonary pressure

3. Intrapleural pressure

The period during which air exits the lungs is called?

Expiration

The period during which air enters the lungs is called?

inspiration

Why is atmospheric pressure important when thinking about ventilation?

Air moves from high pressure to low pressure

Define intrapulmonary pressure

Pressure inside the lungs

Define intrapleural pressure and describe how it is important for ventilation

Pressure in pleural cavity; keeps lungs expanded against chest wall

Which pressure is always negative in healthy adults?

Intrapleural pressure

What happens if the transpulmonary pressure equals zero? What is this condition called and what might cause it?

Lung collapses; pneumothorax. Caused by punctured pleura.

What does it mean for air to “flow down its pressure gradient?”

Air moves from high pressure to low pressure

What is Boyle’s law?

Pressure and volume are inversely related; volume increase = pressure decrease.

Relative to atmospheric pressure, during which phase of ventilation is intrapleural pressure highest? In which phase is it lowest?

Highest pressure: Expiration

Lowest pressure: Inspiration

Is ventilation an active or passive process?

Combination; inspiration is driven by muscle contraction but quiet expiration is driven by elastic recoil.

Which muscle must contract to create a normal quiet inspiration?

Diaphragm

What muscles must contract to create a forced inspiration?

Diaphragm, external intercostals, accessory muscles

What happens to intrapulmonary and intrapleural pressures when the diaphragm contracts? What happens when the diaphragm relaxes?

Thoracic volume increases; intrapulmonary pressure decreases. Air flows into lungs.

Is normal quiet expiration active or passive?

Passive; driven by elastic recoil

Which muscles must contract to create a forced expiration?

Internal intercostals and abdominal muscles

What are the five steps of inspiration?

1. Inspiratory muscles contract

2. Thoracic cavity volume increases

3. Lung volume increases

4. Intrapulmonary pressure drops

5. Air flows into the lungs

What are the five steps of expiration?

1. Inspiratory muscles relax

2. Thoracic cavity volume decreases

3. Elastic lungs recoil

4. Lungs stretch; Intrapulmonary pressure rises

5. Air flows out of the lungs

Name three physical factors that influence pulmonary ventilation

1. Airway resistance

2. Alveolar surface tension

3. Lung compliance

What is the relationship between airway resistance and air flow during ventilation?

Higher resistance = less air flow

What is the relationship between lung compliance and air flow during ventilation?

lower compliance = harder to inflate lungs

What is the relationship between alveolar surface tension and air flow during ventilation?

increased surface tension = lower ventilation

Why is surfactant important for lung function? What would happen to alveoli in the absence of surfactant?

It reduces surface tension and prevents alveolar collapse; alveoli would collapse without this

What is the major cause of infant respiratory distress syndrome (IRDS) in premature babies born before 28 weeks of development?

Lack of surfactant in premature infants

What is the typical treatment for IRDS?

Artificial surfactant therapy

Define dalton’s law

Total pressure = sum of partial pressures of all gases

What is Henry’s law?

The amount of gas that dissolves in a liquid depends on its partial pressure and solubility.

What is partial pressure? What units do we normally use to measure partial pressure of a gas?

Pressure exerted by one gas in a mixture; mmHg

Describe how atmospheric and alveolar air differ in composition and explain these differences.

Alveolar air has lower partial pressures of nitrogen and oxygen, but higher partial pressures of carbon dioxide and water vapor compared to atmospheric air.

Is the partial pressure of oxygen higher in the atmosphere or in the alveoli

Its higher in the atmosphere

Is the partial pressure of oxygen higher in the alveoli or in the pulmonary capillary blood?

Its higher in the alveoli than in the pulmonary capillary

Is the partial pressure of carbon dioxide higher in the alveoli or in the pulmonary capillary blood

pulmonary capillary blood

Which are the three major gases found in the atmosphere? what is the typical percentage of each gas at sea level? What is the typical partial pressure of each gas at sea level?

Nitrogen (78%), Oxygen (21%), Carbon dioxide (1%); 760mm Hg

Where does external respiration occur? Where does internal respiration occur?

External respiration: occurs in the lungs (exchange between lungs and capillaries).

Internal respiration: occurs in the body tissues (exchange between tissues and capillaries).

What three factors influence external respiration

1. Thickness and surface area of the respiratory membrane

2. Partial pressure gradients and gas solubilities

3. Ventilation (amount of air reaching the lung) and Perfusion (blood flow to lung capillaries)

On what three factors does the amount of a gas that will dissolve in a liquid depend

1. Partial pressure of gas

2. Solubility of the gas

3. Temperature (temp inc. = solubility dec.)

What are the two ways in which oxygen is transported through the blood? which one is, by far the most important?

1. Bound to hemoglobin within RBC’s

2. Dissolved in plasma

3. Most important thing: binding to hemoglobin is the primary method

Define hypoxia. What is a visible sing of hypoxia in pale-skinned people? Name a few common causes

Def: Not enough oxygen delivery to tissues

Signs: Cyanosis

Causes: breathing issues, cardiovascular disease, reduced oxygen environments

What is the relationship between the arterial partial pressure of oxygen and the binding of oxygen to hemoglobin

pressure of oxygen is directly related to the oxygen saturation of hemoglobin

What is the relationship between pH and oxygen binding to hemoglobin?

Decreasing pH decreases hemoglobin’s affinity for oxygen

What is the relationship between carbon dioxide partial pressure and oxygen binding to hemoglobin?

Increasing pressure of oxygen decreases oxygen saturation/affinity of hemoglobin

What is the name of the effect that describes the relationship between pH, PCO2, and hemoglobin binding to oxygen?

The bohr effect

What is the relationship between temperature and oxygen binding to hemoglobin?

Increasing temperature decrease hemoglobin’s affinity for oxygen, promoting oxygen unloading to active tissues

What is the relationship between BPG and oxygen binding to hemoglobin?

Increase BPG decreases affinity

Name three ways carbon dioxide is transported through the blood. Which is most typical?

1. As bicarbonate ions in plasma

2. Bound to hemoglobin

3. Dissolved in plasma

What is the relationship between the partial pressure of oxygen and the amount of carbon dioxide that hemoglobin can carry? what is the name of this effect?

• As hemoglobin releases oxygen, it more readily forms bonds with Carbon dioxide

• Effect name: The Haldane effect

Where are the respiratory centers located?

In the pons and medulla oblongata

What is a normal breathing rate during eupnea

12-15 breaths per minute

Which two peripheral nerves innervate respiratory muscles?

1. Phrenic nerve (diaphragm)

2. Intercostal nerve (external intercostals)

Describe the relationships between blood pH, oxygen partial pressure, carbon dioxide partial pressure, and breathing rate

• an increase in co2 pressure leads to the formation of carbonic acid which increase H+ (decreases pH)

• The drop in pH stimulate chemoreceptors, which stimulate respiratory centers in the brain to increase breathing depth and flush out CO2

Under normal circumstances, which factor has the biggest impact on breathing?

• Rising CO2 levels are the most powerful stimulant under normal conditions

Under what circumstances does the partial pressure of oxygen have the biggest impact on breathing?

Pressure of oxygen only becomes a major respiratory stimulant when arterial oxygen pressure levels fall significantly below 60mm Hg

What factors can stimulate peripheral chemoreceptors?

Stimulated by decreased pressure of oxygen, increased pressure of carbon dioxide, and decreased arterial pH

What factors can stimulate central chemoreceptors?

primarily stimulated by increased H+ (dec. pH) in the brain tissue that results from rising co2 levels

Define Apnea

Temporary cessation of breathing

Define hyperventikation

increase in breathing rate and depth that exceeds the body’s need to remove carbon dioxide

How does hyperventilation differ from hyperpnea?

Hyperpnea is an appropriate increase in breathing to meet metabolic needs (like exercise), whereas hyperventilation leads to excessively low $CO_2$ levels.

Why can hyperventilation be dangerous?

It causes low CO2 levels (hypocapnia), which leads to cerebral vasoconstriction, dizziness, and fainting.

What is a simple method to reduce the symptoms of hyperventilation?

Breathing into a paper bag helps by allowing the person to re-breathe exhaled carbon dioxide