Respiratory Mechanics Quiz

Questions and Answers

What role does hydrogen bonding play in the surface tension of water?

It creates a cohesive force that allows water molecules to cling together. (correct)

It promotes the evaporation of water.

It decreases the density of water.

It increases the temperature of the water.

How does increased surface tension affect lung compliance?

It increases lung compliance.

It decreases lung compliance. (correct)

It only affects the alveoli during inspiration.

It has no effect on lung compliance.

What effect does surface tension have on alveolar size?

It promotes alveolar expansion.

It has no impact on alveolar size.

It causes alveoli to collapse. (correct)

It maintains a constant alveolar size.

What is a consequence of damage to the alveoli walls in emphysema?

Decreased lung surface area. Signup and view all the answers

What role do alveolar macrophages play in response to irritants in smokers?

They secrete an enzyme that breaks down elastin fibers. Signup and view all the answers

What is the primary factor that causes air to flow out of the lungs during expiration?

Higher alveolar pressure compared to atmospheric pressure Signup and view all the answers

During active expiration, which muscles primarily contribute to increasing intra-alveolar pressure?

Internal intercostals and abdominal muscles Signup and view all the answers

What happens to the diaphragm at the end of inspiration?

It relaxes and returns to a dome-shaped position Signup and view all the answers

Which of the following statements is true regarding the normal, resting ventilation rate for an adult?

It commonly ranges from 12-20 breaths per minute Signup and view all the answers

What mechanism prevents the lungs from collapsing during expiration, despite the increase in intrapleural pressure?

Transmural pressure gradient Signup and view all the answers

Which physiological change characterizes expiration?

Lung and thoracic volumes decrease Signup and view all the answers

What is the effect of abdominal muscle contraction during active expiration?

It exerts an upward force on the diaphragm Signup and view all the answers

What occurs when alveolar pressure equals atmospheric pressure?

Air stops flowing Signup and view all the answers

How does air flow during expiration according to Boyle's law?

Air flows from high pressure to low pressure Signup and view all the answers

What is the role of the suction pump in managing pneumothorax?

To remove air from the pleural cavity Signup and view all the answers

What is the main characteristic of hypoxic hypoxia?

Low arterial PO2 Signup and view all the answers

Which condition is typically associated with ischemic hypoxia?

Heart failure Signup and view all the answers

What blood pH value is considered normal in arterial blood?

7.4 Signup and view all the answers

Which of the following causes is classified under histotoxic hypoxia?

Cyanide poisoning Signup and view all the answers

Which factor contributes to anemic hypoxia?

Altered hemoglobin binding Signup and view all the answers

What characterizes chronic obstructive pulmonary disease (COPD)?

Increased airway resistance during expiration Signup and view all the answers

Which of the following factors can trigger chronic bronchitis?

Frequent exposure to cigarette smoke Signup and view all the answers

How does asthma primarily differ from COPD in terms of airway obstruction?

Asthma typically has reversible airway obstruction Signup and view all the answers

What causes the thickening of airway walls during an asthma attack?

Smooth muscle spasms and histamine-induced edema Signup and view all the answers

What is the effect of pulmonary fibrosis on lung function?

Reduced elastic recoil Signup and view all the answers

Which of the following defines hypoxia?

Too little oxygen Signup and view all the answers

What is the primary role of the body in response to hypoxia and hypercapnia?

To regulate gas exchange variables Signup and view all the answers

In chronic bronchitis, what primarily causes the airways to narrow?

Thickening of airway linings and mucus production Signup and view all the answers

What primarily stimulates the diaphragm during inspiration?

Phrenic nerve Signup and view all the answers

Which of the following muscles is NOT considered an inspiratory muscle?

Rectus abdominis Signup and view all the answers

During quiet breathing, expiration is primarily considered a ___ process.

Passive Signup and view all the answers

What happens to intra-alveolar pressure during inspiration?

Decreases below atmospheric pressure Signup and view all the answers

What is the role of the intercostal muscles during inspiration?

Raise the rib cage Signup and view all the answers

What occurs at the end of inspiration regarding lung volume?

Lung volume is at its maximum Signup and view all the answers

Which pressure is lower than atmospheric pressure during inspiration?

Intra-alveolar pressure Signup and view all the answers

How is a pneumothorax created?

By a knife puncturing the pleural membrane Signup and view all the answers

What happens to the diaphragm during expiration?

It relaxes and moves upward Signup and view all the answers

Which accessory muscles assist during deeper inspirations?

Scalenes and sternocleidomastoid Signup and view all the answers

The transmural pressure gradient is responsible for what effect during breathing?

Stretching the lungs to fill the thoracic cavity Signup and view all the answers

What pressure is generally considered as atmospheric pressure at sea level?

760 mmHg Signup and view all the answers

During a single inspiration, what happens to the thoracic volume?

Increases, allowing air to flow in Signup and view all the answers

What is the normal adult ventilation rate at rest?

12-20 breaths/min Signup and view all the answers

Study Notes

Respiratory Mechanics: Inspiration and Expiration

Diaphragm moves downward and ribs elevate during inspiration.
Inspiratory muscles expand thoracic cavity: external intercostals, sternocleidomastoid, anterior serrati, and scalenes.
Phrenic nerve stimulates diaphragm to contract, leading to abdominal muscle bulging.
External intercostals contract, lifting ribs and sternum up and out.
Decreased intra-alveolar pressure (759 mmHg) allows air to flow into lungs.
Intrapleural pressure decreases to allow lung expansion.
Quiet breathing occurs at 12-20 breaths/minute in adults.

Breathing Dynamics

Single inspiration starts at alveolar pressure equal to atmospheric pressure.
During inspiration, thoracic volume increases, lowering alveolar pressure, which results in airflow into the lungs.
End of inspiration reaches maximum lung volume, and intrapleural pressure decreases.
Expiration is primarily passive; inspiratory muscles relax, diaphragm returns to dome shape, and rib cage falls due to gravity.
Lung volume decreases as air pressure in the lungs increases, facilitating air expulsion until alveolar pressure equals atmospheric pressure.

Active Expiration

Occurs during exercise or forced breathing.
Involves contraction of internal intercostal and abdominal muscles to raise intra-alveolar pressure.
Abdominal muscles push diaphragm upwards; intercostal muscles pull ribs down and inwards.
Intrapleural pressure rises without lung collapse due to the transmural pressure gradient.
Ventilation rates can increase to 30-40 breaths/minute during active respiration.

Pneumothorax

Occurs when air enters the pleural cavity, leading to equalization of intrapleural and intra-alveolar pressures with atmospheric pressure.
Loss of transmural pressure gradient causes lung collapse and thoracic wall expansion.
Treatment involves air removal with a suction pump and sealing the puncture.

Types of Hypoxia

Hypoxic hypoxia: Low arterial oxygen, caused by high altitude or poor ventilation.
Anemic hypoxia: Low oxygen bound to hemoglobin due to anemia or carbon monoxide poisoning.
Ischemic hypoxia: Reduced blood flow due to heart failure or shock.
Histotoxic hypoxia: Cells can't use oxygen due to metabolic poisoning.

Normal Blood Values

Arterial PO2: 95 mmHg (range 85–100)
Venous PO2: 40 mmHg
Arterial PCO2: 40 mmHg (range 35–45)
Venous PCO2: 46 mmHg
Normal blood pH: 7.4 (range 7.38–7.42)

Conditions Affecting Lung Compliance

Emphysema: Damage to alveoli decreases lung surface area and elastic recoil, making expiration effortful.
Chronic obstructive pulmonary disease (COPD): Includes chronic bronchitis, leading to airway inflammation and increased resistance.
Asthma: Characterized by airway inflammation, mucus production, and muscle spasms prompting severe airway constriction.

Respiratory Resistance and Compliance

Increased airway resistance in conditions like COPD complicates expiration.
Normal compliance indicates the lungs can easily expand; impaired compliance results in retention of air, affecting lung mechanics.
Surface tension from alveolar fluid, stemming from hydrogen bonding, resists lung expansion and contributes to elastic recoil after inspiration.

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Description

Test your knowledge on the mechanics of respiration, focusing on the processes of inspiration and expiration. This quiz covers the roles of various muscles, pressures involved in breathing, and the dynamics of lung volume changes. Perfect for students studying respiratory physiology.