Physiology: Respiratory System Overview

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Questions and Answers

What occurs when an alveolus has increased resistance?

It fills to a lower volume faster than normal.

It fills to the same volume as a normal alveolus given sufficient time. (correct)

It will fill with air slower than normal, regardless of time.

It will remain collapsed and not fill with air.

How does the solubility of gases in blood affect their movement during respiration?

Gases move down their partial pressure gradient influenced by their solubility. (correct)

Only gases with high solubility can move into the alveoli.

Gases move into blood regardless of their solubility.

The solubility of a gas has no impact on gas exchange.

Which statement about the dynamics of respiratory gases is accurate?

Bound gas molecules significantly increase the partial pressure.

Partial pressure contributions come only from unbound gas molecules. (correct)

Carbon dioxide has the same solubility as oxygen in blood.

Gases move against their concentration gradient during respiration.

What is the effect of reduced compliance in an alveolus?

It fills with approximately the same amount of air in a given time. Signup and view all the answers

What happens to oxygen that is bound to hemoglobin in the blood?

It does not contribute to the partial pressure of oxygen. Signup and view all the answers

What is the transpulmonary pressure (PL) equation?

PL = PA - PPL Signup and view all the answers

What occurs when alveoli pressure (PA) exceeds 20 cm H2O?

Rupture of alveoli Signup and view all the answers

During tidal inspiration, what happens to the plural pressure (PPL)?

It slightly decreases Signup and view all the answers

What does high lung compliance indicate?

Lungs easily distend with less pressure Signup and view all the answers

What is the relationship between compliance and elastic recoil?

Compliance is the inverse of elastic recoil Signup and view all the answers

Which phase of breathing causes an increase in alveoli pressure (PA)?

Expiratory relaxation Signup and view all the answers

What happens to lung compliance at high lung volumes?

It becomes lower Signup and view all the answers

Prior to inspiration, what is the average plural pressure (PPL)?

-5 cm H2O Signup and view all the answers

What percentage of carbon dioxide is primarily transported as bicarbonate ion in plasma?

60-70% Signup and view all the answers

Which enzyme significantly accelerates the hydration of carbon dioxide in red blood cells?

Carbonic anhydrase Signup and view all the answers

What process occurs when bicarbonate is exchanged for chloride ions in the red blood cells?

Electroneutrality maintenance Signup and view all the answers

What role do mechanoreceptors play in respiration?

Terminate inspiration to prevent lung overstretching Signup and view all the answers

Which muscles are primarily involved in the physical act of breathing?

Diaphragm and intercostal muscles Signup and view all the answers

What component of carbon dioxide transport accounts for about 7-10% of CO2 in the blood?

Dissolved in plasma Signup and view all the answers

Which of the following processes contributes to bronchodilation?

Relaxation of bronchial smooth muscle Signup and view all the answers

How is carbon dioxide primarily converted in the blood?

By forming carbamino compounds and bicarbonate Signup and view all the answers

What is the primary function of the conducting airways in the respiratory system?

Filter, warm, and humidify incoming air Signup and view all the answers

Which structures are classified as part of the lower airway system?

Trachea, bronchi, and bronchioles Signup and view all the answers

What type of airways are characterized by the presence of cartilage?

Trachea and bronchi Signup and view all the answers

How do capillaries relate to alveoli in the respiratory system?

They facilitate the exchange of gases Signup and view all the answers

What major muscle is responsible for driving inspiration?

Diaphragm Signup and view all the answers

How far can the diaphragm move during active breathing?

Up to 10 cm Signup and view all the answers

What role does the larynx serve in the respiratory system?

Serves as the voice box Signup and view all the answers

What is the significance of the high density of capillaries around each alveolus?

It enhances gas exchange efficiency Signup and view all the answers

What is the average volume of tidal volume (TV) in the lungs?

500 ml Signup and view all the answers

Which lung volume is the maximum amount of air that can be inspired after normal expiration?

Inspiratory reserve volume (IRV) Signup and view all the answers

Which of the following is the formula for calculating vital capacity (VC)?

TV + ERV + IRV Signup and view all the answers

What is the average measurement of expiratory reserve volume (ERV)?

1000 ml Signup and view all the answers

What is the volume of air remaining in the lungs after a maximal expiration called?

Residual volume (RV) Signup and view all the answers

How is functional residual capacity (FRC) calculated?

ERV + RV Signup and view all the answers

What primarily drives exhalation during quiet breathing?

Relaxation of the diaphragm Signup and view all the answers

Which lung capacity represents the total amount of air the lungs can hold?

Total lung capacity (TLC) Signup and view all the answers

What is the average total lung capacity (TLC)?

5700 ml Signup and view all the answers

During active breathing, which muscles assist in exhalation?

Internal intercostals and abdominal wall muscles Signup and view all the answers

What is the typical breathing rate during maximum exercise in adults?

40-45 breaths/min Signup and view all the answers

What does transmural pressure (PW) represent?

Difference between pleural and barometric pressures Signup and view all the answers

Which law describes the relationship between pressure and volume in the context of breathing?

Boyle’s Law Signup and view all the answers

What role does the pleural cavity serve in respiration?

Allows the lungs and ribs to slide relative to each other Signup and view all the answers

What is the definition of transpulmonary pressure (PL)?

Difference between alveolar and pleural pressures Signup and view all the answers

What is the primary characteristic of pleural pressure (PPL)?

It is generally kept at negative pressure Signup and view all the answers

Study Notes

Physiology (0603302)

Course covers the respiratory system, gas exchange, and control of respiration.
Course offered during the Summer semester of 2023/2024.
Instructor: Dr. Mohammad A. Abedal-Majed
Institution: School of Agriculture, The University of Jordan.

Respiration Overview

Respiration is the body process of taking in oxygen and releasing carbon dioxide.
External respiration: gas exchange between the external environment and the body's cells.
Internal respiration: gas exchange between the blood and tissues (this process happens in the mitochondria).
Respiration has 4 steps:
- Ventilation or gas exchange between atmosphere and air sacs (alveoli) in the lungs.
- Gas exchange between air in alveoli and blood.
- Transport of the gases between the lungs and tissues.
- Exchange of oxygen and carbon dioxide between blood and tissues.

Respiratory System Functions

Primary function: Gas exchange (oxygen enters blood, carbon dioxide leaves).
Other functions:
- Regulates blood pH (altered by carbon dioxide levels).
- Produces voice.
- Protects against microorganisms.

Respiratory System Divisions

A- Conducting airways:
- No gas exchange.
- Upper Airway (before trachea): filters, warms, and humidifies air, and protects the delicate lower tract. Includes the nose, pharynx, and larynx.
- Lower Airway (trachea, bronchi, bronchioles): conducts air to and from the gas exchange surfaces.
B- Respiratory airways (gas exchange):
- Bronchioles, alveolar ducts, and alveolar sacs.
- Large surface area for gas exchange (70-80 m² for capillaries, 50-100 m² for alveoli)
- High density of capillaries around alveoli (~1000 capillaries per alveolus)
- RBCs pass through the network in less than 1 second.

Muscles of Inspiration

Inspiration: inhalation of air into the lungs.
Diaphragm drives inspiration (contraction increases thoracic cavity size and pushes against abdominal contents).
Other inspiratory muscles help expand the rib cage (e.g., external intercostals).
Normal quiet breathing moves the diaphragm about 1 cm, active breathing can be up to 10 cm.

Muscles of Expiration

Expiration: exhalation of air out of the lungs.
Passive during quiet breathing (diaphragm relaxes).
Active during exercise or hyperventilation (e.g., internal intercostals, abdominal wall muscles are used for expelling air rapidly.
Normal resting breathing rate (10-20 breaths per minute).

Static Lung Mechanics

Lung Pressure:
- PB: Pressure surrounding the chest wall (barometric pressure).
- PPL: Pressure surrounding the lung (pleural pressure).
- PA: Pressure within the alveoli.
Transpulmonary Pressure (Ptp) = PA - PPL.
Transmural Pressure (Pw) = PPL-PB.
Compliance: Measure of lung elasticity; slope of the pressure-volume curve (AV/AP).
- High compliance: lungs expand easily.
- Low compliance: lungs resist expansion.
Elastic recoil: tendency of the lung to return to its original size.
Surface tension: contributes to elastic recoil (in alveoli), lowering it is crucial.

Static Lung Mechanics- Surface Tension

Elastic properties (e.g., elastin, collagen) are responsible for some elastic recoil, but surface tension is the other significant factor.
Law of Laplace: pressure in alveoli is directly proportional to surface tension and inversely proportional to the radius.

Surfactant

Mixture of phospholipids, lipids, fatty acids, and proteins, secreted by type II pneumocytes.
Reduces surface tension in alveoli; preventing collapse (especially at the end of exhalation).
Keeps alveoli inflated, especially smaller ones.

Clinical Applications

Premature births: surfactant production begins late, causing issues with inflating lungs.
Pulmonary volumes and capacities:
- Tidal volume (TV): volume of air inhaled or exhaled in a single breath.
- Inspiratory reserve volume (IRV): extra volume of air above the normal tidal breath.
- Expiratory reserve volume (ERV): extra volume of air that can be forcefully exhaled after a normal breath.
- Residual volume (RV): volume of air remaining in lungs after maximal exhalation.
- Functional residual capacity (FRC): volume of air in lungs at end of normal exhalation (ERV+RV).
- Inspiratory capacity (IC): maximum volume of air that can be inhaled (TV+IRV).
- Vital capacity (VC) : total volume of air that can be exchanged during a breath (TV+IRV+ERV).
- Total lung capacity (TLC): total volume of air lungs can contain (VC+RV).
Obstructive pulmonary disease: Characterized by increased airway resistance.
Restrictive pulmonary disease: Characterized by decreased lung compliance related to decreased surface area available for gas exchange (e.g., pulmonary fibrosis).

Control of Respiration

Regulation of bronchial/bronchiolar smooth muscle: contraction → bronchoconstriction, relaxation → bronchodilation.
Respiratory center in the brain:
- Sensors (chemoreceptors in the lungs and other areas) detect changes in O2, CO2, and pH.
- Effectors (respiratory muscles like diaphragm, intercostal, and abdominal muscles) respond to the sensors to regulate ventilation.
Summary for control of respiration:
- Parasympathetic system generally causes bronchoconstriction.
- Sympathetic system generally causes bronchodilation.
Regulation of respiration:
- Mechanoreceptors: (stretch receptors in bronchial airways) Prevent overstretching of the lung and pulmonary rupture.
- Chemoreceptors: detect changes in CO2 and O2 and help regulate breathing.

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Description

This quiz covers key concepts of the respiratory system, including gas exchange mechanisms and the control of respiration. It analyzes external and internal respiration processes, as well as the four essential steps of respiration. Ideal for students in the physiology course during the Summer semester of 2023/2024.