Physiology Chapter 4: Respiratory System

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Questions and Answers

What is the primary function of respiration?

Gas exchange (correct)

Protection against microorganisms

Voice production

Regulation of blood pH

Which process refers to gas exchange between the blood and tissues?

Transport of gases

Ventilation

External respiration

Internal respiration (correct)

How does an increase in carbon dioxide levels affect blood pH?

It lowers the pH (correct)

It raises the pH

It has no effect

It stabilizes the pH

What role do the nasal cavity and mucus play in the respiratory system?

They filter foreign bodies Signup and view all the answers

Which of the following is considered an external function of the respiratory system?

Gas exchange with the environment Signup and view all the answers

What happens during ventilation in the context of respiration?

Gas exchange between atmosphere and alveoli Signup and view all the answers

Which gas is primarily responsible for the regulation of blood pH?

Carbon dioxide Signup and view all the answers

Which function of the respiratory system is specifically involved in sound production?

Voice production Signup and view all the answers

What is the primary function of the conducting airways?

Filters, warms, and humidifies incoming air Signup and view all the answers

Which part of the respiratory system is involved in gas exchange?

Alveolar sacs Signup and view all the answers

What distinguishes cartilaginous airways from non-cartilaginous airways?

Composition and structural support Signup and view all the answers

Which muscle primarily drives the process of inhalation?

Diaphragm Signup and view all the answers

What happens to the thoracic cavity during quiet breathing?

It increases in size by up to 1 cm Signup and view all the answers

How many capillaries typically surround each alveolus?

1000 capillaries Signup and view all the answers

Which part of the respiratory system serves as a common passageway for both respiratory and digestive systems?

Pharynx Signup and view all the answers

What is the approximate total surface area of the alveoli available for gas exchange?

50-100 m² Signup and view all the answers

What is the primary function of surfactant in the alveoli?

Lower alveolar surface tension Signup and view all the answers

Which cells are responsible for secreting surfactant?

Type II pneumocytes Signup and view all the answers

What happens to surface tension in smaller alveoli with the presence of surfactant?

Decreases Signup and view all the answers

How does surfactant affect the compliance of the lungs?

Increases compliance Signup and view all the answers

What is one of the physiological benefits of surfactant related to alveoli?

Prevents alveolar collapse Signup and view all the answers

What effect does surfactant have on pressure required to inflate alveoli as lung volume increases?

Pressure required increases Signup and view all the answers

In the absence of surfactant, how would the alveoli behave?

They would collapse due to high surface tension Signup and view all the answers

What is one role of surfactant in maintaining alveolar health?

Maintains dryness of alveoli Signup and view all the answers

What does the formula for transpulmonary pressure (PL) represent?

The difference between alveoli pressure and pleural pressure Signup and view all the answers

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

There is a risk of rupturing the alveoli Signup and view all the answers

How does the contraction of the diaphragm affect pleural pressure (PPL) during inhalation?

PPL becomes more negative Signup and view all the answers

What does compliance in lung mechanics measure?

The volume change per unit pressure change Signup and view all the answers

What happens to lung compliance as lung volume increases?

Compliance decreases Signup and view all the answers

What is the primary role of elastic recoil in lung mechanics?

To facilitate the expulsion of air during expiration Signup and view all the answers

What occurs during tidal inspiration prior to diaphragm contraction?

Pleural pressure (PPL) is slightly negative Signup and view all the answers

What effect does elastic recoil have on lung behavior during breathing?

It prevents over-inflation of the lungs. Signup and view all the answers

What is the function of surfactant in the lungs?

To prevent lung collapse by reducing surface tension Signup and view all the answers

Which lung volume represents the air breathed in and out during normal breathing?

Tidal Volume Signup and view all the answers

How is Total Lung Capacity (TLC) calculated?

Vital Capacity + Residual Volume Signup and view all the answers

What is the typical volume range of Residual Volume (RV) in females?

1000 ml Signup and view all the answers

Which lung capacity includes both Expiratory Reserve Volume (ERV) and Residual Volume (RV)?

Functional Residual Capacity Signup and view all the answers

What is the typical range for Inspiratory Reserve Volume (IRV)?

1500 – 2000 ml Signup and view all the answers

Which volume is NOT included in the calculation of Vital Capacity (VC)?

Residual Volume Signup and view all the answers

What is the role of cortisol in lung development during gestation?

To stimulate the production of surfactant Signup and view all the answers

What is the primary method of carbon dioxide transport in the blood?

As bicarbonate ion in plasma Signup and view all the answers

Which enzyme accelerates the hydration of CO2 in red blood cells?

Carbonic anhydrase Signup and view all the answers

What percentage of CO2 is typically transported as carbamino compounds?

20-30% Signup and view all the answers

What role do mechanoreceptors play in the respiratory system?

They prevent overstretching of the lung. Signup and view all the answers

Which ions are exchanged in RBCs to maintain electroneutrality when bicarbonate is transported out?

Cl- Signup and view all the answers

What happens to carbonic acid after it is formed in RBCs?

It dissociates into HCO3- and H+. Signup and view all the answers

What does bronchodilation refer to in the context of respiratory control?

Widening of bronchioles Signup and view all the answers

What is the result of increased inspiration or specific diseases regarding mechanoreceptors?

They prevent lung overstretching. Signup and view all the answers

Study Notes

Physiology (0603302) - Chapter 4: Respiratory System

Focuses on the respiratory system, gas exchange, and control of respiration
Course offered in the Summer semester of 2023/2024
Presented by Dr. Mohammad A. Abedal-Majed
Provided by the School of Agriculture, The University of Jordan

Overview of Respiration

Respiration is the process of taking in oxygen (O2) and releasing carbon dioxide (CO2).
External respiration is gas exchange between the external environment and the cells of the body.
Internal respiration is gas exchange between the blood and tissues (metabolic processes in the mitochondria).
External respiration steps:
- Ventilation, or gas exchange between the atmosphere and air sacs in the lungs.
- Gas exchange between air in the alveoli (air sacs) and the blood.
- Transport of O2 and CO2 between the lungs and the tissues.
- Gas exchange between the blood and the tissues.

Respiratory System Functions

Primary functions:
- Gas exchange: Oxygen enters blood, carbon dioxide exits.
Other functions:
- Regulation of blood pH: Changes in CO2 levels alter pH.
- Voice production: Movement of air past vocal folds creates sound.
- Protection: Prevents microorganisms from entering the respiratory system.

Respiratory System Divisions

A - Conducting Airways:
- No gas exchange occurs here (anatomical dead space).
- Upper Airways (before trachea):
  - Nose, pharynx, larynx
  - Functions include filtration, warming, and humidification of incoming air and protecting delicate lower tract.
- Lower Airways (trachea, bronchi, bronchioles):
  - Conducts air to and from gas exchange surfaces.
B - Respiratory Airways (gas exchange):
- Bronchioles, alveolar ducts, alveolar sacs.
- High surface area for gas exchange.
- Dense capillary networks surround alveoli, enhancing gas exchange.
- RBCs (red blood cells) pass through alveolar capillary networks rapidly (~ <1 sec).

Muscles of Inspiration

Inspiration (inhalation): The process of drawing air into the lungs.
Diaphragm contraction increases the thoracic cavity size, pushing against abdominal contents.
Other inspiratory muscles (e.g., external intercostals) help expand the rib cage.
Normal quiet breathing involves movement of about 1 cm of the diaphragm and 10 cm of active breathing.

Muscles of Expiration

Expiration (exhalation): The process of expelling air from the lungs.
Passive during quiet breathing: Diaphragm relaxes, rib cage descends, and thoracic cavity shrinks.
Active during exercise: Abdominal and internal intercostal muscles contract, expelling more air.
Breathing rates are 10-20 breaths per minute at rest; increasing to 40-45 during maximum exercise.

Static Lung Mechanics

Lung pressures:
- PB = barometric pressure (surrounding chest wall).
- Ppl = intrapleural pressure (pressure in the pleural space).
- PA = alveolar pressure (pressure within alveoli).
Transpulmonary pressure: (a measure of the lung's tendency to collapse)
- Difference between alveolar pressure (PA) and intrapleural pressure (Ppl).
Transmural pressure:
- Difference between intrapleural pressure (Ppl) and barometric pressure (PB).

Principles of Breathing

Follows Boyle's Gas Law: Pressure x Volume = Constant
Volume changes lead to pressure changes, causing air movement into and out of the lungs.
Pleural cavity: Small space with negative pressure, allowing lungs and ribs to move smoothly.

Pulmonary Volumes and Capacities

Volumes: Specific amounts of air.
Capacities: The sum of two or more volumes.
- Tidal volume (TV): Amount of air inhaled/exhaled in a single breath.
- Inspiratory reserve volume (IRV): Extra air inhaled beyond tidal volume.
- Expiratory reserve volume (ERV): Extra air exhaled beyond tidal volume.
- Residual volume (RV): Amount of air remaining in lungs after maximal exhalation.
- inspiratory capacity(IC): Total volume of air that can be inhaled.
- Functional residual capacity(FRC): Volume of air in the lungs after a normal exhalation.
- Vital capacity (VC): Maximum volume of air that can be exhaled after maximal inhalation.
- Total lung capacity (TLC): Maximum volume of air lungs can hold.

Clinical Applications

Premature births: Infants born prematurely often have inadequate surfactant, resulting in lung difficulties.
Restrictive lung diseases: Characterized by a reduction in lung compliance (difficulty inflating lungs). Lung volumes will be smaller than normal.
Obstructive lung diseases: Characterized by increased airway resistance (difficulty exhaling). Lung volumes may be normal, but maximum airflow may be decreased.

Control of Respiration

Regulation of bronchial/bronchiolar smooth muscle.
Breathing centers in the brain:
- Pons, medulla.
- Chemoreceptors in lungs and other tissues monitor blood gases and pH.
Effectors:
- Diaphragm..
- Intercostal muscles..
- Abdominal muscles.

Summary for Control of Respiration

Parasympathetic responses
- bronchoconstriction
Sympathetic responses
- bronchodilation

Regulation of Respiration

Mechanoreceptors (stretch receptors in airways) respond to lung inflation and prevent over-expansion.
Chemoreceptors respond to changes in O2, CO2, and H+ levels in the blood.
Peripheral chemoreceptors monitor blood gases and pH, and central chemoreceptors are located in the medulla.

Pulmonary Function Tests

Useful for assessing lung function (e.g., FVC, FEV1).
Can diagnose restrictive or obstructive lung diseases.

Oxygen Transport

Oxygen is poorly soluble in blood plasma.
Most oxygen is carried by hemoglobin within red blood cells .

Carbon Dioxide Transport

Majority of CO2 is transported as bicarbonate ions in the blood.

PO2 and PCO2 in Blood

Partial pressure gradients drive O2 and CO2 movement between the lungs and tissues.

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Description

Explore the intricacies of the respiratory system in this quiz based on Chapter 4 of the Physiology course. Learn about gas exchange processes, ventilation, and the control of respiration. This is an essential chapter for understanding how oxygen is transported and carbon dioxide is released in the body.