Respiratory System Overview

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Questions and Answers

What is primarily responsible for directly stimulating the respiratory center?

Nitrogen levels

Oxygen levels

Blood sugar levels

Hydrogen ion concentration (correct)

Which cranial nerves innervate the diaphragm?

C1 - C2

C6 - C7

C3 - C5 (correct)

C8 - T1

Where is the respiratory center located within the brain?

Cerebellum

Cerebral cortex

Hippocampus

Medulla oblongata and pons (correct)

What type of nerve control allows both involuntary and voluntary functions of respiratory muscles?

Somatic nerve Signup and view all the answers

Which chemical has the smallest effect on ventilation?

Oxygen Signup and view all the answers

What is the primary function of the respiratory zone?

Gas exchange Signup and view all the answers

What structure is considered part of the upper airways?

Pharynx Signup and view all the answers

Which of the following describes the function of goblet cells?

Fluidic mucus secretion Signup and view all the answers

What is the significance of the mucociliary escalator?

Facilitates the movement of mucus Signup and view all the answers

What happens to ciliary movement during smoking?

It is temporarily inhibited Signup and view all the answers

How many capillaries are typically associated with each alveolus?

1000 Signup and view all the answers

What is the role of smooth muscle in the respiratory system?

Contributes to airway contraction and dilation Signup and view all the answers

What is affected by cystic fibrosis in the respiratory system?

Decreased fluidic secretion Signup and view all the answers

What is the main method by which oxygen is transported in the blood?

Chemically combined to hemoglobin Signup and view all the answers

Which factor does NOT affect the diffusion of gases through the respiratory membrane?

Molecular weight of the gas Signup and view all the answers

How is carbon dioxide primarily transported in the blood?

As bicarbonate ions Signup and view all the answers

What effect does hypoxia have compared to hypercapnia?

More significant physiological effects Signup and view all the answers

In pulmonary circulation, which statement is true regarding pulmonary arteries?

Exhibit low resistance Signup and view all the answers

What is the primary role of the pulmonary lymphatic system?

Protection against pulmonary edema Signup and view all the answers

What is the Bohr effect primarily associated with?

Increase in O2 release under high CO2 levels Signup and view all the answers

Which statement accurately describes the distribution of pulmonary air?

Influenced by the effect of gravity Signup and view all the answers

What effect does increased sympathetic activity have on the bronchi?

Relaxation of smooth musculature Signup and view all the answers

Which local factors can affect bronchial contraction?

Environmental pollutants Signup and view all the answers

What measurement does the spirometry assess?

Pulmonary function volumes and capacities Signup and view all the answers

In a healthy individual, what is the typical FEV1/FVC percentage?

<blockquote> 80% </blockquote> Signup and view all the answers

What technique uses inert gas to measure lung volumes like RV and TLC?

Helium dilution technique Signup and view all the answers

What is the primary determinant of the work of breathing?

Transpulmonary pressure and lung volume changes Signup and view all the answers

Which pulmonary capacity measures the sum of vital capacity and residual volume?

Total lung capacity Signup and view all the answers

What is the primary purpose of measuring FEF50 in a flow-volume loop?

Determine airway obstruction Signup and view all the answers

What is the role of pulmonary surfactant in the alveoli?

It reduces surface tension and increases compliance. Signup and view all the answers

Which muscle primarily facilitates inspiration?

Diaphragm Signup and view all the answers

During expiration, what is the state of intrapleural pressure?

Becomes less negative Signup and view all the answers

What determines lung compliance?

The change in volume divided by the change in pressure Signup and view all the answers

Which disorder is categorized as restrictive pulmonary disease?

Fibrosis Signup and view all the answers

What occurs to the alveoli when there is a lack of pulmonary surfactant?

The alveoli collapse spontaneously. Signup and view all the answers

In a series configuration of airways, how is total resistance calculated?

It is the sum of individual resistances. Signup and view all the answers

What happens to airway resistance during expiration compared to inspiration?

Resistance increases more than in inspiration. Signup and view all the answers

What is the typical number of alveoli in a single lung?

300 – 500 million Signup and view all the answers

What primarily contributes to the negative pleural pressure during inspiration?

Negative pressure due to lung expansion Signup and view all the answers

Study Notes

Respiratory System Structures

The respiratory system is divided into the upper and lower airways.
The upper airways include the nasal and oral cavity, pharynx, and larynx.
The lower airways include the trachea, bronchi, bronchioles, and alveoli.
The conducting zone consists of the upper and lower airways and is responsible for conducting air to the respiratory zone for gas exchange.
The respiratory zone includes the respiratory bronchioles, alveolar ducts, and alveolar sacs.

Mucociliary Escalator

The mucociliary escalator is a protective mechanism that removes foreign particles from the airways.
Goblet cells secrete mucus, which traps foreign particles.
Ciliated epithelial cells move the mucus up the airways, where it is swallowed.
Bronchitis is caused by a thick mucus secretion in the airways.
Cystic fibrosis is characterized by a decreased fluidic secretion.

Alveoli

Alveoli are the small air sacs where gas exchange occurs.
The alveolar-capillary unit is composed of the alveoli and capillary networks.
Each alveolus has approximately 1000 capillaries.
The average lung contains 300–500 million alveoli, resulting in a respiratory area of approximately 75m2.
The alveolar membrane is very thin, only 0.2um.
Alveolar pores allow for gas exchange between adjacent alveoli.

Gas Exchange

Gas exchange occurs across the alveolar-capillary membrane via diffusion.
The barrier to gas exchange includes the alveolar fluid lining, alveolar epithelial cells, interstitial space, capillary endothelial cells, and blood plasma.

Respiratory Mechanics

Inspiration is an active process that requires the contraction of inspiratory muscles, primarily the diaphragm.
Inspiration overcomes elastic recoil and surface tension, and results in negative pleural pressure.
Weakness of inspiratory muscles can lead to respiratory difficulties.
Expiration is a passive process that relies on elastic recoil and surface tension.
Maximal expiratory pressure can be used to overcome airway resistance during forced expiration.

Lung Volume Change

Lung volume changes during inhalation and exhalation.
Alveolar pressure decreases during inspiration and increases during expiration.
Pleural pressure becomes more negative during inspiration and less negative during expiration.
Air flow is greatest during the middle of inspiration and expiration.

Surface Tension and Compliance

Surface tension in the alveoli creates pressure that makes inspiration more difficult.
Pulmonary surfactant, produced by type 2 alveolar cells, reduces surface tension by 4 cm H2O, improving lung compliance and stability.
Surfactant deficiency, as seen in infant respiratory distress syndrome, can lead to alveolar collapse.

Lung Diseases

Obstructive pulmonary diseases, such as asthma, chronic bronchitis, and emphysema, are characterized by increased airway resistance.
Restrictive pulmonary diseases, such as fibrosis, are characterized by decreased lung compliance.

Airway Resistance

Airways in series have greater resistance than airways in parallel.
Expiration often has greater resistance than inspiration.
Bronchial diameters are regulated by the autonomic nervous system.
Sympathetic activation causes bronchodilation.
Parasympathetic activation causes bronchoconstriction.
Local factors like pollen, smoke, and dust can also stimulate bronchoconstriction.

Pulmonary Function Tests

Pulmonary function tests evaluate lung function and identify respiratory diseases.
Spirometry measures lung volumes and airflow.
Tidal volume is the amount of air inhaled or exhaled during normal breathing.
Inspiratory reserve volume is the maximum amount of air that can be inhaled after a normal inspiration.
Expiratory reserve volume is the maximum amount of air that can be exhaled after a normal expiration.
Residual volume is the amount of air remaining in the lungs after a maximal expiration.
Vital capacity is the maximum amount of air that can be exhaled after a maximal inspiration.
Inspiratory capacity is the maximum amount of air that can be inhaled after a normal expiration.
Functional residual capacity is the amount of air remaining in the lungs after a normal expiration.
Total lung capacity is the maximum amount of air that the lungs can contain.

Gas Exchange in the Alveoli

Gas exchange occurs in the alveoli.
Ventilation is the movement of air into and out of the lungs.
Inspiratory gas is warmed and humidified during inhalation.
Gas movement occurs due to differences in partial pressure.
Gravity influences the distribution of pulmonary air.
Diffusion is the movement of gases across the alveolar-capillary membrane according to partial pressure gradients.
Factors affecting diffusion include surface area, distance, gas solubility, and partial pressure differences.
Arterial blood gas analysis assesses respiratory and acid-base status.

Pulmonary Circulation

Pulmonary arteries carry deoxygenated blood from the right ventricle to the lungs.
Pulmonary blood flow is characterized by low pressure and resistance.
Pulmonary hypertension is abnormally high pressure in the pulmonary arteries.
The lymphatic system plays a role in fluid drainage and immune defense in the lungs.
Gravity influences blood flow in the pulmonary circulation.
Pulmonary edema is an accumulation of fluid in the lungs.

Ventilation/Perfusion Ratio

The ventilation/perfusion (VQ) ratio represents the balance between air flow and blood flow in the lungs.
A well-matched VQ ratio allows for efficient gas exchange.
Mismatched VQ ratios occur when ventilation and perfusion are not balanced, leading to hypoxemia or hypercapnia.

Transport of Gases in the Blood

Oxygen is transported in the blood in two forms: dissolved in plasma (1.5%) and bound to hemoglobin (98.5%).
Hemoglobin is a protein in red blood cells that binds oxygen.
Factors affecting oxygen transport include anemia, hemoglobinopathies, and carbon monoxide intoxication.
Cyanosis is a bluish discoloration of the skin and mucous membranes due to low oxygen levels in the blood.

Oxyhemoglobin Dissociation Curve

The oxyhemoglobin dissociation curve illustrates the relationship between oxygen partial pressure and hemoglobin saturation.
The Bohr effect describes the shift of the curve to the right, indicating a decreased affinity of hemoglobin for oxygen in the presence of increased carbon dioxide, hydrogen ions, or temperature.

Transport of Carbon Dioxide

Carbon dioxide is transported in the blood in three forms: dissolved in plasma, bound to blood proteins as carbamino compounds, and as bicarbonate.
CO2 is highly soluble in lipids and diffuses easily across cell membranes.
Hypoxia (low oxygen levels) is more common than hypercapnia (high carbon dioxide levels) because CO2 is transported more readily than oxygen.

Regulation of Respiration

Breathing is an automatic process regulated by the respiratory center in the medulla oblongata and pons.
The respiratory center is responsible for generating the basic rhythm of breathing.
The diaphragm is innervated by the phrenic nerve, allowing for both voluntary and involuntary control of breathing.
Chemoreceptors monitor the levels of CO2, H+, and O2 in the blood and cerebrospinal fluid.
CO2 is the most potent stimulus for ventilation, directly stimulating the respiratory center.
H+ also stimulates the respiratory center directly.
O2 levels are monitored by peripheral chemoreceptors in the carotid and aortic bodies.

Autonomic Nervous System

Controls involuntary functions.
Divided into sympathetic and parasympathetic divisions.
Sympathetic nervous system ("fight or flight"): prepares body for stressful situations; increases heart rate and breathing, dilates pupils, and inhibits digestion.
Parasympathetic nervous system ("rest and digest"): conserves energy and promotes digestion; slows heart rate, constricts pupils, and stimulates digestion.

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Description

Explore the essential structures of the respiratory system, including upper and lower airways. This quiz covers the mucociliary escalator's protective role and the function of alveoli in gas exchange. Test your knowledge on the key concepts of respiratory anatomy and physiology.