respitatory system Flashcards
What is pulmonary ventilation?
The process of inspiration and expiration of air in the lungs.
What is atmospheric pressure at sea level?
760 mmHg.
Define negative respiratory pressure.
Pressure lower than atmospheric pressure.
Define positive respiratory pressure.
Pressure higher than atmospheric pressure.
What is zero pressure in respiratory terms?
Pressure equal to atmospheric pressure.
What is the intrapulmonary pressure at rest?
Intrapulmonary pressure (Ppul) = Patm.
What is the intrapleural pressure at rest?
Intrapleural pressure (Pip) = 756 mmHg.
What is transpulmonary pressure?
Transpulmonary pressure = Ppul - Pip.
What happens when intrapleural pressure equals intrapulmonary pressure?
It leads to lung collapse.
What condition is characterized by the presence of air in the pleural cavity?
Pneumothorax.
What does Boyle’s law state in relation to pulmonary ventilation?
P1V1 = P2V2, indicating that pressure and volume are inversely related.
What muscles are involved in quiet inspiration?
Diaphragm and external intercostal muscles.
What is the volume of air inspired during quiet inspiration?
Around 500 mL.
What is the pressure difference during quiet expiration?
Ppul is 1 mmHg greater than Patm.
What additional muscles are employed during forced inspiration?
Sternocleidomastoid, scalenes, and pectoralis minor.
What are the factors affecting ventilation?
Airway resistance, alveolar surface tension, lung compliance.
What is the major nonelastic source of resistance to airflow?
Airway resistance due to friction.
How does airway diameter affect resistance?
Resistance is mostly determined by the diameter of the airway.
What role does surfactant play in the alveoli?
It reduces surface tension and prevents alveoli from collapsing.
What does lung compliance refer to?
The effort required to stretch the lungs and thoracic wall.
Define tidal volume (TV).
The amount of air moved into or out of the lungs during a normal breath (~500 mL).
What is inspiratory reserve volume (IRV)?
The amount of air that can be forcefully inspired after a normal tidal volume (~3100 mL).
What is expiratory reserve volume (ERV)?
The amount of air expired forcefully after a normal expiration (~1200 mL).
What is residual volume (RV)?
The volume remaining in the lungs after the most forceful expiration (~1200 mL).
What is inspiratory capacity (IC)?
Tidal volume + inspiratory reserve volume (~3600 mL).
What is functional residual capacity (FRC)?
Expiratory reserve volume + residual volume (~2400 mL).
What is vital capacity (VC)?
Inspiratory reserve volume + tidal volume + expiratory reserve volume (~4800 mL).
What is total lung capacity (TLC)?
Inspiratory reserve volume + expiratory reserve volume + tidal volume + residual volume (~6000 mL).
What does spirometry evaluate?
Loss in respiratory function and can follow the course of certain diseases.
What is forced vital capacity (FVC)?
The amount of gas expelled during a forceful maximal exhalation after a deep breath.
What does forced expiratory volume (FEV) measure?
The amount of air expelled during specific intervals of the FVC test.
What characterizes obstructive disorders in spirometry results?
Increased TLC, FRC, and RV; FEV shows that the patient can’t exhale 80% FVC in 1 second.
What characterizes restrictive disorders in spirometry results?
Declined VC, TLC, FRC, and RV; FEV is often normal despite decreased FVC.
What is minute ventilation?
The volume of air ventilated per minute, normal at 6L/min during quiet breathing.
What is alveolar ventilation?
A better index of effective ventilation, calculated as AVR = frequency x (TV - dead space).
True or False: Shallow breathing does not affect minute ventilation.
True.
True or False: Alveolar ventilation is less accurate than minute ventilation in assessing ventilation.
False.
What are the organs of the respiratory system?
- Nose
- Pharynx
- Larynx
- Trachea
- Bronchi
- Lungs
These organs work together to facilitate breathing and gas exchange.
What are the two main anatomical divisions of the respiratory system?
- Upper respiratory tract
- Lower respiratory tract
The upper respiratory tract includes the nose and pharynx, while the lower includes the larynx, trachea, bronchi, and lungs.
What is the function of the conducting zone in the respiratory system?
Allows the flow of air from the nose to the respiratory bronchioles
It provides a rigid passageway for air and cleanses, humidifies, and warms incoming air.
What is the respiratory zone responsible for?
Actual site of gas exchange
It includes microscopic structures such as respiratory bronchioles, alveolar ducts, and alveoli.
What is the function of the external nose and nasal cavity?
- Produces mucus
- Filters, warms, and moistens incoming air
- Resonance chamber for speech
The roof of the nasal cavity contains olfactory epithelium for sensory functions.
What are the three sub-divisions of the pharynx?
- Nasopharynx
- Oropharynx
- Laryngopharynx
The pharynx serves as a passageway for air and food and houses tonsils.
What are the three functions of the larynx?
- Provides a patent passageway for air
- Acts as a switching mechanism for air and food
- Voice production
The larynx is also known as the voice box.
What is the Valsalva maneuver?
Involves closing the glottis during abdominal straining
It increases intra-abdominal pressure, helping with rectal emptying or stabilizing the body during heavy lifting.
What does the trachea connect?
Connects the larynx to the two main bronchi
The trachea is also known as the windpipe and contains C-shaped cartilages.
What are the types of bronchi in the bronchial tree?
- Primary bronchi
- Secondary (lobar) bronchi
- Segmental bronchi
- Bronchioles
- Terminal bronchioles
Each type serves a specific role in conducting air to the lungs.
What structural changes occur from primary bronchi to terminal bronchioles?
- Reduced or no cartilage
- Thinner epithelium
- Sparse mucus-producing cells and cilia
- Increased smooth muscle
These changes facilitate airflow regulation as passageways become smaller.
What is the composition of the respiratory membrane?
Walls of alveoli consist of a single layer of squamous epithelial cells on a thin basement membrane
The respiratory membrane is surrounded by capillaries and is crucial for gas exchange.
What are the types of alveolar cells?
- Type I alveolar cells
- Type II alveolar cells
- Alveolar macrophages
Type II cells secrete surfactant and antimicrobial substances.
What are alveolar pores responsible for?
Equalizing pressure throughout the lung and providing alternative air routes
They are crucial in case bronchi collapse due to disease.
What are the main features of the lungs?
- Soft, spongy, elastic organs
- Apex, base, and hilum
- 3 lobes in right lung, 2 in left lung
- Cardiac notch in left lung
The lungs are surrounded by pleurae and contain bronchopulmonary segments.
What is the function of pleurae?
Thin double-layered serous membrane
It contains pleural fluid for easy gliding of lungs over the thoracic wall.
What are the functions of the respiratory system?
- Provision of O2 and elimination of CO2
- Regulation of blood pH
- Phonation
- Protection against microbes and environmental variations
- Emotional expression
- Assistance in abdominal compression
- Providing olfactory sensations
The first two functions are specifically performed by the respiratory system.
What are the four processes of respiration?
- Pulmonary ventilation
- External respiration
- Transport of respiratory gases
- Internal respiration
Only pulmonary ventilation and external respiration are performed by the respiratory system.
What is external respiration?
An exchange of gases occurring between the alveoli and pulmonary blood
What is internal respiration?
An exchange of gases occurring between the blood and tissue cells
What process do gas exchanges occur via?
Diffusion
What is passive diffusion?
Random movement of molecules from an area of high concentration to an area of low concentration
What is Dalton’s law?
Total pressure of a mixture of gases is the sum of the pressures of the individual gases
What is partial pressure?
Pressure of a single gas in a mixture
What is the atmospheric air pressure at sea level?
760 mmHg
What happens to the partial pressures of gases if atmospheric pressure decreases?
Partial pressures decline in direct proportion to the decrease in atmospheric pressure
What is Henry’s law?
The amount of gas that will dissolve in a liquid is proportional to the partial pressure of that gas
What is the composition of alveolar gas compared to atmospheric air?
Alveolar air contains more water vapor and higher partial pressures of CO2 and lower O2 compared to atmospheric air
What are the alveolar pressures for O2 and CO2?
O2 = 104 mmHg; CO2 = 40 mmHg
What factors affect external respiration?
- Thickness and surface area of respiratory membrane
- Lipid solubility of gases
- Ventilation-perfusion coupling
What is ventilation?
The amount of gas reaching the alveoli
What is perfusion?
The blood flow in pulmonary capillaries
What physiological adaptations occur at high altitude?
- Increased respiratory rate
- Increased heart rate
- Elevated haematocrit
What is internal respiration?
Exchange of gases between capillary blood and tissue cells
What is the role of hemoglobin?
A protein in red blood cells that binds oxygen
How much oxygen is bound by hemoglobin?
98% bound to hemoglobin; 2% dissolved in plasma
What is the Haldane effect?
The amount of CO2 transported in blood is affected by the degree of oxygenation
What is hypoxia?
Inadequate oxygen delivery to body tissues
What are the types of hypoxia?
- Anaemic Hypoxia
- Ischemic Hypoxia
- Histotoxic Hypoxia
What is the role of the ventral respiratory group (VRG)?
Rhythm-generating and integrative centre for respiration
What does the dorsal respiratory group (DRG) do?
Integrates information from peripheral stretch receptors and chemoreceptors
What influences breathing rate and depth?
Excitatory influences increase frequency of impulses; inhibitory influences decrease frequency
What is the Bohr effect?
Greater CO2 leads to greater unloading of oxygen from hemoglobin
What is the primary driving force of lung-blood and blood-cells gas exchanges?
Partial pressure gradient
What are the main symptoms of asthma?
Episodes of coughing, wheezing, dyspnoea, chest tightness
Asthma symptoms often present as acute periods followed by symptom-free periods.
What happens to the airways during an asthma attack?
Airways tend to close before exhalation is complete
This leads to constricted airways and wheezing.
What is a significant consequence of asthma on lung function?
Reduction in vital capacity & expiratory reserve volume
What is the leading cause of lung cancer?
Smoking
Smoking is largely predictable, highly metastatic, and has a low cure rate.
How does smoking affect respiratory efficiency?
Smokers have lowered respiratory efficiency
What effect does nicotine have on the bronchioles?
Nicotine constricts terminal bronchioles
This results in reduced airflow.
What is the effect of carbon monoxide in smoke on oxygen transport?
CO in smoke binds to Hb, reducing O2 carried
What impact do irritants in smoke have on the respiratory system?
Increase mucus secretion & swelling of mucosal lining, impede airflow
Irritants also destroy cilia, leading to excess mucus and debris not being removed.
What condition is characterized by the destruction of alveolar walls?
Emphysema
What happens to the alveolar surface area in emphysema?
Decrease in alveolar surface area
What is a consequence of the loss of elasticity in the lungs due to emphysema?
Accessory muscles must be used for quiet breathing
What is obstructive sleep apnoea?
Collapse of the upper airway during sleeping
What is central sleep apnoea?
Reduced drive from respiratory centres
Often treated using a continuous positive airway pressure (CPAP) device.
Fill in the blank: Smoking paralyzes the cilia that clean mucus from the airways, allowing _______ and pathogens to accumulate.
[irritants]
Fill in the blank: Destruction of elastic fibres causes _______.
[emphysema]
