Respiratory system Flashcards
Purpose of the respiratory system?
Contribute to HOMEOSTASIS by allowing for gas exchange (O2 and CO2)
Adjusts the PH of body fluids
(extra info only: also contain receptors for sense of small, filters, vocal sounds, excrete small amounts of water and heat)
What are the 3 basic steps in the respiratory system?
- ventilation (breathing)
- external respiration (pulmonary)
- internal respiration (tissue)
The respiratory system is divided into the upper and lower systems. What are considered the upper and lower organs?
Upper: Larynx and above (nose, nasal cavity and pharynx)
Lower: Larynx and lower (larynx, trachea, airways, lungs)
Functionally the respiratory system can be divided into two systems. What are they called and what are their main functions?
- Conducting zone - filter, warm and moisten air and conduct it to the lungs
- Respiratory zone - gas exchange
The superior olfactory region and inferior respiratory region are divisions of what organ?
The nose
What are the 3 main functions of the nose?
- warm, moisten and filter incoming air
- detect olfactory stimuli
- modify speech vibrations
What type of epithelium is found in the nose?
Pseudostratified ciliated columnar epithelium with goblet cells
Name the functions of the pharynx (throat)
- passageway for food and air
- resonating chamber for speech
- tonsils protect the entryway into the body
What is deglutition?
Swallowing
The larynx (voice box) connects what two parts of the respiratory system?
The pharynx (laryngopharynx) with the trachea
What is the primary function of the larynx?
Voice production
The trachea (windpipe) wall has four layers - what are they?
- Mucosa (protects from dust and foreign particles)
- Submucosa (areolar connective tissue w seromucous glands)
- Hyaline cartilage (cartilage rings that maintain patency)
- Adventita (areolar connective tissue)
Name the branching of the bronchial tree.
- Trachea
- Primary bronchi
- Secondary (Lobar) bronchi
- Tertiary (Segmental) bronchi
- Bronchioles
- Terminal bronchioles
What is the carina?
An internal ridge at the point where the trachea divides into the right and left primary bronchi
What are the two layers of the pleural membrane of the lungs?
Visceral pleura (covers the lungs themselves)
Parietal pleura (lines the thoracic cavity)
How many lobes does the right and left lung have?
Right = 3 (separated by the oblique and horizontal fissures)
Left = 2 (separated by the oblique fissure)
What does the pleural cavity do?
Primary: Reduces friction between the two membranes so they slide over each other in breathing
Bonus: holds the layers together through surface tension
Where do bronchi, pulmonary blood vessels, lymphatic vessels and nerves exit and enter the lungs?
The hilum
A bronchopulmonary segment has many small compartments called LOBULES. Each lobule is wrapped in connective tissue and contains what a lymphatic vessel, an arteriole, a venule and a branch from a terminal bronchiole.
What do the terminal bronchiole subdivide into?
Microscopic branches, called respiratory bronchioles
[These start the respiratory zone]
What do the microscopic airways consist of (in order)?
- terminal bronchioles
- respiratory bronchioles
- alveolar ducts
- alveolar sacs
- alveoli
What are the two main types of cells that make up alveoli and their function, and two minor types of cells?
MAJOR:
>Type I alveolar cells - provide a site for gas exchange
>Type II alveolar cells - secrete fluid to lower surface tension (preventing collapse each expiration)
MINOR:
>Alveolar dust cells - wandering macrophages that remove debris
>Fibroblasts - produce reticular and elastic fibres
How is blood supply maintained in the lungs?
- Arterial supply:
> PULMONARY arteries (deoxygenated blood from the right atrium to the lungs for oxygenation)
> BRONCHIAL arteries (oxygenated blood to lungs) - Venous drainage:
(four pulmonary veins drain into the left atrium) - Ventilation-perfusion coupling:
> Vasoconstriction in response to hypoxia diverse pulmonary blood from poorly ventilated areas of the lungs to well-ventilated regions for more efficient gas exchangen
Inhalation is when the pressure inside the lungs is greater or less than atmospheric pressure?
Less than
(expansion of lungs)
Exhalation is when the pressure inside the lungs is greater or less than atmospheric pressure?
Greater than
(decrease in lung volume)
What are the two main factors that change the thoracic cavity size when breathing?
The diaphragm and intercostal muscles
(contract during normal quiet inhalation and relax during passive exhalation)
Name four other factors affecting pulmonary ventilation (apart from pressure changes)
- Alveolar surface tension
- Compliance of the lungs
- Airway resistance
The exchange of oxygen and carbon dioxide between alveolar air and pulmonary blood occurs via…?
Passive diffusion
According to Dalton’s Law, gases will move from areas of higher/lower partial pressure to areas of higher/lower partial pressure?
Higher partial pressure to lower
Henry’s Law states that the quantity of gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility. This means, that the higher the partial pressure of a gas over a liquid, the higher the solubility and the more gas will stay in solution.
The solubility of CO2 is 24 times greater than that of O2 which is why CO2 dissolves in blood plasma and oxygen needs a carrying molecule (haemoglobin).
Breathing O2 under pressure dissolves more O2 in the blood.
What is external respiration?
The gas exchange between alveoli and pulmonary blood capillaries, converting deoxygenated blood from the right side of the heart into oxygenated blood that returns to the left side of the heart.
What is internal respiration?
Exchange of O2 and CO2 between systemic capillaries and tissue cells
Quiet expiration is passive. The inspiratory muscles relax due to what two factors?
- elastic recoil
- inward pull of surface tension due to alveolar fluid
What is a spirogram?
Equipment used to measure lung volumes and capacities during breathing
(important in the diagnosis of chronic obstructive pulmonary disease and to monitor treatment)
Order of events for inhalation and exhalation?
- diaphragm and external intercostal contract
- thoracic cavity increases in size
- lung volume increases
- alveolar pressure decreases (758mmHg)
- influx of air into lungs
- diaphragm and intercostals relax
- thoracic cavity decreases in size
- lungs recoil
- alveolar pressure increases (762mmHg)
- efllux of air out of lungs
What is the air called that remains after the expiratory reserve volume is exhaled?
Residual volume
What is the sum of inspiratory reserve volume, tidal volume and expiratory reserve volume?
Vital capacity
What is the volume of one breath called?
Tidal volume
What is total lung capacity?
Vital capacity + residual volume
What is the most important factor determining how much oxygen combines with haemoglobin?
Oxygen partial pressure
The greater the PO2 (partial pressure), the more oxygen will combine with haemoglobin until saturated. In the pulmonary capillaries, is PO2 high or low? Why?
PO2 is high so lots of oxygen binds to haemoglobin and is then transported into systemic circulation
What is a major factor that influences the association (or affinity) that haemoglobin has for oxygen?
pH of the blood
As acidity increases (pH decreases), the affinity of haemoglobin for O2 decreases and it dissociates more readily (i.e. making more available for tissue cells)
CO2 can also bind to haemoglobin. As the carbon dioxide partial pressure rises, does haemoglobin release O2 more or less readily?
What effect does this have on blood pH?
As PCO2 increases, haemoglobin releases O2 more readily
A high PCO2 causes low blood pH (i.e. releases more O2 into the system)
The respiratory centre in the brain is responsible for controlling respiration. It’s a collection of neurons dispersed in what areas of the brain?
Medulla oblongata and pons of the brain stem
What are the three areas of the respiratory centre?
- Medulla rhythmicity area (in medulla oblongata)
- Pneumotaxic area (pons)
- Apneustic area (pons)
What is the medulla rhythmicity area primarily responsible for?
Controls the basic rhythm of respiration
What is the pneumotaxic area primarily responsible for?
Coordinates the transition between inspiration and expiration
(shortens the duration of inhalation)
What is the apneustic area primarily responsible for?
Coordinates the transition between inspiration and expiration
(prolongs the duration of inhalation)
The rhythm of respiration can be modified in response to:
- cortical regulation
- chemoreceptor regulation
- proprioception stimulation
- baroreceptor stimulation
- limbic system stimulation
- temperature
- pain
- stretching the anal sphincter muscles
- irritation of airways
- blood pressure
What is cortical regulation and chemoreceptor regulation?
Cortical regulation - voluntary altering of breathing
Chemoreceptor regulation - respond to changes in partial pressure of CO2 or levels of hydrogen ions in cerebral spinal fluid
What is hypoxia?
Oxygen deficiency at the tissue level
What area of the brainstem modifies the rhythm of breathing during speaking, exercise and sleep?
Pneumotaxic area
Which area in the brainstem makes up the inspiratory and expiratory areas, and control the basic rhythm of respiration?
Medullary rhythmicity area
Which area sends impulses to accessory muscles involved in forceful exhalations?
Expiratory area
Which area sends impulses to muscles involved in normal quiet breathing for 2 sec during inhalation?
Inspiratory area
This area in the cerebrum controls the voluntary action of muscles breathing.
Cortical regulation
This area in the brainstem prolongs the duration of inhalation by stimulating the inhalation area.
Apneustic area
Where are peripheral chemoreceptors located?
The wall of the aorta and common carotid arteries
