respiratory system Flashcards
what is the anatomy of the lungs
large, spongy like structures, each contained within its own pleural cavity on each side of the heart. each lung is surrounded by a double layered pleural membrane consisting of parietal and visceral layers separated by space filled with serous fluid. in the lungs, the primary bronchus gives rise to a bronchial tree, a continuously branching system of progressively smaller and smaller bronchii to bronchioles. bronchioles eventually open into alveoli and alveolar clusters which mostly fill the lungs
what is part of the upper respiratory tract
pharynx, nasal cavity and larynx
what is part of the lower respiratory tract
lungs and bronchii and trachea
what does the conducting zone do (1/2 of the functional zones of the respiratory tract)
it conducts air from the external environment towards the respiratory zone. it is lined with the respiratory mucosa which;
- warms air
- cleanses air
- moisturises air
- from nasal cavity to terminal bronchioles
- lined with respiratory mucosa
what does the respiratory zone do (1/2 of the functional zones of the respiratory tract)
the respiratory zone is defined by the presence of alveoli which have the capability of gas exchange.
- includes respiratory bronchioles and alveoli
- lined with the respiratory membrane
- permits gas exchange
nasal cavity (structure of the conducting zone)
divided into left and right sides by the nasal septum. The nasal conchae generates a turbulent air flow to ensure all air comes into contact with the respiratory mucosa. Air enters the nasal cavity via the nostrils and exits into the pharynx via the nasal aperture.
pharynx (structure of the conducting zone)
divided into 3 parts and conducts both food and air
larynx (structure of the conducting zone)
- conducts air to the trachea
- contains the vocal folds which produce sound.
trachea (structure of the conducting zone)
- it is a connective tissue tube that extends from the larynx divides into 2 primary bronchi.
- C shaped cartilages surround the trachea to prevent collapse
- smooth muscle extends down the trachea which can rapidly force air out upon contraction.
bronchial tree (structure of the conducting zone)
- It has 23 branches
- the bronchi are lined with respiratory mucosa surrounded by a layer of smooth muscle with outer cartilage rings
- Smooth muscle layer progressively forms thickened bands around bronchioles
- The increased smooth muscle and lack of supportive cartilage in the smaller bronchioles allows a greater ability for dilation or constriction to control air flow into the respiratory zone.
alveoli (structure of the respiratory zone)
alveoli are thin-walled sacs that contain air. alveoli begin to bud off respiratory bronchioles and alveolar ducts, but the majority of alveoli form clusters at the end of alveolar ducts in close association with extensive capillary beds.
- pores exist between alveoli clusters to permit the spread of air throughout the cluster for optimum aeration and gas exchange
- diffusion of gases between air in the alveoli and blood in the capillaries.
volume-pressure relationships
the increase in one results in a decrease in the other, known as Boyle’s law
what happens during pulmonary ventilation
gases move between the atmosphere and the lungs. this movement occurs due to change in the volume of the lungs which either decreases or increases lung/intrapulmonary pressure compared to atmospheric pressure, driving air in or out of the lungs.
what are the mechanisms of inspiration
- inspiratory muscles contract
- thoracic cavity expands
- lungs stretch
- lung volume increases
- lung pressure decreases
- air moves into lungs
what are the mechanisms of expiration
- inspiratory muscles relax
- thoracic cavity narrows
- lungs recoil
- lung volume decreases
- lung pressure increases
- air moves out of lungs
what drives the movement of air in and out of lungs
the difference between atmospheric and lung/ intrapulmonary pressure
what is airway resistance
it is the friction or drag that air encounters as it flows through the respiratory tract. it is most influenced by the diameter of airways (bronchial tree) or the presence of excess or foreign material (mucus). airway resistance is related to lung volume
what is alveolar surface tension
occurs in alveoli due to the presence of body fluids. the surface tension must be reduced to make it easier for the lungs to expand and fill with air and to prevent alveolar collapse upon expiration.
what substance reduces alveolar surface tension
surfactant
what is lung compliance
the stretchiness of the lungs. compliant lungs require less energy to fill with air, but less compliance makes it harder to fill up with air. lung compliance is determined by 2 factors
- how elastic lung tissue is (distensibility of lung tissue)
- alveolar surface tension- the greater the surface tension, the harder it is for lungs to expand and inflate
what is the tidal volume or air an adult inhales and exhales
500mL of air, a 1mmhg difference allows us to inhale or exhale
what part of the brain controls the rate and depth of pulmonary ventilation
the brainstem (pons and medulla) are where the respiratory centres are
our body relies on oxygen to generate cellular energy and produce carbon dioxide which is toxic and must be removed from the body
yes
what does the medulla oblongata do
it sets the baseline for respiratory rate
