respiratory system Flashcards
what is the primary function of the respiratory system?
to supply the body with oxygen and dispose of carbon dioxide
what are the four processes involved in the respiratory system?
- pulmonary ventilation
- external respiration
- transport of respiratory gases
- internal respiration
what does pulmonary ventilation involve?
movement of air into and out of the lungs
what does external respiration involve?
exchange of oxygen and carbon dioxide between air within lungs and blood
what does internal respiration involve?
exchange of oxygen and carbon dioxide between blood and tissues (ISF)
how can respiratory structures be classified structurally?
upper and lower respiratory systems
what does the upper respiratory system do?
- clean, humidify and warm incoming air
- reabsorb heat and water
what does the lower respiratory system do?
- conducts air to gas exchange surfaces (trachea and bronchi)
- gas change
how can the respiratory structures be classified functionally?
- conducting zone
- respiratory zone
what does the conducting zone of the respiratory system do?
- passageways conduct air
- cleanses, humidify and warm incoming air
- reabsorb heat and water
what structures are apart if the respiratory zone?
- respiratory bronchioles
- alveolar ducts
- alveoli
what occurs in the respiratory zone?
gas exchange
what does the nasal cavity contain?
- hair
- olfactory epithelium
- sensory nerve endings
what lines the nasal cavity?
mucosal epithelium
what does hair in the nasal cavity do?
filters course particles from air
what does the olfactory epithelium in the nasal cavity bear?
olfactory receptors
what do the sensory nerve endings in the nasal cavity trigger?
sneezing to dislodge irritants
what does the mucosal epithelium produce and how much per day?
mucus and ~1-1.5L
what does cilia do?
moves contaminated mucus to throat and stomach, protects respiratory zone from damage and infection
what does the nasal conchae increase and enhance?
increases surface area and enhances air turbulence
what are some key functions of the nasal cavity?
- filters air
- warms and humidifies
- traps particulates
- resonating chamber for speech
- kills bacteria
what is the pharynx?
passageway for air (nasal cavity to larynx) and food (oral cavity to oesophagus)
what does the pharynx contain and what does this help do?
contains lymphoid tissue (tonsils) which helps protect against pathogens
what is the larynx?
cartilage that surrounds and protects opening of trachea
what are the functions of the larynx?
- provides open airway
- routes air and food into proper channels
- voice production
- includes mucocilliary escalator
what does the mucocilliary escalator do?
moves contaminated mucus upwards
what does the trachea include?
mucocilliary escalator
what is the trachea supported by to prevent collapsing during breathing?
C-shaped cartilage rings
what does the trachea divide to form?
right and left primary bronchi
do bronchioles have mucocilliary escalators?
no
do the bronchioles have cartilage rings?
no
what do the abundant elastic fibres in the bronchioles permit?
expansion
what does the circular smooth muscle do in the bronchioles?
allows diameter of bronchioles to be altered
what do capillaries and fine elastic fibres permit in the alveoli?
stretch and recoil
what do alveoli form from?
type I epithelial cells
how do alveoli connect to each other?
via pores
what does alveoli do?
equalises air pressure in lungs
what do scattered type II epithelial cells on the alveoli secrete?
fluid containing surfactant (prevents alveolar collapse) and antimicrobial proteins
what is the respiratory membrane composed of?
- single alveolar epithelial cell (type I)
- basement membrane
- pulmonary capillary endothelial cell
what is the respiratory membrane the site of?
gas exchange via simple diffusion
what is the apex of the lungs?
the narrow, superior tip
where does the apex of the lungs lie?
deep to the clavicle
where does. the base of the lungs rest?
on diaphragm
where are the external surfaces of the lungs adhered to?
walls of thoracic cavity
what is the entry and exit point from the bronchi, blood, lymphatic vessels and nerves to the lungs?
hilum
what are the two circulations where blood enters the lungs?
pulmonary and bronchial circulation
what are the lungs innervated by?
- visceral sensory fibres
- sympathetic fibres
- parasympathetic fibres
do sympathetic fibres in the lungs constrict or dilate the bronchioles?
dilate
do parasympathetic fibres in the lungs constrict or dilate the bronchioles?
constrict
where do bronchial arteries arise from in bronchial circulation?
aorta
what do the visceral sensory fibres of the lungs monitor?
conditions of the lungs such as degree of stretch, presence of irritants
what does the bronchial circulation system provide?
oxygenated systemic blood to all lung tissue except alveoli
what is each lung suspended in?
its own pleural cavity
what covers both the external lung and pleural cavity?
continuous plural membrane
what covers the thoracic cavity wall and diaphragm?
parietal pleura
what does the parietal pleura become as it covers lungs?
visceral pleura
what is the pleural space filled with?
pleural fluid
what are the three processes of respiration?
- ventilation of lungs (breathing)
- exchange of gases
- use of oxygen in cellular metabolism
what are the two phases of pulmonary ventilation?
- inspiration/inhalation
- expiration/exhalation
what is Boyle’s Law?
the pressure of a gas in a chamber is inversely proportional to the volume
what are the five steps of inspiration?
- inspiratory muscles contract > diaphragm descends
- thoracic cavity volume increases
- lungs stretch
- intrapulmonary pressure drops
- air flows in to lungs
how much does the intrapulmonary pressure drop by during inspiration?
1 mmHg
what are the five steps of expiration?
- inspiratory muscles relax
- thoracic cavity volume decreases
- elastic lungs recoil passively
- intrapulmonary pressure rises
- airs flows out
how does air flow into the lungs?
down its pressure gradient, until intrapulmonary pressure is equal to atmospheric presure
what does passive expiration involve?
muscle relaxation only, not contraction
what does passive expiration depend on?
elastic recoil of lungs
when does forced (active) expiration occur?
in physical activity or specific vocalisations
how does surfactants stop lungs collapsing?
reduces surface tension of alveolar fluid
how does pleural fluid stop lungs collapsing?
pleural fluid between the parietal and visceral pleura “sticks” the lungs to the inner wall of the thoracic cavity
how does elasticity stop lungs collapsing?
elasticity of the chesty walls pulls thorax outwards while elastic recoil of lungs creates inward pull
what are three factors that influence gas flow in airways to the alveoli?
- resistance
- compliance
- alveolar surface tension
what type pulmonary disorders can result from changes in resistance?
obstructive diseases
what type pulmonary disorders can result from changes in compliance?
restrictive diseases
what type pulmonary disorders can result from changes in alveolar surface tension?
respiratory distress
what is pulmonary compliance?
is the measure of the ability of the lungs and/or thoracic cavity to expand/stretch and thus enable inhalation
what does pulmonary compliance depend on?
- lung elasticity
- alveolar surface tension (surfactant production)
- flexibility of muscles and joints of thoracic wall
what is alveolar surface tension?
surface tension between water molecules in alveolar fluid
what does surfactants do for alveolar surface tension?
reduces surface tension which prevents alveolar collapse and reduces effort required to expand alveoli
do premature infants produce adequate surfactants?
no
what is the treatment for premature babies that don’t have adequate surfactants?
spray airways with synthetic or natural surfactant
what is the cause of obstructive disorders?
reduced airway diameter
what is dyspnea?
difficulty breathing
what is the cause of restrictive disorders?
decreased compliance of lungs and/or thoracic wall. inability to change volume and draw in air
what does gas in the conducting zone move down a pressure gradient via?
bulk flow