1: Respiratory System Flashcards
functions
gas exchange between air and blood
move air between exchange surfaces of lungs
protect respiratory surface from outside environment
produce sound
helps smell
respiratory tract
passageway for air to travel to and from lungs
conducting portion = from nasal cavity to terminal bronchioles
respiratory portion = respiratory bronchioles and alveoli
upper respiratory system = nose, nasal cavity, sinuses, pharynx
lower respiratory system = larynx, trachea, bronchi and lungs
conducting and respiratory zones
airways branch total of 23 times
irregular dichotomous patter - each airway divides into two daughter airways
alveoli appear as buds in the bronchiole wall from branch 17 onwards
from branch 20 onwards, whole airway is alveoli
left lung smaller for heart
left lung = 2 lobes
right lung = 3 lobes
respiratory mucosa
lining of conducting portion of respiratory tract
made of epithelial layer and an areolar layer
epithelial layer = ciliated columnar epithelium containing many mucous cells
areolar layer = called lamina propria, contains many mucous glands that secrete onto epithelial surface
conducting portion of lower respiratory system contains smooth muscle
nasal cavity
air enters through nostril (external nares) then into nasal vestibule (at front of nasal cavity)
nasal hairs for filtration
air flows through three nasal meatuses (channels created by bony structures called nasal conchae)
palates in oral cavity
hard palate = form bottom of nasal cavity above oral cavity
soft palate = extends posterior to hard palate, divides superior nasopharynx from lower pharynx
pharynx
chamber for respiratory and digestive uses
3 division - nasopharynx, oropharynx, laryngopharynx
air then enters the larynx which is a cartilaginous structure that surrounds the glottis (voice box)
glottis = opening between vocal folds, production of sound by changing air flow past vocal folds
sound and speech
sound produced by air passing through glottis, vibrating the vocal folds and producing sound waves
sound variation caused by tension on vocal folds (voluntary muscle)
during speech, phonation = sound production at the larynx
articulation = modification of sound by other structures
trachea
2.5cm diameter, 11cm length
15-20 cartilaginous rings
C shaped so posterior wall can easily distort for large amounts of food
end of trachea connected by elastic ligament and trachealis muscle which can contract to change diameter - autonomic control
sympathetic stimulation also increases diameter
bronchi
right and left primary bronchi separated by an internal ridge called the carina
right bronchus is larger in diameter and descends at steeper angle
each primary bronchi travel to hilum along medial surface of lung
bronchial tree
formed by primary bronchi and their branches
primary bronchus branch to form secondary bronchi
1 secondary bronchus goes to each lobe
extrapulmonary bronchi = the left and right bronchi branches outside the lungs
intrapulmonary bronchi = branches within the lungs
secondary bronchi
branch to the tertiary bronchi
each tertiary (segmental) bronchi supplies air to single bronchopulmonary segment
right lung = 10 segments
left lung = 8 or 9 segments
bronchi structure
walls contain progressively less cartilage as go down bronchial tree
this increase muscle effects on airway constriction and resistance
each tertiary bronchus branches into multiple bronchioles
bronchioles have no cartilage so are dominated by smooth muscle
autonomic control regulates smooth muscle, controlling diameter and airflow
control bronchodilation and bronchoconstriction
alveoli
air filled pockets within lungs
gas exchange takes place
surrounded by dense network of capillaries
oily secretion called surfactant onto alveolar surfaces where it forms a superficial coating over a thin layer of water - plays key role in keeping alveoli open by reducing surface tension
pleural cavities
thoracic cavity walls are the ribcage and diaphragm
each lung surrounded by single pleural cavity which is lined by serous membrane called the pleura
pneumothorax = air in pleural cavity, breaking fluid bond between pleurae and allowing lung’s elastic fibres to recoil
haemothorax = blood accumulates in pleural cavity
external respiration
all processes involved in exchanging O2 and CO2 with environment including pulmonary ventilation, gas diffusion, storage and transport
pulmonary ventilation = the physical movement of air in and out of respiratory tract, provide alveolar ventilation
internal respiration
cellular respiration - uptake of O2 and production of CO2 within individual cell
medical conditions
hypoxia = low tissue oxygen levels
anoxia = supply of O2 gets cut off, killing cells very quickly
Boyle’s law
define relationship between gas pressure and volume
P = 1/V
pressure forces molecules together and the movement of the molecules exerts pressure onto container
pressure difference = air flows from area of high pressure to area of low pressure
compliance of lung
compliance = the ease with which the lungs stretch and expand
low compliance requires great force, high compliance requires less force as lungs fill and empty easier
affected by: connective tissue structure, level of surfactant produced, mobility of thoracic cage
diaphragm and ribs control
when resting, pressure outside lungs = pressure inside
to breath in: diaphragm drawn down to increase volume, decreasing pressure
to breath out: diaphragm relaxes decreasing volume of lungs, increasing pressure
external intercostal muscle elevate rib cage to increase volume
internal intercostal muscle lower ribcage decreasing volume
mechanics of breathing
initiated by respiratory control centre in medulla oblongata, leading to contraction of diaphragm and intercostal muscles
quiet breathing - thoracic cavity movement is 1cm
forced inhalation - movement up to 10cm
normal breathing expiration is passive process
elastic recoil occurs because of the elastic fibres in connective tissue and because of the surface tension of the film of fluid that lines the alveoli
attractive forces between adjacent molecules of the liquid are stronger than those between the liquid and gas
respiratory formulae
volume air moved each minute = breaths per minute x tidal volume
alveolar ventilation = breaths per minute x (tidal volume - dead anatomical space)
forced expiratory ratio = FEV1/FVC
respiratory volumes
inspiratory reserve volume = volume inspirated at end of tidal inspiration
tidal volume = volume inspired/expired during unforced cycle
expiratory reserve volume = volume expired at end of tidal expiration
residual volume = volume left after maximal expiration
functional residual capacity = volume left after normal quiet breathing
inspiratory reserve capacity = maximum amount of gas that can be inspired after normal quiet breathing
vital capacity = maximum amount of gas that can be expired after maximal inspiration
total lung capacity = total gas in lungs after maximal inspiration
