Respiratory system: Function and control Flashcards
4 major functions
pulmonary ventilation
diffusion of O2 and CO2 between alveoli and the blood
transport of O2 and CO2 in the blood and body fluids
regulation of ventilation
organs of upper respiratory system
nose
nasal cavity
oral cavity
pharynx
larynx
trachea
organs of Lower respiratory system
primary bronchus
lungs
conducting zone
warms and humidifies inspired air
37 degrees
water vapour
protective function of the upper airways
conducting zone: condition inspired air
nose: filter, entrap and clear particles
nasal resistance increases with viral infections and increased airflow e.g. exercise
nasal secretions: contain important immunoglobulins, inflammatory cells and interferons
upper airways
have a ciliated lining
white blood cells
function of the ciliated lining
mucus secretion from epithelial cells and glands
cilia proper the mucus up towards the trachea at 1cm/min
function of white blood cells in the upper airways
leave nearby capillaries to populate the surface of the airway and alveoli
how many lobes does the left and right lung have
right has 3: superior middle and inferior
left has 2: superior and inferior
respiratory zone components
terminal bronchiole
respiratory bronchioles
alveolar sacs
alveolus
components of conducting zone
nose
pharynx
larynx
primary bronchi
pressure gradient
flow of o2 across barrier separating the blood from the air or water occurs by diffusion down a pressure gradient from high partial pressure of o2 to lower partial pressure o2
occurs throughout respiratory system
what is the basic functional unit of the lungs
acinus
acinus structure
resembles bunch of grapes
visualises as tiny air bubbles
acinus function
site of gas exchange
arise from single terminal bronchiole
stem of branch branches into around 100 alveolar ducts
2 types of alveolar cells
type 1 and type 2
alveolar type 1
structural cells
epithelial cell CHIEF structural cell of the alveolar wall
main function is mechanical support
rarely divides and not very metabolically active
when damaged is replaced by type 2 cells
alveolar type 2
secrete surfactant
contains lamellate bodies that contain phospholipids which forms surfactant
gas exchange at the alveoli
alveolar sacs are lined with simple squamous epithelium
lined with surfactant to prevent closing in
have large capillary network to allow oxygen passage
role of surfactant
within the alveoli surface tension is due to attraction between water molecules at the surface of alveolar fluid: draws water molecules closer together, if lined with pure water it would collapse
what is surfactant
mixture of phospholipids and lipoproteins
lowers the surface tension of alveolar fluid
types of receptors involved in controlling respiration
central chemoreceptors
peripheral chemoreceptors
lung receptors
chemical control of respiration
negative feedback control system
controlled variables are blood gas tensions especially co2
chemoreceptors sense values of gas tension
chemoreceptors
specialised tissue that respond to changes in the chemical composition of blood or other fluids
e.g. central and peripheral
central chemoreceptors
situated close to the surface of the medlla
respond to pH changes in the cerebrospinal fluid (CSF)
changes the rate and depth of ventilation
CSF
separated from the blood by the blood-brain barrier
relatively impermeable to H+ and HCO3-
CO2 diffuses readily, activating central chemoreceptors
regulation of respiratory centre
chemoreceptor to input to increase ventilation
central receptors in the medulla oblongata
sensitive to pH or PCO2 in CSF
peripheral receptors in the arch of aorta and common carotids: respond to lowers PO2 and increased H+ or PCO2 in blood
peripheral chemoreceptors
monitor pH, PCO2 and PO2 of arterial blood
vagus and glossopharyngeal nerves
sense tension of oxygen and CO2 and H+ in the blood
set the respiratory pace
glomus cell
activated in response to decreased PO2 or pH
increased PCO2
process of gloms cell
- Calcium channels – inactivated
- Cell depolarization
- Opens – voltage gated calcium channels
- Exocytosis of neurotransmitter onto sensory neurons
- Signals to sensory neurons to increase ventilation
