Year 11 Human Biology - Respiratory Sytem

what is the function of this system

to continually supply oxygen and remove carbon dioxide

what are the main parts of the system

air passages, respiratory surfaces and respiratory muscles

describe the nasal cavities

passages line swith ciliated mucosa and have 3 bony shelves (conchi) and senosry neurons

what does ciliated mucosa do

the mucus traps foreign particles and the cilia beat to move the mucus and particles along

what do conchi do

increase surface area of nasal cavities so they can humidify, warm and filter air

describe the pharynx (throat)

the passage from the nasal cavities and mouth to the trachea

it is muscular and lined with mucosa (stratified epithelium)

has 2 upper opens which lead to ear via eustachian tubes

carries food and air

describe the larynx (voice box)

links pharynx and trachea

made of cartilage

vocal cords (flaps of connective tissue) span across it

thyroid attached to it

describe the trachea (wind pipe)

duct from larynx to lungs

c shape cartilage rings keep it open all the time

connective tissue and smooth muscle between rings

lined with ciliated mucosa

describe bronchi

trachea splits into 2 primary bronchi

primary split into secondary then tertiary (27 times total)

narrower bronchi have less cartilage and more smooth muscle

lined with mucosa

describe bronchioles

narrow bronchi tubes which lead to alveolar sacs

only smooth muscle so they can constrict when muscle contracts

describe the lungs

deep in chest cavity

made of alveoli

covered in pleura

describe alveoli

spherical sacs surrounded by simple epithelial and capillaries for gas exchange and have a moist lining

describe pleura

a membrane surrounding the lungs which secretes pleural fluid into the pleural cavity

what brings blood to and from the lungs

pulmonary arteries and veins

describe the steps when we inhale

diaphragm and intercostals contract

chest moves up and out

chest cavity and lung volume increases and pressure decreases

air follows pressure gradient from high outside to low inside

describe steps when we exhale

diaphragm and intercostals relax

chest moves in and down

chest cavity volume decrease and pressure increases

air follows pressure gradient from high inside to low outside

what does pleural fluid do

adheres lungs to cavity wall so they move simultaneously when chest expands or contracts

where does gas exchange occur

between alveolar air and blood in lung capillaries

describe steps of gas exchange

inhaled air containging 02 diffuses from inside alveoli into blood

02 follows concentration gradient from high in air to low in blood

02 chemically combines with haemoglobin

C02 in blood diffuses into alveolar air from blood, following concentration gradient

what must gases do before they diffuse

dissolve in moist film of alveoli

how is the 02 and C02 concentration gradient maintained

the continual flow of blood and breathing

where does 02 go from after diffusing

97% becomes oxyhaemoglobin

3% dissolves in blood plasma

where does C02 go

70% becomes bicarbonate ions (HC03-)

22% becomes carboaminohaemoglobin (HbNHC00H)

8% dissolves in blood plasma

what is the exchangable equation for carbon dioxide

CO2 + H20 → OR