chapter 8 Flashcards
the nose
structure and function
nasal cavity with l&r chamber (nostrils) that lead to pharynx
projections known as conchae increase surface area
filters (hair), warms (capillaries), moistens (mucus) the air before it enters the lungs
has olfactory receptors
enhances sound produced in speech
mucus and hair trap dust
pharynx
air from nasal cavity passes through here
13cm, direct air to larynx
used to pass food to oesophagus
larynx
stretched between cartilage are two folds of mucus membrane called vocal folds
the edges have elastic ligaments that vibrate (vocal chords)
epiglottis
flap of tissue that closes the trachea when swallowing so food and liquid doesn’t enter the lungs
trachea
has c-shaped cartilage bands that allowing the oesophagus to expand into the gaps in the trachea when swallowing
lined with ciliated mucus membrane to trap solid particles
mucus is produced from goblet cells
bronchi
where trachea divides into secondary and tertiary bronchi
kept open with cartilage and lined with cilia and mucus
bronchioles
very fine tube that lead to the alveoli
walls of smooth muscle, no cartilage
alveoli
around 300 million each lung
tiny air sacs, in clusters, wall have very thin membrane for diffusion
1 cell thick, large sa
surrounded by dense network of capillaries
chemical surfactant coast the inside alveoli to lubricate it and prevent friction and closing of alveoli
lung structure
right has 3 lobe
left has 2 lobe
covered in pleural membrane, moist to reduce friction as lungs move in chest
between the membrane is a pleural cavity filled with pleural fluid, allows pleura to slide over each other whilst breathing
intercostal muscles
muscles between ribs, internal and external
when the external muscles contract they they pull the ribs upwards and outwards, increasing volume of thoracic cavity
contraction of the internal muscles pulls ribs closer, decreasing the thoracic cavity. this increase pressure inside lungs and air is diffused out
diaphragm
dome shaped muscle
contraction increases volume of thoracic cavity
ventilation
air moving in and out of the lungs
how are lungs specialised for their function of gas exchange
x5
- alveoli give lungs a very large internal surface area, so lots of gas can be exchanged in a short amount of time
- each alveoli is well supplied with blood vessels, so that as much blood as possible is close to the air in the alveolus. the continuous flow of blood helps maintain a difference in concentration of o2 and co2 in blood and lungs. concentration gradient is necessary for diffusion
- wall of alveolus is very thin (1 cell thick), gas doesn’t have to travel far when moving in and out of blood.
- lungs positioned deep inside body to prevent excessive evaporation of fluid that covers the respiratory surfaces, it is important that the alveolus membrane is covered by a thin layer of moisture because gases can only diffuse in and out of the blood when they are dissolved in fluid.
- the lung volume can be changed by movements of the respiratory muscles, so that the air is made to move in and out of lungs. constant changing of air in the alveoli helps to ensure that there s always a difference in o2 and co2 concentration in the lungs and blood.
inspiration
external intercostal muscles contract (ribcage up + out)
diaphragm contracts chest cavity extends down
increase in lung volume
air flows from H-L (H=outside body, L= inside lungs)
breathe in
expiration
intercostal external muscles relax (ribcage down + inward) (passive breathing)
diaphragm relaxes, chest cavity pushes up
lung volume decreases, more pressure
air flows from H-L (H= inside lungs, L= outside body)
breathe out
