ch 9 gas exchange Flashcards
what is the pathway of air
air drawn in through nose or mouth -> pharynx -> trachea -> bronchi -> bronchioles -> alveoli
what is the function of the nasal cavity
contains hair which filters the air (traps particles of size around 5-10micrometer e.g. sand, dust and pollen)
how is nasal cavity adapted
- large number of capillaries and moist lining which warm and humidify the incoming air respectively which prevents excessive heat and H2O loss from from the respiratory surface
- olfactory cells for smelling
what is pharynx
a common passage for both air and food
what is epiglottis
a moveable flap in the throat which bends over to close up the glottis when food is being swallowed
what is the glottis
opening from throat to trachea
what is the larynx
- the voice box (adam’s apple)
- sits on top the trachea
what are the functions of larynx
- voice production
- acts as a valve; during swallowing, the larynx is raised and comes in contact with the epiglottis and forms a lid to close off the trachea to prevent choking
what is the trachea
branches into the left and right bronchi (bronchus-singular) which lead air into and out of the lungs
what is the bronchus
-left and right bronchi branch further into smaller and smaller tubes and end up in alveoli
what is the alveoli
branching into alveoli increases surface area:volume ratio and facilitates gas exchange in alveoli
what are the microscopic structures
- cartilage
- goblet cells
- smooth muscle
- cilia of epithelial cells
- blood vessels
- elastic fibre
what is the function of cartilage
- keeps the airways open to reduce air resistance and allow rapid air flow
- prevents the tube from collapsing or bursting when the air pressure changes during breathing
what is the arrangement of cartilage
- c shaped cartilage rings in interior of trachea
- irregular cartilage blocks in bronchi
where are goblet cells found
in between the ciliated epithelial cells
what is the function of goblet cells
- produce and secrete mucus
- moist lining also humidifies the incoming air to prevent desiccation of respiratory surfaces
what is mucus
a slimy solution of mucin, which is made up of glycoproteins with many carbohydrate chains to make them sticky to trap air particles in inhaled air (e.g. sand, dust, pollen, bacteria, fungal spores and viruses)
where is smooth muscle found
at the posterior side of trachea and bronchi arranged transversely and longitudinally
what is the function of the smooth muscle
- expands and recoils to adjust the diameter and length of trachea and bronchi during inhalation and exhalation
- the muscle can also contract during coughing to force the air out
- at terminal bronchiole, can contract or relax to adjust the diameter of the terminal bronchiole
how does smooth muscle help during exercise
smooth muscle relaxes, so the diameter of the terminal bronchiole increases, increasing air flow to the alveoli
what is the function of the cilia of epithelial cells
the cilia, each with a hooked end, beat continuously to sweep the mucus and trapped particles upwards into the pharynx
function of blood vessels in gas exchange
- warm the incoming air to body temperature to prevent excessive heat loss
- carries macrophage and other white blood cells which can leave the capillaries into the lining of air passages to remove dust particles and pathogens
where is elastic fiber found in the gas exchange system
found in alveolar walls
function of elastic walls in gas exchange system
- found in alveolar walls
- elastic to allow alveoli to expand according to air volume inhaled during inspiration and recoil during expiration to help force the air out efficiently
in which airways is lumen present in
trachea, bronchus, T. bronchiole, R. bronchiole, alveolus (all)
properties of epithelium in the trachea
(see diagram in table)
- ciliated
- pseudostratified
- columnar
properties of epithelium in bronchus
- goblet cell
- mucin droplets
properties of epithelium in T. bronchiole
- ciliated
- columnar
properties of epithelium in R. bronchiole
- ciliated
- cuboidal
properties of epithelium in alveolus
- no cilia
- squamous
in which airways is goblet cell present it
trachea and bronchus
which airways have connective tissue
trachea, bronchus, T. bronchiole, R.bronchiole, alveolus (all)
which airways have connective tissue
trachea, bronchus, T. bronchiole, R.bronchiole, alveolus (all)
which airways have connective tissue
trachea, bronchus, T. bronchiole, R.bronchiole, alveolus (all)
which airways have connective tissue
trachea, bronchus, T. bronchiole, R.bronchiole, alveolus (all)
which airways have smooth muscle
trachea, bronchus, T. bronchiole, R. bronchiole
which airways have elastic fibre
trachea, bronchus, T. bronchiole, R. bronchiole, alveolus (all)
what type of cartilage does the trachea have
c-shape
what type of cartilage does the bronchus have
fragmented
how many trachea are there
1
how many bronchus are there
2
how many T. bronchiole are there
48000
how many R. bronchiole are there
300000
how many alveoli are there
3x10^9
what is the size differences between the airways
the diameter decreases from trachea to alveoli, from 1.8cm to 250micrometer
what cells are present inside an alveolus
- endothelial cell (capillary)
- red blood cell
- macrophage
- white blood cell
- squamous epithelial cell
- surfactant secreting cell
where does gas exchange occur
gas exchange occurs between the air in the alveoli and the blood in the capillary
(the site of gas exchange is between the alveolus and capillary)
what is the formula for rate of diffusion (ficks law)
diffusion rate = (surface area x concentration gradient)/length
functions of surfactant
- moisten gas exchange surface on alveoli
- to allow gases to diffuse across the alveolar wall - reduce surface tension (due to extensive H bonds in water surface)
- prevents alveolus from collapsing - kill bacteria
how is the gas exchange system adapted to increase surface area:volume ratio
- branching of tubes leads to millions of alveoli
- alveoli are small
what are the features of gas exchange system to increase diffusion rate
- surfactant
- large surface area to volume ratio
- short diffusion distance
- steep diffusion gradient
- umbrella shaped red blood cells
how is the gas exchange system adapted for short diffusion distance
-alveolus and capillary are very close to each other and only 2 cells apart/thick
(2 squamous epithelial cells thick)
how is the gas exchange system adapted for steep diffusion gradient
ventilation of the lungs for continuous blood flow
- oxygenated blood transported away
- deoxygenated blood transported to alveolus
- partial pressure of O2 is high due to constant breathing
how are red blood cells adapted for gas exchange
the red blood cell squeezes through the capillary
-it can do this because it is small (7micrometer) and flexible due to specialized cytoskeleton
the red blood cell is also umbrella shaped for greater surface area : volume for rapid uptake of O2
Where are the lungs located?
Thoracic chest cavity
How are the lungs (area around lungs) adapted to ventilation
- Lungs are surrounded by an airtight space between the 2 pleural membranes
- pleural cavity between the 2 pleural membranes
