- passage to lungs
- membrane around lungs
- structure in passage to lungs
- whole lungs part
- trachea
- pleural membrane
- C shaped cartilage
- Thorax
approx size of alveoli
200 x 10^-6 m
Approx surface area of lungs
70m^2
How are alveoli adapted for gas exchange
- one cell think wall
- high surface area
- moist walls (dissolve gasses)
- steep conc gradient
How a steep diffusion gradient maintained in lungs
- Ventilation refreshes alveoli air
- Blood flow carries gasses away
O2 high in alveoli, low in bloodstream and CO2 vice versa
External vs internal intercostal muscles
External contract when breathing in
(pressure in lungs below atmospheric)
Internal contract when blowing, coughing, heavy breathing etc
Function of cartilage (tissue) in gas exchange system
- prevents trachea from collapsing
- keeps airways open when pressure changes
- C shaped
trachea and bronchi and large bronchioles
Goblet cells
- secrete mucus which traps dirt, dust and pathogens
Trachea, bronchi and larger bronchioles
Ciliated epithelial cells
- Columnar shape
- waft mucus up and out of respiratory system
Trachea, bronchi, larger bronchioles
Smooth muscle in gas exchange system
- contract to narrow airway
- can control airflow
Trachea, bronchi and bronchioles
Elastic fibres in gas exchange system
- Stretch during inhalation
- Recoil during exhalation (and after constriction be smooth muscle)
Trachea, bronchi, bronchioles, alveoli
Squamous epithelial cells in gas exchange system
- Very thin cells, good for gas exchange
- make up the alveoli
How to draw low resolution microscopy of tissues
Tissue plan (not individual cells)
Apparatus to measure lung capacity
Spirometer
How does a spirometer work
- Chamber filled with oxygen which floats on tank of water
- person breathes from disposable mouthpiece attached to tube to chamber
- Breathing in takes oxygen from tank so it sinks down and vice versa
- movements of chamber recorded using data logger for spirometer trace
Validity and safety things when using
- medical grade oxygen
- fresh soda lime to absorb CO2
- sterilised or disposable mouth piece
- nose clip so valid
Vital capacity
Tidal capacity
Residual volume
Max volume of air that can be inhaled and exhaled (~4 dm^3)
Volume of normal breaths at rest (~0.5dm^3)
Volume of air left in lugs after deepest exhalation (~1.5dm^3)
Factors which affect vital capacity
Size - height, weight
Age, sex
Exercise and fitness
Smoking, asthma
Insect tracheal system
Spiracles (holes for entrance)
Trachea (main tube) (air)
Tracheoles (air) (end IN the tissue)
Tracheal fluid (oxygen diffuses into)
Tracheal fluid in active insect tissue
Fluid withdrawn from tracheoles so more surface area for gas exchange
Ventilation for larger insects
- Tracheal air sacks expand and pushed during flight - repetition
- wing movement increases thorax volume so pressure decrease so air in
- Locusts - front spiracles open and back close and vice versa
Ventilation in water
- water more dense and viscous than air
- too much energy for in and out
- water only moves in one direction
Gills structures
5 pairs of gills
Operculum - bony plate covering it
Thin Gill filaments (primary lamellae), folded into many gill plates (secondary lamellae)
Blood in countercurrent with water flow
How sharks (cartilaginous fish) ventilate gills
Ram ventilation
require continual movement
