3.1 Exchange surfaces and breathing Flashcards
3 features of a good exchange surface
large SA- more space for molecules to pass through
thin barrier- reduce diffusion distance
good blood supply- keep steep concentration gradient
3 factors that affect the need for a transport system
size
sa:v
activity levels
Adaptations of the mammalian gaseous exchange system (3)
alveoli small but numerous
thin barrier alveolus wall 1 squamous cell thick
good blood supply large capillary network over alveoli
5 steps to inspiration
- diaphragm contracts
- external intercostal muscles contract, raising ribs
- volume of chest cavity is increased
- pressure drops below atmospheric pressure
- air is moved into lungs down pressure gradient
total lung capacity= x + y
vital capacity
residual volume
describe the tracheal system of an insect (5)
spiracles
tracheae
tracheoles
tracheal fluid withdraws to allow bigger sa for exchange
What is tidal volume?(3)
volume of air, inhaled / exhaled ;
in, one / each, breath ;
during, steady / regular, breathing
What is vital capactiy?(2)
the maximum volume of air ;
inhaled / exhaled, in one breath
Explain significance of relationship between SA:V and rate of diffusion in large plants.(5)
have a, small / low, SA : VOL ratio ;
idea of diffusion too slow (to supply requirements) ;
idea of need transport system (for water / minerals /
assimilates) ;
idea of need (special) surface area for, gaseous exchange
/ uptake of minerals ;
Why would a large mammal need a specialised exchange system?(3)
low / small, surface area to volume ratio ;
diffusion, too slow / distance too great ;
to supply enough, oxygen / (named) nutrients ;
Do small animals have a small or large SA:V?
large
Why do multicellular oranisms need good exchange surfaces?
diffusion is too slow
Small SA:V
Explain expiration (5)
intercoatal and diaphragm musles relax
ribcage moves downwards and inwards, diaphram relaxes
thorax volume decreases causing pressure to increase above atmospheric pressure
air is forced out of the lungs
this is passive process/ doesnt require energy
What 3 things do the lungs have and need for efficient gaseous exchange?
large surface area- increase diffusion rate- e.g. many alveoli
thin-short diffusion distance to increase diffusion rate- e.g. alveoli good blood supply
Which of the following contain cartiledge: trachea bronchi bronchioles alvioli?
trachea and bronchi
what do goblet cells do?
secrete mucus to trap microoranisms stopping them reaching alvioli
what do cilia do?
beat mucus upwards toward throat
what is the purpose of smooth muscle in the walls of the trachea, bronchi and bronchioles?]
what happens to it during exercise?
diameter to be controlled- in exersise it relaxes making tubes wider so theres less resistance and air can move in more easily
explain how a spirometer works 4
breathe into tube connected to oxygen chamber
as person breathes in and out lid moves up and down
which moves a pen creating a spirometer trace
soda lime absorbs carbon dioxide
