3.1.1 exchange surfaces Flashcards
why do organisms exchange things with their environments
to take in things for metabolic reactions and to excrete waste products from these reactions
how do we calculate surface area to volume ratio
SA:V = SA/V
why do multicellular organisms need specialised exchange surfaces
there is too big of a distance between most internal cells and the environment so diffusion directly would take too long
multicellular organisms have a high metabolic rate so they use up oxygen and glucose faster
how does a large surface area improve efficiency of an exchange surface
it increases the rate of diffusion as there is a bigger area for the exchange to happen so more can happen at once
how does thickness effect efficiency of an exchange surface
a thin exchange surface is more efficient as there is less diffusion distance so it takes less time to take place
how does a good blood supply effect efficiency of an exchange surface
it maintains concentration gradients making exchange more efficient
what are the exchange organs in mammals
lungs
what is the structure of the lungs
trachea branches into two bronchi one bronchus leading to each lung.
the bronchi split into smaller tubes called bronchioles which end in small sacs called alveoli.
what is the function of goblet cells in the gaseous exchange system
they secrete mucus which traps microorganisms and dust particles inhaled stopping them reaching alveoli
what is the function of cilia in the gaseous exchange system
they beat the mucus which moves it up and away from the alveoli towards the throat to avoid infections
what is the function of elastic fibres in the gaseous exchange system
allow the parts of the lung to stretch when inhaling and recoil when exhaling
what is the function of smooth muscle in the gaseous exchange system
allows the diameter of the tubes in the lungs to be controlled e.g. it relaxes during exercise making tubes wider so air moves in easier
what is the function of the rings of cartilage gaseous exchange system
it provides support. it is strong and flexible and stops the trachea and bronchi collapsing when you inhale and pressure drops
which parts of the lungs contain cartilage
trachea (large C shaped pieces)
bronchi (smaller pieces)
which parts of the lungs contain smooth muscle
trachea, bronchi and larger bronchioles
which parts of the lungs contain elastic fibres
trachea, bronchi, bronchioles and alveoli
which parts of the lungs contain goblet cells
trachea, bronchi and larger bronchioles
which parts of the lungs contain cilia
trachea, bronchi and larger bronchioles
what is inspiration
air flowing into the lungs, it is an active process
how does inspiration happen
external intercostal muscles and diaphragm contract causing the ribcage to move upwards and outwards and the diaphragm to flatten. this increases the volume of the thorax, this decreases the pressure this causes air to flow into the lungs
what is expiration
air flowing into the lungs, it is an passive process but can be forced actively
how does expiration happen
external intercostal muscles and diaphragm relax causing the ribcage to move downwards and inwards and the diaphragm to curve. this decreases the volume of the thorax, this increases the pressure this causes air to be forced out of the lungs
in forced expiration the intercostal muscles contract to pull the ribcage down and in
what is the tidal volume
the volume of air in each breath
( average tidal volume is about 0.4dm3)
what is the vital capacity
the maximum volume of air that can be breathed in or out
what is the breathing rate
how many breaths are taken in a certain time
what is the oxygen consumption/uptake
the rate at which an organism uses up oxygen
what is the residual air
air that cant be expelled from the lungs
how does a spirometer work
it has an oxygen filled chamber with a moveable lid, the person breathes through a tube connected to the oxygen chamber as the person breaths it moves up and down, these movements are recorded by a pen attached to the lid of the chamber which writes on a rotating drum or it can be hooked up to a motion sensor to create electronic signals picked up by a data logger
how do we analyse data from a spirometer
breathing rate is the number of peaks in a certain time.
tidal volume is the length of the peaks is the tidal volume
oxygen consumption is the decrease in volume of gas in the spirometer chamber
what is the structure of gills in fish
each gill is made up of lots of thin branches called gill filaments which give a large surface area. these are covered in gill plates which increase surface area even more
each gill is supported by a gill arch
what is a counter current system
when the water flows in the opposite direction to the blood
how does a counter current system allow for as much oxygen as possible to diffuse into the blood
it maintains the concentration gradient so water always has a higher oxygen content than blood so net movement is always into the blood
how are the gills in fish ventilated
- fish opens mouth which lowers the buccal cavity floor so the volume of the buccal cavity increases decreasing the pressure inside so water is sucked in
- fish closes its mouth raising the buccal cavity floor decreasing volume and increasing pressure so the water is forced out across the gills
- each gill is protected by a bony flap called the operculum which is forces pen by the increase in pressure allowing water to lave the gills
what are tracheae
microscopic air filled pipes which insects use for gas exchange
what are spiracles
the pores in the insects body that air moves in and out of the tracheae
how does gas exchange take place in insects
oxygen travels down the concentration gradient towards the cells and carbon dioxide moves to the spiracles
tracheae branch off into smaller tracheoles which have thin permeable walls and go to single cells. they contain fluid that the oxygen dissolves in
oxygen then diffuses into body cells and carbon dioxide diffuses out
how do insects ventilate
rhythmic abdominal movement to change the volume in their bodies
large insects also use wing movements
