Flashcards in :) Exchange And.Transport Deck (107):
What do cells need to take in?
Things like oxygen and glucose for aerobic respiration and other aerobic reactions
What do cells need to excrete?
Waste products from these reactions- like carbon dioxide and urea
What does how easy the exchange of substance depend on?
The organisms surface area to volume ratio (SA:V)
Smaller animals have compared to bigger animals?
Higher surface area: volume ratio
Which has the bigger surface area relative to its volume a mouse or a hippo?
How can you work this out mathematically?
Hippo block 2cm x 4cm x4cm
Surface area= 64cm2
Hippos SA:V= 2:1
Mouse 1cm x 1cm x 1cm
Surface area= 6cm2
How do calculate surface area to volume ratio?
Surface area/ volume
How to calculate sphere?
4/3 Pi r3
What does an organism need to supply?
Every one of its cells with substances like glucose and oxygen (for respiration)
What does an organism need to remove?
Waste products from every cell to avoid damaging itself
How can a single-celled organism deal with getting what it needs and removing waste products?
Substances can diffuse directly into or out of the cell across the cell surface membrane. The diffusion rate is quick because of the small distances the substances have to travel
Why can't multicellular animals use diffusion across the outer membrane like single-celled organisms can?
It's too slow
Give three reasons why in multicellular organisms diffusion is too slow?
Some cells are deep inside the body (big distance between them and outside environment
Low SA:V (difficult to exchange substances to supply large volume of animal through relatively small outer surface)
Higher metabolic rate (use up oxygen and glucose faster)
What do multicellular animals need therefore?
Specialised exchange surfaces like alveoli in the lungs
What do most exchange surfaces have and what are they?
A large surface area
They are thin
Animal example of exchange surface?
Cells on plant root grow into long hairs which stick into soil. Each branch of root coveted in millions of microscopic hairs.
Gives roots large SA:V helped my increase rate of absorption of water (by osmosis) and mineral ions ( active transport) from the soil
Animal example of exchange surface?
Alveoli are gas exchange surface in lungs
Each alveolus made from single layer of thin flat cells (alveolar epithelium)
O2 diffuses out of alveolar space into blood CO2 diffuses into opposite direction
Thin alveolar epithelium helps decrease distance over O2 and CO2 diffusion takes place increasing rate of diffusion.
What else do most exchange surfaces have?
Good blood supply or ventilation
Example in mammals?
Alveoli surrounded by larger capillary network giving each alveolus own blood supply. Blood takes oxygen away from alveoli and brings more carbon dioxide
What does every organism no matter what their size need to do?
Exchange things with its environment
Are fish gills to fish?
Exchange surface in fish.
What exchange happens in the gills of a fish
Exchange In the gills, O2 and CO2 are exchanged between the fish's blood and surrounding water
What features do fish gills have?
a large network of capillaries- keeps them well-supplied with blood.
well-ventilated- fresh water constantly passes over them.
What do these features help the fish do?
These features help maintain concentration gradient of O2 increasing rate at which O2 diffuses into the blood.
Where does air go when you breathe in?
Air enters the trachea (windpipe)
What does the trachea split up into?
Two bronchi- one bronchus leading to each lungs
What does each bronchus branch off into?
Smaller tubes called bronchioles
What do bronchioles end in?
Small air sacs (alveoli) where gases are exchanged.
What work together to move air and out?
The ribcage, inter coastal muscles and diaphragm
What is the gaseous exchange system made of?
Rings of cartilage
Lining the airways
Mucus traps microorganisms and dust particles in the inhaled air stopping them from reaching the alveoli
On surface of cells lining the airways
Moves mucus plus trapped microorganisms and dust upwards away from the alveoli towards the throat where it's swallowed. This helps prevent lung infection
In the walls of the trachea, bronchi, bronchioles and alveoli help the process of breathing out. On breathing in the lungs inflate and the elastic fibres are stretched. Then the fibres recoil to help push the air out when exhaling
Wall of trachea, bronchi and bronchioles allow their diameters to be controlled. During exercise the smooth muscles relax making the tubes wider meaning there's less resistance to air flor and air can move in and out of lungs more easily
Rings of cartilage
Walls of trachea and bronchi provide support
Strong but flexible- it stops trachea and bronchi collapsing when you breathe in and the pressure drops
Trachea description of cross section
Smooth muscle trachea?
Elastic fibres trachea?
Trachea goblet cells?
Bronchi cross section describe
Small cartilage pieces Elastic fibres
Bronchi smooth muscle
Bronchi elastic fibres
Goblet cells bronchi
Outer layer- smooth muscle and elastic fibres
Inner layer- ciliated epithelium
Large bronchioles smooth muscle, elastic fibres, goblet cells?
Yes yes yes
Smaller bronchioles smooth muscle, elastic fibres, goblet cells?
Yes yes no
Smallest bronchioles smooth muscle, elastic fibres and goblet cells?
No, yes, no
Epithelium smaller bronchioles and small bronchioles?
Ciliated, no cilia
Smooth muscle alveoli
Elastic fibres alveoli
Alveoli goblet cells?
What's ventilation consisting of?
Inspiration (breathing in) and expiration (breathing out)
How is ventilation controlled?
Diaphragm, internal and external intercostal muscles and ribcages
Eternal intercostal and diaphragm muscles contract
Causing ribcage to move upwards and outwards and the diaphragm to flatten increasing the volume of the thorax
As volume of thorax increases the lung pressure decreases (below atmospheric pressure)
Causing air to flow into the lungs
What is inspiration?
An active process- it requires energy
External intercostal and diaphragm muscles relax
Ribcage moves downwards and inwards and diaphragm becomes curved again.
As the thorax volume decreases, causing air pressure to increase (to above atomspheric pressure)
Air is forced out of lungs
During normal expiration what is it?
A passive process
Doesn't require energy
Can you choose to expire?
Expiration can be forced (if you want to blow out candles on your birthday cake).
During, forced expiration, internal intercostal muscles contract to pull the ribcage down and in
The volume of air in each breath- usually about 0.4 dm3
Maximum volume of air that can be breathed in or out
How many breaths are taken- usually in a minute
Oxygen consumption/ oxygen uptake?
The rate at which an organism uses up oxygen (number of dm3 used per minute
What is dm3 short for?
Decimetres cubed- it's the same as litres
What's a spirometer?
A machine that can give readings of tidal volume, vital capacity, breathing rate and oxygen uptake
How does the person breathe when using a spirometer?
A spirometer has an oxygen-filled chamber with a moveable lid
The person breathes through a tube connected to the oxygen chamber
As the person breathes in and out, the lid of the chamber moves up and down?
How is a trace picked up?
lid of the chamber moves as the person breathes
These movements can be recorded by a pen attached to the lid of the chamber- this writes on a rotating drum, creating a spirometer trace. Or the spirometer- this will use the movements to produce electronic signals which are picked up by a data logger
Why doesn't the person eventually end up breathing in carbon dioxide?
The soda line in the tube the subject breathes into absorbs carbon dioxide
What happens to the total volume of gas in the chamber?
It decreases over time
This is because air breathed is a mixture of oxygen and carbon dioxide. The carbon dioxide is absorbed by the soda lime so there's only oxygen in the chamber which the subject inhales from. As this oxygen gets used up by respiration the total volume decreases
How do work out the breathing rate in the first minute?
Count the peaks and then say n breaths per minute
n= number of peaks
Tidal volume measure?
Measure from top to bottom of normal peak
Top of vital capacity-bottom of vital capacity wave
What's oxygen consumption?
Decrease in volume of gas in spirometer chamber. Can be read from graph by taking average slope of the trace.
What's the problem with fish breathing?
Lower concentration of oxygen in water than in air so fish have special adaptations
Step 1 fish breathing?
Water, containing oxygen enters the fish through its mouth and passes through the gills
Step 2 fish breathing?
Each Gill is made of lots of thin branches called hill filaments or primary lamellae which give a big surface area for exchange of gases. The gill filaments are covered in lots of tiny structures called Gill plates or secondary lamellae which increase the surface area even more. Each gill is supported by a Gill arch.
Step 3 fish breathing
The Gill plates have lots of blood capillaries and a thin surface layer of cells to speed to up diffusion
Step 4 fish breathing
Blood flows through the gill played in one direction and water flows over in the opposite direction (counter-current system). Maintains large concentration gradient between water and blood. The concentration of oxygen in the water is always high than that in the blood, so as much oxygen as possible diffuses from water into the blood
Do all fish have skeletons?
Bony fish including salmon and cod unsurprisingly, have a Skelton but not all fish do
How are bony fish ventilated step 1
Fish opens its mouth which lowers the floor of the buccal cavity (space inside the mouth). The volume of the buccal cavity increases, decreasing the pressure inside the cavity. Water is sucked in to the cavity
How are bony fish ventilated step 2
When fish closes its mouth, floor of buccal cavity is raised again. The volume inside the cavity decreases the pressure increases and water is forced out of the cavity across the gill filaments.
How are bony fish ventilated step 3
Each gill is covered by a bony flap (operculum which protects the gill) the increase in pressure forces the operculum on each side of the head to open, allowing water to leave the gills.
What happens in some bony fish?
The operculum bulges out (increasing volume of cavity behind the operculum) just after the floor of the buccal cavity lowers. This contributes to the decrease in pressure that causes water to enter the fish's mouth
What do you need to do before you dissect a fish?
Make sure you're wearing an apron or lab coat and gloves
Step 1 of fish dissection
Place chosen fish (something like perch or salmon works well) in a dissection tray or on a cutting board
Step 2 of fish dissection
Push back the operculum and use scissors to carefully remove the gills. Cut each Gill arch through the bone at the top and bottom.
Step 3 of fish dissection
If you are looking closely, you should be able to see the gill filaments.
Finish off by drawing the gill and labelling it
What do insects use for gas exchange?
Microscopic air-filled pipes (tracheae)
Air moved into tracheae through pores on the insects surface (spiracles)
How does oxygen get to the cell from the tracheae?
Oxygen travels down the concentration gradient towards the cells.
How does carbon dioxide get from the cell to the tracheae?
Carbon dioxide from the cells move down its own concentration gradient towards the spiracles to be released into the atmosphere
What do tracheae branch off into?
Smaller tracheoles which have thin, permeable walls and go to individual cells. The tracheoles also contain fluid which oxygen dissolved in
Where does oxygen go from tracheoles?
Oxygen diffuses from this fluid into body cells. Carbon dioxide diffuses in the opposite direction
What do insects use to change the volume of their bodies move air in and out of spiracles?
Rhythmic abdominal movements
When larger insects are flying, they use their wing movement to pump their thoraxes too
What do you need to dissect an insect
An insect that's been killed humanely fairly recently. Big insects like grasshoppers or cockroaches are usually best because they are easy to handle
Why do some living insect need to be handled carefully?
Can cause allergic reactions in some people
Step 1 dissecting insect
First fix insect to dissecting board. You can put dissecting pins through its legs to hold it in place
Step 2 insect dissecting
To examine the trachea, you'll need to carefully cut and remove a piece of exoskeleton. The insects hard outer shell from along the length of the insect's abdomen.
Step 3 dissecting insect
Use syringe to fill the abdomen with saline solution. You should be able to see a network of very thin, silvery-grey tubes- these are the tracheae. They look silver because they are filled with air