Gas Exchange Flashcards
What is diffusion?
The net movement of particles down a concentration gradient from an area of high concentration to low concentration
2 substances an organism needs to take in from the environment ?
Glucose
Oxygen
2 substances that an animal needs to release?
CO2
Urea
How do single cell organism diffuse substances ?
-directly in or out the cell across the cell surface membrane.
Why is diffusion rate quick in single cell organisms
Short diffusion distance
Relatively high SA:V ratio
How do multi-cellular organisms diffuse substances?
Require specialised exchange surfaces such as alveoli
What are the 3 reasons multicellular organisms need specialised exchange surfaces?
1) some cells are too deep within the body
2)larger animals have low SA:V
3)higher metabolic rate so use more oxygen and glucose
What are the 3 special features of exchange surfaces?
1)a large surface area
2) they’re thin
3) a good blood supply or ventilation
Why are root hair cells good exchange surfaces?
Each hair branched of a root and is covered in millions of microscopic hairs
-gives root hair cell a large SA:V ratio increases water absorption by osmosis and mineral ions by active transport
Why are alveoli good exchange surfaces?
-made of alveolar epithelium-> decreases the distances O2 and CO2 takes place increasing rate of diffusion
Why are the alveoli surrounded by a large capillary network?
-gives each alveolus its own blood supply
-helps maintain concentration gradient
-lungs are ventilated so air in each alveoli is constantly replaced
Why are fish gills good exchange surfaces?
-contain large network of capillaries-> well supplied with blood
-well ventilated -> fresh water constantly flows over them
What is the structure of the gaseous exchange system?
1) trachea
2) splits into 2 bronchi-> 1 to each lung
3)each bronchi branches into bronchioles
4)the bronchioles end in alveoli
Ribcage, inter coastal muscles and diaphragm work to move air in and out
Where are goblet cells found?
Line the airways
Function of goblet cells?
-secrete mucus
-traps microorganisms and dust particles inhaled by air stopping them getting to alveoli
Where are cilia found?
On epithelial cells lining airways
Role of cilia?
-hair like structures
-beat mucus secreted by goblets cells
-moving mucus toward throat away from alveolus
-prevent lung infections
Where are elastic fibres found?
-trachea
-bronchi
-bronchioles
-alveoli
Role of elastic fibres
-when inhaling lungs inflate stretching elastic fibres
-fibres then recoil to push air out when exhaling
Where is smooth muscle found
Walls of
-trachea
-bronchi
-bronchioles (except the smallest ones)
Role of smooth muscle
-allows diameter to be controlled
-during exercise smooth muscle relaxes making the tubes wider
-less resistance so air can move in and out lungs easier
-supplying muscles with more oxygen
Where are rings of cartilage found?
-walls of
Trachea
Bronchi
Role of rings of cartilage?
-provide support
-strong and flexible
-stops trachea and bronchi collapsing when breathe in and pressure drops
What happens to pressure during inhalation ?
Pressure drops below atmospheric pressure as volume of thorax increases
What happens to pressure during inhalation ?
Pressure increases above atmospheric pressure as volume of thorax decreases
What features do the trachea have ?
-large C shaped cartilage
-smooth muscle
-elastic fibres
-goblet cells
-ciliated epithelium
What features do the bronchi have?
-small cartilage pieces
-smooth muscle
-elastic fibres
-goblet cells
-ciliated epithelium
What features do the LARGE bronchioles have?
-smooth muscle
-elastic fibres
-goblet cells
-ciliated epithelium
What features do the LARGE bronchioles have?
-smooth muscle
-elastic fibres
-goblet cells
-ciliated epithelium
What features do the SMALLER bronchioles have?
-smooth muscle
-elastic fibres
-ciliated epithelium
What features do the SMALLEST bronchioles have?
-elastic fibres
What features do the alveoli have?
-elastic fibres
What is ventilation?
Inhalation and exhalation
What is ventilation controlled by?
Movements of diaphragm, intercostal muscles and ribcage
What happens to external intercostal muscles and the diaphragm during inhalation?
They contract
What happens during inhalation?
-Ribcage moves up and out
-diagram flattens
-volume of thorax increased
Causing air to flow into lungs
Why is inspiration an active process?
Requires energy
What happens to external intercostal and diaphragm muscles during exhalation?
-they relax
What happens during expiration?
-Ribcage moved down and in and diaphragm curves
-air is forced out lungs
Why is NORMAL expiration a passive process?
-doesn’t require energy
What happens during forced expiration?
Internal intercostal muscles contract bulling ribcage down and in
What is tidal volume ?
Volume of air in each breath
What is the usual measurement for tidal volume ?
0.4 dm3
What is vital capacity?
Maximum volume of air that can be breathed in or out
What is breathing rate?
How many breathes are taken per unit time
What is oxygen uptake?
The rate at which someone uses up oxygen
What direction does air flow?
From areas of high pressure to areas of low pressure
What are the 3 main structures of the gills?
-primary lamellae/ gill filaments
-secondary lamellae/ gill plates
-gill arch
What is the function of the gill arch?
Provides structure and holds gill in place
What is the function of the gill raker?
To filter out solids, preventing damage to gill filaments/ primary lamellae
Function of primary lamellae/ gill filaments?
Provide large surface area for gas exchange
Function of secondary lamellae/ gill plates?
Main sight of gaseous exchange which water flows over
What is a counter current system in fish?
Blood thoughts the the gill plates in one direction and water flows over in the opposite direction
What does a countercurrent system mean?
Water with a relatively high oxygen concentration always flows next to blood with low concentration of oxygen -> steep concentration maintained
How much less oxygen does water have than air?
20-40%
Ventilation in bony fish
1)opens mouth-> lowers floor of by all cavity
2)volume of buccal cavity increases
3)decreases pressure
4) water enters cavity
5) closes mouth floor of buccal cavity raised
6) increasing pressure
7)water forced out of cavity across gill filaments
8) pressure open operculum forces water out gills
What is the operculum ?
Bony flap that covers fill to protect it
What features do insects use for gas exchange/ ventilation
-spiracles
-trachea
-thoracic and abdominal movement to chance body volume
-tracheal fluid
Ventilation in insects
1)air moves into trachea through spiracles (pores)
2) oxygen travels down the concentration gradient
3) carbon dioxide from cells move down its own concentration gradient towards spiracles to be removed into atmosphere
4) trachea branch into small tracheoles which contain fluid oxygen dissolves in
5)oxygen diffuses form fluid to cells
6) carbon dioxide diffuses in opposite direction
Why do insects use rhythmic abdominal movements?
-change the volume of their body
- to move air in and out spiracles
-when larger insects fly they use wind movement to pump their thoraxes
