Gas Exchange Flashcards
What is the total oxygen requirement proportional to?
the volume of the organism
What is the rate of absorption of oxygen proportional to?
the organisms surface area
What are the common features of gas exchange surfaces?
large surface area relative to volume
permeable
thin
moist
mechanism to maintain diffusion gradients
What are the 3 main factors that affect the need for a specialised transport system?
Volume -> an increase in the layers of cells means that less oxygen can diffuse into the organism (can only occur across 2 cells w/o specialised carriers) as it would be used up by outer cells first
Level of Activity -> animals require the energy released by food in respiration to enable them to move around, if the animals is active or needs to keep warm the animal requires larger volumes of oxygen and nutrients to supply energy
Surface area to volume ratio
Describe gas exchange generally for small organisms
don’t need a transport system
their cells are surrounded by the environment they live in
can rely on diffusion to supply the substances required
Describe gas exchange in amoeba
a single-celled organism that has a very large SA:V (pseudopodia) so that simple diffusion through cell membrane is fast enough to meet oxygen demands (short diffusion pathway)
lives in fresh water ponds
removes CO2 fast so cytoplasm doesn’t become acidic and enzymes can’t function
Describe gas exchange in flatworms
a multicellular organism with a smaller surface area to volume ration but are flattened to reduce diffusion distance and so they can rely on their external surface for gas exchange
Describe gas exchange in earthworms
a multi-cellular organism
smaller SA:V as it’s cylindrical but it’s elongated
diffusion happens across the moist skin but has a closed circulation with haemoglobin to carry oxygen to tissues and each cell
haemoglobin and circulation maintain a steep concentration gradient
since the skin has to stay moist it restricts the environment to damp soil
Why do terrestrial organisms have gas exchange organs inside the body?
to reduce water and heat loss
Describe the gas exchange in amphibians (e.g. frogs)
both terrestrial and aquatic
gas exchange takes place across the skin (at rest) and lungs (when active)
the skin is moist, permeable and has a well developed capillary network
undergoes metamorphosis when going from the larval form to the adult form
Describe the gas exchange in reptiles
gas exchange takes place across the lungs with in-growths of tissue to increase SA
movement of the ribs aid in the ventilation of the lungs
Describe the gas exchange in birds
gas exchange takes place in the lungs with air sacs
air sacs act as bellows, when the bird breathes in any air that remains in the lungs from the last breath gets sucked into air sacs = lungs always filed with fresh air
no diaphragm but ribs and flight muscles ventilate lungs
Describe the gills as the special respiratory surface in fish
one-way current of water kept flowing by ventilation mechanisms which maintains concentration gradient
large surface area provided by the gill filaments (density of water flowing through prevents gills from collapsing)
extensive network of blood capillaries to allow efficient diffusion and haemoglobin for oxygen carriage
thin layer of cells separate blood from outside water
Describe the gas exchange organ in bony fish?
called gills
fish possess several gills located between their buccal cavity (mouth cavity) and a chamber at the sides of their mouth called the opercular cavity
Compare bony fish to cartilaginous fish
Bony:
skeleton made of bones
lives in sea or fresh water
covered in scales (= no exchange through surface)
gills inside opercular cavity
gas exchange involves a counter-current system
Cartilaginous:
skeleton made of cartilage
mostly live in the sea
covered in scales
contain gill clefts
gas exchange involves a parallel system where the water and blood travel in the same direction
Draw a labelled diagram of a gill (bony fish)
Gill Arch: bony structure to support gill filaments and rakers
Gill Rakers: filter water and trap prey
Gill Filament (gas exchange surface): provides a large SA, filled with blood and short diffusion path (gill plates)
Why is water harder to respire in than air?
contains a low concentration of oxygen (1/30th of the concentration in air)
denser and more viscous than air making it harder to move in
What is the ventilation mechanism for taking in water?
mouth opens
operculum cavity closes
floor of the mouth is lowered
volume inside the mouth cavity increases
pressure inside the mouth cavity decreases
water flows in as the external pressure is higher than the pressure inside the mouth
What is the ventilation mechanism to force water out?
mouth closes
operculum opens
floor of the mouth is raised
volume inside the mouth cavity decreases
pressure inside the mouth cavity increases
water flows out over the gills because the pressure in the mouth cavity is higher than in the opercular cavity
What is meant by a counter current flow?
blood and water flow in opposite directions at the gill lamellae, maintaining the concentration gradient across the entire length
Why is counter current flow more efficient?
Concentration gradient maintained over entire distance of gill lamellae (diffusion occurs across entire length)
What is meant by parallel flow?
blood and water flow in the same direction at the gill lamellae, maintaining the concentration gradient for oxygen to diffuse into the blood only up to the point where its concentration in the blood and water is equal (50% max and not maintained across entire length)
Define the term ‘breathing’
the passage of air into and out of the lungs to supply the blood with oxygen
Define the term ‘ventilation’
movement of diaphragm and rib cage that brings air into and out of the lungs
Define the term ‘respiration’
the metabolic process by which an organism obtains energy by reacting O2 with glucose to give H2O, CO2 and ATP
What is the function of the human breathing system?
to supply respiring tissues with oxygen
reduce heat and water loss
Name and draw a diagram of the lungs
tongue
epiglotis
oesophagus
trachea
cartilage rings
ribs
intercostal muscles
bronchi
bronchioles
pleural membranes
pleural space
diaphragm
Why are the cartilage rings not complete?
allows the oesophagus behind it to bulge as food is being swallowed
Name the parts of the trachea section
larynx
trachea
rings of cartilage
bronchi
bronchioles
Draw and label the cross section of a bronchiole
smooth muscle
ciliated epithelium
loose tissue with elastic fibres
goblet cell
blood vessel
Draw and label the cross section of the trachea
cartilage
smooth muscle and elastic fibres
ciliated epithelium with goblet cells
small blood vessel
mucus secreting gland
What is the function of the goblet cells and positions in the gas exchange system?
secrete a sticky mucus which traps tiny particles in the air (e.g. pollen and bacteria)
this reduces the chance of infection as they are removed from the lungs
found in the trachea, bronchi and large bronchioles
What is the function of ciliated epithelial cells and positions in the gas exchange system?
cells have tiny hair like structures which waft the mucus up the airway to the back of the throat where it can be swallowed
trachea, bronchi and large bronchioles
What is the function of cartilage and positions in the gas exchange system?
supports the trachea and bronchi by holding them open and preventing them from collapsing during pressure changes in inspiration or expiration
trachea, bronchi and large bronchioles
What is the function of elastic fibres and positions in gas exchange system?
stretch during inhalation, the alveoli expand increasing the SA
elastic recoil of alveoli in expiration, helps force air out
found in trachea, bronchi, bronchioles and alveoli
What is the function of smooth muscle and positions in the gas exchange system?
adjusts the size of the airways, it can contract which causes the constriction of airway, restricting flow
trachea, bronchi and bronchiole
What are the parts of the alveoli?
branch of pulmonary vein
branch of pulmonary artery
capillary network
bronchiole