Gas exchange in animals Flashcards
How do you work out the surface area?
Length x width
How do you work out the volume?
Length x width x height
How does size affect surface area?
Larger the size, the greater the surface area
How does size affect volume?
Larger the size, larger the volume
What happens to the surface area : volume ratio as the size increases?
Decreases
What adaptions do amoeba have to increase SA : volume ratio?
Large SA
Thin - short diffusion pathway
Permeable
Moist
How does a wet/moist habitat aid gas exchange?
Dissolve O2 on skin and can freely cross cell membrane
What adaptions do flatworms have to increase SA : volume ratio?
Large SA : volume ratio
Permeable
No haemoglobin meaning very thin and flat
What adaptions do earthworms have to increase SA : volume ratio?
Slightly smaller SA : volume ratio compared to flatworm
Low oxygen requirements - low metabolism
Moist
Contain haemoglobin
What are the common features of a gas exchange surface?
Large SA : volume ratio
Short diffusion distance - thin
Maintain a conc gradient
Moist
Permeable
What are the gas exchange surfaces for amphibians and what are it’s features?
E.g. frogs - both lungs and skin
Large SA
Permeable
Short diffusion pathway
Moist
Good blood supply
What is the gas exchange surface for reptiles and what are it’s features?
Lungs - in-out bellows
Ingrowth of tissues to increase SA
What is the gas exchange surface for birds and what are it’s features?
Lungs - attached air sacs (act as bellows)
Why are organs inside the body?
Prevent heat and water loss
What circulatory system do fish use?
Single
What circulatory system do amphibians use?
Mixed double
What circulatory system do birds and mammals use?
Double
What are the features of a single circulatory system?
Closed
2 chambers
Low pressure
Least efficient
Less gas exchange
Only one pump per circuit
No mixed blood
What are the features of a mixed double circulatory system?
Closed
3 chambers
High pressure
Less efficient
Not much gas exchange
Double pump per circuit
Mixed blood
What are the features of a double circulatory system?
Closed
4 chambers
High pressure
Most efficient
Most gas exchange
Double pump per circuit
No mixed blood
What is the function of goblet cells?
Secrete sticky mucus - trap tiny particles in the air. Reduce infection chance as removed from lungs
What is the substance called that covers the surface of the alveoli?
Surfactant
What is the function of surfactant?
Cover surface of alveoli and them collapsing when breathing out by reducing the surface tension
What is the function of ciliated epithelial cells?
Numerous cilia at the end. Waft mucus to back of throat which is swallowed and destroyed by stomach acids
What is the function of cartilage?
Support trachea and bronchi - prevent collapse
Why does cartilage not form a full ring in the trachea?
Allow expansion e.g. swallow
What is the function of elastic fibres?
Stretch when inhaling. Alveoli to expand which increases SA. Recoil when exhaling - force out more air
Prevent alveoli bursting
What is the function of smooth muscle?
Adjust size of airways. Can contract. Reduce lumen diameter. Constrict airway and restrict air flow
Why are alveoli efficient at gas exchange?
Provide large SA
Moist
Thin - short diffusion pathway
Large blood supply as surrounded by large capillaries
Permeable
What happens during inspiration?
External intercostal muscles contract pulling ribcage up and out
Pressure reduced as pleural membrane pulled outwards
Diaphragm contracts going from a domed to flat shape
Volume in thorax and lungs increase
Air travels down the pressure gradient into the lungs
What happens during relaxed expiration?
External intercostal muscles relax and ribcage falls back under its own weight
Pressure increases
Diaphragm relaxes back into domed shape due to gut pressure
Volume in thorax and lungs decreases
Air forced out
What happens in forced expiration?
Internal intercostal muscles contract pulling the ribcage down and in
Pressure increases
Abdominal muscles contract pushing diaphragm upwards
Volume in thorax and lungs decreases
Air forced out
When does forced expiration occur?
During exercise or singing
What is the respiratory system in insects called?
Tracheal system
How many pairs of spiracles are involved in the tracheal system of a grass hopper?
10 pairs (2 thoracic and 8 abdominal)
Where are valves found in the insect tracheal system?
End of the spiracles
What are the function of valves in the insect tracheal system?
Reduce water loss
What do spiracles open into?
Tracheae which connect to air sacs
What are tracheae made up of?
A wall of single layered epithelial cells
What is the function of the single layered epithelial cells in tracheae?
Secrete cuticular thickenings that give support to the tubes and prevent them from collapsing during inhalation (chitin)
From the top of the grasshopper to the bottom, what are the body parts called?
Head, thorax, abdomen
What shape are the cuticular thickenings (chitin) in the tracheae?
Spiral
What do the tracheae open up into?
Tracheoles
What happens at the tracheoles of the insect during rest?
- Water moves out of muscle cells into the ends of tracheoles
- Oxygen has to diffuse through water to reach the cells
- Results in a longer diffusion pathway and slower diffusion
What happens at the tracheoles when insects are flying?
- Muscle cells produce lactic acid
- Lowers the water potential of muscle cells
- Water moves by osmosis from tracheoles into muscle cells
- Reduces distance for diffusion resulting in faster diffusion
What happens during inspiration in insects?
- Thoracic and first 2 abdominal spiracles open
- Abdomen expands causing an increase in volume and a decrease in pressure
- Air flows in
What happens during expiration in insects?
- Thoracic spiracles and first two abdominal spiracles close. The other abdominal spiracles open
- Abdomen contracts causing a decrease in volume and an increase in pressure
- Air slows out
What happens during inhalation in a fish?
Mouth opens
Operculum closes
Floor of mouth cavity lowers
Volume of mouth cavity increases and pressure falls
Water is pulled in
What happens during exhalation in a fish?
Mouth closes
Floor of mouth cavity is raised
Volume of mouth cavity decreases and pressure increase
Water flows across the gills
The operculum is forced open
What is parallel flow in fish?
Water and blood flow in the same direction
Deoxygenated blood meets oxygenated water at start of gill plate
O2 diffuses into blood down a steep conc gradient
Halfway across the gill plate, equilibrium has been reached due to % saturation being the same in the water and the blood
Least efficient system as blood is only 50% saturated
What is counter current flow in fish?
Water and blood flow opposite directions across the gill plate
Blood always meeting water with slightly higher % of oxygen saturation
Meaning diffusion gradient always maintained
Blood leaves about 95% saturated with oxygen
More efficient system
