Exchange Surfaces and Transport in Animals Flashcards
can the cell membrane be an exchange surface for small organisms?
Yes
do small organisms have a high or low metabolic rate?
Low
do small organisms have a low or high surface area to volume ratio?
A high surface area to volume ratio
how do you calculate the surface area to volume ratio?
Surface area/volume
(SA:1)
in insects has the gas exchange system evolved to provide oxygen directly to cells?
Yes
do the specialised transport systems in insects transport oxygen or nutrients?
Nutrients
what is the surface of an insect covered with?
An exoskeleton
What is an insects exoskeleton make out of?
The polysaccharide chitin
Why do insects need spiracles on their exoskeleton?
So that gases like oxygen and carbon dioxide can diffuse into the insect
What do the spiracles lead to ?
The trachea
what is the diameter of the trachea in insects?
1mm
is the diameter of the trachea in insects larger or smaller than the diameter of the trachea in animals?
Smaller
What are walls of the trachea in insects made up of?
Chitin
What are walls of the trachea in animals made up of?
cartilage
Why does the trachea in insects need chitin?
To prevent the trachea from collapsing
What extends from the trachea in insects?
Very fine tubes called tracheoles
What is the diameter of tracheoles?
1 micrometre or less
is each tracheole a single cell?
Yes
are tracheoles supported by chitin?
No
Why is there a short diffusion distance between the tracheoles and the insects cells?
-because tracheoles have a narrow diameter
-because tracheoles are extremely close to cells
What is the oxygen from the tracheoles needed by the cells for?
Aerobic respiration, which produces carbon dioxide
What are the ends of the tracheoles filled with ?
tracheal fluid
Why does water from the tracheal fluid move into the insect cells during intense activity?
-Because during intense activity, cells around the tracheoles undergo anaerobic respiration and this produces lactic acid.
-This lowers the water potential of the cells and causes water to move from the tracheoles into the cells by osmosis.
-This reduces the volume of the tracheal fluid, drawing air down into the tracheoles
is gas exchange in insects an active or a passive process?
A passive process
what is a significant problem faced by insects?
Water loss
are the walls of the tracheoles moist or dry?
They’re moist
how can water vapour diffuse out of an insect?
Via the spiracles
What is each spiracle surrounded by ?
A muscular sphincter
What does the muscular sphincter do?
Control the opening and closing of the spiracles
How many main body segments do insects have?
3
What are the 3 main body segments of an insect?
The head, the thorax and the abdomen
Why do the trachea contain air sacs in some insects?
Because changes in the thorax and abdomen can squeeze the air sacs and cause air to move from the air sacs to the tracheoles . Insects can also use the oxygen in the air sacs during times when spiracles have been closed for water conservation
why do bony fish have a large oxygen requirement?
Because they are very active
Can gases pass through the scaly surface of fish?
No
do fish get their oxygen from air or water ?
From the water
where is the concentration of oxygen higher- in the air or in water?
In the air- the concentration of oxygen is much lower in the water
what is the operculum?
the flap of tissue on either side of the fish’s head
What is behind the operculum?
The opercular cavity
what can be found inside the opercular cavity?
The gills
what do the gills consist of ?
gill arches
what extends from each gill arch?
gill filaments
what are gill filaments covered with?
gill lamellae (gill plates)
are the gill lamellae where has exchange in a fish occurs?
Yes
how are the gill lamellae adapted for the efficient diffusion of gases?
- they have a massive surface area for diffusion to occur
- there’s a very short diffusion distance between the walls of the lamellae and the bloodstream
- gill lamellae have an extensive network of capillaries
- The counter current exchange system
Describe the counter current exchange system
-Water and blood move in opposite directions
-Blood with a low concentration of oxygen passes into the capillaries of the gill lamellae
- As the blood passes through the gill lamellae, oxygen diffuses from the water into the blood
- Oxygenated blood passes out of the gill lamellae and leaves the gills
what is the major advantage of the counter current exchange system?
A steep concentration gradient is always maintained
what is it called when water and blood flow in the same direction ?
Parallel flow
with a counter current exchange system , roughly what percentage of oxygen in the water diffuses into the bloodstream?
About 80%
Describe how bony fish maintain constant water flow through the gas exchange system
- A bony fish opens its mouth and water flows into the buccal cavity (the mouth space)
- The floor of the buccal cavity lowers and increases the volume available for water
- The fish then shuts the operculum and this increases the volume of the opercular cavity
- Due to the increased volume, the pressure in the opercular cavity falls and the floor of the buccal cavity moves upwards.
- This increases the pressure of water and so the water moves down a pressure gradient and flows over the gills in the opercular cavity.
- Now, the fish closes its mouth and opens the operculum.
- The sides of the opercular cavity squeeze inwards on the water.
- This increases the pressure of water and forces it out of the operculum
Can water enter a bony fish’s mouth even when it’s not swimming?
Yes
What are the 2 main adaptations of the trachea?
- The walls of the trachea contain cartilage. This prevents the walls of the trachea from collapsing when we inhale
- The trachea walls are lined with ciliated epithelia and goblet cells
what is the function of the goblet cells?
They secrete mucus, which traps dust particles and pathogens
What do the ciliated epithelial cells do?
The cilia wafts mucus to the throat. The mucus is then swallowed and the dust and the pathogens are then digested by the enzymes in the stomach
does the bronchi also contain cartilage, ciliated epithelia and goblet cells ?
Yes
what do the bronchioles contain?
Cartilage and smooth muscle.
what do the elastic fibres between the alveoli do during breathing?
they stretch and recoil
how thick are the walls of the capillary?
Only one cell thick
how thick are the walls of the alveoli?
Only one cell thick
Use test for alveoli adaptations
What is another name for breathing?
Ventilation
What 2 sets of muscles work together to change the volume of the throrax during ventilation?
The intercostal muscles and the diaphragm
What happens during inhalation?
-The intercostal muscles contract
- The diaphragm contracts and flattens
- The volume of the thorax increases
- Air pressure in the lungs decreases
-Because air pressure in the lungs is now less than atmospheric pressure, air is drawn into the lungs
-Air consequently moves into the alveoli
What happens during exhalation?
- The intercostal muscles relax
- The diaphragm relaxes and becomes domed
- The volume of the thorax decreases
-Now, the air pressure in the lungs is greater than atmospheric pressure and so air is pushed out of the lungs
Why is inhalation an active process?
Because it requires muscle contraction
Why is exhalation a passive process?
Because the muscles relax
What membranes are the lungs surrounded by?
Pleural membranes
What is between the pleural membranes?
Pleural fluid, which acts as a lubricant as the lung volume changes
In which occasion can exhalation be an active process?
When you exhale strongly during intense exercise . In this case the internal intercostal muscles come to play.
What is mass transport?
When molecules are carried in a transport medium, such as blood, through a circulatory system