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Flashcards in Gas exchange Deck (30):

What is transpiration?

the evaporation of water vapour from the leaves or other above-ground areas of the plant, out through the stomata into the atmosphere


Describe the stages of Expiration in humans (5)

1. External intercostal muscles relax so the ribs move down and inwards and outer pleural membranes move inwards
2. The Diaphragm relaxes and moves upwards
3. the pressure increases in the pleural cavity and inner pleural membranes move inwards
4. this action pushes on lung surface, contracting the alveoli
5. alveolar pressure increases above the atmospheric pressure so air is forced out


Describe the stages of Inspiration in humans (5)

1. External intercostal muscles contract so the ribs move up and out and pulls outer pleural membranes outwards
2. Diaphragm contracts and flattens
3. this reduces the pressure in the pleural cavity and inner pleural membranes move outwards
4. this pulls on the lung surface and alveoli expand
5. alveolar pressure decreases below atmospheric pressure so air is drawn in


What is sufactant and what produces it?

--> produced by the alveoli
--> contains phospholipids, proteins and lowers surface tension to prevent the alveoli collapsing and sticking together
--> allows gases to dissolve


Describe the structure of the human respiratory system (Lungs)

--> LUNGS enclosed in an airtight compartment called the THORAX which is surrounded by RIBS
--> Thorax lined with PLEURAL MEMBRANES
--> base of thorax is the muscly DIAPHRAGM
--> INTERCOSTAL MUSCLES are between the ribs
--> TRACHEA (with cartilaginous rings for support) branch into 2 BRONCHI which enter the lungs
--> Bronchi branches into BRONCHIOLES
--> Bronchioles end in alveoli where gas exchange takes place


How are alveoli adapted for gas exchange

--> large surface area (700 million of them) comapred to volume of body
--> permeable to gases
--> contain collagen so can contract and expand
-->alveoli and capillary network surrounding them are each 1 cell thick which means a short diffusion pathway
--> vast capillary network maintains the concentration gradients


What is the ventilation mechanism for insects when active?

The muscles in their abdomen and thorax contact and expand rhythmically causing movements which ventilate the tracheole tubes and maintain concentration gradients


How are leaves adapted to reduce water loss?

--> waxy, waterproof cuticle covering surface so water and gases cant pass through
--> stomata on underside of leaf only open during the day so close at night or in drought conditions


How are birds adapted for gas exchange ?

--> flight generates high metabolic rate and higher oxygen requirements so they have adapted an efficient ventilation mechanism to increase the concentration gradient across the lung's surface


How are earthworms adapted for gas exchange?

--> secrete mucus keeping their surface moist
--> low metabolic rate so require less oxygen
--> rich capillary network
--> blood vessels contain haemoglobin to transport oxygen
--> blood plasma transports carbon dioxide


Describe the structure of an insects gas exchange system

-->SPIRACLES run the length of the body and lead into chitin-lined TRACHEAE which branch into TRACHEOLES
-->CHITIN in rings so tracheae can expand and contract
-->TRACHEOLES touch every tissue to supply oxygen and remove carbon dioxide so haemoglobin is not needed
--> end of tracheole tubes contain fluid for gases to dissolve


What are the characteristics of a good gas exchange surface? (* characteristics not in single celled organisms, insects or plants)

--> moist to allow gases to dissolve
--> large surface area to volume ratio
--> permeable
--> thin to reduce diffusion distance
--> *blood supply*
-->* ventilation mechanism to maintain concentration gradient*


How do single-celled organisms exchange gases and materials?

-->they have a large surface area to volume ratio so materials can be exchanged directly across it's thin, permeable cell surface membrane to meet it's needs
-->cytoplasm always moving to maintain concentration gradient


What is 1 issue with maintaining a moist respiratory surface, and how is this issue minimised?

--> issue= water loss
--> minimised by having an internal gas exchange surface (e.g. lungs)


How are Flatworms adapted for Gas exchange?

--> large surface area to volume ratio
--> flat which decrease diffusion distance from cell surface membrane to cells


Why do larger multi cellular animals require specialised exchange--> surfaces?

--> their surface area to volume ratio is too small so so diffusion across the external surface is insufficient with their needs
--> increasing size also increases their metabolic rate which increases their oxygen requirements


Describe the ventilation mechanism of water Expulsion in bony fish

1. Mouth closes
2. the Buccal cavity floor rises
3. operculum valve opens
4. this decreases the cavity's volume and increases the pressure so water flows out down a pressure gradient over the gills


Describe the ventilation mechanism of water intake in bony fish

1. Mouth opens
2. Buccal cavity floor lowers
3. Operculum valve closes
4. this increases the cavity's volume and decreases the pressure so water flows in down a pressure gradient over the gills


What is an operculum in bony fish?

A flap covering the gills which opens during water expulsion and closes during water intake


Why is counter-current flow more efficient than Parallel flow?

--> concentration gradient is maintained along the entire length of the gill filament and as there i always a higher concentration of oxygen in the water than the blood, the oxygen will always diffuses into the blood as an equilibrium is not reached
--> more carbon dioxide diffuses out of the blood into the water than parallel flow


How are gases exchanged in the alveoli?

1. deoxygenated blood arrives from the pulmonary artery and enters the capillaries surrounding the alveoli
2. oxygen diffuses out of the air in the alveoli into the red blood cells in the capillaries and carbon dioxide diffuses out of the plasma in the capillary into the air in the alveoli where it's then exhaled


How are leaves adapted for gas exchange?

--> large surface area to volume ratio and are wide
--> flat which shortens diffusion distance
--> have stomata which open and close
--> spongy mesophyll surrounded by air spaces where gases diffuse


Describe the stomatal opening stages

1. the guard cells containing chloroplasts photosynthesis producing ATP
2. energy from the ATP is used to actively transport potassium ions into the guard cells
3. this triggers starch (insoluble) to be converted to malate (soluble) and this decreases the water potential of the guard cells
4. water flows into the guard cells via osmosis down a water potential gradient
5. as inner walls are thicker than the outer walls, the guard cells bend as they become turgid, opening the stomata


How are reptiles adapted for gas exchange?

More complex internal lungs than amphibians with a larger surface area


What is the name of a fish's gas exchange surface and what is it's structure?

--> gills
--> made of numerous gill filaments containing gill lamellae (gill plates) which increases the gills surface area for the exchange of oxygen and carbon dioxide


What is parallel flow in cartilaginous fish?

when water an blood flow in the same direction over the gill lamellae which maintains a concentration gradient for oxygen diffuse into the blood only until it's concentration is equal to the oxygen in the water


What is the ventilation system in cartilaginous fish?

open their mouths as they swim to allow water to pass over gills


How do spiracles in insects reduce water loss

--> close when insect is inactive


What is counter-current flow in Bony fish

--> when water and blood flow in the opposite direction to each other over the gill lamallae
--> this maintains the concentration gradient over the entire gill length so oxygen can diffuse into the blood over the entire gill


What do terrestrial animals risk and why

--> dehydration from water loss as water evaporates off their body surface