Exchange Surfaces Flashcards
(40 cards)
How do insects draw oxygen further into the muscles during intense activity?
1) Leak a bit of water across muscle membrane
2) Anaerobic respiration produces lactate, which is soluble and lowers water potential
3) Previously leaked water returns into the muscles, drawing air in with it too
What occurs during inspiration?
1) External intercostal muscle contract while intercostal muscles relax and ribs are moved up and out, increasing volume of thoracic cavity
2) Diaphragm muscles contract and flatten
3) Increased volume in thoracic cavity decreases pressure in the lungs, forcing air down the pressure gradient into the trachea
What is the flow of air in the human respiratory system?
Pharynx - Larynx - Trachea - Bronchi - Bronchioles - Alveoli
What are the advantages and disadvantages of retrospective studies?
+ cheap and easy to perform
- people may have forgotten information or deliberately deceive or exaggerate information, making it fairly unreliable
What are the key features/adaptations of the trachea?
- rings of cartilage to keep the walls open
- walls made of muscle and elastic tissue
- lined with ciliated epithelium, which help to move mucus along, and goblet cells, which trap excess mucus
- epiglottis closes entrance to trachea when swallowing
What is counter current flow?
In the gill filaments, the blood and water flow in opposite directions, maintaining the diffusion gradient along the entire lamellae
What is an example of a single-celled organism?
Chlamydomonas
What is the digestion pathway?
1) begins in mouth with mechanical (chewing) and chemical (enzymes) digestion
2) food travels to stomach where mechanical (churning) and chemical (enzymes and acid) digestion continues
3) food moves to small intestine where chemical digestion continues as it gets mixed with enzymes from the pancreas and bile
What two organelles maintain diffusion gradients in a leaf?
Mitochondria and chloroplasts
What are the two ways insects reduce water loss?
Spiracles can open and close and tiny hairs round edge of spiracles
What are the four different substances that need to be exchanged with the environment?
- respiratory gases
- nutrients
- excretory products
- heat
What are the enzymes involved in the digestion of proteins?
Endopeptidases - hydrolyse bonds within the central regions to form peptides
Exopeptidase - hydrolyse bonds on the terminal amino acids of a peptide to release dipeptides and single amino acids
Membrane-bound Dipeptidases - exopeptidase that specifically work on dipeptides
What ensures tracheae stay open?
Rings of chitin
What is the structure of the gills?
- each gill has two stacks of filaments
- a row of lamellae is positioned perpendicular to each filament
- each lamellae is a single layer of cells covering a vast network of capillaries
- all the gills are attached to a primary gill arch
What are the key features/adaptations of the alveolar epithelium?
- network of capillaries to ensure continuous blood flow and movement of oxygen
- walls consist of flattened singular cells, reducing diffusion distance
- capillary walls are very thin and narrow, further reducing diffusion distance
- inner surface of the alveolus wall is covered in a thin film of water, as cell-surface membranes are permeable to water, which reduces diffusion rate and increases distance, so other mechanisms need to try to overcome this
What adaptations do cacti have?
- leaves can roll up so only one side is exposed to wind
- exposed surface has no stomata
- inner surface has many hairs to trap water
How are gills adapted to increase the rate of diffusion?
- lots of lamellae, increasing SA:V ratio
- lamellae are only covered with a very thin layer of cells, reducing diffusion pathway
- rich supply of capillaries, so diffusion pathway is maintained
- counter-current flow maintains diffusion gradient along the whole length of the lamellae
What are some of the main risk factors of COPD?
- smoking (around 90% of COPd patients have been heavy smokers)
- air pollution
- genetics
- infections
What are the key features/adaptations of the bronchi and bronchioles?
- bronchi have sections of cartilage in their walls to maintain their structure
- bronchioles repeatedly branch into smaller and smaller tubes
- bronchioles can contract and relax during ventilation
What are the 5 key features of exchange surfaces?
- Large SA:V ratio
- Very thin walls
- Selectively permeable membranes
- Movement of environmental medium
- Moderation of internal medium
What occurs during expiration?
1) Internal intercostal muscles contract while external intercostal muscles relax and ribs are moved down and in, decreasing thoracic cavity volume
2) Diaphragm muscles relax
3) Decreased volume of thoracic cavity increases pressure in lungs, forcing air out
What adaptations do xerophytes have?
- thick cuticle
- rolled up leaves that form spines
- stomata in pits or grooves to trap moist air
- reduced SA:V ratio of the leaf
- few stomata
- hairs around the stomata to trap any water
Why do insects require a high rate of oxygen?
Very high metabolism due to their small size
What adaptations do cacti have?
- leaves reduced to spines to reduce water loss
- stem with chloroplasts and water storing sacs
- shallow and deep roots to penetrate as much of the water table as possible
