Chapter 6 - Exchange Flashcards
what are the features of a specialised exchange surface? (5)
- large SA:Vol
- thin, short DP
- selectively permeable
- movement of environmental medium to maintain DG
- transport system to maintain DG
What is the calculation for diffusion?
surface area x difference in concentration
_________________________________
length of diffusion pathway
How are single celled organisms able to survive with no transport system?
large SA:Vol
simple diffusion
no part too far from external substances
what is the main factor in conflict with gas exchange in terrestrial organisms?
water conservation
list the structures of insects gas exchange system in order from smallest to largest (4)
fluid filed ends
tracheoles
trachea
spiracles
How do gases move in/out of the tracheal system? (3)
- along a diffusion gradient, oxygen used by surrounding cells
- mass transport, muscle contraction
- fluid filled ends, water enters surrounding cells by osmosis during times of activity meaning a lower vol. of water in the system leaving a shorter diffusion pathway for gas exchange in times of high metabolic activity
What are the limitations of the tracheal system? (2)
- rely solely on diffusion
- needs short diffusion pathway therefore limits insect size
state the structures of the gills from largest to smallest
gill bar
gill filaments
gill lamella
What is the importance of the counter-current exchange system for diffusion?
- maintains a constant favourable diffusion gradient for oxygen to diffuse into the blood e.g. when blood with little oxygen meets water with little oxygen the oxygen still diffuses down the gradient into the blood
how do gases enter/exit the leaf of a plant (the process)?
diffusion
how are leaf tissues gas exchange systems similar to that of an insect? (2)
- cells not far from external air, short DP
- diffusion takes place in gas phase, more rapid
State an adaptation of a leaf for rapid diffusion
stomata -short DP
air spaces throughout mesophyll
large SA of mesophyll = large SA
state the structures of a leaf from top to bottom (5)
waxy cuticle upper epidermis mesopyhll air spaces lower epidermis
How are stomata adapted for limiting water loss?
when flacid due to low water potential stomata close, when turgid they remain open
state 3 adaptations of insects to reduce water loss
- small SA:Vol
- waterproof coverings
- spiracles, open/close
adaptations of non-xerophitic plants to limit water loss? (2)
- waxy cuticle
- close stomata
adaptations of xerophytes? (5)
- thick cuticle
- rolling up of leaves
- hairy leaves
- stomata in pits/grooves
- reduced SA:Vol e.g. cactus
state the structures of the lungs passed through by air entering the lungs (mouth onwards) (4)
trachea
bronchus
broncheole
alveoli
why must the lungs be located inside the body?
- air not dense enough to support the delicate structure
- significant water loss, body would dry out
describe the structure of the trachea
flexible airway supported by ācā shaped cartilage, lined by goblet cells
describe the structure of the bronchi
less cartilage as bronchi get smaller
describe the structure of bronchioles
muscle walls able to constrict, lined with epethelial cells
describe the structure of alveoli
air sacs with collagen and elastic fibres between to allow it to expand and recoil
state the 3 sets of muscle involved with the mechanism of breathing
- internal intercostal muscles
- external intercostal muscles
- diaphragm
describe the diaphragm
sheet of muscle separating thorax from abdomen
outline the process of inspiration (6)
- external contract, internal relax
- ribs pull upwards and outwards
- volume of thorax is increased
- diaphragm contracts and flattens
- reduction of pressure in lungs
- atmospheric pressure is then greater than in lungs = air flows into lungs
adaptations of alveoli for diffusion into blood (5)
- red blood cells slowed as they move through capillaries - more time for diffusion
- red blood cells flattened against walls of capillaries
- thin walls of both - shorter DP
- both have large SA
- constant ventilation, constant heartbeat maintains DG
state the risk factors for lung disease (5)
- smoking
- air pollution
- genetics
- infections
- occupation (chemicals)
what is the difference between a correlation and a causation?
correlation = change of one variable reflected by change in other variable causation = one variable is the result of the change in the other variable
state the major parts of the digestive system (5)
oesophagus stomach ileum large intestine rectum (salivary glands) (pancreas)
what is the difference in function of the ileum and the large intestine?
ileum:
- food digested
- absorbs products of digestion
large intestine:
- absorbs water
outline the process of carbohydrate digestion (chemical). (5)
- saliva enters mouth from salivary glands, mixes with food through chewing (contains salivary amylase, breaks down starch to maltose)
- acid in stomach denatures salivary amylase
- food passes into ileum, mixes with pancreatic juice containing pancreatic amylase
- muscles in intestine push food along ileum
- membrane-bound disaccharidase maltase hydrolyses maltose to alpha glucose
what is the term used to describe enzymes that hydrolyse carbs?
carbohydrases
what the the two other types of hydrollytic enzymes other than maltase for carbs?
sucrase
lactase
what is the optimum pH for amylase?
around neutral
outline the process of lipid digestion (3)
- bile salts split lipids into micelles
- process called emulsification
- increases SA for action of lipases
name of protein enzymes?
peptidases
name the 3 types of peptidases
endopeptidases
exopeptidases
dipeptidases
state adaptations of the exchange surface of the ileum + function of adaptation (5)
- villi, SA
- microvilli, SA
- thin walls, DP
- muscle walls for movement//mixing, DG
- capillary network, DG
how are amino acids absorbed in the ileum?
co-transport using sodium and co-transport carrier proteins
outline how lipids are absorbed (5)
- micelles associated with bile salts
- contact epethelial cells and break down releasing monoglycerides and fatty acids (lipid soluble) pass through PB-L
- transported to ER reform into triglycerides
- continue to Golgi where they become associated with cholesterol and lipoproteins to form chylomicron
- excytosis out of cell into lymphatic capillaries which drain into blood
