Exchange Flashcards
What happens during inspiration?
- Ribcage moves up and out,
- Diaphragm contracts to flatten
Internal intercostal muscles relax and external contract - Increased volumes, and decreased pressure allow air to move down its concentration gradient into the lungs
What happens during expiration?
- Ribcage moves down and in,
-Diaphragm relaxes back to a domed position - External contract, internal relax
- Decreased volumes, and increased pressure, allow air to move down the concentration gradient out of the lungs
What are some advantages of the alveoli?
-Red blood cells slowed in capillaries so more time for diffusion
- Walls of both alveoli and capillaries thin - short diffusion distance
- Alveoli - large SA:Vol
- Blood flow through pulmonary capillaries maintains a concentration gradient
What is countercurrent flow?
Blood flows in the opposite direction to water which helps maintain a concentration gradient across the lamellae
Where is gill lamellae placed?
90deg to filaments
How did insects respire along a different gradient?
- Cells respiring -> oxygen conc falls towards ends of tracheoles -> diffuses gradient -> oxygen diffuses into tracheoles
- Carbon dioxide produced when respiring -> diffusion gradient in the opposite direction -> diffuse out of the tracheae into the atmosphere
How did insects respire along an abdominal pumping?
- contraction of muscle in insects’ trachea enabling mass movement of air in and out
How do insects react during anaerobic respiration?
During intense actions: muscle cells around tracheoles respire anaerobically -> produce lactate -> lower w.p -> water moves (osmosis) into cells from tracheoles -> lowers volume in tracheoles and draw air down into tracheoles.
What are some features of plant that increase ROR?
- No living cell far from the external air
- Diffusion takes place in gas phase - more rapid
- Stomata - short diffusion pathway
- Air space in mesophyll
- Large surface area of mesophyll cells - rapid diffusion
How do insects limit water loss?
- Small SA:VOL - minimise area over which water is lost
- Waterproofing on body surfaces
- Spiracles - can be closed to reduce water loss
What are some adaptations of plants that limit water loss?
- Waxy cuticle - waterproofing
- Rolled-up leaves - trap water vapour, high water potential prevent osmosis
- Hair leaves - trap vapour and reduce w.p gradient - reduce water lost by evaporation
- Reduced SA: VOL - less area that water can be lost at
Suggest and explain why xerophytic plants would be slower in growth.
- less number of stomata
Explain how the counter current mechanism in fish gills ensures the maximum amount of oxygen passes into the blood flowing through the gills?
- water and blood flow in opposite directions
-blood passing always passing water with increased oxygen concentration
Explain two ways in which the structure of fish gills is adapted for exchange?
- many lamellae large surface area for absorption
- thin surface so short diffusion pathway
What are some characteristics of tracheal system?
- tracheoles have thin walls allows for short diffusion distance
- fluid in the end of the tracheoles that moves out during exercise so faster diffusion through the air to the gas
exchange surface; - abdominal pumping
What are some adaptations of the iluem?
- Inner walls folded into villi - large SA
- Microvilli - villi is further increased by millions of tiny projections
- Thin-walled, reducing the distance over which diffusion takes place
- Supplied with blood vessels - maintain diffuse gradient
- The ileum has glands that produce enzymes
What is physical digestion?
physical breakdown (large food - smaller pieces by teeth and churned food in the stomach),
What is chemical digestion?
chemical digestion (hydrolyses large insoluble molecules into smaller soluble ones)
What are the 4 main types of digestive enzymes?
Carbohydrases - hydrolyse carbohydrates (monosaccharides)
Lipases - hydrolyse lipids (fats and oils) into glycerol and fatty acids
Proteases hydrolyse proteins, ultimately to amino acids
Amylase - maltose - maltase - glucose
What is the human process for digestion?
Saliva - salivary amylose -> hydrolyses any starch into food to maltose -> stomach acid denatures the amylase further preventing hydrolysis of the starch -> small intestine - food mixes with pancreatic juice -> pancreatic amylase continues hydrolysis of starch to maltose -> ileum -> epithelial lining produces the disaccharides maltase (membrane-bound)
How are lipids digested?
Lipases (produced in the pancreas) - hydrolyse the ester bond found in triglycerides.
Lipids -> split into tiny droplets called micelles by bile salts (produced by the liver) = emulsification
How are proteins digested?
Hydrolysed by peptidases
- endopeptidases - hydrolyse the peptide bonds between amino acids in the central region of a protein molecule
- Exopeptidases - hydrolyse the peptide bonds on the terminal amino acids
- Dipeptides - hydrolyse the bonds between the amino acids of a dipeptides
How are trigylcerides absorbed?
Micelles break down - releasing the monoglycerides and fatty acids -> diffuse across the cell-surface membrane -> once inside the epithelial cells monoglycerides and fatty acids are transported to the endoplasmic reticulum -> triglycerides associate with cholesterol and lipoproteins forming chylomicrons -> move out of epithelial cells by exocytosis -> enter lymphatic capillaries called lacteals
