Please enable JavaScript.
Coggle requires JavaScript to display documents.
Strand 3 - Coggle Diagram
Strand 3
gas exchange (insects)
insects have an exchange system made up of many tubes called tracheae which branch into smaller tracheoles
-
-
-
walls of the tracheoles are thin to allow for a short diffusion distance to speed up rate of diffusion
tracheoles are in contact with individual cells and contain a small amount of fluid in which the gases are dissolved. the fluid is drawn into the muscle tissue during exercise. this increases the surface area of air in contact with the cells, increasing the rate of diffusion (diffusion happens faster through air than water).
limiting water loss
-
-
-
tiny hairs (spiracles): trap a layer of humid air which lowers the concentration gradient of water vapour and reduces water loss
gas exchange (plants)
-
-
-
-
large surface area of mesophyll cells for rapid diffusion of gases into and out of these cells, many interconnecting air spaces between the mesophyll cells in the leaf
-
digestion
enzymes
during digestion, large biological molecules are hydrolysed to smaller molecules that can be absorbed across cell membranes
large biological molecules in food e.g. starch/proteins too big to be absorbed across cell membranes
digestion breaks them into smaller molecules e.g. glucose/amino acids → absorbed from the gut to the blood
digestion (mammals)
digestion of starch: polysaccharide
- amylase hydrolyses starch to maltose (polysaccharide to disaccharide)
- amylase produced by salivary glands, released into mouth
- amylase produced by pancreas, released into small intestine
digestion of disaccharides:
- membrane bound disaccharidases e.g. maltase, sucrose, lactase, (attached to epithelial cells lining the ileum of the small intestine)
- hydrolyse disaccharides to 2 named monosaccharides
- maltose - maltose = glucose + glucose
- sucrase - sucrose = fructose + glucose
- lactase - lactose = galactase + glucose
- hydrolysis of glycosidic bond
digestion in mammals of proteins by endopeptidases, exopeptidases and membrane-
bound dipeptidases
endopeptidases
hydrolyse peptide bonds within a protein/between amino acids in the central region by breaking proteins into two or more smaller peptides
-
-
absorption
lipid digestion
-
after emulsification lipases break down lipids by hydrolysing the ester bond found in triglycerides to form 2 fatty acids and a monoglyceride (1 fatty acid and glycerol joined together by an ester bond)
protein digestion
-
endopeptidases hydrolyse peptide bonds between amino acids in the central region of the protein forming a series of peptides
exopeptidases hydrolyse the peptide bond of the terminal amino acid of the peptide formed by endopeptidases which releases dipeptides and amino acids
-
triglyceride absorption
micelles are formed during digestion which contain the monoglycerides and fatty acids associated to the bile salt
-
the triglycerides in the chylomicrons are hydrolysed by an enzyme in the endothelial cells of blood capillaries
micelles break down releasing the monoglycerides and fatty acids which can diffuse across the cell surface membrane into the epithelial cell as they are non polar
-
-
moving into the golgi apparatus triglycerides are associated with cholesterol and lipoproteins to form chylomicrons
-
-
the triglycerides in chylomicrons are hydrolysed by an enzyme in the endothelial cells of blood capillaries
gas exchange (lungs)
the lungs ensure efficient gas exchange between the air and the blood with:
- large surface area ~ provided by the many air sacs or alveoli
- good blood supply ~ many capillaries
- thin walls ~ short diffusion distance
INSPIRATION
- occurs when lung pressure decreases below atmospheric pressure
- external intercostal muscles contract and internal intercostal muscles relax
- the rib cage moves up and out
- diaphragm muscles contract and flatten
- increasing the volume of the thorax and decreasing the pressure
- atmospheric pressure is higher than the pressure in lungs
- air moves into the lungs
- ACTIVE PROCESS
EXPIRATION:
- expiration occurs when lung pressure increases above atmospheric pressure
- internal intercostal muscles contract whereas the external intercostal muscles relax
- the rib cage moves down and inward
- the diaphragm relaxes and moves upwards
- the volume in the thorax decreases and the pressure increases
- atmospheric pressure is lower than pressure in the lungs
- air moves out of the lungs
- PASSIVE PROCESS
gas exchange (fish)
structure of gills
-
-
gill filaments have a rich blood supply which helps to maintain a concentration gradient between the blood and the water
-
counter current flow
-
the diffusion gradient for oxygen is therefore maintained along the entire length of the gill structure
-
-