Metabolism and homeostasis Flashcards
Define the term metabolism
the sum of chemical reactions that take place in each cell of a living organism
What are the 4 main pathways through which dietary components are metabolised?
1) Biosynthetic
2) Fuel storage
3) Oxidative
4) Detoxification
Define Anabolic metabolism and give an example
Synthesising larger molecules from smaller components
Eg. anabolic steroids are used by body builders to build muscle
Which metabolic pathways are anabolic?
Biosynthetic pathway and fuel storage pathway
Define Catabolic metabolism
The breakdown of larger molecules into smaller components
Which metabolic pathways are catabolic?
Oxidative pathway and waste disposal pathway
Explain a biosynthetic pathway
The sequence of enzymatic steps in the synthesis of a specific end product -> structural molecules (eg. proteins)
Explain the fuel storage pathway
The synthesis of molecules that have a function to store energy (eg. ATP)
Explain the oxidative pathway
Cells use enzymes to oxidize nutrients/energy rich molecules, releasing chemical energy
Explain the detoxification pathway
The removal of waste products/products that are not useful and have no nutritional value
What are cofactors? Give an example
What are cofactors? Give an example
How is adipose tissue specialised?
It is approx. 85% fat and the storage site for fat (in the form of triglycerides)/energy rich molecules
What percentage of body weight is water?
60%
What percentage of total body water is intracellular fluid?
40%
Is water freely permeable thought ICF and ECF?
Yes
What is the predominant cation in ICF?
Potassium
Sodium is the main contributor to ECF …….. and ………
osmolality and volume
What else is present in the extracellular fluid?
1) anions chloride and bicarbonate
2) glucose & urea
3) protein (colloid osmotic pressure)
What fluid surrounds the cells but does not circulate?
Interstitial fluid
What fluid circulates as a component of the blood?
Plasma
What is osmolality?
concentration of all small ions and molecules in the plasma
How do we estimate plasma osmolality?
2[Na] + 2[K] + urea + glucose mmol/L
Are intra and extracellular osmolality equal?
Yes
Under ………… circumstances, fluid intake = fluid loss
normal
What is our normal plasma osmolality?
275-295 mmol/kg
What is our normal plasma osmolality?
275-295 mmol/kg
3 causes of water depletion
1) Reduced intake
2) sweating
3) vomiting/diarrhoea/diuresis
Clinical symptoms of dehydration
Thirst Dry mouth Inelastic skin Sunken eyes Raised haematocrit Weight loss Confusion Hypotension
What are ascites?
accumulation of fluid in peritoneal space
What is hypernatremia?
an increase in sodium ions (excess) in the blood plasma
What is hyponatremia?
Loss of sodium ions due to renal loss
What percentage of body water is found as extracellular fluid?
20% - split into intravascular and interstitial.
Why we don’t give water intravenously?
1) hypo-osmolar/hypotonic vs. cells
2) water causes blood cells to burst after entering
3) this only occurs in vicinity of intravenous cannula
4) instantaneous mixing would prevent this
What is the condition where there is an excess accumulation of fluid in the interstitial space?
Oedema
