Clinical Biochemistry Flashcards
What does insulin stimulate?
- Glucose uptake in muscle and adipose tissue
- Glycolysis
- Glycogen synthesis
- protein synthesis
- uptake of ions (especially K+ and PO43-)
What does insulin inhibit?
- Glucogenesis
- Glyconeogenesis
- Lipolysis
- Ketogenesis
- Proteolysis
What does reduced cellular uptake of glucose result in?
Hyperglycaemia
What does hyperglycaemia cause?
Excess glucose spills into urine
- glycosuria
- osmotic diureses
What results from dehydration?
Hypotension and shock
What happens if the body is resistant to insulin or deficient?
Body tries to source insulin from other fuels
-triglycerides
What are ketones?
Intermediates of fat breakdown- strongly acidic, dissociate and release protons
What do ketones cause?
Vomitting
What does hypotension and shock cause?
Stimulate release of hormones which exacerbate the process (anti-insulin) >AVP >Growth hormone >Cortisol >Catecholamine
What is lipolysis?
Breakdown of lipids
What is the role of hormone sensitive lipase?
> Releases free fatty acids and glycerol
>occurs when energy is needed
Where are ketone bodies formed?
Liver mitochondria
Where do ketone bodies diffuse to?
Blood stream and peripheral tissues
What is ketone body acid load?
Highly acidic ketone bodies release hydrogen ions into the blood
What happens to bicarbonate buffering in blood during keto-acidosis?
excess hydrogen ions mop up most of the available bicarbonate ions
Because carbon dioxide is blown off the reaction never reaches equilibrium
What is kussmaul breathing?
Deep sighing respiration
acidotic breathing
How can DKA be identifies?
Ketones= dipstick
DKA can be smelt from across the room
Air hunger
Why can some people mobilise glycogen stores?
Lack of enzyme
- Phosphorylase
- Transferase
- a-1,6-glucosidase
What is the problem with lactate?
Yields much less energy than oxidative metabolism
What is the long term consequence of not being able to bread down glycogen?
Accumulates;
- hepatomegaly, portal hypertension
- fibrosis of the liver
What are the clinical features of not being able to break-down glycogen?
Hypoglycaemia in early llife
Hepatomegaly
Heart can be affected- heart failure, lung failure, death
What are the main components of the plasma membrane?
Phospholipid
Sphingomyelin
Cholesterol
What does cholesterol do in the membrane?
Maintain structure and fluidity of cell membrane
What is cholesterols role in cell singnalling?
Form lipid ‘rafts’ that form bridges between receptor proteins and second messengers
-lipid rafts are parts of membrane that serve as centres for assembly of signalling molecules
