Cell metabolism 3 Flashcards
(33 cards)
what is metabolic adaption?
when your metabolism changes depending on your nutritional state.
what are the two states of metabolic adaption?
absorptive and postabsorptive
why is it important to maintain steady blood glucose levels?
because nervous system and red blood cells depend upon glucose
what happens during the absorptive state?
ingested nutrients are entering the blood stream and glucose is readily available for ATP production
what do pancreatic beta-cells release?
insulin
what happens during the postabsorptive state?
absorption of nutrients from GI tract is complete.
Describe the absorptive state (principle metabolic pathways)
- After a meal, nutrients enter body - glucose, amino acids and triglycerides in chylomicrons
- 2 metabolic hallmarks :
- oxidation of glucose for ATP production in all body cells
- storage of excess fuel molecules in hepatocytes, adipocytes and skeletal muscle cells
Describe the postabsorptive state - how are normal blood glucose levels maintained?
- About 4 hours after the last meal, absorption in the small intestine is nearly complete
- Blood glucose level starts to fall
- Main metabolic challenge to maintain normal blood glucose levels
- Glucose production – Breakdown of liver glycogen, lipolysis, gluconeogenesis using lactate and/or amino acids
- Glucose conservation – Oxidation of fatty acids, lactate, amino acids, ketone bodies and breakdown of muscle glycogen
optimal levels of nutrients
We do not know with certainty what levels and types of carbohydrates, fat and protein are optimal
• Different populations around the world each radically different diets
– Adapted to lifestyle
• We do know some don’ts
– Too much sugar – Too much saturated fat – Processed foods
What are minerals?
Inorganic minerals that occur naturally in Earth’s crust
What is the major role of minerals?
- Enzyme reactions
- DNA binding proteins
- Oxygen binding
Haemoglobin
Cytochrome P450s
What happens to excess minerals?
• Excess minerals are excreted in urine and faeces
– Extremely toxic in high concentrations
– Build-up in disease
- Freidrich’s ataxia (iron)
- Wilson’s disease (copper)
What are vitamins?
Organic nutrients required in small amounts to maintain growth and normal metabolism
– “Vital amines”
- Do not provide energy or serve as body’s building materials
- Most are co-enzymes – Vitamin B6
- Most cannot be synthesised by the body – Vitamin K produced in the GI tract by gut flora
What are the two groups of vitamins?
• 2 groups
– Fat-soluble – A, D, E, K
– Water-soluble – several B and C vitamins
What happens to excess vitamins?
- Excess water-soluble are excreted in the urine
- Excess fat-soluble build up in the body and cause significant toxicity
What happens as a result of vitamin deficiencies? + give examples
Deficiencies lead to disease
- Rickets (vitamin D)
- Scurvy (vitamin C)
What is metabolic syndrome and how is it diagnosed?
Caused by an underlying disorder of energy usage and storage
- Unknown cause
- Diagnosed by the clustering of at least three of the following:
– Central obesity
– High blood pressure
– High blood sugar
– High serum triglycerides
– Low HDL
- Between 25 - 35% of the US adult population are classed as having metabolic syndrome
- Closely related to insulin resistance and prediabetes
What is inborn error of metabolism?
- A large class of genetic diseases involving congenital disorders of metabolism
- Defects in single genes for enzymes
- Affect all metabolic pathways
- Symptoms vary due to the nature of the genetic mutation
What is disorder of carbohydrate metabolism? + Give examples
• Glycogen storage disease
– Von Gierke’s disease
Glucose-6-phosphatase deficiency
• 1:50,000
– Forbe’s disease
- Glycogen debranching enzyme deficiency
- 1:100,000
– Andersen disease
- Glycogen branching enzyme deficiency
- 1:500,000
What is disorder of amino acid metabolism and how is it treated?
Phenylketonuria
– Due to a deficiency in phenylalanine hydroxylase (PAH)
– Autosomal recessive
– Treatment with food low in phenylalanine
– Aspartame is metabolised into Phe so should be avoided
What are the consequences of amino acid disorder?
Lack of treatment can cause significant developmental problems
– Intellectual disability
– Seizures
– Behaviour problems
– Microcephaly
• Build-up of Phe competes for the LNAA transporter in the blood-brain-barrier
– Reduces entry of key amino acids which are used to synthesise neurotransmitters and neuronal proteins
• Lack of PAH also reduces Tyr synthesis
– Reduced dopamine, norarenaline and adrenaline synthesis
What is disorder of fatty acid oxidation? Symptoms?
• Medium-chain acyl-coenzyme A dehydrogenase deficiency
– MCADD
– Prevention of the breakdown of fatty acids into acetyl-CoA
– Hypoglycaemia and sudden death
• Brought on by periods of fasting or vomiting
What is incidence? Treatment?
Autosomal recessive
– ACADM gene
– Dehydrogenation step of fatty acids between C6-C12
• Common in Northern European caucasians
– 1:4,000 – 1:17,000
• Treatment is by the avoiding of fasting
– During illness, need to supplement using glucose
• Patients have potentially reduced survival – Needs to be diagnosed as an infant
What is diabetes? Symptoms? Long term problems?
- High blood sugar levels over a prolonged time due to the pancreas not producing, or the body not responding to insulin
- Onset of a variety of symptoms
– Frequent urination
– Increased thirst
– Increased hunger
– Diabetic ketoacidosis
• Long-term problems
– Cardiovascular disease
– Kidney disease
– Foot ulcers
