Metabolism S1 - Nutrition, Diet & Body Weight Flashcards
Which is the most common form of diabetes in the young?
Type I
What is Type I diabetes characterised by?
- Progressive loss and destruction of all or most of the β-cells
- Autoimmune
- Fatal if not treated immediately
What is Type II diabetes characterised by?
- Slow, progressive loss of β-cells but with disorders of insulin secretion and tissue resistance to insulin
- May not initially need treatment with insulin but all do eventually
The classic presentation of a Type I diabetic is a lean young person with history of a viral infection who present a Triad of symptoms - what are these?
1) Polyuria - Excess urine production. High levels of glucose in urine increases osmotic load on the nephron and less water is reabsorbed
2) Polydipsia - Thirst due to increased water loss + osmotic effects of glucose on the thirst centres
3) Weight loss - fat and protein are metabolised by tissue because insulin is absent
What genetic markers are considered genetic markers for Type I diabetes?
HLA DR3
HLA DR4
If high blood glucose levels in a type I diabetic is not treated, what is the outcome?
Diabetic ketoacidosis - life-threatening crisis
What symptoms do Type II diabetics present?
Classic triad of symptoms and:
- Lack of energy
- Persistent infection, especially thrush infections of the genitalia or infections of the feet
- Slow healing of minor skin damage
- Visual problems
Diabetics suffer from a number of macrovascular complications, particularly when blood glucose levels are poorly managed, what are they?
- Increased risk of stroke
- Increased risk of myocardial infarction
- Poor circulation to the periphery, particularly the feet
Diabetics suffer from a number of microvascular complications, particularly when blood glucose levels are poorly managed, what are they?
- Diabetic Eye disease (Glaucoma, cataracts and most important problem, diabetic retinopathy)
- Nephropathy (diabetic kidney disease)
- Diabetic Neuropathy
- Diabetic Feet
Explain Diabetic eye disease
- Osmotic effects of elevated glucose levels can lead to glaucoma and possibly cataracts
- Diabetic retinopathy
- Damage to blood vessels in the retina that leak and form protein exudates or rupture and cause bleeding in the eye
- New, weak blood vessels may form (proliferative retinopathy) which are prone to bleeding
Explain diabetic kidney disease
The kidney is affected by:
- Damage to the glomeruli or Poor blood supply because of changes in blood supply
- Damage from infections or the urinary tract which is more common in diabetics
What is an early sign of nephropathy?
Increased amount of protein in the urine - microalbuminuria
Explain neuropathy
High glucose levels damage nerve fibres, particularly in the legs and feet thought to be caused by microvascular damage to vessels that supply these nerves
Explain diabetic feet
Poor blood supply, damage to nerves, and increased risk of infection all conspire to make the feet of a diabetic particularly vulnerable. In the past, loss of feet through gangrene was not uncommon.
Living cells require energy for:
- Biosynthetic work
- synthesis of cellular components
- Transport work across cell membranes
- maintenance of ion gradients, uptake of nutrients
- Mechanical work
- Muscle contraction
- Osmotic work
- Kidney
What type of energy is used to drive the energy-requiring action of the body?
Chemical-bond energy
What is an exergonic reaction?
When the energy released is greater than the energy input
What is an endergonic reaction?
When the energy input is greater than the energy released
What are the three components of daily energy expenditure?
1) Basal metabolic rate
2) Voluntary physical activities
3) Diet-induced thermogenesis (food processing)
Basal metabolic rate is mainly controlled by hormones of which origin?
Thyroid
What are the 9 essential amino acids
If Learnt This Huge List May Prove Truly Valuable:
Isoleucine, Leucine, Threonine, Histidine, Lysine, Methionine, Phenylalanine, Tryptophan, Valine
Why are some amino acids termed non-essential?
They can be synthesised by the body
Explain Marasmus
Complete lack of nutrition commonly seen in children under the age of 5. Child looks emaciated with obvious signs of muscle wasting and loss of body fat although there is no oedema. Hair is thin and dry, diarrhoea is common and anaemia may be present
Explain Kwashiorkor
Occurs typically in young children displaced by a new baby and fed a diet with some carbs but very low protein. The abdomen is distended due to hepatomegaly and/or ascites (accumulation of fluid in the peritoneal cavity). General oedema due to low serum albumin.
Define Obesity
Excess body fat has accumulated to the extent that it may have an adverse effect on health (BMI>30), leading to reduced life expectancy and/or increased health problems.
Define homeostasis
A dynamic equilibrium The maintenance of a stable internal environment within set limits occurring at all levels; Cellular, organ/system and whole body.
Describe the main features of the control system in the body - Communication
- Nervous system
- Endocrine system (hormones)
Describe the main features of the control system in the body - Control Centres
- Establishes the reference set points, analyses the afferent input and determines the appropriate response
- Eg The hypothalamus and the medulla oblongata
Hypothalamus - involved in the control of the endocrine system
Medulla oblongata - involved in control of ventilation and the cardiovascular system
Describe the main features of the control system in the body - Receptors
- Required to detect stimuli such as changes to the internal environment
- Usually specialised nerve endings such as chemoreceptors and thermoreceptors
- Sensors communicate input to the control centre via the afferent nerves
Describe the main features of the control system in the body - Effector
- These cause change
- The control centre produces an output, which is communicated via the efferent pathways to the effectors
List the essential components of the diet
Fats, Carbohydrates, Protein, Vitamins, Minerals and water
Why are fats required by the body?
- Absorption of fat soluble Vitamins A, D, E and K
- Essential fatty acids linolenic and linoleic needed for structural components of the cell membrane and precursors important regulatory molecules such as eicosanoids
Why is protein required by the body?
Maintain nitrogen balance Nitrogen loss = Nitrogen intake
Essential amino acids that cannot be synthesised by the body
How much water is lost by the body daily and by what mechanism?
2.5L Sweating, Expiration, Urine and Faeces
Define Metabolism
Set of processes which derive energy and raw materials from food stuffs and use them to support repair, growth and activity of the tissues of the body to sustain life
How is BMI calculated
Weight (KG) / Height Squared (M)
Define cell metabolism
Highly integrated network of chemical reactions that occur within the cell
What is the function of creatine phosphate
- Acts as a small store of phosphate for energy release in cardiac and skeletal muscle
- During low ATP levels, donates a phosphate to ADP via creatine kinase
What is the clinical relevance of measuring creatinine concentration?
Indicator of renal function and skeletal muscle mass
What is the clinical relevance of measuring creatine kinase levels?
Marker of muscle damage in conditions such as myocardial infarction
