Clinical Chemistry Flashcards
List the various forms of carbohydrates
Simple- mono and disaccharides
Short chains- oligosaccharides
Complex CHO’s- polysaccharides
List the isomers of glucose
Galactose- mirror image of glucose
Fructose
What are the 3 disaccharides that can be made using glucose
Maltose= 2x glucose molecules
Lactose= glucose and galactose
Sucrose= fructose and glucose
What is glucose and what is it used for?
C6h12O6
Used to make ATP
Only converted to ATP when needed as ATP cannot be stored
List the 5 metabolic pathways
1.Glycolysis
2. Gluconeogenesis
3. Glycogenolysis
4. Lipogeneis
5. Glycogenesis
Describe glycolysis
Occurs in cell cytoplasm
Conversion of glucose- pyruvate
Converts free energy- ATP
10 enzyme- catalysed reaction= 2 x ATP produced
Describe gluconeogenesis
Release of glucose into the blood
The glucose is made from non-CHO sources such as triglycerides, amino acids and lactate
Describe glycogenolysis
Breaking down of glycogen to glucose
Glycogen comes from liver and muscles
Describe lipogenesis
Making of lipids
Lipids made from excess glucose in the blood
Glucose is made into triglycerides and then adipose tissue
Describe glycogenesis
Making of glycogen from excess glucose in the blood
Glycogen then stored in liver and muscles
What is the main hormone that controls blood glucose?
Insulin
What is insulin?
Peptide hormone
Made of 2 polypeptide chains:
Alpha- 21 amino acids
Beta- 30 amino acids
Describe hormonal control of blood glucose after a meal
Blood sugar is high
So insulin is released from the Beta cells in the pancreas
This stimulates the uptake of glucose by the liver and muscles
What happens when blood glucose concentration is low?
Glucagon is release from alpha cells in the pancreas
Glycogen is converted to glucose
Glucose is released into the blood
Define hyperglycaemia
High blood glucose concentration
Define hypoglycaemia
Low blood glucose concentration
What does glucagon do?
Stimulates glycogenolyis and promotes gluconeogenesis
Reduces glucose consumption by the liver
Promotes lipolysis
Outline the process of hepatic glycogenesis and glycogenolysis
- Glucose enters the liver
- The enzyme glycogen synthase to convert the glucose to glycogen
- The enzyme glycogen phosphorylase converts glycogen back to glucose
What effect does insulin have on hepatic and adipose tissue lipogenesis
Hepatic- Increases the action of acetyl co enzyme A in converting glucose to fatty acids
Adipose- Increases the amount of glucose entering the adipose tissue, which increases the glycerol and fatty acids produced
Prevents the conversion of triacyglycerol back to glycerol and fatty acids
When is insulin released and when its release stopped?
Released when plasma glucose concentration gets above 4.4 mmol/L
When blood glucose concentration decreases insulin is rapidly removed
Describe Type I diabetes and how is it treated?
Tends to be early onset
Autoimmune disease, which causes the destruction of the pancreas
Beta- cels are unable to produce insulin, meaning there’s no/ little insulin present
Therefore insulin needs to e injected
What are some of the chronic complication of Type I diabetes?
Heart attack and stroke
Kidney problems
Nerve damage
Sexual problems
What is diabetic ketoacidosis?
Life threatening emergency where lack of insulin and high blood sugars lads to a build up ketones
Blood becomes highly osmotic so water leaves cells into blood and cells then become dehydrated
What is Type 2 diabetes and how is it treated?
Often late onset and secondary to obesity
Beta-cells become insensitive to insulin combined with the inability of the Beta- cells to produce appropriate quantities of insulin
Treated via lifestyle changes, exercise, hypoglycaemic drugs and blood pressure control
How is the Oral Glucose Tolerance Test carried out?
Performed in the morning, following a 12hr fast
Oral admission of 75g of glucose
In normal patients the blood glucose concentration will return back to normal after 2 hours
In diabetic patients the blood glucose conc remains high after 2 hrs
How do diabetes test strips monitor blood glucose levels?
0.5-1 ul of blood is used
Blood placed on test strip and reacts with glucose oxidase enzyme to make gluconic acid
Blood glucose meter transfers a current to the test strip
Current changes depending on he amount of gluconic acid that as been produced
How does HbA1c work?
Measures average blood glucose for the last 2-3 months because the half life is aprox 180 days
The more glucose in the blood, the more will stick to red blood cells
Non-diabetics will have a 4-5.9% glycated haemoglobin
Diabetics will have a 6.5% glycated haemoglobin
Outline the gross anatomy of the kidneys
2 kidneys
Both surrounded by perinehric fat
Lie outside the abdominal all
Each supplied by a renal artery
Use up 1/5 of cardiac output
Outline renal function
Produce urine:
Filter glomerulus
Reabsorbtion
Secretion
What are the 3 major types kidney functions?
- Homeostasis
- Excretion
- Synthetic
What is GFR?
Glomerular Filtration rate
Amount of filtrate the kidneys produce each minute
What is the average GFR in healthy kidneys?
100-125 ml/min
What 3 things does the kidney synthesise?
- Synthesis of vitamins D
- Synthesis of renin
- Synthesis of erythropoietin
What does the production of Renin by the kidneys do?
Maintains blood pressure
What id the importance and function of erythropoietin?
Erythropoietin is essential to the production of red blood cells
The hormone acts upon bone marrow to signal the production of RBC’s
What is the importance of water in the body?
Acts as a coolant and solvent
Needed for transport and physically pushing osmotic gradients
What is the importance of sodium?
Concentration of sodium is a prime determinant of the extracellular fluid volume
Intake and excretion needs to be balanced to maintain volume and function
How is water homeostasis maintained?
Antidiuretic hormone (ADH) secretion is increased following dehydration
ADH causes water reabsorption in the kidney and triggers aldosterone
Aldosterone works primarily in the colon causing the absorption of salt and water
What effect does ADH have on distal collecting tubules and collecting ducts?
Causes them to be more permeable, so more water can be reabsorbed so a smaller amount of urine is collected for excretion
What is the function of aldosterone?
Primary function is to act on the ate distal tubule and collecting duct, impacting Na absorption and K excretion
Also indirectly affects excretion of H+, by changing the amount of K in the lumen of the nephron
Affects blood pressure by regulating the amount of Na in the, inc/ dec the ECF volume
Which waste products does the kidney excrete?
Urea- from toxic ammonia
Uric cid- from Nucleic acid catabolism
Creatine- from muscle metabolism
What is chronic renal failure?
Slow progressive loss of renal function
Causes inflammation of the glomerulus and inflammation of the renal pelvis
What is acute renal failure?
Sudden loss of renal function- within a few hours/ days
Cause by kidney tones, UTI’s, Calculi or Prostitis
What is the oliguric phase of ARF?
When nothing is filtered= low urine volume
Tubules are ok, so there’s a rapid increase of urea and creatine in the blood
What is the polyuric phase of ARF?
Glomerulus is starting to be filtered again
Tubules fail to absorb= lots of urine
Results in a rapid inc in Na and K in blood
Why is urine analysed?
No interference form proteins or RBC’s
What are the 3 types of urinalysis?
- Complete- in a lab, looks at urine composition
- Rapid- at the doctors, checks for common renal abnormalities
- 24-hr- at home, gives a clearer picture of renal function
What can you analyse in urine?
- Colour
- Turbidity
- Volume
- Odour
Define proteinuria
Excessive protein excretion in the urine
Sig not glomerular/ tubular disease
What is haematuria and what is it caused by?
When red blood cells have been shed and end up in the urine
Usually caused by:
Infection, kidney stones, tumours in the bladder or kidney, leakage from the urinary bladder
Why hare biochemical markers used for assessing kidney function?
They allow for:
1. Accurate diagnosis
2. Asessing risk
3. Adopting therapy
What are biomarkers?
“a characteristic that is objectively measured and evaluated as an indicator of normal biological, pathologic processes, or pharmacologic responses to a therapeutic intervention”
What is creatine?
Breakdown product of creatine phosphate in muscles
Usually produced at family constant rate by the body
Renal failure diagnosis supported when serum creatine is in the upper limit of “normal”
What is the scrum Creatine reference range in the UK?
Male- 59-104umol/l
Female- 45-84 umol/l
What is the normal creatine clearance value in the UK?
Male- 110-150 ml/min
Femal- 100-130 ml/min
Why way creatine levels be elevated?
Muscular dystrophy
Paralysis
Anaemia
Leukaemia
Why way creatine levels be decreased?
Glomerulonephritis
Congestive heart failure
Acute tubular necrosis
Shock
Polcystic kidney disease
What is urea?
Major nitrogenous end product of protein and amino acid catabolism
Processed by liver and distributed throughout intracellular and extracellular fluid
Filtered out from the blood by glomeruli, partially reabsorbed with water
Why is blood urea nitrogen (BUN) tested?
Most specific marker of the kidney
Inc in BUN is associated with kidney disease/ failure
High BUN levels can sometimes occur during late pregnancy or eating large amounts of protein rich foods
Higher than 1000 mg/dL= severe kidney damage
Low BUUN levels see in trauma, surgery etc
What is renal clearance?
Measurement that allows the analysis of the activity of the kidney
Volume of plasma from which a substance is completely removed by the kidney in a given amount of time (usually a minute)
How is clearance calculated?
Clearance= Urine conc x Urine volume excreted per min/ Plasma concentration
Give the Cockcroft- guilt equation that calculates GFR without urine
(140-age) x weight x 1.23(male) or 0.85 (female)/ serum creatine concentration (micromol/L)
List the biological functions of lipids
Rich energy source
Structural components of cell memebrane
Essential for fat soluble vitamains
Maintain body temp
Absorb shock
List the fat soluble vitamins
A
D
K
What are the different types of lipid?
Fatty acids- saturated/ unsaturated
Glycerides
Complex lipids
Nonglycerde lipids- sphingolipids/ steroids
Give the 3 roles of fatty acids in the body
- Components of more complex membrane lipids.
- Major components of stored fat in the form of triglycerides.
- Precursors for the synthesis of bioactive lipids.
What is the difference between saturated and unsaturated fatty acids?
Saturated have no double bonds, whereas unsaturated fatty acids do
The double bonds lower meting temp
What are Eicosanoids?
3 groups of structurally related compounds
They produce 3 bioactive lipids:
Prostaglandins
Leukotrienes
Thromboxanes
What is the function of Eicosanoids?
Blood clotting
Inflammatory response
Reproductive system- stimulate smooth muscle
How are triglycerides formed?
Formation of ester bonds between a glycerol and 3 fatty acids
What are the steroid class of lipids?
Cholesterol
Linked to CVD
Important in lipid digestion
What are the complex lipids?
Lipoproteins- molecular complexes found in blood plasma that contain a neutral lipid core of cholesterol and/ triocide glycerols
What are the major classes of lipoproteins and what do they transport?
Chylomicrons- transport intestine to adipose
VLDL- transport lipids to tissues
LDL- carry cholesterol to tissues
HDL- scavenge cholesterol esters
List the common lipid disorder stat lead to atherosclerosis (narrowed arteries)
Dyslipidemia- abnormal lipoprotein levels
Hyperlipidemia- elevates blood lipid levels
Hypercholesterolemia- elevated total cholesterol (>200 mg/dL)
Hypertriglyceridemia- elevated triglyceride levels
Hyperlipoproteinemia- elevates levels of certain lipoprotein
Give the “good” levels of total, LDL and HDL cholesterol
Total- below 200 mg/dL (5.2 mmol/L)
LDL- below 130 mg/dL (3.4 mmol/L)
HDL- above 40 mg/dL (1 mmol/L) in men and above 50 mg/dL (1.3 mmol/L) in women
Give some wider impact of elevated lipid levels
Renal impairment
Cognition
Cardiovascular disease
Sensory neuropathy
Erectile dysfunction
What is Xanthelasmas?
Common dyslipideamia disorder
Raised, yellowish macules that typically appear around the medial canthus
Involvement can extend to the eyelids or skin immediately below the eye.
What is Lipemia retinalis?
A common lipid disorder
Lipemic blood causes opalescence of retinal arterioles,
This can be observed during funduscopic examination
Common in those with Type II diabetes
What is Tendon xanthomas?
Common lipid disorder
When nodular deposits of cholesterol that accumulate in tissue macrophages in the Achilles and other tendons, including the extensor tendons in the hands, knees, and elbows
What is Tuberous?
Common lipid disorder
Range from pea-sized to lemon-sized and can be seen in dysbetalipoproteinemia and FH
List the 4 function of apolipoproteins
- Structural
- Control cellular uptake of lipoproteins through binding to memebrane receptors
- Guiding formation of lipoproteins
- Activating/ inhibiting enzymes involved in metabolism of lipoproteins
Describe the structure of apolipoprotein
Group of plasma proteins associated with variety of diseases
What 3 things can be down to manage the risk of CVD?
- Diet- inc intake of fruit and veg, replace saturated fats with complex carbs
- Inc physical exercise
- Blood pressure- risk of CVD inc as blood pressure inc
