The Composition of Blood

What does blood volume depend on?

size

What are the main 4 functions of the blood?

• delivery

• waste collection

• communication route

• defence

What are the main components of the blood?

plasma, white blood cells, platelets, erythrocytes (red blood cells)

What percentage of blood volume does plasma make up?

55%

What percentage of blood volume do white blood cells, platelets and buffy coat make up?

1%

What percentage of blood volume does erythrocytes make up?

45%

What is plasma made up of?

• proteins

• anions

• small molecules

What small molecules are found in plasma?

• glucose

• amino acids

• lactate

• glycerol

• urea

• ketones

Serum

liquid component of blood when blood is allowed to clot

What is the difference between plasma and serum?

plasma contains clotting factors but serum does not

What are the functions of plasma proteins?

• transport

• inflammatory response and immunity

• haemostasis

• oncotic pressure

What do plasma proteins transport?

albumin, proteins which transport iron, copper, hormones, lipids, etc

What plasma proteins are involved in the inflammatory response and immunity?

immunoglobulins, complement proteins, acute phase proteins

Does water move in or out at the arterial end of blood vessels?

out

Does water move in or out at the venous end of blood vessels?

in

Why does water move into blood vessels at the venous end?

due to oncotic pressure

What happens to fluid when hydrostatic pressure > oncotic pressure?

fluid leaks out into interstitial space

What happens to fluid when hydrostatic pressure < oncotic pressure?

water moves back into capillary

What is the most abundant protein in plasma?

albumin

Characteristics of albumin

• negatively charged at physiological pH

• highly polar

• large capacity to non-specifically bind ligands

Features of albumin bound molecules

• solubilise

• retained in blood stream

• regulated

• may be neutralised -antioxidant function of albumin

Why do fatty molecules bind to albumin?

they aren’t soluble in water so binding to albumin makes them more soluble

low levels of albumin

hypoalbuminaemia

What does hypoalbuminaemia do?

reduce oncotic pressure and lead to oedema

What are 3 causes of hypoalbuminaemia?

• chronic liver disease

• malnutrition

• chronic renal disease

What are the symptoms of hypoalbuminaemia?

• swelling of extremities

• vomiting

• weakness

• diarrhoea

• distended abdomen

• breathing difficulty

What substance does transferrin transport?

iron

What substance does caeruloplasmin transport?

copper

What transport proteins are involved in transporting hormones?

• thyroid hormone binding globulin

• cortisol binding globulin

• sex hormone binding globulin

Globulin

generic term given to many plasma proteins

What substance does haptoglobin transport?

haemoglobin

What substances do apoproteins transport?

lipids

What determines the concentration of proteins in the plasma?

• blood volume

• rate of synthesis

• rate of breakdown and loss

What determines blood volume?

hydration

Where are proteins synthesised?

• liver

• cells of immune system

What determines breakdown of proteins?

uptake and degradation of proteins by cells

Where can proteins be lost?

via kidney and/or gut

What measurements can be made to use plasma proteins as diagnostic tools?

• total protein conc (limited use)

• serum electrophoretic pattern

• enzyme measurements

What do serum electrophoretic patterns allow for?

separation and semi-quantitative assessment of individual proteins

What can enzyme measurements be used for?

detecting cell damage

Benefits of serum protein electrophoresis (SPE)

• inexpensive

• easy to perform

Serum protein electrophoresis (SPE)

agarose or polyacrylamide gel electrophoresis separates proteins on the basis of their charge and size

In serum protein electrophoresis, what does the size of band equal?

size of protein

When do albumin levels decrease?

• prolonged malnutrition

• chronic liver or renal disease

When do albumin levels increase?

in dehydration

What does increased alpha-globulins cause?

acute inflammatory diseases

What can increased beta-globulins be indicative of?

liver disease

What does the concentration of acute phase proteins increase in response to?

inflammation

What are acute phase proteins an important part of?

innate immune response

What do increased alpha 3 bands reflect?

increase in proteins indicating likelihood of infection

What do low levels of albumin indicate?

acute phase reaction

What do decreased gamma-globulins indicate?

immune suppression or immune deficiency conditions (hypogammaglobulinaemia)

What do increased gamma-globulins indicate?

chronic infection

When is a sharp, distinct increase in one area of the y band in serum protein electrophoresis seen?

in multiple myeloma

multiple myeloma

cancer caused by monoclonal expansion of a single type of antibody producing cell and hence a single antibody

What are some limitations of SPE?

• important proteins produced in quantities too low to detect

• changes in band density can be missed

What can abnormalities in sodium, potassium and chloride ions indicate?

• metabolic disorders

• dehydration

• renal dysfunction

Is concentration of cellular enzymes in serum normally high or low?

LOW

When can enzyme activity in serum be increased?

by cell proliferation or damage (e.g. cancer, cell death, trauma)

What is analysis of the enzyme ALT indicative of?

liver damage

What is analysis of the enzyme ALP indicative of?

bone deposition, liver damage, hyperthyroidism, biliary disease, increased steroid levels

What is analysis of the enzyme GDH indicative of?

liver disease

What is analysis of the enzyme yGT indicative of?

liver disease

What is analysis of the enzyme CK indicative of?

muscle damage

What is analysis of the enzyme AST indicative of?

muscle and liver damage

What is analysis of the creatinine indicative of?

kidney malfunction