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Questions and Answers
What percentage of total blood plasma is made up of proteins?
What percentage of total blood plasma is made up of proteins?
Which type of plasma protein is primarily responsible for maintaining oncotic pressure?
Which type of plasma protein is primarily responsible for maintaining oncotic pressure?
Where are the majority of blood serum proteins synthesized?
Where are the majority of blood serum proteins synthesized?
What is the function of haptoglobin in the blood?
What is the function of haptoglobin in the blood?
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Which globulin fraction contains ceruloplasmin?
Which globulin fraction contains ceruloplasmin?
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What happens to the body if the albumin concentration drops below 30 g/L?
What happens to the body if the albumin concentration drops below 30 g/L?
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What is the total concentration range of globulins in blood plasma?
What is the total concentration range of globulins in blood plasma?
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Which of the following is NOT a function of blood proteins?
Which of the following is NOT a function of blood proteins?
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What is the main diagnostic significance of ceruloplasmin levels in the blood?
What is the main diagnostic significance of ceruloplasmin levels in the blood?
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Which protein is primarily responsible for inhibiting trypsin and other proteolytic enzymes?
Which protein is primarily responsible for inhibiting trypsin and other proteolytic enzymes?
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What is the primary function of transferrin in the body?
What is the primary function of transferrin in the body?
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In which condition is α1-antitrypsin deficiency particularly associated?
In which condition is α1-antitrypsin deficiency particularly associated?
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What happens to the levels of α1-antitrypsin during inflammatory processes?
What happens to the levels of α1-antitrypsin during inflammatory processes?
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Which of the following proteins is considered an 'acute phase' protein associated with inflammation?
Which of the following proteins is considered an 'acute phase' protein associated with inflammation?
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Which of the following statements about cryoglobulin is true?
Which of the following statements about cryoglobulin is true?
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Which plasma protein is responsible for binding free heme?
Which plasma protein is responsible for binding free heme?
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What is the primary inducer of acute phase protein synthesis in hepatocytes?
What is the primary inducer of acute phase protein synthesis in hepatocytes?
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What percentage of residual nitrogen in blood is constituted by urea under normal conditions?
What percentage of residual nitrogen in blood is constituted by urea under normal conditions?
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In which condition is the creatinine level primarily increased?
In which condition is the creatinine level primarily increased?
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Which of the following is a characteristic of renal retention azotemia?
Which of the following is a characteristic of renal retention azotemia?
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Which of the following proteins is considered an acute phase protein?
Which of the following proteins is considered an acute phase protein?
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What causes extrarenal retention azotemia?
What causes extrarenal retention azotemia?
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What is a common cause of increased ammonia levels in the blood?
What is a common cause of increased ammonia levels in the blood?
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What is productive azotemia typically caused by?
What is productive azotemia typically caused by?
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What is the role of 2,3-DPG in relation to hemoglobin?
What is the role of 2,3-DPG in relation to hemoglobin?
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Why is stored blood often unsuitable for transfusion to hypoxic patients?
Why is stored blood often unsuitable for transfusion to hypoxic patients?
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What happens to 2,3-DPG levels during storage of blood in blood banks?
What happens to 2,3-DPG levels during storage of blood in blood banks?
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What is the primary reason inositol is added to stored red blood cells instead of 2,3-DPG?
What is the primary reason inositol is added to stored red blood cells instead of 2,3-DPG?
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Which pathway accounts for the metabolism of 5-10% of glucose in erythrocytes?
Which pathway accounts for the metabolism of 5-10% of glucose in erythrocytes?
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What is the primary function of aminotransferases in the body?
What is the primary function of aminotransferases in the body?
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In cases of myocardial infarction, how much can AST activity increase in blood serum?
In cases of myocardial infarction, how much can AST activity increase in blood serum?
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Which serum enzyme is primarily associated with liver function?
Which serum enzyme is primarily associated with liver function?
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Which condition is indicated by low AST activity in the bloodstream?
Which condition is indicated by low AST activity in the bloodstream?
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Which type of enzyme is NOT correctly categorized in the three groups of serum enzymes?
Which type of enzyme is NOT correctly categorized in the three groups of serum enzymes?
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What is a common diagnostic use of serum enzymes?
What is a common diagnostic use of serum enzymes?
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Which enzyme's increased activity is most frequently seen in acute viral hepatitis?
Which enzyme's increased activity is most frequently seen in acute viral hepatitis?
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The highest concentration of ALT is found in which organ?
The highest concentration of ALT is found in which organ?
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Study Notes
Blood Plasma Proteins
- Proteins makeup 6.5-8.5% of dry blood plasma
- Total protein levels are 65-85 g/L
- Albumin 40-50 g/L
- Globulin 20-40 g/L
- Fibrinogen 1.5 - 3.5 g/L
- Liver synthesizes most blood proteins
- Some proteins are formed in other tissues
- Lymphocytes: γ-globulins
- Endocrine glands: peptide hormones
- Kidney cells: erythropoietin
- Most blood plasma proteins are glycoproteins, albumin is the exception
- Functions of blood proteins:
- Blood clotting
- Blood viscosity
- Acid-base balance
- Transport
- Protection
- Amino acid reserve
- Regulation
- Oncotic pressure
- Maintaining cation levels in blood
Albumin
- 35-50 g/L in blood plasma
- Makes up 60% of total plasma protein
- Functions:
- 75-80% of plasma oncotic pressure
- Decreased levels below 30 g/L contribute to edema
- Transports:
- Free fatty acids
- Calcium
- Steroid hormones
- Bilirubin
- Copper
- Drugs
Globulins
- Divided into subcategories:
- α1-globulins (3-6 g/L)
- α2-globulins (4-9 g/L)
- β-globulins (6-11 g/L)
- γ-globulins (7-15 g/L)
- Perform transport and protective roles
α-Globulins
-
Haptoglobin (Hp)
- Component of α2-globulin fraction
- Glycoprotein that binds extracorpuscular hemoglobin
- Haptoglobin-hemoglobin complex is absorbed by macrophages, preventing loss of free hemoglobin through the kidneys.
- Promotes iron conservation and reutilization
-
Ceruloplasmin (α2–globulin)
- Blue, copper-containing (0.32%) glycoprotein in blood plasma
- Contains 3% of the body's total copper and over 90% of blood plasma copper
- Weakly catalytic in the oxidation of ascorbic acid, adrenaline, dihydrophenylalanine, and other compounds
- Exhibits ferrooxidase activity, oxidizing Fe2+ to Fe3+
- Antioxidant
- Decreased levels in Wilson's disease, a major diagnostic marker
-
α1-Antitrypsin
- Inhibits trypsin and other proteolytic enzymes
- Increased levels during inflammation, pregnancy, and other physiological states
- Increased synthesis in hepatocytes during inflammation
- Delivery of active pancreatic proteinases increases levels during acute pancreatitis
- Deficiency associated with emphysema and a type of liver disease (α1-antitrypsin deficiency liver disease)
-
α2-Macroglobulin
- Large plasma glycoprotein (720 kDa)
- Inhibits serine, thiol, carboxy, and metal proteinases
- Involved in regulation of blood clotting, immunologic processes, and inflammatory processes
- Binds cytokines (platelet-derived growth factor, transforming growth factor-β, etc.) and helps target them to tissues
β-Globulins
-
C-reactive protein
- Forms a precipitate with the somatic C polysaccharide of pneumococcus
- Not present in the blood serum of healthy individuals
- Detected in various pathologic states associated with inflammation and tissue necrosis
- An "acute phase" protein
-
Hemopexin
- Binds free heme
-
Transferrin
- Glycoprotein with a molecular mass of approximately 80 kDa
- Transports iron (2 moles of Fe3+ per mol of transferrin) in the circulation to sites where iron is required
- Plays a central role in the body's iron metabolism
- Transports iron from the gut to the bone marrow and other organs
γ-Globulins
-
Cryoglobulin
- Absent in healthy individuals, only found in pathologic states
- Soluble at 37°C but precipitates or forms a gel at 4°C
- Detected in multiple diseases including myeloma, nephrosis, cirrhosis of the liver, rheumatism, lymphosarcoma, leucosis and other diseases
- "Acute phase" proteins involved in inflammatory reactions
- Interleukin-1, released by mononuclear phagocytes, is a main inducer of their synthesis in hepatocytes
- Haptoglobin, C-reactive protein, α1-antitrypsin, acid α1-glycoprotein, and fibrinogen are all "acute phase" proteins
Non-protein Organic Compounds in Blood
-
Total nitrogen
- Includes protein nitrogen and nonprotein nitrogen
- Total nitrogen = Protein nitrogen + Residual nitrogen
- Residual nitrogen = 14.3-25 mmol/L
-
Residual nitrogen
- Includes:
- Urea nitrogen (50%)
- Amino acid nitrogen (25%)
- Creatine nitrogen (5%)
- Creatinine nitrogen
- Ammonia nitrogen
- Indican nitrogen
- Bilirubin nitrogen
- Uric acid nitrogen
- Includes:
-
Ammonia level
- 25-40 μmol/L
- Increased in liver diseases and inherited disturbances of the ornithine cycle
-
Urea level
- 3.3-8.3 mmol/L
- Increased in chronic kidney diseases, cancer of the ureteral ducts, tuberculosis of the kidney, some infectious diseases, sepsis, and other conditions
- Decreased in liver diseases (like hepatitis and cirrhosis), pregnancy, and inherited disturbances of the urea cycle
-
Creatinine
- 53-105 μmol/L
- Increased in retentional azotemia, indicating the degree of chronic renal insufficiency
-
Uric acid level
- 149-405 μmol/L
- Increased in gout
Azotemia
- Increased level of residual nitrogen in blood
-
Productive azotemia
- Excessive delivery of nitrogenous products to the blood due to accelerated degradation of tissue proteins
- Occurs in states like inflammation, wounds, extensive burns, cachexia, and other conditions
-
Retention azotemia
- Incomplete urinary discharge of nitrogen-containing products
-
Renal retention azotemia
- Reduced excretory function of the kidneys (reduced renal clearance)
- Urea is mainly responsible for the increased residual nitrogen level, making up 90% instead of 50% in normal conditions
-
Extrarenal retention azotemia
- May arise from acute circulatory insufficiency, low arterial pressure, reduced renal blood flow, and obstruction to urine outflow from the kidney
Blood Plasma Enzymes
-
Enzyme diagnostics
- Branch of enzymology with two main directions:
- Using enzymes as reagents to determine normal and pathological components in serum, urine, gastric juice, etc.
- Determining enzyme activity in biological material for diagnostic purposes
- Branch of enzymology with two main directions:
-
Serum enzymes
- Divided into three groups:
-
Cellular enzymes:
- Enter the blood from different organs
- Serum activity depends on organ enzyme content, molecular weight, intracellular localization, and elimination rate
- Divided into non-specific and organ-specific enzymes
-
Secretory enzymes:
- Synthesized by cells, enter the bloodstream, and perform specific functions in the circulatory system
- Examples: enzymes of the coagulation system, fibrinolysis, choline esterase
-
Excretory enzymes:
- Synthesized by glands of the gastrointestinal tract and enter the blood
- Examples: amylase and lipase
-
Cellular enzymes:
- Divided into three groups:
Aminotransferases (ALT and AST)
- Catalyze the process of transamination
- Present in all organs and tissues
- AST isoenzymes are localized in both the cytoplasm and mitochondria, while ALT predominates in the cytoplasm
- High concentrations of AST are found in the heart, skeletal muscles, liver, kidneys, pancreas, and erythrocytes. Damage to any of these organs can lead to significant increases in AST levels in the blood serum.
- ALT is found in highest concentrations in liver cells, but also in skeletal muscles, kidneys, and heart, although in smaller amounts
-
AST
- Significant increases seen in myocardial damage, especially myocardial infarction, where AST activity in blood serum can increase 4-5 times.
- 93-98% of patients with acute myocardial infarction have high AST activity.
- Increases in AST activity reveal hepatic pathology, including:
- Acute viral and toxic hepatitis (most significant increase)
- Liver cirrhosis (mild to moderate increase, 2-3 times)
- Obstructive jaundice
- Liver metastasis
- Can also increase in skeletal muscular pathology (like progressive muscular dystrophy), pancreatitis, and intravascular hemolysis.
- Low AST activity is usually associated with vitamin B6 deficiency, renal failure, and pregnancy.
-
ALT
- Increased ALT activity is most frequently revealed in acute liver and biliary duct diseases.
2,3-Diphosphoglycerate (2,3-DPG)
- Decreases the affinity of hemoglobin (Hb) to oxygen, helping oxygen dissociation and unloading oxygen in tissue capillaries.
- Levels of 2,3-DPG increase markedly in peripheral hypoxic tissues and hypoxic conditions.
- Red blood cells have a high concentration of 2,3-DPG (4 - 5 mM, equimolar to Hb) in contrast to trace amounts in other cells.
- During blood storage, 2,3-DPG concentration decreases, making the Hb less suitable for blood transfusions to hypoxic patients.
- RBCs membrane is impermeable to 2,3-DPG. Inosine is added to stored blood instead, as it easily penetrates RBCs and its ribose can be converted into 2,3-DPG by the HMP shunt and glycolysis pathways.
- Fetal hemoglobin binds 2,3-DPG less strongly than adult hemoglobin, allowing it to extract oxygen more readily from the mother's blood.
Erythrocyte Metabolism
-
Glycolysis
- Energy source for enzymatic reactions
- Produces ATP and NADH
- Lacks Krebs cycle and electron transport chain
- Generates 2,3-DPG, a key regulator of oxygen delivery
-
Pentose phosphate pathway
- 5-10% of glucose metabolized through this pathway
- Produces NADPH for glutathione reduction
- Deficiency of glucose-6-phosphate dehydrogenase can cause drug-induced hemolytic anemia (Favism)
-
Glutathione
- Synthesized within erythrocytes
- Required for elimination of peroxides
-
Methemoglobin (metHb)
- Formed through Hb autooxidation (1.7% normally)
- Results in the formation of O2^- (superoxide radical)
- Converts metHb back to Hb via NADH-dependent methemoglobin reductase
-
Synthesis pathways
- Erythrocytes lack the enzymes required for the synthesis of glycogen, fatty acids, proteins, and nucleic acids
- Cholesterol and other lipids can be exchanged with corresponding lipids in the plasma.
-
Nucleotide metabolism
- Erythrocytes contain enzymes involved in nucleotide metabolism.
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Description
This quiz covers the major proteins found in blood plasma, their functions, and synthesis locations. Learn about albumin, globulins, and fibrinogen, along with their roles in bodily functions such as blood clotting and transport. Test your knowledge on blood protein composition and significance.
