Human Blood Composition and Functions

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Questions and Answers

What is the average lifespan of red blood corpuscles (R.B.Cs)?

90 days

120 days (correct)

150 days

60 days

What is the concentration of hemoglobin in red blood corpuscles?

50%

34% (correct)

40%

30%

What is the primary ion found inside red blood corpuscles?

Chloride (Cl-)

Calcium (Ca+2)

Potassium (K+) (correct)

Sodium (Na+)

How many red blood corpuscles are typically found in one cubic millimeter for adult males?

5-6 million Signup and view all the answers

What percentage of blood buffering action is attributed to hemoglobin?

85% Signup and view all the answers

Which enzyme is contained within red blood corpuscles that is important for CO2 carriage?

Carbonic anhydrase Signup and view all the answers

What is the function of the specific agglutinogens found in the membrane of R.B.Cs?

Determine blood group Signup and view all the answers

Where are red blood corpuscles formed in the fetus?

Liver and spleen Signup and view all the answers

What is the main hormone released due to hypoxia that stimulates erythropoiesis?

Erythropoietin Signup and view all the answers

At what age does the production of red blood cells transition primarily to membranous bones?

At 20 years Signup and view all the answers

Which form of iron is better absorbed in the diet?

Ferrous iron (Fe2+) Signup and view all the answers

Which vitamin is responsible for the maturation of RBC nuclei and cell division?

Vitamin B12 Signup and view all the answers

Excessive consumption of which compounds may inhibit iron absorption?

Oxalates and phytic acids Signup and view all the answers

What is the primary function of albumin in blood plasma?

Colloidal osmotic pressure Signup and view all the answers

What protects vitamin B12 from digestion and facilitates its absorption?

Intrinsic factor Signup and view all the answers

Which of the following is NOT a function of blood?

Production of hormones Signup and view all the answers

What is the lifespan of a red blood cell before it is typically engulfed and hemolysed?

120 days Signup and view all the answers

Which part of the body is primarily responsible for the destruction of old red blood cells?

Spleen Signup and view all the answers

What percentage of blood is composed of blood plasma?

55% Signup and view all the answers

Which type of plasma protein is primarily responsible for blood clotting?

Fibrinogen Signup and view all the answers

What does a decreased A/G ratio indicate in a patient?

Kidney disease Signup and view all the answers

What is the approximate volume of blood in an average adult human (in liters)?

5.6 L Signup and view all the answers

Which ion is NOT typically found in blood plasma?

Magnesium (Mg++) Signup and view all the answers

What is the primary purpose of the defensive function of globulins?

Immune response Signup and view all the answers

What is the primary storage location of Vitamin B12 in the body?

Liver Signup and view all the answers

Which nutrient is specifically known to stimulate tissue growth and metabolism in the body?

Vitamin C Signup and view all the answers

Which hormone is primarily responsible for stimulating erythropoiesis?

Erythropoietin Signup and view all the answers

Where in the body is the majority of erythropoietin produced?

Kidney Signup and view all the answers

What type of anemia is primarily caused by excessive destruction of red blood cells?

Normochromic normocytic anemia Signup and view all the answers

What is a common cause of microcytic hypochromic anemia?

Iron deficiency Signup and view all the answers

What role does intrinsic factor play in the body?

Facilitates vitamin B12 absorption Signup and view all the answers

Which of the following is a consequence of renal failure related to erythropoiesis?

Severe anemia Signup and view all the answers

Study Notes

Blood

Blood is a vital fluid tissue circulating inside blood vessels
It constitutes 8% of the body weight, approximately 5.6 liters
Functions:
- Transport: O2, CO2, nutrients, waste, hormones
- Defense: White blood cells and antibodies
- Hemostasis: Stoppage of bleeding
- Homeostasis: maintaining internal environment (extracellular fluid) stability for cell function (pH, osmotic pressure, volume, gases, minerals, temperature, nutrients)

Blood Composition

Consists of blood tissue (45%) and blood plasma (55%)

Blood Tissue

Consists of erythrocytes, leukocytes, and platelets

Blood Plasma

Clear yellow fluid
Composition:
- 91% Water
- 7% Proteins:
  - Albumin: responsible for colloidal osmotic pressure due to high concentration, also transports substances
  - Globulin: defensive function (gamma globulins), transport of substances
  - Fibrinogen and prothrombin: involved in blood clotting
- 2% Other substances:
  - Ions: Sodium, calcium, chloride, etc.
  - Nutrients
  - Waste products
  - Gases
  - Regulatory Substances: hormones & vitamins

Plasma Proteins

Albumin (4 gm/100 ml plasma): highest concentration responsible for colloidal osmotic pressure, transports substances, formed in the liver
Globulins (2.5 gm/100 ml plasma): defensive function (gamma globulins), transport of substances, formed in the liver and plasma cells
Fibrinogen (0.4 gm/100 ml plasma): blood clotting, highest molecular weight, formed in the liver
Prothrombin (10 mg/100 ml plasma): blood clotting, formed in the liver

Albumin/Globulin (A/G) Ratio

Ratio of albumin and globulin in the blood: 1.2 – 1.7 (Albumin/Globulin)
Decreases in:
- Liver disease: decreased albumin due to decreased formation
- Kidney disease: loss of albumin in urine
- Infections: increased globulin concentration

Red Blood Cells (Erythrocytes)

Non-nucleated, circular biconcave discs containing hemoglobin
Average lifespan: 120 days
Hemoglobin concentration: 34% of RBCs
Key ions: Potassium
Contains enzymes like carbonic anhydrase and glucose-6-phosphate dehydrogenase (G-6-PD)

Hemoglobin Content (Normal)

Adult male: 14-17 gm/100 ml blood (average 15 gm/100ml)
Adult female: 12-15.5 gm/100 ml blood (average 13.5 gm/100ml)
Newborn: 20 gm/100 ml blood

Red Blood Cell Count

Adult male: 5-6 million per cubic mm
Adult female: 4-5 million per cubic mm
Newborn: 7 million per cubic mm

Functions of Red Blood Cells

Hemoglobin carries O2 to tissues and CO2 from tissues
Hemoglobin buffers (85% of blood buffering capacity)
Carbonic anhydrase enzyme in RBCs aids in CO2 carriage
Biconcave shape increases surface area for efficient gas exchange
The RBC membrane acts like a barrier protecting the hemoglobin from:
- Heart failure: free hemoglobin increases blood viscosity and volume, putting strain on the heart
- Renal failure: free hemoglobin can obstruct renal tubules
RBC membrane has specific agglutinogens which determine blood group
Flexible membrane allows RBCs to compress while passing through narrow capillaries, then resume their normal shape.

Red Blood Cell Formation (Erythropoiesis)

Sites of Formation:
- Fetus: Liver and spleen
- Last 3 months of fetal life and after birth: bone marrow of all bones
- Adolescence: bone marrow of upper humerus, femur, and membranous bones
- After 20 years: bone marrow of membranous bones (skull, vertebra, sternum, ribs)
Erythropoiesis balance: rate of formation must equal rate of destruction to maintain normal RBC count
After 120 days, RBCs are engulfed and destroyed by reticulo-endothelial cells (mainly spleen) due to loss of flexibility

Factors Affecting Erythropoiesis:

Oxygen Supply to Tissues:
- Hypoxia: a lack of oxygen
- Causes: hemorrhage, high altitude, heart failure
- Hypoxia → stimulates erythropoietin hormone release from the kidney → stimulates bone marrow → increased production of RBCs
Diet:
- Erythropoiesis requires:
  - Protein: high biological value, essential amino acids for globin formation
  - Iron:
    - Average daily intake: 20 mg
    - Ferric iron (Fe 3+) is poorly absorbed, ferrous iron (Fe 2+) is better absorbed
    - Conversion: Ferric to ferrous in the stomach by HCl and Vitamin C
    - Absorption: Intestinal epithelial cells contain apoferrtin protein, which combines with ferrous iron to form ferritin (form in which iron is absorbed)
    - Transportation: Transferrin protein carries iron to bone marrow or liver
    - Excessive oxalates, phytic acids, and phosphates in the diet can precipitate iron, decreasing absorption
  - Vitamins:
    - Vitamin B12: extrinsic factor, essential for RBC nuclear maturation and cell division, myelination of nerves, and digestive system mucosa integrity. Combines with intrinsic factor (released by stomach mucosa) to form an intrinsic factor-vit B12 complex. Protects vitamin B12 from digestion and aids absorption in the ileum. Stored in the liver
    - Folic acid: crucial for RBC nuclear maturation and cell division
    - Vitamin C: stimulates tissue growth and metabolism including bone marrow
  - Trace Elements: copper and cobalt (cofactors for hemoglobin formation)
Hormones:
- Specific: Erythropoietin hormone
- Non-specific: thyroid hormones (increase metabolism), male sex hormones (androgen) increase erythropoietin hormone
Healthy Organs:
- Bone Marrow: site of formation, requires healthy function
- Liver:
  - forms globin
  - secretes 15% of EPO
  - stores iron and vitamin B12
- Kidney: releases 85% of EPO in response to hypoxia, anemia, and androgen
- Stomach:
  - HCl converts ferric iron to ferrous
  - Intrinsic factor for B12 absorption
- Small Intestine: site of iron and B12 absorption

Anemia:

Decreases in RBC number or hemoglobin content (or both)

Types and Causes of Anemia:

Normocytic Normochromic Anemia:
- Hemolytic Anemia: excessive RBC hemolysis (destruction)
  - Causes: incompatible blood transfusion, snake venoms, drug sensitivity, some types of malaria, antibodies against RBCs, increased RBC fragility (in spherocytosis, sickle cell anemia, and thalassemia)
- Aplastic Anemia: bone marrow depression
  - Causes: radiation exposure, chemotherapy, drugs (like chloramphenicol), bone marrow destruction by malignant tumors
- Hemorrhagic Anemia: acute blood loss (hemorrhage)
Microcytic Hypochromic Anemia:
- Iron deficiency anemia:
  - dietary deficiency (most common cause)
  - failure of iron absorption: absence of acid-producing part of the stomach, etc.

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Description

This quiz explores the essential components and vital functions of human blood. Participants will learn about blood tissue, plasma composition, and the physiological roles blood plays in transport, defense, and homeostasis. Test your knowledge on the intricacies of this critical bodily fluid.