Human Physiology: Body Water and Blood Volume

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Questions and Answers

What is the first step in the intrinsic pathway of blood coagulation?

Activation of factor XI

Formation of the IXa-VIIIa complex

Conversion of fibrinogen to fibrin monomers

Activation of factor XII to factor XIIa (correct)

Which factor is directly activated by tissue phospholipid (TPL) in the extrinsic pathway?

Factor X

Factor IX

Factor VII (correct)

Factor XI

What role does thrombin play in the common pathway of blood coagulation?

Releases thromboplastin

Converts fibrinogen to fibrin (correct)

Activates factor VII

Activates factor X

In the intrinsic pathway, which factor complex is essential for the activation of factor X?

The IXa-VIIIa complex Signup and view all the answers

What initiates blood clotting in response to vascular injury?

Release of thromboplastin Signup and view all the answers

Which condition is characterized by a decrease in RBC mass and normal MCH and MCV values?

Normocytic normochromic anemia Signup and view all the answers

Which of the following is NOT a manifestation of aplastic anemia?

Jaundice Signup and view all the answers

What is a common cause for the extrinsic form of hemolytic anemia?

Incompatible blood transfusion Signup and view all the answers

Which type of anemia is associated with severe pain due to the occlusion of blood vessels?

Sickle cell anemia Signup and view all the answers

What management strategy is effective in treating aplastic anemia?

Bone marrow transplantation Signup and view all the answers

Which of the following conditions is characterized by premature destruction of red blood cells?

Hemolytic anemia Signup and view all the answers

Which of the following conditions leads to a decreased production of blood cells due to bone marrow failure?

Aplastic anemia Signup and view all the answers

In G6PD deficiency, which factor primarily triggers acute hemolysis?

Oxidizing agents Signup and view all the answers

What is the primary function of ADP in platelet activation?

Promoting the aggregation and fusion of platelets Signup and view all the answers

Which group of coagulation factors is activated by thrombin?

Fibrinogen group Signup and view all the answers

What role does platelet factor 3 play during platelet pro-coagulant activity?

It provides a surface for coagulation factor activation Signup and view all the answers

What triggers the intrinsic pathway of coagulation?

Exposure to subendothelial collagen Signup and view all the answers

Which substance is released from dense granules to enhance platelet activation?

Calcium Signup and view all the answers

What initiates the platelet release reaction?

High concentration of thrombin Signup and view all the answers

Which statement about the fusion of aggregated platelets is correct?

Irreversible fusion is triggered by ADP and thrombin Signup and view all the answers

What is the main mechanism by which fibrin threads stabilize a blood clot?

By entrapping red blood cells and platelets Signup and view all the answers

What is the primary role of albumin among plasma proteins?

Regulation of osmotic pressure Signup and view all the answers

Which of the following constituents accounts for the majority of plasma volume?

Water Signup and view all the answers

What could cause a decrease in the Albumin-Globulin Ratio (A/G Ratio)?

Liver cirrhosis Signup and view all the answers

What is the composition of serum after blood is allowed to clot?

Plasma minus clotting factors Signup and view all the answers

Which plasma component supports the transport of lipids in the bloodstream?

Plasma proteins Signup and view all the answers

What is the combined contribution of red blood cells (RBCs) and platelets to total blood volume?

44% Signup and view all the answers

Which substance is primarily responsible for maintaining the blood's osmotic pressure?

Albumin Signup and view all the answers

What is the normal plasma volume range in milliliters?

3000-3500 ml Signup and view all the answers

What is the average lifespan of erythrocytes?

120 days Signup and view all the answers

Which form of hemoglobin has a higher affinity for oxygen?

HbF Signup and view all the answers

What is the primary cause of hereditary methemoglobinemia?

Deficiency of NADH-met-Hb reductase Signup and view all the answers

Which statement about the function of the hemoglobin is correct?

It has a buffering function 12 times that of plasma proteins. Signup and view all the answers

What happens to the heme component of hemoglobin after erythrocytes rupture?

It is converted to iron and bilirubin. Signup and view all the answers

What is the effect of hemoglobin being present in the plasma?

It leads to renal tubule blockage. Signup and view all the answers

What are the normal hematocrit values for adult males and females, respectively?

46% and 42% Signup and view all the answers

Where does erythropoiesis primarily occur in the fetus?

Liver and spleen Signup and view all the answers

What is the primary function of folic acid in the body?

It is crucial for DNA synthesis. Signup and view all the answers

What is the relationship between vitamin B12 and cobalt?

Cobalt acts as a stimulator of erythropoietin secretion and is part of vitamin B12. Signup and view all the answers

How does a deficiency in folic acid directly affect red blood cells?

It results in macrocytic anemia due to impaired DNA synthesis. Signup and view all the answers

Which of the following best defines anemia?

A decrease in the oxygen-carrying capacity of the blood. Signup and view all the answers

What is the formula for calculating Mean Corpuscular Hemoglobin (MCH)?

MCH = Hb content / RBC count x 10 Signup and view all the answers

Which condition indicates a hypochromic status in red blood cells?

MCH less than 25 picograms. Signup and view all the answers

What are common symptoms associated with anemia?

Shortness of breath and fatigue. Signup and view all the answers

Which demographic is most affected by anemia globally?

Preschool-age children. Signup and view all the answers

Study Notes

Blood

Total body water (TBW) is 60% of body weight in adult males, 75% in infants, and less than 60% in adult females and obese individuals.
Total blood volume is about 8% of body weight.

Distribution of Body Water

Intracellular fluid (ICF) is water inside cells (2/3 TBW, 40% body weight).
Extracellular fluid (ECF) is water outside cells (1/3 TBW, 20% body weight).
- Intravascular fluid (IVF) is 5% in blood vessels (plasma).
- Interstitial fluid (ISF) is 15% outside the vessels, between cells.
Main cations in ICF include potassium (K).
Main cations in ECF include sodium (Na), calcium (Ca), and chloride (Cl).
Main anions in ECF include protein, phosphate (PO4), and bicarbonate (HCO3).

Measurement of Water Volumes

Fick's principle is used to determine compartment volumes by measuring the amount of indicator injected and its concentration in plasma.
Indicators used include heavy water (D₂O), inulin, and Evan's blue.
- TBW volume uses heavy water (D₂O).
- ECF volume uses inulin.
- Plasma volume uses Evan's blue.
- ICF volume cannot be directly determined (calculated by TBW - ECF).
- ISF volume cannot be directly determined (calculated by ECF - plasma).

Homeostasis

Homeostasis is maintaining a stable internal environment despite external or internal changes.
The internal environment is the interstitial fluid.
Most body functions work to maintain homeostasis.

Blood Functions

Transport function carries oxygen, nutrients, hormones, waste products etc throughout the body.
Defensive function protects the body from infection and disease through immune responses.
Hemostatic function involves stopping bleeding through clot formation.
Homeostatic function maintains fluid balance and pH levels.

Blood Composition

Plasma accounts for about 55% of total blood volume.
Cellular elements account for about 45%, including red blood cells (RBCs), white blood cells (WBCs), and platelets.

Plasma Constituents

Water accounts for 90% of plasma volume. The main cation is sodium (Na).
Main anions include chloride (Cl) and bicarbonate (HCO3).
Plasma proteins have a role in osmotic balance and other functions.

Differences in Plasma and Serum

Serum is plasma minus clotting factors.

Plasma Protein Ratio

Albumin-globulin ratio (A/G Ratio) is between 1.2-1.6. This ratio changes based on the specific health condition.
- Liver diseases result in a decreased ratio (decreased albumin synthesis).
- Renal diseases result in an increased ratio (increased albumin loss in urine).
- Infections result in an increased ratio (increased globulin production).

Plasma Protein Functions

Osmotic function, maintains osmotic pressure.
Buffering function, acts as buffer in blood.
Defensive function via immunoglobulins (gamma globulins).
Blood clotting involving fibrinogen and prothrombin.
Blood viscosity mediated by RBCs and plasma proteins. Viscosity is important for maintaining normal arterial blood pressure.
Capillary function by limiting their permeability.
Transport of hormones, vitamins, etc; and prevents their rapid loss in urine

Red Blood Corpuscles (RBCs)

RBC shape is circular and biconcave.
RBCs are non-nucleated.
RBC contains hemoglobin, the oxygen-carrying protein.
Hemoglobin constitutes about 34% of RBCs weight and has two main forms, HbA (adult) and HbF (fetal).
Normal Hemoglobin values vary based on gender and age.
Functions of RBCs include oxygen and carbon dioxide transport. Buffering capacity and maintaining blood viscosity.

Hemoglobin Reactions

Hemoglobin combines with oxygen, carbon dioxide, and carbon monoxide to accomplish gas transport.

Life Span of RBC

The average lifespan of a RBC is 120 days.

Role of the Spleen

Spleen filters blood (removing aged and abnormal cells).
Blood storage function

Erythropoiesis

Erythropoiesis is the formation of new red blood cells. The process occurs in bone marrow.
Factors affecting erythropoiesis include oxygen supply to tissue and erythropoietin hormone.

Hypoxia and Erythropoietin

Hypoxic conditions stimulate erythropoietin production.
Erythropoietin is produced mainly by the kidneys, and in lesser amounts by the liver.
Erythropoietin activates the processes involved in creating new RBC production, mitosis and inhibits apoptosis,

Iron Requirements and Balance

About 30 mg of iron needed daily for hemoglobin synthesis.
Iron is mostly recycled from aged RBCs (macrophages) in liver and spleen.
Dietary iron absorption occurs in the duodenum
Heme iron from animal sources is readily absorbed while non heme iron from plant sources is not as easily absorbed.
Dietary factors influence iron absorption

Iron Absorption

Absorbed iron is transported by transferrin to bone marrow/liver/muscle cells.
Iron is absorbed in duodenum.
Dietary factors that regulate iron absorption:
- High levels of dietary iron reduce the amount of iron absorbed.
- Hepcidin, a liver-produced hormone, promotes iron storage and reduces iron absorption in the intestines.

Blood Coagulation

Coagulation factors(plasma proteins) are involved in forming a blood clot.
Coagulation factors are grouped into different contact/fibrinogen/and prothrombin groups.
Active factors in coagulation form a cascading chain/cascade reaction; this involves clotting factors that activate each other in sequential activation until a stable fibrin clot forms.
Intrinsic pathway will be activated when blood is exposed to a wettable surface (in vitro), or if a subendothelial collagen becomes exposed (in vivo).
Extrinsic pathway will occur in a situation when tissues are exposed to blood.
Clotting factors are activated to form a fibrin clot at the site of injury, thereby entrapping RBCs, platelets, and plasma in the clot.
The extrinsic system reacts faster than the intrinsic system.
Platelets work to initiate vasoconstriction to slow down blood flow, which is critical for effective clot formation.
Thromboxane A2, ADP, serotonin, and other factors facilitate platelet aggregation to form the temporary hemostatic plug that stops bleeding.
Blood loss and damage to blood vessels initiate a cascade of reactions to form a clot to stop the bleeding, and to prevent blood loss.

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Description

This quiz explores the concepts of total body water distribution, blood volume, and the measurement of water volumes in the human body. Understand the differences between intracellular and extracellular fluids, and how various indicators are used in these measurements. Perfect for students of human physiology and related fields.