blood Physiology Flashcards
Total body water (TBW)
60% of the body weight, in adult male.
In infants → 75%
n adult female & obese → less than 60% (high fat content).
Distribution of water in the body Compartments
intracellular fluid (lCF) : 40%
extracellular fluid : 60 %
Distribution of water in the Extracellular fluid (ECF)
Intravascular fluid (IVF) :5% in vessels → plasma
Interstitial fluid (ISF): 15% outside the vessels
→ between cells
what is the main cation and anion in the Intracellular fluid (lCF)
Main cations: Potassium (K)
Main anions: Protein; Phosphate (PO4)
what is the main cation and anion in the Extracellular fluid (ECF)
Main cations : Sodium (Na); Calcium (Ca)
Main anions: Chloride (Cl); Bicarbonate (HCO3)
Indicator for TBW (Total Body Water)
Indicator Used: Heavy water (D₂O)
Distribution: In all compartments (Intracellular + Extracellular)
Indicator for ECF (Extracellular Fluid)
Indicator Used: Inulin
Distribution: In extracellular water only
Indicator for Plasma Volume
Indicator Used: Evan’s blue dye
Distribution: Plasma only
ICF (Intracellular Fluid) Volume Calculation
ICF = TBW - ECF
Direct Measurement: Not possible
ISF (Interstitial Fluid) Volume Calculation
ISF = ECF - Plasma volume
Direct Measurement: Not possible
Importance of homeostasis:
Homeostasis is Essential for life.
Failure of homeostasis → diseases and death
Cells are capable of living within a narrow change in O2, CO2, glucose,
temperature, pH, arterial blood pressure ……..
Homeostasis is maintained by ??
Components of control system:
1- Stimulus 2- Receptor
3- Control center 4- Effector organ(s).
5- Feedback mechanism
What is the total blood volume in a 70 Kg man?
Total Blood Volume: 5600 ml
What are the main functions of blood?
Transport Function
Defensive Function
Hemostatic Function
Homeostatic Function
What is plasma?
Plasma is a yellow, clear fluid.
What is the normal plasma volume?
3000 - 3500 ml ( 55% of total blood volume)
what is The composition of the Blood???
a. Plasma: 55% of total blood volume.
b. Cellular elements: 45% of total blood
[RBC’s, WBC’s & platelets].
What is the difference between plasma and serum?
Serum = Plasma minus clotting elements.
When blood is left in a glass tube, a clot forms, and the remaining fluid is serum.
What are the constituents of plasma?
Water: 90% of plasma volume.
Inorganic substances:
Chief cation: Sodium (Na⁺)
Chief anions: Chloride (Cl⁻) and Bicarbonate (HCO₃⁻)
Organic substances:
Plasma proteins
Lipids (carried as lipoproteins)
Glucose, amino acids, vitamins, enzymes, uric acid, urea
Gases: Soluble O₂ and CO₂
What are the chief cation and anions in plasma?
Chief Cation: Sodium (Na⁺)
Chief Anions: Chloride (Cl⁻) and Bicarbonate (HCO₃⁻)
What are the plasma proteins and their concentration?
Plasma Proteins: 7.2 - 7.4 g/dl
Types:
Albumin
Globulins (α₁, α₂, β₁, β₂, ɤ)
Fibrinogen
Other coagulation factors
What are plasma lipids carried as?
Plasma lipids are carried in blood as lipoproteins.
Where are most plasma proteins synthesized?
Liver
is the main site for:
Albumin
Fibrinogen
Prothrombin
50% of globulins
Where are gamma globulins formed?
Gamma globulins are formed in the plasma cells of lymphoid tissue.
What is the Albumin-Globulin Ratio (A/G Ratio)?
It is the ratio between albumin and globulin concentration in plasma.
Normal Value: 1.2 – 1.6
When does the A/G ratio decrease?
1)Liver diseases: ↓ Albumin synthesis (e.g., liver cirrhosis, hepatitis)
2)Renal diseases: ↑ Albumin loss in urine (small size)
3)Infections: ↑ Immunoglobulin formation
What is the osmotic pressure of plasma?
Total osmotic pressure = 5000 mmHg (290 mmol/L)
Most pressure is due to crystalloids (Na⁺, Cl⁻, HCO₃⁻).
What is the contribution of plasma proteins to osmotic pressure?
Plasma proteins (mainly albumin) contribute 25-28 mmHg.
What is the main plasma protein responsible for osmotic pressure?
Albumin due to its greatest concentration.
List the main functions of plasma proteins.
Osmotic Function: Maintains osmotic balance and fluid retention.
Transport Function: Binds and carries substances (e.g., hormones, drugs).
Defensive Function: Involves immunoglobulins (antibodies).
Hemostatic Function: Fibrinogen and clotting factors help in blood clotting.
What is the buffer function of plasma proteins?
Plasma proteins are responsible for 15% of blood buffering power.
At normal plasma pH (7.4), they are negatively charged (alkaline).
What is the defensive function of plasma proteins?
Gamma globulins → antibodies → humoral immunity
Which plasma proteins are involved in blood clotting?
Fibrinogen and prothrombin are essential for blood coagulation.
What causes blood viscosity?
RBCs and plasma proteins contribute to blood viscosity.
#Fibrinogen contributes most due to its elongated shape.#
How does blood viscosity affect arterial blood pressure?
Viscosity helps maintain normal arterial blood pressure.
How do plasma proteins limit capillary permeability?
Plasma proteins close pores in capillary walls, limiting permeability.
How do plasma proteins help in transport and conservation of important elements?
Albumin, α and β globulins act as carriers for hormones, vitamins, etc.
Binding to plasma proteins:
Prevents rapid loss in urine.
Provides a reservoir for later use.
Which plasma protein contributes most to blood viscosity? Why?
Fibrinogen due to its elongated shape.
The main functions of Plasma Proteins?
- Osmotic Function:
- Buffer function:
- Defensive function
- Blood clotting:
- Blood viscosity:
- Capillary function:
- Transport and conservation of
important elements: - Use of plasma proteins as a source of amino acids:
Why are RBCs called corpuscles and not true cells?
RBCs lack nuclei; hence, they are not true cells.
What is the normal RBC count?
Males: 5.4 million/mm³
Females: 4.8 million/mm³
When does RBC count increase?
Newly born infants
People living at high altitudes
Athletes
When does RBC count decrease?
Growing children
Old age
What are the shape and size characteristics of RBCs?
Shape: Circular, biconcave, non-nucleated discs
Size: 7.2 microns diameter
Lack mitochondria and ribosomes
What are the advantages of the biconcave shape of RBCs?
1)Larger surface area for gas exchange.
2)Enhanced flexibility to squeeze through capillaries.
3)Minimal tension on the membrane when RBC volume increases.
What is the hemoglobin content of RBCs?
Hemoglobin makes up 34% of RBC weight.
What are the types of hemoglobin?
Adult Hemoglobin (HbA):
2 alpha and 2 beta polypeptide chains.
#Fetal Hemoglobin (HbF):
2 alpha and 2 gamma (ɣ) chains.
HbF has a higher O₂ affinity → extracts O₂ from maternal blood.
What is the hemoglobin content in different groups?
1)Adult Males: 15-16 g/dL
2)Adult Females: 13-14 g/dL
3)Newborns: 19 g/dL (due to intrauterine O₂ hypoxia).
What is Hematocrit (PCV)?
Hematocrit = Percentage ratio of RBC volume to total blood volume.
Normal values:
#Males: 46%
#Females: 42%
What is oxyhemoglobin?
Hemoglobin (Hb) unites loosely with oxygen (O₂) to form oxyhemoglobin.
#O₂ attaches to Fe²⁺ (ferrous) → oxygenation not oxidation.
What is carbaminohemoglobin?
Hemoglobin combines with carbon dioxide (CO₂) to form carbaminohemoglobin.
What is carboxyhemoglobin?
Hemoglobin reacts with carbon monoxide (CO) to form carboxyhemoglobin.
What is methemoglobin? Why is it harmful?
Strong oxidizing agents convert Fe²⁺ in Hb to Fe³⁺ (ferric) → forms methemoglobin.
Methemoglobin can’t carry O₂
How is methemoglobin normally reduced?
by NADH-met-Hb reductase.
What are the functions of hemoglobin in RBCs?
1)O₂ and CO₂ transport
2)Buffering function: 6 times greater than plasma proteins
What is the function of the RBC membrane?
The RBC membrane keeps hemoglobin inside the cell.
What are the hazards of free hemoglobin in plasma?
Blocks renal tubules.
Increases blood viscosity → increases heart workload.
Increases osmotic pressure → increases heart workload.
What is the life span of RBCs? What happens after it ends?
Life span: ~120 days.
RBCs become fragile and rupture in the spleen.
Released hemoglobin is picked up by macrophages → broken into globin and heme.
Where do RBCs rupture at the end of their lifespan?
RBCs rupture in the spleen (due to fragility).
What happens to hemoglobin when RBCs rupture?
Released hemoglobin is picked up by macrophages and broken into:
Globin
Heme
What happens to the heme component of hemoglobin?
Heme is broken into:
Iron → reused in the formation of new RBCs.
Protoporphyrin → converted into bilirubin.
What happens to bilirubin after it is formed?
Bilirubin is secreted by the liver in the bile.
What is the role of iron released from heme?
Iron is reused for the formation of new RBCs.
What is the fate of protoporphyrin from the heme breakdown?
Protoporphyrin is converted to bilirubin → secreted in bile by the liver.
What percentage of platelets does the spleen store?
The spleen stores about 30% of the body’s platelets.
What happens after splenectomy?
Increased RBC count
Increased platelet count
Where does erythropoiesis occur during fetal life?
In the liver and spleen.
Where does erythropoiesis occur in children?
In the active red marrow of all bones.
What happens to erythropoiesis in long bones by age 20?
The marrow in long bones becomes inactive, except in the upper humerus and femur.
