BLOOD PHYSIOLOGY
Annual 2022
Q1 a)Enlist different types of lymphocytes.Briefly discuss function
of each type.
Types of lymphocyte
1. T lymphocytes
2. B lymphocytes
3. Natural killer lymphocytes.
Function:
All the lymphocytes have role in immunity
T lymphocyte:
T lymphocytes are responsible for cell-mediated immunity.Activated T lymphocytes
destroy the foreign agent.
● Helper T cells: produce cytokines that direct the immune response.
● Cytotoxic T cells: (killer cells) release cytotoxic substances directly into the
pathogen infected cell.
● Regulatory T cells:suppress both cytotoxic and T helper cells.They have an
important role in immune tolerance and prevent cytotoxic cells from causing
excessive immune reactions.
B lymphocytes:
B lymphocytes are responsible for humoral immunity.They respond to pathogens by
producing antibodies which then neutralize foreign objects like bacteria and may
cause lysis
Natural killer lymphocytes:
Natural killer cells have role in innate immunity.They can recognize and destroy
foreign cells,tumor cells,and even some infected cells
(Ref: Guyton and Hall 14 ed. Chapter 35)
b)Define active and passive immunity.
Active immunity:
Active immunity develops when the person’s own body produces antibodies or
activated T cells in response to invasion of the body by a foreign antigen.
Passive immunity:
Passive immunity is achieved by transfer of antibodies or activated T cells from the
blood of someone else or from some other animal that has been actively immunized
against the antigen.
(Ref: Guyton and Hall 14ed. Chapter 35 Pg#469)
Annual 2021
Q2 a)Define anemia.Write down the effects of anemia on the human
body.
Anemia:
1
,Anemia is the deficiency of hemoglobin in the blood,which can be caused by too few
RBCs or too little hemoglobin in the cell.
Effects on human body:
1. Causes hypoxia and skin becomes pale and yellow
2. Causes dizziness
3. Viscosity of the blood decreases
4. Resistance to blood flow in peripheral blood vessels decreases which in turn
increases the blood flow in tissues.
5. Venous return to the heart and cardiac output increases.
6. If a person with anemia begins to exercise,extreme tissue hypoxia and acute
cardiac failure may ensue.
(Ref: Guyton and Hall 14 ed. Chapter 33 Pg#446)
b)A 30 year old man stays for 45 days in a village at a height of
7000 feet.What change is likely to occur in his RBCs count and
how?
His RBCs count will increase.
Reason:
At high altitude,the quantity of oxygen in air decreases and due to which tissue
oxygenation decreases and hypoxia develops.Hypoxia increases formation of
erythropoietin in the body which stimulates RBC production.
(Ref: Guyton and Hall 14 ed. Chapter 33 Pg#442)
Supplementary 2021
Q3) Mr. Ali goes to a hilly area at an altitude of 10000 feet. What will
be the effect on erythropoiesis? Explain the mechanism of this
effect.
Erythropoiesis i-e RBC production will increase
Mechanism:
At high altitude,the quantity of oxygen in air decreases and due to which tissue
oxygenation decreases and hypoxia develops.Hypoxia increases formation of
erythropoietin in the body which stimulates RBC production.
2
, (Ref: Guyton and Hall 14 ed. Chapter 33 Pg#442)
Annual 2020
Q4 a) Describe the mechanism of formation of platelet plug.
● Platelet adhesion and activation:
1. When platelets come in contact with damaged vascular surface especially
with their collagen fibers,they swell and assume irregular forms with
irradiating pseudopods.
2. Their contractile proteins contract and cause release of granules.
3. They become sticky so that they adhere to collagen in tissues and to protein
von Willebrand factor(vWF)
● Aggregation:
1. The platelets then secrete more ADP, Thromboxane A2 and platelet-activating
factor(PAF) which in turn,activate nearby platelets and cause them to adhere
to the original activated platelets.
2. Hence more and more platelets get activated and form a platelet plug.
3
Annual 2022
Q1 a)Enlist different types of lymphocytes.Briefly discuss function
of each type.
Types of lymphocyte
1. T lymphocytes
2. B lymphocytes
3. Natural killer lymphocytes.
Function:
All the lymphocytes have role in immunity
T lymphocyte:
T lymphocytes are responsible for cell-mediated immunity.Activated T lymphocytes
destroy the foreign agent.
● Helper T cells: produce cytokines that direct the immune response.
● Cytotoxic T cells: (killer cells) release cytotoxic substances directly into the
pathogen infected cell.
● Regulatory T cells:suppress both cytotoxic and T helper cells.They have an
important role in immune tolerance and prevent cytotoxic cells from causing
excessive immune reactions.
B lymphocytes:
B lymphocytes are responsible for humoral immunity.They respond to pathogens by
producing antibodies which then neutralize foreign objects like bacteria and may
cause lysis
Natural killer lymphocytes:
Natural killer cells have role in innate immunity.They can recognize and destroy
foreign cells,tumor cells,and even some infected cells
(Ref: Guyton and Hall 14 ed. Chapter 35)
b)Define active and passive immunity.
Active immunity:
Active immunity develops when the person’s own body produces antibodies or
activated T cells in response to invasion of the body by a foreign antigen.
Passive immunity:
Passive immunity is achieved by transfer of antibodies or activated T cells from the
blood of someone else or from some other animal that has been actively immunized
against the antigen.
(Ref: Guyton and Hall 14ed. Chapter 35 Pg#469)
Annual 2021
Q2 a)Define anemia.Write down the effects of anemia on the human
body.
Anemia:
1
,Anemia is the deficiency of hemoglobin in the blood,which can be caused by too few
RBCs or too little hemoglobin in the cell.
Effects on human body:
1. Causes hypoxia and skin becomes pale and yellow
2. Causes dizziness
3. Viscosity of the blood decreases
4. Resistance to blood flow in peripheral blood vessels decreases which in turn
increases the blood flow in tissues.
5. Venous return to the heart and cardiac output increases.
6. If a person with anemia begins to exercise,extreme tissue hypoxia and acute
cardiac failure may ensue.
(Ref: Guyton and Hall 14 ed. Chapter 33 Pg#446)
b)A 30 year old man stays for 45 days in a village at a height of
7000 feet.What change is likely to occur in his RBCs count and
how?
His RBCs count will increase.
Reason:
At high altitude,the quantity of oxygen in air decreases and due to which tissue
oxygenation decreases and hypoxia develops.Hypoxia increases formation of
erythropoietin in the body which stimulates RBC production.
(Ref: Guyton and Hall 14 ed. Chapter 33 Pg#442)
Supplementary 2021
Q3) Mr. Ali goes to a hilly area at an altitude of 10000 feet. What will
be the effect on erythropoiesis? Explain the mechanism of this
effect.
Erythropoiesis i-e RBC production will increase
Mechanism:
At high altitude,the quantity of oxygen in air decreases and due to which tissue
oxygenation decreases and hypoxia develops.Hypoxia increases formation of
erythropoietin in the body which stimulates RBC production.
2
, (Ref: Guyton and Hall 14 ed. Chapter 33 Pg#442)
Annual 2020
Q4 a) Describe the mechanism of formation of platelet plug.
● Platelet adhesion and activation:
1. When platelets come in contact with damaged vascular surface especially
with their collagen fibers,they swell and assume irregular forms with
irradiating pseudopods.
2. Their contractile proteins contract and cause release of granules.
3. They become sticky so that they adhere to collagen in tissues and to protein
von Willebrand factor(vWF)
● Aggregation:
1. The platelets then secrete more ADP, Thromboxane A2 and platelet-activating
factor(PAF) which in turn,activate nearby platelets and cause them to adhere
to the original activated platelets.
2. Hence more and more platelets get activated and form a platelet plug.
3
