Seventh lecture
Hematopoiesis
Factors affecting erythropoiesis:A)-Oxygen supply of tissues:
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Decreased oxygen supply (hypoxia) to tissues stimulates
secretion of erythropoietin (EP) hormone.
Hypoxia stimulates kidney to release renal erythropoietic
factor (REF).
Hypoxia stimulates liver to produce a special type of
globulin.
Both REF & globulin unite in plasma and form EP.
EP then stimulates bone marrow to produce RBCs.
Erythropoietin accelerates nearly all stages of RBCs
formation,
i.e. it stimulates proliferation & differentiation of
progenitor stem cells to produce mature RBCs.
Hematopoiesis
Factors affecting erythropoiesis:B) Dietary factors:
i-Proteins: Proteins of high biological value are needed in
the formation of RBCs.
ii-Metal ions:
 Iron Fe: is essential for RBCs formation because it
enters in the formation of the hem part.
 Copper Cu: It is carried & transported by plasma protein
ceruloplasmin. It catalyses the oxidation of Fe++ to
Fe+++, a reaction that must occur before transferrin
can combine and transport iron.
 Cobalt Co: It stimulates EP release from kidney. So,
excess Co may produce polycythaemia.
Hematopoiesis
Factors affecting erythropoiesis:B) Dietary factors:
iii-Vitamins:
 Both vitamins B12 & folic acid are essential for final
maturation of RBCs because they are needed in DNA
synthesis.
 Deficiency of either B12 or folic acid results in failure
of nuclear maturation and causing maturation failure
anemia.
 Vitamin C is a strong reducing agent which is
important in reducing the ferric form of iron to
ferrous to facilitate its absorption and transport.
Hematopoiesis
Factors affecting erythropoiesis:C) Hormonal factors:
i-Androgens: increase erythropoiesis by stimulating
the production of erythropoietin from kidney.
ii-Thyroid hormones:
 Stimulate the metabolism of all body cells
including the bone marrow cells, thus, increasing
erythropoiesis.
 Hypothyroidism is associated with anemia while
hyperthyroidism is associated with
polycythaemia.
Hematopoiesis
Factors affecting erythropoiesis:C) Hormonal factors:
iii-Glucocorticoids:
 Stimulate the general metabolism and also stimulate the
bone marrow to produce more RBCs.
 In Addison’s disease (hypofunction of adrenal cortex)
anemia present, while in Cushing’s disease (hyperfunction of
adrenal cortex) polycythaemia present.
Hematopoiesis
Factors affecting erythropoiesis:C) Hormonal factors:
iv-Pituitary gland: Affects erythropoiesis both
directly and indirectly through the action of
several hormones.
v- Haematopoietic growth factors: Are secreted by
lymphocytes, monocytes & macrophages to
regulate the proliferation and differentiation of
proginator stem cells to produce blood cells.
Hematopoiesis
Factors affecting erythropoiesis:D)-State of liver & bone marrow:
i-Liver: Healthy liver is essential for normal
erythropoiesis because the liver is the
main site for storage of vitamin B12 , folic
acid, iron & copper. In chronic liver
disease anemia occurs.
ii-Bone marrow: When bone marrow is
destroyed by ionizing irradiation or drugs,
aplastic anemia occurs.
Anemia
Anemia means a decrease in
hemoglobin content,
 or RBCs count,
 or both of them below the normal
range.
 Anemia leads to a decrease in blood
ability to transport oxygen to tissue
cells.
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Anemia
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Types & causes of anemia:
I-Blood loss anemia:
A-Acute blood loss anemia:
 Due to severe hemorrhage.
 Plasma volume is replaced rapidly by the fluids
present in tissue spaces.
 This leads to marked dilution of the blood.
 RBCs are replaced within 2-3 weeks.
 Sufficient iron gives normocytic cells but
insufficient iron will produce microcytic RBCs.
Anemia
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Types & causes of anemia:
I-Blood loss anemia:
B-Chronic blood loss anemia:
 Due to repeated loss of small amounts of blood
over a long period e.g.:
-Gastrointestinal bleeding (peptic ulcer)
-Excessive menstruation.
-Hemorrhagic diseases.
 Due to depletion in iron stores the newly formed
RBCS are microcytic.
Anemia
Types & causes of anemia:
II-Aplastic anemia:
It results from destructione of bone marrow.
 It may result from:
1-Excessive exposure to x-rays or gamma rays.
2-Chemical toxins e.g. cancer therapy & prolonged
exposure to insecticides or benzene.
3-Invasion of bone marrow by cancer cells.
4-Following infection by hepatitis.
 Damaged bone marrow don’t produce any RBCs, so in
aplastic anemia RBCS are normocytic.
 It is associated with decrease in WBCs & platelets.
Anemia
Types & causes of anemia:
III-Hemolytic anemia:
It results from increased rate of destruction of RBCs inside
the cardiovascular system.
 Causes of hemolytic anemia:
A-Hereditary:
1-Membrane abnormalities.
2-Enzyme deficiency e.g. G-6-P Dehydrogenase.
3-Hemoglobin abnormalities.
B-Acquired:
1-Incompatible blood transfusion.
2-Parasitic infection e.g. malaria.
3-Toxic agents e.g. snake venom & insect poisons.
4-Thermal e.g. several burns.
Anemia
Types & causes of anemia:
IV-Dyshemopoietic anemia: Which may be due to:
1-Iron deficiency anemia.
2-Maturation failure (megaloblastic) anemia:a-Vitamin B12 deficiency.
b-Folic acid deficiency.
3-Anemia of endocrine disorders.
4-Nutritional anemia.
5-Anemia of renal failure.
Polycythemia
It is an abnormal increase in the number
of circulation RBCs.
A-Primary polycythemia:
It is caused by tumor of bone marrow.
B-Secondary polycythemia:
It occurs as a result of prolonged tissue
hypoxia.
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II-Respiration
Respiratory system
Respiration serves the
following functions
Supplies
tissues with O2
Eliminate CO2 from tissues.
Regulates the pH of the blood.
Maintain normal body temperature
Respiration
I- External Respiration:
Exchange of respiratory gases
between air in lungs and blood in
pulmonary capillaries.
Respiration
II-Internal Respiration:
Exchange of respiratory gases between
the tissue cells and the internal
environment which is the fluids bathing
the cells.
 Oxidation of food stuffs within cells to
yield energy (in presence of oxygen).
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The respiratory system is divided
into two zones:
I- The Conducting Zone
II -Respiratory Zone
I- The Conducting Zone:
Includes : nose, nasopharynx, larynx, trachea and 2 main
bronchi one for each lung, and smaller bronchioles .
Function of the conducting part:
1. Conducting air into the respiratory zone.
2. Air conditioning
3. Humidification
4. Filtration
5. Protective reflexes
a- Sneezing reflex
b- Cough reflex
6. Non respiratory function.
II -Respiratory Zone:
Consists of respiratory units each of which
composed of respiratory bronchioles which
subdivided into alveolar ducts which end in
clusters of small thin walled air sacs called
alveoli
Functions of Respiratory
Passages
1-The nose
a) The vestibule.
b) The respiratory area.
c) The olfactory area.
The olfactory area is lined by olfactory
mucosa which consists of:
(A) Olfactory epithelium consists of three
types of cells:
 1- Sustentecular (supporting) columnar
cells
 2- Olfactory (sensory) cells
 3- Basal cells
(B) Corium
2- Pharynx
The pharynx is the part of the digestive
system of many animals lies immediately
behind the mouth and in front of the
esophagus
The human pharynx is divided into:
• Nasopharynx.
• Oropharynx.
• Laryngopharynx.
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3- The Larynx
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The larynx has the following functions:
1- Control of the airflow during breathing.
2- Protection of the airway.
3- Production of sound for speech.