Seventh lecture

Seventh Seventh lecturelecture

HematopoieHematopoiesissis Factors affecting erythropoiesis:-Factors affecting erythropoiesis:-

A)-Oxygen supply of tissues:A)-Oxygen supply of tissues: 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.

HematopoiesisHematopoiesisFactors affecting erythropoiesis:-Factors affecting erythropoiesis:-

B) Dietary factors:B) Dietary factors:

i-Proteins:i-Proteins: Proteins of high biological value are Proteins of high biological value are needed in the formation of RBCs.needed in the formation of RBCs.

ii-Metal ions:ii-Metal ions: Iron FeIron Fe: : is essential for RBCs formation because is essential for RBCs formation because

it enters in the formation of the hem part.it enters in the formation of the hem part. Copper CuCopper Cu: It is carried & transported by plasma : It is carried & transported by plasma

protein ceruloplasmin. It catalyses the oxidation protein ceruloplasmin. It catalyses the oxidation of Fe++ to Fe+++, a reaction that must occur of Fe++ to Fe+++, a reaction that must occur before transferrin can combine and transport before transferrin can combine and transport iron.iron.

Cobalt CoCobalt Co: It stimulates EP release from kidney. : It stimulates EP release from kidney. So, excess Co may produce polycythaemia. So, excess Co may produce polycythaemia.

Factors affecting erythropoiesis:-Factors affecting erythropoiesis:-

B) Dietary factors:B) Dietary factors:

iii-Vitamins:iii-Vitamins: Both vitamins BBoth vitamins B1212 & folic acid are essential for & folic acid are essential for

final maturation of RBCs because they are final maturation of RBCs because they are needed in DNA synthesis.needed in DNA synthesis.

Deficiency of either BDeficiency of either B1212 or folic acid results in or folic acid results in

failure of nuclear maturation and causing failure of nuclear maturation and causing maturation failure anemia.maturation failure anemia.

Vitamin C is a strong reducing agent which is Vitamin C is a strong reducing agent which is important in reducing the ferric form of iron to important in reducing the ferric form of iron to ferrous to facilitate its absorption and ferrous to facilitate its absorption and transport.transport.

HematopoiesHematopoiesisis


C) Hormonal factors:C) Hormonal factors:

i-Androgens:i-Androgens: increase erythropoiesis by increase erythropoiesis by stimulating the production of erythropoietin stimulating the production of erythropoietin from kidney.from kidney.

ii-Thyroid hormones:ii-Thyroid hormones: Stimulate the metabolism of all body cells Stimulate the metabolism of all body cells

including the bone marrow cells, thus, including the bone marrow cells, thus, increasing erythropoiesis.increasing erythropoiesis.

Hypothyroidism is associated with anemia Hypothyroidism is associated with anemia while hyperthyroidism is associated with while hyperthyroidism is associated with polycythaemia.polycythaemia.

HematopoiesiHematopoiesiss

HematopoiesisHematopoiesis



iii-Glucocorticoids:iii-Glucocorticoids:

Stimulate the general metabolism and also Stimulate the general metabolism and also

stimulate the bone marrow to produce more RBCs. stimulate the bone marrow to produce more RBCs.

In Addison’s disease (hypofunction of adrenal cortex) In Addison’s disease (hypofunction of adrenal cortex)

anemia present, while in Cushing’s disease anemia present, while in Cushing’s disease

(hyperfunction of adrenal cortex) polycythaemia (hyperfunction of adrenal cortex) polycythaemia

present.present.



iv-Pituitary glandiv-Pituitary gland: Affects erythropoiesis both : Affects erythropoiesis both directly and indirectly through the action of directly and indirectly through the action of several hormones.several hormones.

v- Haematopoietic growth factors:v- Haematopoietic growth factors: Are secreted Are secreted by lymphocytes, monocytes & macrophages by lymphocytes, monocytes & macrophages to regulate the proliferation and to regulate the proliferation and differentiation of proginator stem cells to differentiation of proginator stem cells to produce blood cells.produce blood cells.


Factors affecting erythropoiesis:-Factors affecting erythropoiesis:-D)-State of liver & bone marrow:D)-State of liver & bone marrow:i-Liver:i-Liver: Healthy liver is essential for Healthy liver is essential for

normal erythropoiesis because the normal erythropoiesis because the liver is the main site for storage of liver is the main site for storage of vitamin Bvitamin B12 12 , folic acid, iron & copper. , folic acid, iron & copper. In chronic liver disease anemia In chronic liver disease anemia occurs.occurs.

ii-Bone marrow:ii-Bone marrow: When bone marrow is When bone marrow is destroyed by ionizing irradiation or destroyed by ionizing irradiation or drugs, aplastic anemia occurs.drugs, aplastic anemia occurs.


AnemiaAnemia Anemia means a decrease in Anemia means a decrease in

hemoglobin content,hemoglobin content, or RBCs count, or RBCs count, or both of them below the or both of them below the

normal range.normal range. Anemia leads to a decrease in Anemia leads to a decrease in

blood ability to transport oxygen blood ability to transport oxygen to tissue cells.to tissue cells.

Types & causes of anemia:Types & causes of anemia:I-Blood loss anemia:I-Blood loss anemia:

A-Acute blood loss anemiaA-Acute blood loss anemia:: Due to severe hemorrhage.Due to severe hemorrhage. Plasma volume is replaced rapidly by the Plasma volume is replaced rapidly by the

fluids present in tissue spaces.fluids present in tissue spaces. This leads to marked dilution of the blood. This leads to marked dilution of the blood. RBCs are replaced within 2-3 weeks.RBCs are replaced within 2-3 weeks. Sufficient iron gives normocytic cells but Sufficient iron gives normocytic cells but

insufficient iron will produce microcytic insufficient iron will produce microcytic RBCs.RBCs.

AnemiaAnemia

Types & causes of anemia:Types & causes of anemia:I-Blood loss anemia:I-Blood loss anemia:B-Chronic blood loss anemiaB-Chronic blood loss anemia:: Due to repeated loss of small amounts of Due to repeated loss of small amounts of

blood over a long period e.g.:blood over a long period e.g.:-Gastrointestinal bleeding (peptic ulcer)-Gastrointestinal bleeding (peptic ulcer)-Excessive menstruation.-Excessive menstruation.-Hemorrhagic diseases.-Hemorrhagic diseases. Due to depletion in iron stores the newly Due to depletion in iron stores the newly

formed RBCS are microcytic.formed RBCS are microcytic.

AnemiaAnemia

Types & causes of anemia:Types & causes of anemia:II-Aplastic anemia: II-Aplastic anemia:

It results from destructione of bone marrow.It results from destructione of bone marrow. It may result from:It may result from:

1-Excessive exposure to x-rays or gamma rays.1-Excessive exposure to x-rays or gamma rays.

2-Chemical toxins e.g. cancer therapy & prolonged 2-Chemical toxins e.g. cancer therapy & prolonged exposure to insecticides or benzene.exposure to insecticides or benzene.

3-Invasion of bone marrow by cancer cells.3-Invasion of bone marrow by cancer cells.

4-Following infection by hepatitis.4-Following infection by hepatitis. Damaged bone marrow don’t produce any RBCs, Damaged bone marrow don’t produce any RBCs,

so in aplastic anemia RBCS are normocytic.so in aplastic anemia RBCS are normocytic.

It is associated with decrease in WBCs & platelets.It is associated with decrease in WBCs & platelets.

AnemiaAnemia

AnemiaAnemiaTypes & causes of anemia:Types & causes of anemia:

III-Hemolytic anemia:III-Hemolytic anemia:It results from increased rate of destruction of RBCs It results from increased rate of destruction of RBCs

inside the cardiovascular system.inside the cardiovascular system. Causes of hemolytic anemia:Causes of hemolytic anemia:A-Hereditary:A-Hereditary:1-Membrane abnormalities.1-Membrane abnormalities.2-Enzyme deficiency e.g. G-6-P Dehydrogenase.2-Enzyme deficiency e.g. G-6-P Dehydrogenase.3-Hemoglobin abnormalities.3-Hemoglobin abnormalities.B-Acquired:B-Acquired:1-Incompatible blood transfusion.1-Incompatible blood transfusion.2-Parasitic infection e.g. malaria.2-Parasitic infection e.g. malaria.3-Toxic agents e.g. snake venom & insect poisons.3-Toxic agents e.g. snake venom & insect poisons.4-Thermal e.g. several burns.4-Thermal e.g. several burns.

AnemiaAnemia

Types & causes of anemia:Types & causes of anemia:IV-Dyshemopoietic anemia: Which may be due IV-Dyshemopoietic anemia: Which may be due

to:to:1-Iron deficiency anemia.1-Iron deficiency anemia.2-Maturation failure (megaloblastic) anemia:-2-Maturation failure (megaloblastic) anemia:-

a-Vitamin Ba-Vitamin B1212 deficiency. deficiency.b-Folic acid deficiency.b-Folic acid deficiency.3-Anemia of endocrine disorders.3-Anemia of endocrine disorders.4-Nutritional anemia.4-Nutritional anemia.5-Anemia of renal failure.5-Anemia of renal failure.

PolycythemiaPolycythemia

It is an abnormal increase in the It is an abnormal increase in the number number

of circulation RBCs.of circulation RBCs.

A-Primary polycythemia: A-Primary polycythemia:

It is caused by tumor of bone marrow.It is caused by tumor of bone marrow.

B-Secondary polycythemiaB-Secondary polycythemia::

It occurs as a result of prolonged It occurs as a result of prolonged tissue hypoxia.tissue hypoxia.

II-Respiration

Respiratory systemRespiratory system

Respiration serves the following functions

Supplies tissues with O2 Eliminate CO2 from tissues.Regulates the pH of the blood.Maintain normal body temperature

RespirationI- External Respiration:

Exchange of respiratory gases

between air in lungs and blood in

pulmonary capillaries.

RespirationII-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).

The respiratory system is divided into two zones:

I- The Conducting Zone

II- Respiratory Zone

Includes : nose, nasopharynx, larynx, trachea and 2 main bronchi one for each lung, and smaller bronchioles.

I- The Conducting Zone:

Function of the conducting part:

1. Conducting air into the respiratory zone.2. Air conditioning3. Humidification4. Filtration5. Protective reflexes a- Sneezing reflex b- Cough reflex6. 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 -PharynxThe 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.

The larynx has the following functions:

3- The Larynx

1- Control of the airflow during breathing. 2- Protection of the airway.

3- Production of sound for speech.

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Seventh lecture