Seventh lecture

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Seventh lecture
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Hematopoiesis

• Factors affecting erythropoiesis-
• 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.

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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.

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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.

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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.

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Hematopoiesis

• Factors affecting erythropoiesis-
• C) Hormonal factors
• iii-Glucocorticoids
• Stimulate the general metabolism and also
  stimulate the bone marrow to produce more RBCs.
• In Addisons disease (hypofunction of adrenal
  cortex) anemia present, while in Cushings
  disease (hyperfunction of adrenal cortex)
  polycythaemia present.

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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.

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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.

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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

• 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.

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Anemia

• 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.

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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 dont produce any RBCs, so in
  aplastic anemia RBCS are normocytic.
  
• It is associated with decrease in WBCs
  platelets.

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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.

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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.

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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
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Respiratory system
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Respiration serves the following functions

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

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Respiration

• I- External Respiration

Exchange of respiratory gases between air in
lungs and blood in pulmonary capillaries.
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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
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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

• Conducting air into the respiratory zone.
• Air conditioning
• Humidification
• Filtration
• Protective reflexes
• a- Sneezing reflex
• b- Cough reflex
• Non respiratory function.

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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
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Functions of Respiratory Passages

• 1-The nose

a) The vestibule. b) The respiratory area. c) The
olfactory area.
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The olfactory area is lined by olfactory mucosa
which consists of

• Olfactory epithelium consists of three types of
  cells
• 1- Sustentecular (supporting) columnar cells
• 2- Olfactory (sensory) cells
• 3- Basal cells

(B) Corium
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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

• The larynx has the following functions

1- Control of the airflow during breathing. 2-
Protection of the airway. 3- Production of sound
for speech.