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Questions and Answers
What are the two types of bone marrow found in the body?
What are the two types of bone marrow found in the body?
What are hemopoietic cords primarily composed of?
What are hemopoietic cords primarily composed of?
What is the main function of megakaryocytes?
What is the main function of megakaryocytes?
Which component of the bone marrow forms an extensive, communicating network?
Which component of the bone marrow forms an extensive, communicating network?
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How are the nests of erythrocytes organized within the bone marrow?
How are the nests of erythrocytes organized within the bone marrow?
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What characteristic is associated with the nucleus of megakaryocytes?
What characteristic is associated with the nucleus of megakaryocytes?
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Which statement about yellow marrow is accurate?
Which statement about yellow marrow is accurate?
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What type of cells are primarily found in the stroma of the bone marrow?
What type of cells are primarily found in the stroma of the bone marrow?
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What primarily gives red bone marrow its color?
What primarily gives red bone marrow its color?
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Which statement accurately describes the location of yellow bone marrow in adults?
Which statement accurately describes the location of yellow bone marrow in adults?
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What is the primary function of red bone marrow?
What is the primary function of red bone marrow?
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Which of the following can yellow bone marrow do in times of need?
Which of the following can yellow bone marrow do in times of need?
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Which blood cells are generally produced by red bone marrow?
Which blood cells are generally produced by red bone marrow?
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What role do sinusoidal macrophages play in red bone marrow?
What role do sinusoidal macrophages play in red bone marrow?
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The primary difference in function between yellow and red bone marrow is that yellow bone marrow is mainly for:
The primary difference in function between yellow and red bone marrow is that yellow bone marrow is mainly for:
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In the context of blood cell production, erythropoiesis specifically refers to which process?
In the context of blood cell production, erythropoiesis specifically refers to which process?
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What is the primary function of red bone marrow in adults?
What is the primary function of red bone marrow in adults?
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At what stage of development does bone marrow become the main site of hemopoiesis?
At what stage of development does bone marrow become the main site of hemopoiesis?
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Which type of bone marrow is mainly responsible for fat storage?
Which type of bone marrow is mainly responsible for fat storage?
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Where does hematopoiesis occur in normal adult life?
Where does hematopoiesis occur in normal adult life?
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What characterizes the yolk sac phase of hemopoiesis?
What characterizes the yolk sac phase of hemopoiesis?
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Which hematopoietic phase is primarily responsible for the formation of erythroid cells?
Which hematopoietic phase is primarily responsible for the formation of erythroid cells?
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As adults age, what happens to hemopoiesis in the bone marrow?
As adults age, what happens to hemopoiesis in the bone marrow?
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What type of cell is primarily produced in the yellow bone marrow?
What type of cell is primarily produced in the yellow bone marrow?
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Study Notes
Bone Marrow
- Bone marrow is where hematopoiesis occurs in adults.
- Bone marrow is located in the medullary cavity of long bones and spaces of spongy bone.
- There are 2 types of bone marrow in the body: red and yellow.
- Red bone marrow is highly vascular and hemopoietically active.
- Yellow bone marrow is rich in fat and filled with adipocytes.
Stroma
- Stroma consists of loose reticular connective tissue that supports hematopoietic cells.
- The stroma of the bone marrow is composed of modified fibroblasts and reticular fibers.
- Modified fibroblasts (adventitial reticular cells) produce reticular fibers.
- Reticular fibers support hematopoietic cells and macrophages
- Reticular cells have cell adhesion molecules on their surface.
Parenchyma
- The parenchyma of bone marrow is composed of sinusoids and hemopoietic cords.
- Sinusoids are thin-walled vessels.
- Sinusoids form an extensive network.
- The sinusoidal wall is composed of fenestrated endothelial cells, a discontinuous basal lamina and an outer adventitial cell layer.
- Hemopoietic cords are islands of cells that are well organized.
- Hemopoietic cords contain megakaryocytes, developing blood cells, macrophages, mast cells and some adipose cells.
- Erythrocyte nests contain a macrophage and are located near the sinusoidal wall.
- Megakaryocytes are located adjacent to the sinusoidal wall.
- Granulocyte nests are located farther from the sinusoidal wall.
Megakaryocyte
- Megakaryocytes are giant cells that produce platelets.
- Megakaryocytes are up to 150 um in diameter.
- Megakaryocytes contain a large, ovoid or kidney shaped nucleus that is irregularly lobulated with coarse chromatin.
- Megakaryocyte cytoplasm is basophilic and contains numerous mitochondria, a well-developed rough ER, and an extensive Golgi apparatus.
- From the Golgi apparatus arise the conspicuous specific granules of platelets.
- Megakaryocytes are typically found near sinusoidal capillaries.
Types of Bone Marrow
- Red bone marrow is red because of its high hemoglobin content.
- Yellow bone marrow is yellow because of its high fat content.
- In a fetus, most of the marrow is red.
- In adults, most of the marrow is yellow.
- Red bone marrow is found in the epiphyses of long bones, vertebrae, sternum and ribs.
- Yellow bone marrow is mostly found in long bones in adults.
- The function of red bone marrow is to produce blood cells and destroy old RBCs.
- Yellow bone marrow stores fats and can change to active red bone marrow in times of need.
Function of Bone Marrow
- Bone marrow produces RBCs, granulocytes, monocytes and platelets which are released into the circulation
- Lymphocytes require further maturation to become functional.
- Bone marrow destroys old RBCs by macrophages.
- Bone marrow differentiates B lymphocytes.
- Bone marrow stores iron in sinusoidal macrophages.
Hemopoiesis
- Hemopoiesis is the production of all the blood cells.
- Erythropoiesis is the production of RBCs.
- Leukopoiesis is the production of WBCs.
- Thrombopoiesis is the production of platelets.
- Hematopoietic tissues produce new blood cells.
- Hematopoietic tissues include the yolk sac, liver, and bone marrow.
Yolk Sac Phase
- The yolk sac is the main site of hematopoiesis in the 2nd week of gestation.
- The yolk sac is characterized by the formation of blood islands in the wall of the yolk sac.
Hepatic Phase
- The liver is the main site of hematopoiesis from 8 weeks until 6-7 months of fetal life.
- The liver contains hemopoietic centers that mainly produce erythrocytes, although some leukopoiesis occurs as well.
- The liver is the major blood forming organ in the fetus during the second trimester.
Bone Marrow Phase
- The bone marrow is the main site of hematopoiesis from the 2nd trimester of fetal life.
- After birth, the bone marrow (the myeloid phase) and lymphatic tissues produce new blood cells.
- In adults, hematopoiesis occurs mainly in the flat bones: sternum, pelvis, vertebrae, ribs, and the proximal ends of femur
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Description
This quiz explores the structure and function of bone marrow, including its role in hematopoiesis and the characteristics of red and yellow marrow. Additionally, discover the components of stroma and parenchyma that support hematopoietic cells. Test your understanding of these crucial aspects of the human skeletal system.
