Histology Flashcards
- Erythrocytes constitute approximately what percentage of whole blood (i.e., hematocrit) in healthy men and healthy women?
- How many erythrocytes are there in a ml of blood?
- Erythrocytes constitute approximately 37 to 49% of whole blood.
- There are 4.5 x 10^9 – 6.4 x 10^9 erythrocytes in a mL of blood
Platelet
What granulocytes are found in the peripheral blood?
Neutrophils, eosinophils, basophils
What agranulocytes are found in the peripheral blood?
Monocytes, lymphocyte
Neutrophil
Neutrophils constitute what percentage of circulating leukocytes in a normal blood smear?
They make up 48-76% of circulating leukocytes.
What is the function of neutrophils?
Neutrophils contain granules (such as primary – myeloperoxidase, elastase, antibacterial proteins, secondary – lysozyme, tertiary – alkaline phosphatase) that are responsible for fighting off local pathogens in tissue. They are fast acting and often are the first responder in an infection.
Eosinophil
Eosinophils constitute what percentage of circulating leukocytes in a normal blood smear?
Less than 5%.
What are the functions of eosinophils?
Eosinophils can seek out or dampen the inflammatory reactions and are antiparasitic.
Basophil
Basophils constitute what percentage of circulating leukocytes in a normal blood smear?
0-2% of leukocytes.
What is the primary function of basophils?
Basophils incite inflammatory responses. They bind to circulating IgE via IgE receptor on their cell surface and the IgE then binds to antigens, resulting in activation of the basophil and degranulation. Basophil granules contain histamine, which plays a big role in initiating an inflammatory response.
What resident connective tissue cell functions similarly to basophils, and shares a common progenitor cell?
Mast cells
Monocyte
Monocyte
Monocytes constitute what percentage of circulating leukocytes in a normal blood smear?
2.5-8.5%
What is the function of monocytes?
Become macrophages in tissue, engulf foreign invaders, dead tissue, tumor cells.
Small lymphocyte
Large lymphocyte
Lymphocytes constitute what percentage of circulating leukocytes in a normal blood smear?
18-41%
Name the three main classes of lymphocytes.
B cells, T cells, NK cells
Describe the morphologic differences between the erythrocytes seen in iron deficiency anemia and those in the normal blood smear.
The RBCs are smaller and have a larger central pallor, with the staining presenting mainly on the outline of the cell. The shape is consistent.
What is the role of iron in red blood cells?
Necessary co-factor in the transformation of proto-phorphyrin IX into heme
What other nutrients are necessary for proper RBC production?
Vitamin b12 and Folate
Why does iron deficiency lead to anemia?
It limits the formation of heme, which limits hemoglobin synthesis and effects the ability to carry oxygen in circulation.
Cells of the erythroid lineage have [A] nuclei at all stages where nuclei are present and [B] cytoplasm. As these cells mature, the cell and nucleus become [C], the nucleus becomes more [D], and the cytoplasm turns from [E] to [F] to [G] to red. The final stage is the mature erythrocyte, which has no nucleus and is small and red.
[A] round
[B] non- granulated
[C] smaller
[D] heterochromatic
[E] pale blue
[F] dark blue
[G] gray
Cells of the myeloid lineage start as large cells with [A] nuclei and a few small [B] granules, progressing to cells with an [C] nucleus and accumulations of [D] in the cytoplasm. The [D] may be [E] . Mature granulocytes (neutrophils, eosinophils, basophils) are present and can be identified by their characteristically [F] nuclei, and cytoplasm completely filled with specific [D].
[A] round
[B] azurophilic
[C] ovoid or indented
[D] granules
[E] neutrophilic, eosinophilic, or basophilic
[F] lobed
What is the cause of the basophilic (blue) material in the cytoplasm during early stages of erythroid differentiation?
During maturation, the overall size of the erythroid precursor cell reduces with the cytoplasmic to nucleus (C:N) ratio increasing. The nuclear diameter decreases and chromatin condenses with the staining reaction progressing from purplish red to dark blue at the final nuclear stage of Orthochromatic erythroblast, prior to nuclear ejection. The colour of the cytoplasm changes from blue at proerthroblast and basophillic stages to a pinkish red as a result of the increasing expression of haemoglobin as the cell develops. Initially, the nucleus is large in size and contains open chromatin. But, as red blood cells mature, the size of the nucleus decreases, until it finally disappears with the condensation of the chromatin material
Why does the nucleus become more heterochromatic during later stages of erythroid differentiation?
The hemoglobin congregates at the periphery of the cell, creating a pinker pigment here and a lighter color in the center.
Why is there such a high proportion of cells of the myeloid lineage in marrow when the proportion in circulation is relatively small compared to erythrocytes?
Cells of the myeloid lineage have shorter lifespans so we need to produce more, while the erythrocytes have an average lifespan of 120 days so we do not need to produce them as often
In Bone Marrow:
Myeloid precursor cells are typically found in close approximation to the _____. As these cells mature, they migrate toward the ____.
bone trabeculae
sinusoids
In the Bone Marrow:
Erythroid precursor cells typically develop away from the ___ , nearer to ___ , in clumps of cells that are dividing and maturing. These are known as ___.
trabeculae
sinusoids
erythroid islands
In the Bone Marrow:
Megakaryocytes are located adjacent to ___, discharging platelets into circulation.
sinusoids
Bone marrow sinusoid
Erythroid islet
Bone marrow sinusoid
What tissue is shown? What are the two shaded regions?
Adult thymus
Medulla (right)
Cortex (left)
What tissue is shown? Label each box.
Lymph node
Tissue?
Lymph node
Tissue?
Lymph node
Tissue and structure shown?
Lymph node - germinal center
Tissue and structure shown?
Lymph node - HEVs
Tissue and structures shown?
Lymph node
Upper = plasma cell
Lower = macrophages
Tissue and structures shown?
Lymph node
Efferent Lymphatic vessel with valve
Tissue and structures shown?
Endothelium of gut - lacteal (lymphatic vessel in small intestines)
What are the 2 important functions of HEVs?
1) Allow lymphocytes to enter the lymphoid tissue
2) Reabsorb/circulate lymph from rest of lymphatic system
What tissue is shown and what structures are highlighted?
Spleen
What tissue is shown?
appendix
In the appendix, how is the epithelium lining the interior of the appendix characterized?
Simple columnar epithelium
What tissue is shown?
Label the boxes.
This tissue only has what kind of lymphatic vessel?
Palatine tonsil
Efferent lymphatic vessels
