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Questions and Answers
What is the primary function of the spleen within the lymphatic system?
What is the primary function of the spleen within the lymphatic system?
Which component is NOT part of the composition of lymph vessels?
Which component is NOT part of the composition of lymph vessels?
What is the role of macrophages in the marginal zone of the spleen?
What is the role of macrophages in the marginal zone of the spleen?
Which part of the spleen is primarily associated with spleen parenchyma?
Which part of the spleen is primarily associated with spleen parenchyma?
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What is the composition of the capsule that surrounds the spleen?
What is the composition of the capsule that surrounds the spleen?
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How does the spleen differ from other lymphoid organs?
How does the spleen differ from other lymphoid organs?
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What constitutes the white pulp of the spleen?
What constitutes the white pulp of the spleen?
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Where do the nerves, blood, and lymph vessels enter and leave the spleen?
Where do the nerves, blood, and lymph vessels enter and leave the spleen?
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Which reproductive strategy involves the formation of spores from the products of multiple fission?
Which reproductive strategy involves the formation of spores from the products of multiple fission?
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What type of cyst is specifically formed in response to unfavorable environmental conditions?
What type of cyst is specifically formed in response to unfavorable environmental conditions?
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Which protozoan reproductive structure contains a zygote?
Which protozoan reproductive structure contains a zygote?
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What is the primary function of an encystment process in protozoa?
What is the primary function of an encystment process in protozoa?
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During the process of excystment, what happens to the protozoan?
During the process of excystment, what happens to the protozoan?
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Which type of spore may be flagellated?
Which type of spore may be flagellated?
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What happens to the organelles of locomotion during cyst formation?
What happens to the organelles of locomotion during cyst formation?
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What is the main purpose of spores in protozoa?
What is the main purpose of spores in protozoa?
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What is the defining characteristic of plasmotomy?
What is the defining characteristic of plasmotomy?
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In which of the following organisms does endogenous budding primarily occur?
In which of the following organisms does endogenous budding primarily occur?
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Parthenogenesis is best described as:
Parthenogenesis is best described as:
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Which statement about regeneration in protozoa is true?
Which statement about regeneration in protozoa is true?
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Which type of budding results in the separation of buds from the parent organism?
Which type of budding results in the separation of buds from the parent organism?
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What is the typical chromosome condition expected in parthenogenetic organisms?
What is the typical chromosome condition expected in parthenogenetic organisms?
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What distinguishes monotomy from syntomy in the context of plasmotomy?
What distinguishes monotomy from syntomy in the context of plasmotomy?
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Which protozoan reproductive strategy allows for the formation of new organisms from a portion of a parent?
Which protozoan reproductive strategy allows for the formation of new organisms from a portion of a parent?
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What is the primary mode of reproduction in protozoa?
What is the primary mode of reproduction in protozoa?
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Which method of asexual reproduction involves the nucleus dividing before the cell divides?
Which method of asexual reproduction involves the nucleus dividing before the cell divides?
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In binary fission among protozoa, how are flagella distributed between daughter cells?
In binary fission among protozoa, how are flagella distributed between daughter cells?
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What distinguishes multiple fission from binary fission in protozoa?
What distinguishes multiple fission from binary fission in protozoa?
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How does the nuclear division in binary fission differ in most flagellates compared to ciliates?
How does the nuclear division in binary fission differ in most flagellates compared to ciliates?
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What happens to complex organelles during binary fission in protozoa?
What happens to complex organelles during binary fission in protozoa?
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What term is used for a type of cell division that produces four or more progeny without cytoplasm division?
What term is used for a type of cell division that produces four or more progeny without cytoplasm division?
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What is a notable characteristic of the nuclear membrane during binary fission in protozoa?
What is a notable characteristic of the nuclear membrane during binary fission in protozoa?
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Study Notes
Lymphatic Organs
- Lymph nodes, spleen, tonsils, and thymus are all lymphatic organs.
Lymph Vessels
- Lymph vessels transport lymph fluid, which is composed of blood plasma, lymphocytes, and antibodies.
Spleen
- The spleen is the largest lymphoid organ in the body.
- It filters blood, stores erythrocytes, and phagocytoses damaged or aged red blood cells.
- The spleen is the site of proliferation for B and T lymphocytes and the manufacturing of antibodies.
- The spleen is divided into two regions:
- Red pulp: Contains splenic cords and blood sinusoids (Billroth cords).
- White pulp: Includes the central artery and lymphatic nodules.
- The spleen lacks cortex and medulla.
- It is located in the abdomen.
- The spleen has a capsule composed of dense irregular collagenous connective tissue, elastic fibers, and smooth muscle cells. This capsule is thicker at the hilum.
- Sepra (trabecula) are a network of reticular fibers and collagenous connective tissue that form the frame work of the spleen.
- Nerves, blood, and lymph vessels enter and leave the spleen at its hilum.
- It is an intraperitoneal organ covered by simple squamous epithelium (peritoneum).
White Pulp
- Contains a central artery, lymphatic nodules, and antigen-presenting cells.
- Lymphatic nodules primarily consist of B lymphocytes.
Marginal Zone
- The marginal zone is located between the red and white pulps.
- It receives capillary loops from the central artery, which drain into small sinusoids at the periphery of the lymphatic nodules.
- The marginal zone is the initial site where blood contacts the splenic parenchyma.
- It is richly supplied by phagocytic macrophages and antigen-presenting cells.
- The marginal zone is where T and B lymphocytes enter the spleen before being segregated to their specific locations.
Histology of the Spleen
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Splenic Nodules (White Pulp):
- Central zone contains B lymphocytes.
- Red pulp contains RBCs and plasma cells.
- Cords of Billroth
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Capsule:
- Trabeculae
-
Central Artery:
- Periarterial Lymphoid Sheath (PALS): Contains T lymphocytes.
-
Splenic Marginal Artery:
- Arterial loops
- Receive B lymphocytes
- Macrophages
Reproduction in Protozoa
- Protozoa reproduce both asexually and sexually.
- Asexual reproduction is the primary mode of reproduction.
- Asexual reproduction involves fission, which is the division of a parent cell into daughter cells.
- The cell body divides after the nucleus divides.
Asexual Reproduction
-
Binary fission:
- This is the most common type of asexual reproduction in protozoa.
- The nucleus elongates and divides into two parts.
- The cell then constricts in the middle to form two daughter cells.
- This can be transverse or longitudinal depending on the type of protozoa.
- Flagella and cilia are distributed among the daughter cells, and new ones are formed.
- Contractile vacuoles are either shared or formed anew.
-
Multiple fission:
- The nucleus divides repeatedly before the cytoplasm divides.
- The cytoplasm separates into as many parts as there are nuclei, forming spores.
- Spores can be enclosed in a spore case or naked.
- Spores can be amoeboid, flagellated or ciliated.
-
Cyst formation:
- Protozoa can form cysts for protection or reproduction.
- Cysts are formed by a process called encystment.
- During encystment, the protozoan becomes rounded, loses its organelles of locomotion, ejects food vacuoles, and contractile vacuoles disappear.
- The protozoan secretes a gelatinous covering that hardens into a chitinous epicyst.
- Cysts help in the dispersal of species.
-
Plasmotomy:
- Asexual division of a multinucleate protozoan, where the cytoplasm divides but the nuclei do not.
- Each daughter cell later regains the number of nuclei by nuclear division.
-
Budding:
- This is an unequal division of the parent body, producing one or more buds.
- The nucleus of the buds is a part of the parent nucleus.
- The bud is smaller than the parent and may grow into an adult.
- Budding can be exogenous (buds form on the surface of the parent) or endogenous (buds form inside the cytoplasm).
-
Parthenogenesis:
- Development of a gamete into an adult without fertilization.
- Mostly occurs in female gametes.
-
Regeneration:
- The ability to form new tissue to replace a lost part.
- Any nucleated portion of a protozoan is capable of regeneration.
Sub-types of Cysts
-
Resting cysts:
- Enable the protozoan to proceed undisturbed in its normal activities.
-
Resistance cysts:
- Formed against unfavorable environmental conditions.
-
Gametocysts:
- Where gametes unite for reproduction.
-
Oocysts:
- Contain a zygote.
-
Sporocysts:
- Where multiple fissions occur to form sporozoites.
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Description
Explore the key components of the lymphatic system, including lymphatic organs like the spleen, lymph nodes, tonsils, and thymus. Dive into the function of lymph vessels and the specialized structure of the spleen, focusing on its unique regions and roles in the immune response.
