Parts of the Immune System
Content
Chino C. Abalos II-SSC Aristotle
Parts of the Immune System
The human immune system is a complex combination of organs, cells and physiological responses that work together to keep bodies free from disease, bacteria and infection. When the immune system or any of its parts are compromised due to an existing infection or birth defect, an individual may suffer from increased illnesses or become vulnerable to internal corruptions such as cancers or other malignant growths.
White Blood Cells The smallest parts of the immune system are the myriad types of white blood cells that are responsible for demolishing malicious bacterial, viral and tumor cells. T cells serve as both managers and infection killers. They are responsible for activating and communicating with other types of white blood cells before destroying malignant cells like parasites and tumors. Natural killer cells directly attack virus cells and tumor cells such as lymphoma, melanoma and herpes. They work alone without communicating with other parts of the immune system. B cells work to produce antibodies that attach themselves to foreign cells as a sign to natural killer cells and T cells to attack and destroy. Bone Marrow An essential aspect of the immune system--and the origin of all types of immune system cells--is red bone marrow. Bone marrow is a specific type of tissue that grows in the empty centers of bones. This tissue uses the process of hematopoiesis to manipulate its own stem cells into B cells and natural killer cells, as well as the foundational pieces of other immune cells like T cells. Once they are created, these cells migrate out of the marrow tissue and circulate through the blood stream to infection sites, other glands or around the body as general patrol entities. Thymus Gland The foundations of T cells produced in the bone marrow, called thymocytes, leave the tissue and travel to the thymus gland for completion. The thymus is a small gland located near the lungs in the upper torso. Thymocytes complete their maturation in the thymus through the process of thymic education, where each cell is developed and examined for maximum efficiency. Cells that are not strong enough to provide immune support are destroyed and absorbed by the thymus, while the successfully matured cells are excreted from the gland into the blood stream. Spleen The spleen, which is located on the left side of the abdomen just under the lung, is a blood filter that works to remove malignant cells from the blood stream. To assist in this function, it holds a significant store of B cells, T cells and natural killer cells to help eliminate any contaminants that are caught. The spleen also assists in immune function by holding a store of red blood cells and platelets that can be deployed as support for the immune cells in the event of an infection or wound. Lymph Nodes Lymph nodes, found throughout the body, are also integral parts of the immune system that filter tissue fluid for bacteria cells, tumor cells and viral particles. Like the spleen, lymph nodes are full of the various types of white blood cells that clean the lymph fluid before returning it to various areas of the
body. Lymph nodes are located in the head, neck, arms, legs, abdomen and genital area of the human body and are connected through a network of afferent lymphatic vessels. In the event of an infection, white blood cells can use these lymphatic vessels to quickly communicate with other parts of the immune system. Mitosis Definition The process where a single cell divides resulting in generally two identical cells, each containing the same number of chromosomes and genetic content as that of the original cell. Supplement Prior to this, the genetic material of the original (parent) cell has replicated during the S phase of the cell cycle so that when the cell enters mitosis it undergoes four major phases which culminates in the formation of two identical (daughter) cells: 1st phase: Prophase: formation of paired chromosomes, disappearance of nuclear membrane, appearance of the achromatic spindle, formation of polar bodies 2nd phase: Metaphase: arrangement of chromosomes in the equatorial plane. Chromosomes separate into exactly similar halves. 3rd phase: Anaphase: the two groups of daughter chromosomes separate and move along the fibres of the central spindle, each toward one of the asters, forming the diaster. 4th phase: Telophase: two daughter nuclei are formed, the cytoplasm divides, forming two complete daughter cells.
Originally, the term mitosis refers only to nuclear division unaccompanied by cytokinesis (which is the division of the cytoplasm), as in the case of some cells like certain fungi and in fertilized egg of many insects. As used now, mitosis used interchangeably with cell division. Mitosis 1: Prophase During prophase the chromosomes are identical chromatids connected at the center by a centromere, forming a X-shaped object. The distinguishing feature of prophase is the setup of the mitotic spindle, which is used to maneuver the chromosomes about the cell. The spindle is formed by excess parts from the dismantled cytoskeleton. The spindle is initially setup outside the nucleus. The cell's centioles are duplicated to form two pairs of centrioles. Each pair becomes the part of the mitotic center which forms the focus for an array of microtubules, called the aster. The two asters lie side by side close the the nuclear envelope. Near the end of prophase the asters pull apart and the spindle is formed.
Mitosis 2: Metaphase Prometaphase The prometaphase provides a transition from prophase to metaphase. In prometaphase the nuclear envelope, which surrounds the nucleus, breaks up. The spindle now can move into the center of the cell. Kinetochores develop, which are attached to kinetochore fibers, which are linked to the chromosomes. The kinetochores then control the movements of the chromosomes. During this period the kinetochores are wildly oscillating as they try to attach themselves to one of the polar fibers. When they manage to do so the chromosome settles down. Metaphase In Metaphase the kinetochores that are responsible for moving the chromosomes jump begin to orientate the chromosomes. The chromosomes are orientated so that 1. each kinetochore faces the pole and 2. it moves each chromosome into a plane at the center of the spindle so that each chromosome tail is facing each other.
Mitosis 3: Anaphase In anaphase two events occur. First the kinetochores begin to move towards the poles. Then the polar fibers elongate, spreading the poles farther apart from each other.
Mitosis 4: Telophase By telophase there are two separate groups of chromosomes at each pole. A nuclear envelope begins to form around each set of chromosomes to form two nuclei, that are temporarily in one cell. After the envelope reassembles RNA synthesis begins to break down the chromosomes, causing the nucleolus to reappear. Meiosis Definition A form of cell division happening in sexually reproducing organisms by which two consecutive nuclear divisions (meiosis I and meiosis II) occur without the chromosomal replication in between, leading to the production of four haploid gametes (sex cells), each containing one of every pair of homologous chromosomes (that is, with the maternal and paternal chromosomes being distributed randomly between the cells). Supplement
Meiosis encompasses interphase, meiosis I and meiosis II. The interphase consists of G1, S and G2 whereas both meiosis I and II consist of four major subphases such as prophase, metaphase, anaphase and telophase. The process of meiosis is briefly described as follows. During the interphase, the chromosomes in a cell are duplicated. This is followed by meiosis I wherein the chromosomes condense along the center of the nucleus, and pair with their homologues during crossing over. Next, the pairs of chromosomes separate and move to opposite ends of the cell. The cell divides for the first time producing two cells. The two cells will undergo meiosis II wherein both of them divides further into two cells, each containing one of every decoupled chromosome’s sister strands (chromatids), thus, producing four genetically different, haploid cells. Meiosis is a vital process because it reduces the original number of chromosomes to half, and allows genetic variability by genetic recombination and independent assortment. Meiosis produces four haploid cells that may develop into potential gametes so that when fertilization occurs, a new individual with the full number of genes results, thereby maintaining the integrity of chromosomal number across generations while promoting genetic diversity and variability in forms in the population.
Parts of the Immune System
The human immune system is a complex combination of organs, cells and physiological responses that work together to keep bodies free from disease, bacteria and infection. When the immune system or any of its parts are compromised due to an existing infection or birth defect, an individual may suffer from increased illnesses or become vulnerable to internal corruptions such as cancers or other malignant growths.
White Blood Cells The smallest parts of the immune system are the myriad types of white blood cells that are responsible for demolishing malicious bacterial, viral and tumor cells. T cells serve as both managers and infection killers. They are responsible for activating and communicating with other types of white blood cells before destroying malignant cells like parasites and tumors. Natural killer cells directly attack virus cells and tumor cells such as lymphoma, melanoma and herpes. They work alone without communicating with other parts of the immune system. B cells work to produce antibodies that attach themselves to foreign cells as a sign to natural killer cells and T cells to attack and destroy. Bone Marrow An essential aspect of the immune system--and the origin of all types of immune system cells--is red bone marrow. Bone marrow is a specific type of tissue that grows in the empty centers of bones. This tissue uses the process of hematopoiesis to manipulate its own stem cells into B cells and natural killer cells, as well as the foundational pieces of other immune cells like T cells. Once they are created, these cells migrate out of the marrow tissue and circulate through the blood stream to infection sites, other glands or around the body as general patrol entities. Thymus Gland The foundations of T cells produced in the bone marrow, called thymocytes, leave the tissue and travel to the thymus gland for completion. The thymus is a small gland located near the lungs in the upper torso. Thymocytes complete their maturation in the thymus through the process of thymic education, where each cell is developed and examined for maximum efficiency. Cells that are not strong enough to provide immune support are destroyed and absorbed by the thymus, while the successfully matured cells are excreted from the gland into the blood stream. Spleen The spleen, which is located on the left side of the abdomen just under the lung, is a blood filter that works to remove malignant cells from the blood stream. To assist in this function, it holds a significant store of B cells, T cells and natural killer cells to help eliminate any contaminants that are caught. The spleen also assists in immune function by holding a store of red blood cells and platelets that can be deployed as support for the immune cells in the event of an infection or wound. Lymph Nodes Lymph nodes, found throughout the body, are also integral parts of the immune system that filter tissue fluid for bacteria cells, tumor cells and viral particles. Like the spleen, lymph nodes are full of the various types of white blood cells that clean the lymph fluid before returning it to various areas of the
body. Lymph nodes are located in the head, neck, arms, legs, abdomen and genital area of the human body and are connected through a network of afferent lymphatic vessels. In the event of an infection, white blood cells can use these lymphatic vessels to quickly communicate with other parts of the immune system. Mitosis Definition The process where a single cell divides resulting in generally two identical cells, each containing the same number of chromosomes and genetic content as that of the original cell. Supplement Prior to this, the genetic material of the original (parent) cell has replicated during the S phase of the cell cycle so that when the cell enters mitosis it undergoes four major phases which culminates in the formation of two identical (daughter) cells: 1st phase: Prophase: formation of paired chromosomes, disappearance of nuclear membrane, appearance of the achromatic spindle, formation of polar bodies 2nd phase: Metaphase: arrangement of chromosomes in the equatorial plane. Chromosomes separate into exactly similar halves. 3rd phase: Anaphase: the two groups of daughter chromosomes separate and move along the fibres of the central spindle, each toward one of the asters, forming the diaster. 4th phase: Telophase: two daughter nuclei are formed, the cytoplasm divides, forming two complete daughter cells.
Originally, the term mitosis refers only to nuclear division unaccompanied by cytokinesis (which is the division of the cytoplasm), as in the case of some cells like certain fungi and in fertilized egg of many insects. As used now, mitosis used interchangeably with cell division. Mitosis 1: Prophase During prophase the chromosomes are identical chromatids connected at the center by a centromere, forming a X-shaped object. The distinguishing feature of prophase is the setup of the mitotic spindle, which is used to maneuver the chromosomes about the cell. The spindle is formed by excess parts from the dismantled cytoskeleton. The spindle is initially setup outside the nucleus. The cell's centioles are duplicated to form two pairs of centrioles. Each pair becomes the part of the mitotic center which forms the focus for an array of microtubules, called the aster. The two asters lie side by side close the the nuclear envelope. Near the end of prophase the asters pull apart and the spindle is formed.
Mitosis 2: Metaphase Prometaphase The prometaphase provides a transition from prophase to metaphase. In prometaphase the nuclear envelope, which surrounds the nucleus, breaks up. The spindle now can move into the center of the cell. Kinetochores develop, which are attached to kinetochore fibers, which are linked to the chromosomes. The kinetochores then control the movements of the chromosomes. During this period the kinetochores are wildly oscillating as they try to attach themselves to one of the polar fibers. When they manage to do so the chromosome settles down. Metaphase In Metaphase the kinetochores that are responsible for moving the chromosomes jump begin to orientate the chromosomes. The chromosomes are orientated so that 1. each kinetochore faces the pole and 2. it moves each chromosome into a plane at the center of the spindle so that each chromosome tail is facing each other.
Mitosis 3: Anaphase In anaphase two events occur. First the kinetochores begin to move towards the poles. Then the polar fibers elongate, spreading the poles farther apart from each other.
Mitosis 4: Telophase By telophase there are two separate groups of chromosomes at each pole. A nuclear envelope begins to form around each set of chromosomes to form two nuclei, that are temporarily in one cell. After the envelope reassembles RNA synthesis begins to break down the chromosomes, causing the nucleolus to reappear. Meiosis Definition A form of cell division happening in sexually reproducing organisms by which two consecutive nuclear divisions (meiosis I and meiosis II) occur without the chromosomal replication in between, leading to the production of four haploid gametes (sex cells), each containing one of every pair of homologous chromosomes (that is, with the maternal and paternal chromosomes being distributed randomly between the cells). Supplement
Meiosis encompasses interphase, meiosis I and meiosis II. The interphase consists of G1, S and G2 whereas both meiosis I and II consist of four major subphases such as prophase, metaphase, anaphase and telophase. The process of meiosis is briefly described as follows. During the interphase, the chromosomes in a cell are duplicated. This is followed by meiosis I wherein the chromosomes condense along the center of the nucleus, and pair with their homologues during crossing over. Next, the pairs of chromosomes separate and move to opposite ends of the cell. The cell divides for the first time producing two cells. The two cells will undergo meiosis II wherein both of them divides further into two cells, each containing one of every decoupled chromosome’s sister strands (chromatids), thus, producing four genetically different, haploid cells. Meiosis is a vital process because it reduces the original number of chromosomes to half, and allows genetic variability by genetic recombination and independent assortment. Meiosis produces four haploid cells that may develop into potential gametes so that when fertilization occurs, a new individual with the full number of genes results, thereby maintaining the integrity of chromosomal number across generations while promoting genetic diversity and variability in forms in the population.
