Histology Test #1 Questions
Compare and contrast the difference between somatic and germ cells.
1. somatic cell (SC) are the body cells or the non sex cells whereas Germ Cell (GC ) are the sex cells 2. SC generates new cells and replace the old and damaged cells, muscle whereas GC are responsible for the reproduction and propagation of species 3. SC are produced by the process of mitosis whereas GC are produced by the process of meiosis 4.SC contains the diploid (2n ) number of chromosomes whereas GC comprises of the haploid (n) no of chromosomes 5.SC are identical with their parent whereas GC are non identical with their parent 6. SC come from the bone, blood , connective tissues etc whereas the GC comes from the embryos gut 7.SC comprise of two copies of each chromosomes one from father and one from mother whereas GC comprises of either one of them 8.SC never unite with each other whereas GC unite with each other to form a zygote 9.SC e.g.: muscle cell, stomach cell, blood cell , nerve cell and GC e.g. egg cell, sperm cell
Explain membranes. Include the definition and name the four types and which tissues each type contains
Answer : Membranes are the flat sheets of pliable tissue that cover or line a part of the body. The combination of an epithelial layer and an underlying connective tissue layer constitutes an epithelial membranes. These includes, Mucous membranes : These membranes lines the body cavity that opens directlyto the exterior. Mucous membranes lines the entire digestive, respiratory and reproductive tracts and much of the urinary tract. Serous Membranes : A serous membrane or Serosa lines a body cavity that does not open directly to the exterior and it covers the organs that lie within the cavity.serous membranes consist of areolar connective tissue covered by mesothelium and also consists of two layers such as Parietal and visceral layer. Cutaneous Membrane : These membarnes covers the surface of the body and consists of a superficial portion called the epidermis and a deeper portion called the dermis. Synovial Membranes : Like serous membranes, synovial membranes line structures that do not open to the exterior. They lack in epithelium and are composed of discontinuous layer of cells called synoviocytes, which secretes synovial fluid. Synovial fluid lubricates and nourishes the cartilage covering the bones at movable joints and contains macrophages that moves microbes and debris from the joint cavity.
Apoptosis: define apoptosis and give examples of when it occurs. Explain the process that occurs within the cell and how it differs from necrosis.
Apoptosis is also known as programmed cell death, when cells are no longer needed, they commit suicide by activating an intracellular death program. This process is therefore called programmed cell death. When a cell is compelled to commit suicide, proteins called caspases go into action. They break down the cellular components needed for survival, and they spur production of enzymes known as DNases, which destroy the DNA in the nucleus of the cell. The apoptosis in the cell includes the following steps: Blebbing: this is the formation of a bulging up of plasma membrane. It is the changes in the cytoskeleton of the cell that leads to the change in shape of the cell Cell shrinkage: the cell thus shrinks in the size Chromatin condensation: the DNA present inside the cell starts separating and shrinking thus the chromatin condenses Nuclear fragmentation: the nuclear membrane covering the nucleus starts degrading and thus the nucleus now no longer remain protected and the nucleus breaks leading to the breakage of DNA into small fragments of uneven size Thus the cells blebs and are removed by the phagocytic cells Example of apoptosis are: removal of cancer cells by apoptosis, cells of immune system such as phagocytes, the resorption of the tadpole tail etc Necrosis occurs when cells die accidentally due to, trauma or injury, or lack of nutrients. It begins with cell swelling, after which the chromatin gets digested, and the plasma and organelle membranes are disrupted, the endoplasmic reticulum vacuolizes, the organelles break down completely and finally the cell lyses.
Compare the differences between paraffin and plastic resin tissue embedding and why each would be used.
Both are used for the tissue sectioning and to preserve the morphology. Paraffin is most commonly used, it can preserve morphology but it cannot produce sectioning less than 2 micrometer. Platic resin embedding enhances the preservation of morphology and can produce ultrathin sectioning.but this is limited to tissue staining and probing.
Explain the intercellular junctions found on the lateral surface of an epithelial cell starting from the apical pole and progressing to the basal pole of the cell. How is the terminal bar seen on a light microscope related?
Epithelia are tissues composed of closely aggregated cells that cover most body surfaces, cavities, and tubes. Surface epithelia form continuous sheets that can have one or multiple cell layers. Several different types of cell junctions mediate physical strength and cell communication within the epithelium. A basement membrane lies beneath the epithelium and separates it from underlying tissue; because blood vessels do not penetrate the basement membrane, nutrients like oxygen and metabolites reach the epithelium by diffusion. Epithelia are polarized, with an apical surface that faces the external environment and a basal surface that faces the basement membrane. Microvilli are small processes that project from the apical surface of most types of epithelial cells, greatly increasing the surface area. They are notably found at the intestinal brush border and in the proximal convoluted tubule of the kidney. Stereocilia are unusually long, non-motile microvilli that are found on the surface epithelium in the epididymis and ductus deferens. Cilia are actively motile processes with a complex internal structure found on the epithelial lining of the respiratory tract and the female reproductive tract. The basement membrane, a thin non-cellular layer, intervenes between the epithelium and the connective tissue. This membrane is 30 to 60 nanometers thick and made up of collagenous and non-collagenous glycoproteins and proteoglycans. It provides structural support for the epithelium and serves as a selective barrier for the movement of materials to and from the supporting tissue. Using light microscopy, terminar bar appears as a bar at the apical surface of the cell, wherein the structures listed cannot be resolved. With electron microscopy, the terminal bar can be visually disseminated into these structures. The terminal bar is located on the lateral surface of epithelial cells, where the lateral surface meets the apical surface. It should not be confused with the Terminal web, which is an actinous web underlying microvilli on specialized epithelial cells
Explain the various types of vesicular transport across the plasmalemma and how the plasmalemma changes with each.
Exocytosis and endocytosis are two types of vesicular transport across plasmalemma. Exocytosis and endocytosis are two types of vesicular transport across plasmalemma. Exocytosis: process where cell exists the waste materials outside of cell. calcium depenendent and non-calcium depended machanisms are seen here. the Golgi complex packages macromolecules into transport vesicles that travel to and fuse with the plasma membrane. This fusion causes the vesicle to spill its contents out of the cell. Endocytosis: process where cell eats the extracellular fuid and its dissolved contents.1) phagocytosis- process of engulfing solid particals into cell. 2) pinocytosis- only liquid is engulfied here. 3)receptor mediated endocytosis where receptor help is taken for engulfing the particles or liquid unlike phagocytosis and pinocytosis..
A light microscope shows a line separating two epithelial cells which are in juxtaposition. Draw and label a diagram of how this would appear under an electron microscope.
One of the 4 basic animal tissue types is epithelium. Epithelial cells line the walls of blood vessels and organs throughout the body. Simple columnar epithelial cells lie in close contact with each other and separated by a basement membrane from the underlying connective tissue. These cells can be secretory, excretory or absorptive.They can be ciliated or non-ciliated and found in the female reproductive tract and in the trachea. Attached below is the image as seen under electron microscope of two simple columnar epithelial cells in juxtaposition.
Hemopoietic cells: Be able to identify each cell type in bold on the lecture notes and know its function or product. Know which differentiate to a different cell. You do not need to know all of the rest of the cells listed under hematopoietic stem cells - we will get to those later.
Only need to know histology of: B Lymphoctye, plasma cell, monocyte, macrophage, multinucleated giant cells, mast Cells for now.
Briefly explain the ventral and dorsal body cavities and the membranes which line the ventral cavities. What is a mesentery?
The ventral body cavity is a body cavity that is in the anterior (front) aspect of the body. It is made up of the thoracic cavity, and the abdominopelvic cavity. The abdominopelvic cavity is further divided into the abdominal cavity and pelvic cavity, but there is no physical barrier between the two. The abdominal cavity contains digestive organs, the pelvic cavity contains the urinary bladder, internal reproductive organs, and rectum. The thoracic cavity is separated from the abdominopelvic cavity by the diaphragm. The thoracic cavity is further separated into the pleural cavity which contains the lungs and the superior mediastinum which includes the pericardial (heart) cavity. The organs within the ventral body cavity are called the viscera. The walls of the ventral body cavity and outer covering of its organs contain a thin covering called the serosa (also called serous membrane). It is a double-layered membrane made up of two parts called the "parietal serosa" (lines the cavity walls) and "visceral serosa" (covers organs in the cavity). The serous membranes are separated by a thin layer of fluid called "serous fluid". Serous fluid is secreted by both membranes and acts as a lubricant, allowing organs to slide in the cavity without causing friction. The dorsal body cavity is located along the dorsal (posterior) surface of the body, where it is subdivided into the cranial cavity housing the brain and the spinal cavity housing the spinal cord. The two cavities are continuous with one another. The cranial cavity is a large, bean-shaped cavity filling most of the upper skull where the brain is located.The vertebral cavity is a very narrow, thread-like cavity running from the cranial cavity down the entire length of the spinal cord. Just as the brain and spinal cord make up a continuous, uninterrupted structure, the cranial and spinal cavities that house them are also continuous. The brain and spinal cord are protected by the bones of the skull and vertebral column and by cerebrospinal fluid, a colorless fluid produced by the brain, which cushions the brain and spinal cord within the posterior (dorsal) cavity. The covering and protective membranes for the dorsal body cavity are called meninges. Mesentery - a fold of the peritoneum that attaches the stomach, small intestine, pancreas, spleen, and other organs to the posterior wall of the abdomen.
Be able to explain the general structure and function of centrioles, cilia including basal bodies and axoneme, and flagellum
flagellum: a slender threadlike structure, especially a microscopic whiplike appendage that enables many protozoa, bacteria, spermatozoa, etc., to swim. cilia: axoneme: the central strand of a cilium or flagellum. It is composed of an array of microtubules, typically in nine pairs around two single central ones. centrioles: microtubules
Explain the various types of vesicular transport across the plasmalemma and how the plasmalemma changes with each.
regulating which molecules go in and out of the cell and separating incompatible processes occurring within organelles. Without the cell membrane, toxins would inevitably enter the cell and cause damage.