Week 4 case study anatomy and physiology PDF

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Week 4 Case Study: Tissue Describe the five different layers of the skin.

The epidermis is a thin layer of skin. Functions of the epidermis include touch sensation and protection against microorganisms. This skin is further divided into five separate layers. In order from most superficial to most profound, they are the: 

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Stratum Corneum: This layer is composed of the many dead skin cells you shed into the environment—as a result, these cells are found in dust throughout your home. This layer helps to repel water. Stratum Lucidum: This layer is found only on the palms of the hands, fingertips, and the soles of the feet. Stratum Granulosum: This is the layer where part of keratin production occurs. Keratin is a protein that is the main component of the skin. Stratum Spinosum: This layer gives the skin strength as well as flexibility. Stratum Basale: This layer also contains melanocytes. These cells are mainly responsible for determining the color of our skin and protecting our skin from the harmful effects of UV radiation. These harmful effects include burns in the short term and cancer in the long run.

Describe the four different cell junctions. A) Plasmodesmata: These are formed by the continuous plasma membrane of two adjacent cells. It contains a threadlike cytoplasm with a thinner thread of endoplasmic reticulum in it. Plasmodesmata provide a linkage between two adjacent cells. They help in the signaling between cells. These are present in plant cells. B) Gap Junctions: They are present in animals and are analogous to plasmodesmata in plants. They are channels between cells and allow the transport of ions and other molecules from cell to cell and help in cell communication. They form with the help of membrane proteins called connexins that form the channel between two cells. They are present in cardiac muscles allowing them to spread signals among the cells to contract in tandem. C) Tight junctions: They are junctions that seal the space between two cells instead of creating a cytoplasmic connection. They are made up of claudins that interact with a partner claudin of the adjacent cell, thereby sealing that space. Their function is to prevent liquid from leaking out of the cell. This could be helpful for organs or tissues which collect liquids, such as the bladder. D) Desmosomes: Desmosomes are made from proteins called cadherins. These proteins are present between adjacent epithelial cells and interact and become interlinked with each other. Their function is to make the cells in tissues such as skin and muscles remain together even when they stretch.

What is the purpose of the plakophilin gene? The PKP2 gene provides instructions for making a protein called plakophilin 2. This protein is found primarily in cells of the myocardium, which is the muscular wall of the heart. Within these cells, plakophilin 2 is one of several proteins that make up structures called desmosomes. These structures form junctions that attach cells. Desmosomes provide strength to the myocardium and are involved in signaling between neighboring cells. How would mutations in the plakophilin gene disrupt cell-to-cell interactions? Distinct protein complexes mediate cellular adhesion at the cytoplasmic membrane, termed junctions that their morphology on the ultrastructural level has characterized. Desmosomes reveal a characteristic appearance and anchor different intermediate filaments (IF) to the cell membrane. The fundamental functional importance of desmosomal cell contacts for cellular and tissue architecture, differentiation, development, and tissue stability is generally accepted. Three related proteins of the plakophilin family (PKP1_3) have been identified as junctional proteins essential for forming and stabilizing desmosomal cell contacts. Failure of PKP expression can have fatal effects on desmosomal adhesion, leading to abnormal tissue and organ development. Thus, loss of functional PKP 1 in humans leads to ectodermal dysplasia/skin fragility (EDSF) syndrome, a genodermatosis with severe blistering of the epidermis abnormal keratinocytes differentiation. Mutations in the human PKP 2 gene have been linked to severe heart abnormalities that lead to arrhythmogenic right ventricular cardiomyopathy (ARVC) . How would mutation in the plakophilin gene lead to hyperhidrosis? The plakophilin gene is an essential component of stratifying epithelial desmosomes and a nuclear component of many cell types. The mutation in the plakophilin gene leads to hyperhidrosis which is ectodermal dysplasia or skin fragility syndrome. The desmosome formation and arrangement will be lost in plakophilin gene mutation. That is the reason it results in ectodermal dysplasia or skin fragility syndrome. References: Martini, H.F & Bartholomew, F.E (n.d) Essentials of anatomy and physiology. Fifth edition. Marieb, N.E (n.d) Essentials of human anatomy and physiology. Eighth edition. Saladin, S.K (n.d) Anatomy and physiology the unity of form and function. Ninth edition....