Title: Introduction to cell, tissues and organ
To study the different type, function, structure and histology of cell, tissue, and organs in human body. 2.
To learn how to identify different cell and tissue based on their structure and shape. 3.
To learn how to use the microscope properly to observe the slide of different cell and tissue. Introduction:
Cell is the basic structural and functional units of an organism that are composed of chemicals. Cell is the smallest living unit in the human body. Cell is divided into three main parts which are the plasma membrane, cytoplasm, and nucleus. The plasma membrane forms the cell flexible outer surface, separating the cell’s internal environment(everything inside the cell) from the external environment(everything outside the cell). The cytoplasm consists of all the cellular contents between the plasma membrane and the nucleus. The nucleus is a large organelle that houses the most of a cell’s DNA (Tortora & Derrickson, 2011). Tissues are the group of cells and the materials surrounding them that work together to perform a particular function. There are four basic types of tissues in human body, which are the connective tissue, muscle tissue, epithelial tissue, and nervous tissue. Connective tissue connects, supports, and protects body organs while distributing blood vessels to other tissue. Muscular tissue contracts to make body parts move and generates heat. Epithelial tissue covers body surfaces, lines hollow organs and cavities, and forms glands. Nervous tissues carry information from one part of the body to another through nerve impulses. Organs are structures that are composed of two or more different type of tissues. Each of them has specific function and usually has recognizable shape.
Epithelial tissue consists of cell arranged in continuous sheets, in either single or multiple layers. Simple epithelium is a single layer of cells. Pseudostratified epithelium appears to have multiple layers of cells because the cell nuclei lie at different levels and not all the cell reach the apical surface. Stratified epithelium consists of two or more layers of cells. Blood tissue consists of blood plasma and formed elements which are the red blood cells(erythrocytes), white blood cells(leukocytes), and platelets(thrombocytes). Integumentory system consists of superficial, thin epidermis and a deep, thicker dermis, deep to the is the subcutaneous layer which attaches the dermis to underlying fascia. Cartilage is a flexible connective tissue found in many areas of human body. There are three types of cartilage which are hyaline cartilage, fibrocartilage, and elastic cartilage. Cartilage is a relatively inactive tissue that grows slowly and avascular. Bone tissue is classified as either compact or spongy, depending how its extracellular matrix and cells are organized. Compact bone is an osteon or haversian system. Each osteon has four parts, the lamellae, lacunae, canaliculi, and the central canal. Spongy bone lacks osteon. Rather, it consists of columns of bone called trabeculae, which contain lamellae, osteocytes, lacunae and canaliculi.
Simple epithelium is one cell thick, that is, every cell is in direct contact with the underlying basement membrane. It is generally found where absorption and filtration occur. Squamous epithelia are found lining surfaces utilizing simple passive diffusion such as the alveolar epithelium in the lungs. Specialized squamous epithelia also form the lining of cavities such as the blood vessels (endothelium) and pericardium (mesothelium) and the major cavities found within the body. They fit closely together in tissues; providing a smooth, low-friction surface over which fluids can move easily. Cuboidal cells are roughly cuboidal in shape, appearing square in cross section cuboidal epithelium is commonly found in secretive or absorptive tissue: for example the (secretive) exocrine gland the pancreas and the...
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