Produce a written assignment showing an understanding of the four main tissue types (epithelial, muscle, connective and nervous) and what they do in the heart and the intestine.
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Unit 5- Anatomy and physiology Task 1 P2- Outline the structure of the main tissues of the body. Produce a written assignment showing an understanding of the four main tissue types (epithelial, muscle, connective and nervous) and what they do in the heart and the intestine. Tissues are groups of cells with a common structure and function. There are four main tissues in the body - epithelium, muscle, connective tissue and nervous tissue. Epithelial tissue- Epithelial tissue covers external surfaces and internal cavities and organs. Glands are also composed of epithelial tissue. It is made up of cells closely packed and ranged in one or more layers; compound epithelia is made up of several layers of cells and Simple epithelia is a single layer of cells. Simple epithelial includes four different types; squamous, cuboidal, ciliated and columnar. Epithelial tissue, regardless of the type, is usually separated from the underlying tissue by a thin sheet of connective tissue; basement membrane. The basement membrane provides structural support for the epithelium and also binds it to neighbouring structures. As a group, epithelial tissues perform a variety of functions, including protection, absorption, excretion, secretion and lubrication. It is surface tissue so capacity for growth and repair is greater than any other tissue. In the Intestines- The apical surface of epithelial cells may have tiny projections called microvilli.
Going from inside the lumen radially outwards, one passes the mucosa (glandular epithelium and muscularis mucosa), submucosa, muscularis externa (made up of inner circular and outer longitudinal), and lastly serosa. Serosa is made up of loose connective tissue and coated in mucus to prevent friction damage from the intestine rubbing against other tissue. Holding all this in place are the mesenteries which suspend the intestine in the abdominal cavity and stop it being disturbed when a person is physically active. In the heart- Connective tissue provides the final pathway for diffusion of nutrients, oxygen, waste and metabolites to and from the cells of the body. All blood vessels are embedded in connective tissue. The only cells which receive their sustenance directly from the blood are the endothelial cells lining the vessels themselves. All other cells are supplied via diffusion through intermediary connective tissue. The transport functions of blood and connective tissue cannot be separated. The heart and circulatory system simply facilitate the movement of this travelling tissue. The valves in the heart are also made from connective tissues, they control the amount of blood that is passed through the heart and into the blood stream, and it also helps to reduce the flow back to the heart. Nervous tissue- Nervous tissue is found only in the nervous system and consists of nerves, brain and spinal column.
Non-striated muscle tissue is not connected to the bones. It is controlled involuntary, as it includes the organs that operate without conscious thought, although it still requires stimulation from the nervous system. Cardiac muscles are only found in the heart. They are self-contracting, autonomically regulated and continue to contract in rhythmic fashion for the whole life of the organism. Some of the cardiac muscle cells contract without any nervous stimulation. In the heart- Cardiac muscle does have several unique features. Present in cardiac muscle are intercalated discs, which are connections between two adjacent cardiac cells. Intercalated discs help multiple cardiac muscle cells contract rapidly as a unit. This is important for the heart to function properly. Cardiac muscle also can contract more powerfully when it is stretched slightly. When the ventricles are filled, they are stretched beyond their normal resting capacity. The result is a more powerful contraction, ensuring that the maximum amount of blood can be forced from the ventricles and into the arteries with each stroke. This is most noticeable during exercise, when the heart beats rapidly. This pumps blood around to all the cells in the body, helps to retrieve it and re-oxygenate it and pump it back around. In the intestine- Smooth muscle is found in the walls of hollow organs like your intestines and stomach. The muscular walls of the intestines contract to push food through your body and help to break it up, this is an involuntary function.
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Here's what a teacher thought of this essay
This is a very good essay. It discusses tissue types and is generally correct and detailed throughout. There are a few areas that could be corrected through a little more research.
It would be greatly enhanced by including some diagrams.
Marked by teacher Sam Morran 26/06/2013
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