1) using the diagram uploaded distinguish between and to explain the terms Cells, Tissues, Organs And Systems.

2) discuss and explain - some organs belong to more than one body system and their function depends on the body system to which they belong.

3)describe how temperature affects the growth of bacteria?

4) describe and explain one physiological property common to bacteria example like toxin formation or respiration?

Answers:

1: Cells, tissues, organs and systems

Cells are the smallest unit of life, which is independent, composed of a cell membrane, genetic material, cell organelles and cell wall (in plants only). It is the key structural and functional unit of human body that makes up the complex human body structure. Cells are of two types, i.e. prokaryotes and eukaryotes. The prokaryotic cells are primitive cells, like bacteria, consisting cell membrane, genetic material and simple cell organelles. These cells lack compartmentalization. In contrast, the eukaryotic cells are more organized, in which complex cell orgenelles, like mitochondria and chloroplasts are present, the nuclear materials are present within compartment and in some cases they have additional protective layers outside of the cell membrane. Human body is composed of eukaryotic cells (Baquero & Nombela, 2012).

All the cells in a tissue usually work with collaboration to complete a particular physiological function in human body. Two or more types of tissues work in a collaborative way to make up an organ; whereas two or more organs work together to accomplish common purpose, making up an organ system in the human body. With the help of an example the procedure and the inter-relation between these organization levels can be accomplished.

Tissue is composed of sets of cells, working towards a similar function. There are mainly four basic types of tissues, the epithelial tissue, connective tissue, muscle tissue and nervous tissue. Epithelial tissue is composed of lightly packed sheets of cells that cover surfaces of organs and body cavity. For example, the lining of stomach is composed of column shaped epithelial tissue, columnar epithelium, which acts as a barrier to movement of fluid and infectious organism (Sherwood, 2015). Another type is muscle tissue or muscle fibres. One type that is present in stomach is smooth muscle tissue, found in walls of digestive tract, helping in pushing food through digestive tract in an involuntary way. Another tissue type is connective tissue, which supports and connects other tissues. For instance, blood is a loose connective tissue having a fluid matrix, known as plasma, which supports the digestion system by carrying absorbed nutrient and oxygen from food to each body cell. Nervous tissue is involved in sensing stimuli, which is composed of nerve cells or neurones for transmitting signals to CNS, which controls the digestion process (Pocock, Richards & Richards, 2013).

The organs are composed of different types of tissues and works for a particular purpose, like heart is circulating blood through the body, stomach is helping in digestion, pancreas secrete digestive juices and rectum is facilitating the excretory process. Two or more organs working towards a similar function belongs to an organ system, like digestive system, circulatory system, muscular system, excretory system, nervous system, endocrine system and reproductive system. As pancreas and stomach both are working for digestion, they are making up the digestive system with other organs working for the same purpose (Stanfield, 2012).  

2: Relation between organ functions and body system

Human body is composed of a complex array of structures, which collaborate to perform all the physiological and biological functions for growth and survival of the person. Malfunctioning of any one of these organ affects the other’s functions also. Human body is created in levels of structural organization, from the simplest form, i.e. cells to the complex organ system. The hierarchy of this structural level is unique for each organ system in the human body system. The basic unit of structural organization is cell. During the developmental phase, the pluripotent or multipotent stem cells are able to differentiate in different kinds of cells. Upon differentiation, these cells become restricted to specific cell or tissue type. These unipotent cells make up a particular tissue type. These unipotent cells work for accomplishing similar purpose, in a particular organ system (Jenkins & Tortora, 2011).

For instance, digestive system works for digesting the food consumed and providing energy, nutrients, vitamins, minerals and water to body cells, for completing the physiological functions. The digestive system contains mouth, pharynx, esophagus, diaphragm, stomach, spleen, liver, pancreas, small and large intestine. These organs work together to facilitate the digestion process. These organs are made of such tissues and cells, which are working for facilitating the digestion process. As these organs are accomplishing their particular function, at a same time, these are facilitating the function of the nearby organ in the system. For instance, both pancreas and stomach releases digestive juice, which help to facilitate process of breaking complex molecule to simple one, thereby facilitating the role of the entire organ system (Park & Ahima, 2015).

3: Effect of temperature on growth of bacteria

Temperature is a key external factor that affects the growth of bacteria significantly. The nature and function of the bacterial pool depends upon the temperature of the habitat they residing. Based on temperature, the classification of bacteria has been done, i.e. thermophiles, mesophiles and psychrophiles. Thermophiles can live at temperature above 50^oC, while being able to tolerate harsh condition. These organisms live in hot spring or deep in the oceans by thermal vents or hot rocks. On the other hand, the psychrophiles can grow at as low temperature as - 5^oC, with an optimum temperature of 10 to 20 ^oC. High temperature negatively affects their growth. In contrast, mesophiles grow at normal temperature, i.e. 20^oC to 40^oC. These are the key human pathogens, as well as the beneficial microorganisms. In gut or stomach, all the normal flora are from mesophile groups, growing in human body temperature (Park & Ahima, 2015). However, due to high acidity, most organisms cannot survive in stomach, except H. Pylori.

4: Physiological property of bacteria

 Bacteria are unicellular microorganisms; all of their biological functions required for survival, are completed in the single cell. The process of respiration is done in presence or in absence of oxygen, in bacteria. The bacteria, which need oxygen for respiration, are known as the aerobic bacteria; and those, which do not need oxygen for respiration, are known as anaerobic bacteria. Some bacteria, which are actually aerobic, but can survive without oxygen, by shifting to anaerobic respiration in the absence of oxygen, are known as facultative anaerobe (Murray, Rosenthal & Pfaller, 2015). The process of respiration begins with glycolysis, in which process sugar molecule is broken down to produce pyruvate and ATP. In case of oxidative respiration, these products enter into kreb’s cycle, which also gives rise to ATPs, which are then used in electron transport chain, with the help of proton gradient. On the other hand, in the absence of oxygen, pyruvate is used in fermentation procedure to produce organic acid and carbon dioxide (Tille, 2013).

Reference List

Baquero, F., & Nombela, C. (2012). The microbiome as a human organ. Clinical Microbiology and Infection, 18(s4), 2-4.

Murray, P. R., Rosenthal, K. S., & Pfaller, M. A. (2015). Medical microbiology. Elsevier Health Sciences.

Pocock, G., Richards, C. D., & Richards, D. (2013). Human physiology. Oxford university press.

Sherwood, L. (2015). Human physiology: from cells to systems. Cengage learning.

Stanfield, C. L. (2012). Principles of human physiology. Pearson Higher Ed.

Tille, P. (2013). Bailey & Scott's Diagnostic Microbiology-E-Book. Elsevier Health Sciences.

Jenkins, G., & Tortora, G. J. (2011). Anatomy and physiology. Wiley-Blackwell.

Park, H. K., & Ahima, R. S. (2015). Physiology of leptin: energy homeostasis, neuroendocrine function and metabolism. Metabolism, 64(1), 24-34.