Saturday, 28 June 2014

RESPIRATION --- BIOLOGY FORM FIVE .

RESPIRATORY   SYSTEM --- BIOLOGY   FORM   FIVE.

Human respiratory system-NIH.PNG
The respiratory system, also called the gas exchange system is the body getting rid of carbon dioxide and taking in oxygen. Carbon dioxide, a waste product of cellular respiration is exhaled and oxygen is inhaled. The oxygen then goes into the blood due to a concentration gradient (a difference in concentration). The first process of this system is breathing in the air, or inhaling. The second process is gas exchange in the lungs where oxygen from the air is diffused into the blood in exchange for the carbon dioxide. The third process is cellular respiration, where oxygen and glucose in the blood is changed into energy during glycolysis, the Krebs cycle, and the electron transport chain. This produces the high concentration of carbon dioxide found in the blood. Finally, the carbon dioxide from cellular respiration is exhaled out the body from the lungs.[1]

Ventilation

For respiration to happen, the body needs a constant supply of oxygen, which is done by breathing. Inhalation is the breathing in of air. To inhale, the lungs expand, decreasing the air pressure in the lungs. This is caused by the diaphragm (a sheet of muscular tissue that separates the lungs from the abdomen) and the muscles between the ribs contracting to expand the chest, which also expands the lungs. As the air pressure inside the lungs are lower when it has expanded, air from outside at higher pressure comes rushing into the area of low pressure in the lungs.[2] Air first passes through the nose and mouth, then through the larynx (voice box), then down the trachea (windpipe), and into the lungs.
The lungs are made of many tubes or branches. As air enters the lungs, it first goes through branches called the bronchus, then through smaller branches called bronchioles, and finally into the air sacs. Gas exchange occurs in the air sacs where oxygen is exchanged with carbon dioxide. The carbon dioxide in the air sacs now need to be exhaled, or breathed out. In the reverse process to inhaling, the diaphragm and the rib muscles relax, causing the lungs to be smaller. As the air pressure in the lungs is greater when the lungs are smaller, air is forced out. The exhaled air has a high concentration of carbon dioxide and a low concentration of oxygen. The maximum volume of air that can be inhaled and exhaled is called the vital capacity of the lungs and is up to five liters.[2]

Gas Exchange

Structure of the air sac
The inhaled air goes down to the air sacs at the end of each bronchiole. The air sacs are called alveoli — they have a large surface area, and are moist, thin, and close to a blood supply. The inhaled air has a much greater concentration of oxygen than carbon dioxide whilst the blood flowing to the lungs has a more carbon dioxide than oxygen. This creates a concentration gradient between the air in the air sacs and the blood, meaning there is more oxygen in the air than the blood. As the membrane, oxygen can easily diffuse in and out. Oxygen at high concentration in the air sacs diffuses into the blood where oxygen concentration is low, and carbon dioxide at high concentration in the blood diffuses into the air sacs where carbon dioxide concentration is low. The oxygen in the blood enters the circulatory system and is used by the cells in the body. The carbon dioxide in the air sacs are exhaled out of the body.

Cellular Respiration

Cellular respiration is the process of the cells changing oxygen and glucose into carbon dioxide, water, and most importantly energy, in three stages known as glycolysis, the Krebs Cycle, and the electron transport chain. The energy is essential, as cells need it to do work. When there is not enough oxygen being supplied, the body undergoes anaerobic respiration, which doesn’t require oxygen. However, this process produces lactic acid (a poison) and is not as efficient as when oxygen is used. Aerobic respiration, the process that does use oxygen, produces much more energy and doesn’t produce lactic acid. It also produces carbon dioxide as a waste product, which then enters the circulatory system. The carbon dioxide is taken to the lungs, where it is exchanged for oxygen.

References

  1. Pickering, W. Roy. Complete Biology. Oxford [etc.: Oxford UP, 2006. Print 116-127.
  2. King, Rita Mary., Frances Chamberlain, Q. L. Pearce, and W. J. Pearce. Biology Made Simple. New York: Broadway, 2003. Print. 127-133.
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GASEOUS EXCHANGE AND RESPIRATION--- BIOLOGY FORM FIVE.

GASEOUS   EXCHANGE  AND   RESPIRATION--- BIOLOGY   FORM   FIVE.

INTRODUCTION:
Gas exchange is a biological process through which different gases are transferred in opposite directions across a specialised respiratory surface. Gases are constantly required and produced as a by-product of cellular and metabolic reactions so an efficient system for their exchange is extremely important. It is linked with respiration in animals, and both respiration and photosynthesis in plants.[1]
In respiration, oxygen (O2) is required to enter cells whilst waste carbon dioxide (CO2) must be removed – the opposite is true for photosynthesis, where CO2 enters plants and O2 is released.[1] The exchange of gases essentially occurs as a result of diffusion down a concentration gradient – gas molecules moving from an area of high concentration to low concentration.

Diffusion

Diffusion follows Fick’s Law. It is a passive process (doesn’t require energy) affected by factors such as:
  • The surface area available
  • The distance the gas molecules must diffuse across
  • The concentration gradient
Gases must first dissolve in a fluid in order to diffuse across a membrane therefore all gas exchange systems require a moist environment.[2]
In single-celled organisms diffusion can occur straight across the cell membrane; as organisms increase in size so does the distance gases must travel across. Their surface-area-to-volume ratio also decreases. Diffusion alone is not efficient enough and specialised respiratory systems are required. This is the case with humans and fish where circulatory systems have evolved: These are able to transport the gases to and from the respiratory surface and maintain a continuous concentration gradient.[3]

In Humans

Gas exchange in humans - between a capillary and an alveolus
Both oxygen and carbon dioxide are transported around the body in the blood – through arteries, veins and capillaries. They bind to haemoglobin in red blood cells although this is more effective with oxygen. Carbon dioxide also dissolves in the plasma or combines with water to form bicarbonate ions (HCO−
3). This reaction is catalysed by the carbonic anhydrase enzyme in red blood cells:[4]

The main respiratory surface in humans are the alveoli.[5] Alveoli are small air sacs branching off from the bronchioles in the lungs. They are one-cell thick and provide a moist and extremely large surface area for gas exchange to occur. Capillaries carrying deoxygenated blood from the pulmonary artery run across the alveoli - they are also extremely thin so the total distance gases must diffuse across is only around 2-cells thick.
Inhaled oxygen is able to diffuse into the capillaries from the alveoli, while carbon dioxide from the blood diffuses in the opposite direction into the alveoli. The waste carbon dioxide can then be exhaled out of the body. Continuous blood flow in the capillaries as well as constant breathing maintains a steep concentration gradient.

Varying response

During physical exercise excess carbon dioxide is produced as a result of increased respiration: This must be removed and muscles and cells require increased oxygen. The body responds to this change by increasing the breathing rate, therefore maximizing the rate of possible gas exchange.[6]

In Plants

Air diffuses directly into and out of plants through pores on the underside of leaves known as stomata. The stomata are controlled by guard cells (affected by osmosis and turgor pressure). When the guard cells are turgid, stomata are open. When they are flaccid, stomata close and gas exchange cannot take place. The main respiratory surface is the spongy mesophyll cells inside the leaf. They have large air spaces and therefore provide a large surface area for gas exchange. Leaves are also very thin so the diffusion distance is small.[7]
During the day photosynthesis occurs at a faster rate than respiration so there is an overall uptake of CO2 and release of O2. At night (when there is no light available) this is reversed as photosynthesis stops and only respiration can take place.

In Fish

Fish must extract oxygen dissolved in water, not air, which has led to the evolution of gills and opercula. Gills are specialised organs containing filaments and lamellae – the lamellae contain capillaries and provide a large surface area and short diffusion distance as they are extremely thin.[8]
Water is drawn in through the mouth and passes over the gills in one direction while blood flows through the lamellae in the opposite direction – this counter current maintains a steep concentration gradient. O2 is able to continually diffuse down its gradient into the blood and CO2 into the water.[9]

Summary of main systems


 Large surface area Short diffusion distance Maintained concentration gradient
Human Total alveoli = 70-100m2 [10] Alveolus + Capillary = 2-cells Constant blood flow in capillaries; breathing
Fish Many lamellae and filaments per gill Usually 1-cell Counter-current flow
Plant High density of stomata; air spaces within leaf 1-cell Constant air flow

Other examples

Insects such as crickets do not have an inner skeleton so exchange gases across structures known as trachea and tracheoles: These are tubes that run directly into the body of the insect. Air enters the trachea through valves known as spiracles and diffusion can then occur straight into the respiring tissues.[11]
Amphibians are able to use their skin as a respiratory surface, as well as having lungs and sometimes gills.

See also

References

  1. "Gas exchange". Retrieved 19 March 2013.
  2. Piiper J, Dejours P, Haab P & Rahn H (1971). "Oncepts and basic quantities in gas exchange physiology". Respiration Physiology 13: 292–304. doi:10.1016/0034-5687(71)90034-x.
  3. Kety SS (1951). "The theory and applications of the exchange of inert gas at the lungs and tissues". Pharmacological Reviews 3: 1–41.
  4. Raymond H & Swenson E (2000). "The distribution and physiological significance of carbonic anhydrase in vertebrate gas exchange organs". Respiration physiology 121: 1–12. doi:10.1016/s0034-5687(00)00110-9.
  5. "Gas Exchange in humans". Retrieved 19 March 2013.
  6. Wasserman K, Whipp B, Koyal S & Beaver W (1973). "Anaerobic threshold and respiratory gas exchange during exercise". Journal of Applied Physiology 35.
  7. Casson S & Gray JE (2008). "Influence of environmental factors on stomatal development". New Phytologist 178: 9–23. doi:10.1111/j.1469-8137.2007.02351.x.
  8. Newstead James D (1967). "Fine structure of the respiratory lamellae of teleostean gills". Cell and Tissue Research 79: 396–428. doi:10.1007/bf00335484.
  9. Hughes GM (1972). "Morphometrics of fish gills". Respiration physiology 14: 1–25. doi:10.1016/0034-5687(72)90014-x.
  10. Basset J, Crone C, Saumon G (1987). "Significance of active ion transport in transalveolar water absorption: a study on isolated rat lung". The journal of physiology 384: 311–324.
  11. "Gas Exchange in Insects". Retrieved 19 March 2013.
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OEI 210 : TEACHING METHODS FOR ADULT LEARNERS / PEDAGOGY.

PEDAGOGY.

INTRODUCTION:

Pedagogy
Detail from Leonardo da Vinci's "Vitruvian Man"
Disciplines
Research framework
Key theories
Key concepts
Pedagogy (/ˈpɛdəɡɒdʒi/ or /ˈpɛdəɡoʊdʒi/)[1] is the science and art of education. Its aims range from the full development of the human being to skills acquisition. For example, Paulo Freire referred to his method of teaching people as "critical pedagogy". In correlation with those instructive strategies the instructor's own philosophical beliefs of instruction are harbored and governed by the pupil's background knowledge and experience, situation, and environment, as well as learning goals set by the student and teacher. One example would be the Socratic schools of thought.[2][3][4] The teaching of adults, however, may be referred to as androgogy.

Etymology

The word comes from the Greek παιδαγωγέω (paidagōgeō); in which παῖς (país, genitive παιδός, paidos) means "child" and άγω (ágō) means "lead"; literally translated "to lead the child".

Academic degrees

An academic degree, Ped. D., Doctor of Pedagogy, is awarded honorarily by some U.S. universities to distinguished teachers (in the U.S. and U.K., earned degrees within the instructive field are classified as an Ed. D., Doctor of Education or a Ph.D. Doctor of Philosophy). The term is also used to denote an emphasis in education as a specialty in a field (for instance, a Doctor of Music degree in piano pedagogy).

Pedagogues

Douris Man with wax tablet
The word pedagogue actually relates to the slave who escorts Roman children to school. In Denmark, a pedagogue is a practitioner of pedagogy. The term is primarily used for individuals who occupy jobs in pre-school education (such as kindergartens and nurseries) in Scandinavia. But a pedagogue can occupy various kinds of jobs, e.g. in retirement homes, prisons, orphanages, and human resource management. These are often recognised as social pedagogues as they perform on behalf of society.
The pedagogue's job is usually distinguished from a teacher's by primarily focusing on teaching children life-preparing knowledge such as social skills and cultural norms, etc. There is also a very big focus on care and well-being of the child. Many pedagogical institutions also practice social inclusion. The pedagogue's work also consists of supporting the child in their mental and social development. [5]
In Denmark all pedagogues are trained at a series of national institutes for social educators located in all major cities. The programme is a 3.5-year academic course, giving the student the title of a Bachelor in Social Education (Danish: Professionsbachelor som pædagog).[6]
It is also possible to earn a master's degree in pedagogy/educational science from the University of Copenhagen. This BA and MA program has a more theoretical focus compared to the above mentioned Bachelor in Social Education.
In Hungary, the word pedagogue (pedagógus) is synonymous with teacher (tanár); therefore, teachers of both primary and secondary schools may be referred to as pedagogues, a word that appears also in the name of their lobbyist organizations and labor unions (e.g. Labor Union of Pedagogues, Democratic Labor Union of Pedagogues[7]). However, undergraduate education in Pedagogy does not qualify students to become teachers in primary or secondary schools but makes them able to apply to be educational assistants. As of 2013, the 5-year training period was re-installed in place of the undergraduate and postgraduate division which characterized the previous practice.[8]

References

  1. "pedagogy noun - definition in British English Dictionary & Thesaurus - Cambridge Dictionary Online". Dictionary.cambridge.org. 2012-10-10. Retrieved 2012-10-29.
  2. "Analysis of Pedagogy". Educ.utas.edu.au. Retrieved 2010-09-20.
  3. Petrie et al. (2009). Pedagogy – a holistic, personal approach to work with children and young people, across services. p. 4.
  4. Aarhus University Department of Education (DPU) - Research
  5. Taipei Times Learning from Denmark
  6. Educational Guide – Denmark Pædagog – UddannelsesGuiden.dk.
  7. "Front Page". The Official Site of The Labor Union of Pedagogues. Labor Union of Pedagogues. Retrieved 27 May 2013.
  8. "Ezekre a tanári szakokra jelentkeztek a legtöbben [English: These Teaching Areas Proved The Most Popular]". Eduline. 2013-04-19. Retrieved 27 May 2013.

Further reading

Main article: List of important publications in pedagogy
Find more about Pedagogy at Wikipedia's sister projects
Definitions and translations from Wiktionary
Media from Commons
Quotations from Wikiquote
Source texts from Wikisource
Textbooks from Wikibooks
Learning resources from Wikiversity
Library resources about
Pedagogy
  • Bruner, J. S. (1960). The Process of Education, Cambridge, MA: Harvard University Press.
  • Bruner, J. S. (1966). Toward a Theory of Instruction. Cambridge, MA: Belkapp Press.
  • Bruner, J. S. (1971). The Relevance of Education. New York, NY: Norton
  • Bruner, J.S. (1986). A Study of Thinking. New Brunswick, NJ: Transaction Press.
  • Bruner, J. S., Goodnow, J. J., Austin, G. A. (1986). A study of thinking. New Brunswick, NJ: Transaction Press.
  • Freire, P. (1970). Pedagogy of the Oppressed. New York: Continuum
  • Montessori, M. (1909). Il Metodo della Pedagogia Scientifica applicato All'educazione Infantile Nelle Case dei Bambini.
  • Montessori, M. (1910). Antropologia Pedagogica.
  • Montessori, M. (1921). Manuale di Pedagogia Scientifica.
  • Montessori, M. (1934). Psico Geométria.
  • Montessori, M. (1934). Psico Aritmética.
  • Piaget, J. (1926). The Language and Thought of the Child. London: Routledge & Kegan.
  • Piaget, J. (1975/1936). "La Naissance de L'intelligence Chez L'enfant". ["Emergence of Intelligence in the Child"]. Neuchatel: Delachaux et Nieslé. Cited in Tomic, W. & Kingma, J (1996). Three Theories of Cognitive Representation and Their Evaluation Standards of Training Effect. Heerlson, The Netherlands: The Open University.
  • Piaget, J (1975/1936). "La Naissance de L'intelligence Chez L'enfant". ["Emergence of Intelligence in the Child"] in Three Theories of Cognitive Representation and Their Evaluation Standards of Training Effect. Neuchatel: Delachaux et Nieslé/Heerlson, The Netherlands: Heerlson.
  • Johann Karl Friedrich Rosenkranz (1848) Pedagogics as a System. Translated 1872 by Anna C. Brackett, R.P. Studley Company
  • Johann Karl Friedrich Rosenkranz (1899). The philosophy of education. D. Appleton and Co.
  • Vygotsky, D. (1962). Thought and Language. Cambridge, MA: MIT Press.
  • Wood, D. (1976). "The role of tutoring in problem solving". Journal of Child Psychology and Psychiatry 17: 89–100.

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OEI 208 : TEACHING PRACTICE.

TEACHING METHOD.

INTRODUCTION:
A teaching method comprises the principles and methods used for instruction. Commonly used teaching methods may include class participation, demonstration, recitation, memorization, or combinations of these. The choice of teaching method or methods to be used depends largely on the information or skill that is being taught, and it may also be influenced by the aptitude and enthusiasm of the students.

Methods of instruction

Explaining

Main article: Lecture
Explaining, or lecturing, is the process of teaching by giving spoken explanations of the subject that is to be learned. Lecturing is often accompanied by visual aids to help students visualize an object or problem. Explaining may meet the needs of auditory or visual learning preferences[clarify] but often fails to meet the needs of individuals with other learning preferences[clarify], such as kinesthetic or social learners[clarify].[citation needed]

Demonstrating

Main article: Demonstration (teaching)
Demonstrating is the process of teaching through examples or experiments. For example, a science teacher may teach an idea by performing an experiment for students. A demonstration may be used to prove a fact through a combination of visual evidence and associated reasoning.
Demonstrations are similar to written storytelling and examples in that they allow students to personally relate to the presented information. Memorization of a list of facts is a detached and impersonal experience, whereas the same information, conveyed through demonstration, becomes personally relatable. Demonstrations help to raise student interest and reinforce memory retention because they provide connections between facts and real-world applications of those facts. Lectures, on the other hand, are often geared more towards factual presentation than connective learning.

Collaborating

Main article: Collaboration
Collaboration allows students to actively participate in the learning process by talking with each other and listening to other points of view. Collaboration establishes a personal connection between students and the topic of study and it helps students think in a less personally biased way. Group projects and discussions are examples of this teaching method. Teachers may employ collaboration to assess student's abilities to work as a team, leadership skills, or presentation abilities.[1]
Collaborative discussions can take a variety of forms, such as fishbowl discussions. After some preparation and with clearly defined roles, a discussion may constitute most of a lesson, with the teacher only giving short feedback at the end or in the following lesson.

Learning by teaching

Main article: Learning by teaching
In this teaching method, students assume the role of teacher and teach their peers. Students who teach others as a group or as individuals must study and understand a topic well enough to teach it to their peers. By having students participate in the teaching process, they gain self-confidence and strengthen their speaking and communication skills.

Evolution of teaching methods

Ancient education

About 3000 BC, with the advent of writing, education became more conscious or self-reflecting, with specialized occupations such as scribe and astronomer requiring particular skills and knowledge. Philosophy in ancient Greece led to questions of educational method entering national discourse.
In his literary work The Republic, Plato described a system of instruction that he felt would lead to an ideal state. In his dialogues, Plato described the Socratic method, a form of inquiry and debate intended to stimulate critical thinking and illuminate ideas.
It has been the intent of many educators since, such as the Roman educator Quintilian, to find specific, interesting ways to encourage students to use their intelligence and to help them to learn.

Medieval education

Comenius, in Bohemia, wanted all children to learn. In his The World in Pictures, he created an illustrated textbook of things children would be familiar with in everyday life and used it to teach children. Rabelais described how the student Gargantua learned about the world, and what is in it.
Much later, Jean-Jacques Rousseau in his Emile, presented methodology to teach children the elements of science and other subjects. During Napoleonic warfare, the teaching methodology of Johann Heinrich Pestalozzi of Switzerland enabled refugee children, of a class believed to be unteachable[by whom?], to learn. He described this in his account of an educational experiment at Stanz.[citation needed] He felt the key to have children learn is for them to be loved.[citation needed]

19th century - compulsory education

Main article: Prussian education system
The Prussian education system was a system of mandatory education dating to the early 19th century. Parts of the Prussian education system have served as models for the education systems in a number of other countries, including Japan and the United States. The Prussian model required classroom management skills to be incorporated into the teaching process.[2]

20th century

Newer teaching methods may incorporate television, radio, computer, and other modern devices. Some educators[who?] believe that the use of technology, while facilitating learning to some degree, is not a substitute for educational methods that encourage critical thinking and a desire to learn. Inquiry learning is another modern teaching method.

See also

References

  1. "What Is the Collaborative Classroom?". Retrieved 14 December 2012.
  2. Gatto, John Taylor. A Different Kind of Teacher: Solving the Crisis of American Schooling. Berkeley Hills Books. ISBN 1-893163-21-0.

Further reading

  • Paul Monroe, A Text-Book in the History of Education, Macmillan, 1915.
  • Gilbert Highet, The Art of Teaching, Knopf, 1950.
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