Feb 25, 2014

Biological Terms

One of the keys to being successful in biology is being able to understand the terminology. Difficult biology words and terms can be made easy to understand by becoming familiar with common prefixes and suffixes used in biology. These affixes, derived from Latin and Greek roots, form the basis for many difficult biology words.
Below is a list of a few biology words and terms that many biology students find difficult to understand. By breaking these words down into discrete units, even the most complex terms can be understood. 
1. Autotroph
This word can be separated as follows: Auto - troph.
Auto - means self, troph - means nourish. Autotrophs are organisms capable of self nourishment.
2. Cytokinesis
This word can be separated as follows: Cyto - kinesis.
Cyto - means cell, kinesis - means movement. Cytokinesis refers to the movement of the cytoplasm that produces distinct daughter cells during cell division.
3. Eukaryote
This word can be separated as follows: Eu - karyo - te.
Eu - means true, karyo - means nucleus. A eukaryote is an organism whose cells contain a "true" membrane bound nucleus.
4. Heterozygous
This word can be separated as follows: Hetero - zyg - ous.
Hetero - means different, zyg - means yolk or union, ous - means characterized by or full of. Heterozygous refers to a union characterized by the joining of two different alleles for a given trait.
5. Hydrophilic
This word can be separated as follows: Hydro - philic.
Hydro - refers to water, philic - means love. Hydrophilic means water-loving.
6. Oligosaccharide
This word can be separated as follows: Oligo - saccharide.
Oligo - means few or little, saccharide - means sugar. An oligosaccharide is a carbohydrate that contains a small number of component sugars.
7. Osteoblast
This word can be separated as follows: Osteo - blast.
Osteo - means bone, blast - means bud or germ (early form of an organism). An osteoblast is a cell from which bone is derived.
8. Tegmentum
This word can be separated as follows: Teg - ment - um.
Teg - means cover, ment - refers to mind or brain. The tegmentum is the bundle of fibers that cover the brain.
Pneumonoultramicroscopicsilicovolcanoconiosis
Yes, this is an actual word. What does it mean? Biology can be filled with words that sometimes seem incomprehensible. By "dissecting" these words into discrete units, even the most complex terms can be understood. To demonstrate this concept, let's begin by performing biology word dissections on the word above.
To perform our biology word dissection, we'll need to proceed carefully. First, we come to the prefix (pneu-), or (pneumo-) which means lung. Next, is ultra, meaning extreme, and microscopic, meaning small. Now we come to (silico-), which refers to silicon, and (volcano-) which refers to the mineral particles that make up a volcano. Then we have (coni-), a derivative of the Greek word konis meaning dust. Finally, we have the suffix (-osis) which means affected with. Now lets rebuild what we have dissected:
Considering the prefix (pneumo-) and the suffix (-osis), we can determine that the lungs are affected with something. But what? Breaking down the rest of the terms we get extremely small (ultramicroscopic) silicon (silico-) and volcanic (volcano-) dust (coni-) particles. Thus, pneumonoultramicroscopicsilicovolcanoconiosis is a disease of the lungs resulting from the inhalation of very fine silicate or quartz dust. That wasn't so difficult, now was it?
Now that we've honed our dissection skills, let's try some frequently used biology terms. For instance:
Arthritis
(Arth-) refers to joints and (-itis) means inflammation. Arthritis is the inflammation of a joint(s).
Erythrocyte
(Erythro-) means red and (-cyte) means cell. Erythrocytes are red blood cells.
Okay, let's move on to more difficult words. For instance:
Electroencephalogram
Dissecting, we have (electro-), pertaining to electricity, (encephal-) meaning brain, and (-gram) meaning record. Together we have an electric brain record or EEG. Thus, we have a record of brain wave activity using electrical contacts.
Schizophrenia
Individuals with this disorder suffer from delusions and hallucinations. (Schis-) means split and (phren-) means mind.
Thermoacidophiles
These are ancient bacteria that live in extremely hot and acidic environments. (Therm-) means heat, next you have (-acid), and finally (phil-) means love. Together we have heat and acid lovers.
Once you understand the commonly used prefixes and suffixes, obtuse words are a piece of cake! Now that you know how to apply the word dissection technique, I'm sure you'll be able to determine the meaning of the word thigmotropism (thigmo - tropism).

Dec 25, 2013

Much ado over rankings

The nation’s low rankings in a world educational assessment has caused an outcry, yet our schools have nurtured many young Malaysians who have at the global level, excelled academically. 
I REFER to recent comments made on the poor performance of Malaysian students in the Programme for International Student Assessment (Pisa).
Many seem to agree with the declining standards of the Malaysian education system.
If the “leaning indicator of Pisa” is to be accepted as the true picture, Malaysian education seems to be heading towards a calamity.
There was also talk that since Malaysians were not up to the mark, there were none who earned a spot in Harvard University in the United States.
Is failure to gain entry into Harvard the measurement of failure of education in a country? However, let us give credit where credit is due.
Malaysia has done relatively well in using her natural wealth to build her economy.
We managed to transform from a country that relied on the export of natural resources to one that exports manufactured goods.
The success of our transition can be credited to our heavy investment in education.
Education gives birth to human capital. The 25% allocation for education in the budget simply means the importance stressed by the Government on human capital.
Economists have come to believe that the central determinant of a nation’s economic growth is the skill and entrepreneurial courage of the population.
Just look at countries like Japan, Korea, Taiwan and Singa-pore. They are successful for the simple reason that they have put so much emphasis on the quality of their schools.
Comments and actions taken by the pessimists have been shocking. We see parents sending their children to international and private schools.
Well, it is their right. They have the means. Most of them flock to schools that use English as the medium of instruction.
So where does that put Malaysian schools as a start to creating human capital?
If one reads and scrutinises the criticisms on the Malaysian school education system, one will think it produces dullards of the worst kind.
The criticisms seem to show that our school system is a national disgrace.
The strings of As every year in the SPM have been branded as over inflated and not reflective of the actual academic standards of students.
If that is the case, then how is it that local students can achieve excellent results when they sit for pre-university exams conducted by foreign agencies, prior to pursuing studies at high-ranking institutions abroad?
How can this paradox be explained?
Their performance shows that the education system here is a lot better than what the critics say.
So, there must be something right in our school system that contributes significantly to human capital later on.
Simply put, the education system is not as bad as it is painted out to be.
We are a pessimistic lot. We are ever so willing to criticise despite the dynamism and sustained growth performance in many sectors shown over the years.
Compared to many countries, those in our cohort could envy us. Had our education been poor, we would not have been where we are today.
Some may say that the good performances by several sectors may be due to them being highly populated by officers who graduated from overseas’ universities.
If that is so, how did they gain entry into these universities?
The A-Levels, Edexcel, International Baccalaureate and other matriculation exams sat by governing bodies abroad are tough.
So how did our students manage to get the high grades needed in these exams to gain entry into many good universities in the United Kingdom, Canada, Australia and the United States?
Nobody questions over inflated grades simply because they are conducted by foreign agencies.
Didn’t the formative years in the primary and the secondary schools here contribute to their good performance in those exams?
If so, it shows that our education has helped the students have what it takes to gain entry to reputable colleges and universities.
Many may argue that the excellent performance of the students at the pre-university exams may be because of the good colleges they attended.
My answer is simple, those entrusted to teach at these colleges were no wizards. They could not do wonders within one or two years.
The argument could then go on to the high standards that the foreign universities they attended had maintained.
While we accept that not many were able to make it to the Ivy League, our students and many from around the world have made it to other established varsities.
What does this all mean? If our students are bad, they would not have gained entry into these institutions.
Yes, there is a decline in the standard of English among our students and graduates.
There is much to be desired in communication and social skills. Their general knowledge is very embarrassing.
These are also the type of comments made by other countries on their present generation of graduates.
Malaysia is not alone in facing the drop in the standard of education. Yes, even the British and the Americans are complaining that their students’ command of grammar of their own mother tongue is shameful. Their general knowledge is abysmal.
All these should heighten concerns about the quality of the teaching of language and subjects like history and geography, as well as the syllabuses in those subjects in their schools as well as ours and in stressing a two-way communication in classes and improvement in soft skills.
Those skills that are lacking can also be acquired as the graduates move along in organisations they work in.
The problem with organisations is that they expect graduates to be perfect from the first day that they step in as employees.
Organisations expect all shortcomings of the graduates to be overcome at the universities they attend but do not realise that universities too have their limits.
The rest is up to the graduates and the organisations to turn potentials into real human capital.
We can never be complacent about our duty to education.
All must take responsibility to ensure that what is best is passed to the next generation. Every generation is a product of its environment.
My parting shot. On several occasions (not only based on Pisa), the Americans and Western Europeans have lagged behind East Asians in academic performance in elementary education.
Somehow, several Nobel Prize winners consistently every year are Americans and Europeans.
Where are the scientists and thinkers from East Asia? The test scores such as in Pisa may not display the shape of people to come.

Dr. Azmi Yaakob

Dec 12, 2013

Sample STPM Semester I Question

ATP and NADPH are two main molecules which are required for the production of carbohydrate in plants. Describe how these molecules are generated during photosynthesis.

[9 marks]

P680/Photosystem II absorb light energy/photon.
Energy is passed from one pigment molecule to another pigment molecule until reach the reaction centre.
The electron is excited and captured by primary electron acceptor.
Created electron hole in P680/photosystem II.
Which filled up by electron from photolysis of water
Primary electron acceptor passes the electron to a series of electron carriers/plastoquinone, cytochrome complex and plastocyanine
Energy released in the form of ATP through chemiosmosis
P700/photosystem I absorbs light energy/photon
The electron excited and captured by primary electron acceptor
Electron is passed to ferredoxin
NADP+ is reduced to NADPH.

PMR 2014


DALAM satu program temu bual di televisyen penulis ditanya mengenai tindakan pemansuhan peperiksaan Penilaian Menengah Rendah (PMR). Seperti yang dilaporkan dalam akhbar di mana tahun ini adalah merupakan tahun terakhir pelajar Tingkatan 3 menduduki peperiksaan awam tersebut. Penulis menyatakan bahawa sebenarnya peperiksaan PMR tidak dimansuhkan. Peperiksaan itu akan diteruskan pada tahun-tahun yang akan datang. 

Walau bagaimanapun formatnya akan diubahsuai dalam bentuk yang baharu. Perubahan ini selaras dengan transformasi pendidikan iaitu untuk menjadikan kaedah pentaksiran lebih bersifat holistik dan berupaya menilai kebolehan pelajar melalui berbagai komponen.

Huraian transformasi kurikulum dan pentaksiran tersebut dapat dirujuk melalui 'Bab 4 - Pembelajaran Murid' dalam Pelan Pembangunan Pendidikan Malaysia (PPPM) 2013-2025 yang telah dilancarkan oleh Timbalan Perdana Menteri, Tan Sri Muhyiddin Yassin baru-baru ini. 

Sesungguhnya perubahan ketara peperiksaan PMR yang akan datang ialah pelaksanaannya menggunakan kaedah Pentaksiran Berasaskan Sekolah (PBS). PBS itu mempunyai dua komponen iaitu akademik dan bukan akademik. Komponen akademik terdiri daripada Pentaksiran Sekolah (PS) dan Pentaksiran Pusat (PP). Sementara itu komponen bukan akademik mengandungi Pentaksiran Psikometrik (Ppsi) dan Pentaksiran Aktiviti Jasmani, Sukan dan Kokurikulum (PSJSK).

Pentaksiran Sekolah atau PS bermaksud penyediaan soalan dan pemeriksaan jawapan akan diuruskan sendiri oleh guru di sekolah berkenaan. Kandungan soalan yang dikemukakan merangkumi pembelajaran dan pengajaran mulai Tingkatan 1 hingga Tingkatan 3.
Pentaksiran Pusat atau PP pula merupakan penilaian bertulis yang disediakan oleh Lembaga Peperiksaan Malaysia (LPM). LPM akan menyediakan tugasan, instrumen pentaksiran setara, peraturan penskoran, jadual pelaksanaan dan garis panduan. Namun demikian guru akan diberi tanggungjawab untuk mentadbir, mentaksir dan menskor jawapan pelajar berdasarkan peraturan dan panduan yang telah ditetapkan oleh LPM.

Ini bermakna mulai tahun 2014 semua mata pelajaran dalam peperiksaan PMR akan ditaksir dalam bentuk PS dan PP oleh guru-guru di sekolah berkenaan. Tiada lagi peperiksaan berpusat dilaksanakan serentak di seluruh negara yang dikendalikan sepenuhnya oleh LPM seperti yang diamalkan sebelum ini.
Apa yang menariknya peperiksaan PMR 2014 yang berwajah baru itu tidak hanya menilai pelajar melalui komponen akademik atau bidang kognitif semata-mata. Tetapi turut dinilai ialah komponen bukan akademik merangkumi bidang sahsiah, bakat dan kebolehan semula jadi pelajar melalui kaedah Ppsi dan PSJSK.

Menilai
Pentaksiran Psikometrik atau Ppsi merupakan suatu penilaian yang direkabentuk bagi mendapat maklumat pelajar secara kualitatif dan kuantitatif. Ppsi menilai keupayaan seseorang untuk bertindak balas dalam suatu cara tertentu. Ia juga mengukur kebolehan semula jadi atau innate ability dan kebolehan yang diperolehi atau acquired ability daripada pengalaman dan persekitaran. 

Di samping itu Ppsi juga turut menilai bakat pelajar dalam bidang muzik, kreativiti, kemahiran interpersonal dan intrapersonal, kinestatik dan kepintaran naturalis. Pentaksiran ini disediakan dalam bentuk deskriptif mengikut keperluan sama ada secara manual atau berkomputer oleh guru dan pelajar itu sendiri.
Sementara itu, Pentaksiran Aktiviti Sukan, Jasmani dan Kokurikulum atau PSJSK adalah untuk mengukur kecergasan dan kesihatan pelajar dalam pelbagai aktiviti jasmani. Turut ditaksir penyertaan, penglibatan dan prestasi pelajar dalam pelbagai aktiviti kokurikulum dan ekstra kokurikulum. Instrumen dan panduan pentaksiran disediakan oleh LPM dan organisasi berkaitan berdasarkan bidang kepakaran masing-masing.
Ternyata peperiksaan PMR 2014 yang berwajah baru itu merupakan satu langkah kehadapan yang diambil oleh Kementerian Pendidikan sesuai dengan masa dan keadaan. Pada pendapat penulis sekurang-kurang terdapat tiga faktor yang membawa kepada perubahan tersebut.

Pertama ialah hasil daripada transformasi pendidikan menerusi perancangan strategik Pelan Pembangunan Pendidikan Malaysia. Mereka mendapati peperiksaan awam yang dilaksanakan tidak menguji kesemua kemahiran yang dihasratkan dalam sistem pendidikan kita. PPPM menganjurkan agar diambil langkah bagi meningkatkan kerangka pentaksiran dan menggunakan rujukan standard seperti yang terdapat dalam PBS. Format pentaksiran baharu ini membolehkan pelajar dinilai berdasarkan keberhasilan yang lebih luas dan dalam tempoh jangka masa lebih panjang. 

Kedua, kerap kali dikatakan bahawa pendidikan kita terlalu berorientasikan peperiksaan. Kita masih lagi mengamalkan peperiksaan awam berpusat dan dijalankan serentak di seluruh negara. Kebiasaannya penilaian terhadap pelajar tertumpu sepenuhnya kepada peperiksaan di akhir setiap peringkat persekolahan mereka. Sudah sampai masanya pentaksiran dilakukan dalam tempoh masa yang panjang dan turut menilai kebolehan pelajar di luar bidang akademik. Oleh itu semestinya komponen sahsiah, bakat, kebolehan semulajadi dan kokurikulum perlu diberi ruang dan peluang untuk dinilai.

Ketiga mengembalikan semula peranan mentaksir pelajar kepada guru. Ketika ini tugas pengajaran dan pembelajaran dilaksanakan sepenuhnya oleh guru tetapi tugas menilai pelajar diserahkan pula kepada pihak yang lain. Sekiranya peranan mentaksir pelajar diberikan sepenuhnya kepada guru maka ia dilihat lebih memberi keadilan dan kesaksamaan kepada pelajar yang terdiri daripada berbagai tahap kebolehan dan kepintaran.

Pada hakikatnya, isu guru dikatakan mengajar hanya bagi tujuan mendapat keputusan cemerlang dalam peperiksaan sering menjadi polemik. Akibatnya ada yang mengemukakan soalan sama ada peperiksaan awam patut dikekalkan atau dimansuhkan. Seharusnya apa sahaja peperiksaan tidak memberi impak negatif kepada pelajar. Namun demikian cabarannya ialah bagaimanakah peperiksaan awam yang dilaksanakan dapat menguji kesemua kemahiran seperti yang dihasratkan dalam sistem pendidikan kita.
Justeru dengan pengenalan kaedah penilaian yang berwajah baru melalui peperiksaan PMR 2014 diharapkan akan menjadi perintis kepada pentaksiran dalam peperiksaan awam yang lain di masa hadapan.

© Utusan Melayu (M) Bhd

Nov 20, 2013

Sample SPM Biology essay question




Diagram 6.1 shows the part of the regulatory mechanism of oxygen and carbon dioxide contents in the body.
Based on the diagram, explain how the concentration of carbon dioxide in the blood is regulated during a vigorous activity.
[8 marks]
Sample answer
During vigorous activity, the concentration / the partial pressure of carbon dioxide increases as a result of active cellular respiration
Carbon dioxide reacts with water to form carbonic acid which results in a drop in the pH level of the blood and tissue fluid that bathing the brain
The drop in pH is detected by the central chemoreceptors in the medulla oblongata
and also detected by the peripheral chemoreceptors (carotid bodies and aortic bodies)
The central chemoreceptors and pheripheral receptors send nerve impulses to the respiratory centre in the medulla oblongata
The respiratory centre sends nerve impulses to the diaphragm and the intercostal muscles, causing the respiratory muscle to contract and relax faster
As a result, the breathing rate and ventilation rate increase causes more oxygen inhaled and the oxygen concentration return to the normal level
As excess carbon dioxide is eliminated from the body, the carbon dioxide concentration and pH value of the blood return to normal level.

ii) Explain why the pulse rate takes several minutes to return to normal after a vigorous activity.
[4 marks]
Sample answer
After vigorous activity, the pulse rate takes several minutes to return to normal because during the activity the oxygen intake is not able to meet the oxygen demand of the body.
Respiration has to take place anaerobically/anaerobic respiration occurs
As a result, lactic acid accumulates in the muscle.
So more oxygen is needed to oxidise the lactic acid and to provide the energy for the recovery of the muscle

Nov 9, 2013

The Lymphatic System

Closely connected with the blood and circulatory system, the lymphatic system is an extensive drainage system that returns water and proteins from various tissues back to the bloodstream. It is comprised of a network of ducts, called lymph vessels and carries lymph, a clear, watery fluid that resembles the plasma of blood. Some scientists consider this system to be part of the blood and circulatory system because lymph comes from blood and returns to blood, and because its vessels are very similar to the veins and capillaries of the blood system. Throughout the body, wherever there are blood vessels, there are lymph vessels, and the two systems work together.

How Are the Spleen and Lymphatic System Necessary for Living?
The entire lymphatic system flows toward the bloodstream, returning fluid from body tissues to the blood. If there were no way for excess fluid to return to the blood, our body tissues would become swollen. For example, when a body part swells, it may be because there is too much fluid in the tissues in that area. The lymph vessels collect that excess fluid and carry it to the veins through the lymphatic system.

This process is crucial because water, proteins, and other molecules continuously leak out of tiny blood capillaries into the surrounding body tissues. This lymph fluid has to be drained, and so it returns to the blood via the lymphatic vessels. These vessels also prevent the back flow of lymph fluid into the tissues.

The lymphatic system also helps defend the body against invasion by disease-causing agents such as viruses, bacteria, or fungi. Harmful foreign materials are filtered out by small masses of tissue called lymph nodes that lie along the network of lymphatic vessels. These nodes house lymphocytes (white blood cells), some of which produce antibodies, special proteins that fight off infection. They also stop infections from spreading through the body by trapping disease-causing germs and destroying them.

The spleen also plays an important part in a person's immune system and helps the body fight infection. Like the lymph nodes, the spleen contains antibody-producing lymphocytes. These antibodies weaken or kill bacteria, viruses, and other organisms that cause infection. Also, if the blood passing through the spleen carries damaged cells, white blood cells called macrophages in the spleen will destroy them and clear them from the bloodstream.

Basic Anatomy
The lymphatic system is a network of very fine vessels or tubes called lymphatics that drain lymph from all over the body. Lymph is composed of water, protein molecules, salts, glucose, urea, lymphocytes, and other substances.

Lymphatics are found in every part of the body except the central nervous system. The major parts of the system are the bone marrow, spleen, thymus gland, lymph nodes, and the tonsils. Other organs, including the heart, lungs, intestines, liver, and skin also contain lymphatic tissue.

Lymph nodes are round or kidney-shaped, and range in size from very tiny to 1 inch in diameter. They are usually found in groups in different places throughout the body, including the neck, armpit, chest, abdomen, pelvis, and groin. About two thirds of all lymph nodes and lymphatic tissue are within or near the gastrointestinal tract.

Lymphocytes are white blood cells in the lymph nodes that help the body fight infection by producing antibodies that destroy foreign matter such as bacteria or viruses. Two types are T-cells and B-cells. Some lymphocytes become stimulated and enlarged when they encounter foreign substances; these are called immunoblasts.

The major lymphatic vessel is the thoracic duct, which begins near the lower part of the spine and collects lymph from the lower limbs, pelvis, abdomen, and lower chest. It runs up through the chest and empties into the blood through a large vein near the left side of the neck. The right lymphatic duct collects lymph from the right side of the neck, chest, and arm, and empties into a large vein near the right side of the neck.

The spleen is found on the left side of the abdomen. Unlike other lymphoid tissue, red blood cells flow through it. It helps control the amount of blood and blood cells that circulate through the body and helps destroy damaged cells.

Normal Physiology
Lymph drains into open-ended, one-way lymph capillaries. It moves more slowly than blood, pushed along mainly by a person's breathing and contractions of the skeletal muscles. The walls of blood capillaries are very thin, and they have many tiny openings to allow gases, water, and chemicals to pass through to nourish cells and to take away waste products. Interstitial fluid passes out of these openings to bathe the body tissues.

Lymph vessels recycle the interstitial fluid and return it to the bloodstream in the circulatory system. They collect the fluid and carry it from all of the body's tissues and then empty it into large veins in the upper chest, near the neck.

Lymph nodes are made of a mesh like network of tissue. Lymph enters the lymph node and works its way through passages called sinuses. The nodes contain macrophages, phagocytic cells that engulf (phagocytize) and destroy bacteria, dead tissue, and other foreign matter, removing them from the bloodstream. After these substances have been filtered out, the lymph then leaves the nodes and returns to the veins, where it reenters the bloodstream.

When a person has an infection, germs collect in great numbers in the lymph nodes. If the throat is infected, for example, the lymph nodes of the neck may swell. Sometimes the phagocytic cells may not be able to destroy all of the germs, and a local infection in the nodes may result.

Because the lymphatic system extends to the far reaches of the body, it also plays a role in the spread of cancer. This is why lymph nodes near a cancerous growth are usually removed with the growth.

Diseases, Conditions, Disorders, and Dysfunction's
Because the lymphatic system branches through most of the parts of the body, it may be involved in a wide range of conditions. Diseases may affect the lymph nodes, the spleen, or the collections of lymphoid tissue that occur in certain areas of the body.

Disorders of the lymph nodes
Lymphadenopathy. Most lymph nodes in the body can't be felt easily unless they become swollen or enlarged. Lymphadenopathy is an increase in the size of a lymph node or nodes, most often as the result of a nearby infection (for example, lymphadenopathy in the neck might be the result of an infection of the throat). Less commonly (particularly in children), swelling of the lymph nodes can be due to an infiltration of cancerous cells. If lymphadenopathy is generalized (meaning that the swelling is present in several lymph node groups throughout the body), it usually indicates that the person has a systemic disease.

Lymphadenitis, or adenitis, is an inflammation (swelling, tenderness, and sometimes redness and warmth of the overlying skin) of the lymph node due to an infection of the tissue in the node itself. In children, this condition most commonly involves the lymph nodes of the neck.

Lymphomas. A group of cancers that arise from the lymph nodes, these diseases result when lymphocytes undergo changes and start to multiply out of control. The involved lymph nodes enlarge, and the cancer cells crowd out healthy cells and may form tumors (solid growths) in other parts of the body.

Disorders of the spleen
Splenomegaly (enlarged spleen). In children, the spleen is usually small enough that it can't be felt by pressing on the abdomen, but the spleen can enlarge to several times its normal size with certain diseases. There are many possible reasons for this including various blood diseases and cancers, but the most common cause in children is infection (particularly viral infections). Infectious mononucleosis, a condition usually caused by the Epstein-Barr virus (EBV), is one of many viral infections associated with an enlarged spleen. Children and teens with an enlarged spleen should avoid contact sports because they can have a life-threatening loss of blood if their spleen is ruptured.

Disorders of other lymphoid tissue
Tonsillitis. An extremely common condition, particularly in children, tonsillitis occurs when the tonsils, the collections of lymphoid tissue in the back of the mouth at the top of the throat, are involved in a bacterial or viral infection that causes them to become swollen and inflamed. The tonsils normally help to filter out bacteria and other microorganisms to aid the body in fighting infection. Symptoms include sore throat, high fever, and difficulty swallowing. The infection may also spread to the throat and surrounding areas, causing pain and inflammation (pharyngitis).

Glossary

antibodies:
chemicals produced by white blood cells to fight bacteria, viruses, and other foreign substances

immunoblasts:
Lymphocytes that become stimulated and enlarged when they encounter foreign substances

interstitial fluid:
fluid that leaks out of capillaries (the tiniest blood vessels) and bathes body tissues

lymph vessels:
channels or ducts that contain and convey lymph; also called lymphatics

lymph:
pale fluid that bathes the body tissues, passes into lymphatic vessels, and is discharged into the blood by way of the thoracic duct; it consists of a liquid resembling blood plasma and contains white blood cells

lymph nodes:
organized masses of lymphoid tissue that are distributed along the branching system of lymphatic vessels; they contain numerous lymphocytes and other cells that filter bacteria, dead tissue, and foreign matter from the lymph that flows through them

lymphocytes:
white blood cells

macrophages:
white blood cells that remove damaged cells from the bloodstream

spleen: 
organ found on the left side of the abdomen; it helps control the amount of blood and blood cells that circulate through the body and helps destroy damaged cells

thoracic duct:
major lymphatic vessel, which begins near the lower part of the spine and collects lymph from the lower limbs, pelvis, abdomen, and lower chest; lymph flowing through the duct eventually empties into a large vein in the upper chest and returns to the bloodstream.

Oct 27, 2013

Digestion, Absorption and Assimilation in human (SPM level)

Digestion
Mouth
Salivary glands produce saliva which contains salivary amylase. Starch is hydrolysed into maltose.
Stomach
Gastric glands produce gastric juice which contains enzyme pepsin and rennin. Proteins are hydrolysed into polypeptide. Caseinogens is converted into casein.
Duodenum
Liver produces bile. Bile emulsifies lipid. Pancreas produces pancreatic amylase, trypsin & lipase. Starch is hydrolysed into maltose. Polypeptide is hydrolysed into peptide. Lipid is hydrolysed into fatty acids & glycerol.
Ileum
Intestinal gland secretes intestinal juice which contains enzyme maltase, lactase, sucrase and erepsin. Maltase hydrolyses maltose into glucose & glucose. Lactase hydrolyses lactose into glucose and galactose. Sucrase hydrolyses sucrose into glucose & fructose. Erepsin hydrolyses peptide into amino acids

Absorption
Glucose, amino acids, Vitamins B & C are absorbed through facilitated diffusion into blood capillaries in the villi then into hepatic portal vein that leads to liver.

Fatty acids, glycerols, Vitamin ADEK are absorbed into lacteals (FA & G in the form of lipid droplets). Then lacteal converges into lymphatic system. Flows into right lymphatic duct & thoracic duct, finally enters subclavian veins into bloodstream.

Assimilation
In the liver
Liver synthesises plasma proteins from amino acids. Short supply of glucose – liver converts amino acids into glucose. Excess amino acids are broken down – deamination. Urea is produced & transported to kidney to be excreted.
Glucose is converted & stored in the liver. Blood sugar level falls, glycogen is converted back into glucose. Liver full of glucose – converted into lipids.
Lipids enter the heart through subclavian vein transported in the bloodstream to body cells.

In the cells
Amino acids – used for synthesising new protoplasm & repair damaged tissues. Build enzymes & hormones. Synthesise plasma membrane.
Glucose – oxidised to release energy (cellular respiration). Used for muscle contraction, synthesis of proteins. Excess glucose is stored in muscles (glycogen).
Lipids – phospholipids & cholesterol : components of plasma membrane
Fats are stored around organs act as cushions that protect organs from injuries. Excess fats are stored in adipose tissue as reserve energy. When body lacks glucose, fats are oxidised to release energy.