Form 5 Chapter 2 - Locomotion & Support (Part 1)

Here are the summary . .

1) Skeleton is the supporting structure which:

• enable movement when the bones interact with the skeletal muscles
• give shape & give mechanical support for the body
• protect the internal organs. (eg: the skull protects the brain, the ribcage protects the lungs & heart)
• provide firm base for attachment of skeletal muscles.
• produces blood cells - eg Red Blood Cells are formed in the bone marrow of the long bones.
• stores minerals, eg: calcium & phosphate.

2) 3 types of skeletons:

• Hydrostatic skeleton - consists of internal fluid within a confined spaces of the body & is kept under pressure surrounded by muscles. eg: earthworm.


• Exoskeleton - non-living structure (eg: cuticle) that covers the surface of the body. It support the internal organs, protect internal structure from damages. eg: grasshopper.


• Endoskeleton - consists of a rigid framework of bones & cartilage which muscles are attached. It maintains body shape, support soft body tissues, protecting internal organ from injury.
  

3) The Human Skeletal System.

a) Is divided into 2:

• i) Axial skeleton: the skull, the vertebral column, ribs & sternum (ribcage)
• ii) Appendicular skeleton: pectoral girdle, pelvic girdle, bones of the limb

b) A typical vertebra consists of:

• 1) Centrum (solid body)
• 2) Neural canal
• 3) several neural processes

• Function of the structure of a vertebra:
  1) Neural spine - provide surface for attachment of muscles & ligaments.
  2) Transverse process - same as above
  3) Neural arch - protects the spinal cord.
  4) Centrum - provides support, absorb shocks, resists compression.
  5) Neural canal - provides the passage for spinal cord.
  
  
  6) articular processes/facets - provides surfaces which articulates with the next vertebra/bones.

4) Axial skeleton:

• consists of the skull, the vertebral column, ribs, sternum.


• i) Skull
  a) consists of cranial bones (cranium) & facial bones.
  b) functions:
  1) the cranium enclose & protect the brain.
  2) the facial bones protect & support the entrance of digestive & respiratory system.
  
  
• ii) The vertebral column:
  
  
  
  a) consists of 33 small vertebrae.
  b) divided into 5 parts :
  1) Cervical vertebrae (neck, 7 vertebrae, C1-C7, C1 is known as atlas, C2 is known as axis)
  2) Thoracic vertebrae (thorax & chest region, 12 vertebrae, T1-T12)
  3) Lumbar vertebrae (lower back region, 5 vertebrae, L1-L5)
  4) Sacrum (lower back region, 5 sacral vertebrae, fused, S1-S5)
  5) Coccyx (tailbone, 4 fused caudal vertebrae)
  c) Intervertebral disc is located in between the vertebrae.
  
  
  1) made up of cartilage.
  2) functions: act as cushion to absorb shocks when moving, to reduce friction btw
  vertebrae.
  d) Function of vertebral column:
  1) support the head/skull & body
  2) encloses & protect the spinal cord
  3) provide base for attachment of muscles to the back
  4) ...
Question: why the vertebral column is made up of 33 vertebrae, not one long bone?
e)Main characteristic of vertebrae.
1) Cervical vertebra - has a pair of vertebrarterial canals, has thin centrum (plural: centra)
2) Thoracic vertebra - has long & backward/downward pointing neural spine, fairy large centrum, heart-shaped centrum.
3) Lumbar vertebra - thick & big centrum, short & broad neural spine, large & broad/flat transverse process.
4) refer pg 4 of yr notes.



• iii) the ribcage: (ribs & sternum)
  a) 12 pairs of ribs, articulate with the thoracic vertebrae at the back & join to the sternum in the front portion.
  b) ribs are flattened, curved bones.
  c) functions:
  1) protects the heart & lungs
  2) role in breathing.
  d) sternum is a flatenned, kite-shape bone, located at the anterior thoracic wall.

click here - to view animated human skeletal system

.... to be continued ....

Form 5 Chapter 1 - Transport (Part 4)

We have come to the last part of chapter 1. We shall look at the vascular tissues, the movement of water in plant, the factors that affecting the rate of transpiration (RoT) and the potometer experiment to study RoT.

1. The vascular tissues in dicotyledonous & monocotyledonous plant.

• You shld be able to draw & label the cross-section (XS) of stem & root for both dicot. & monocot. plant.
• Able to differentiate between XS of dicot. & monocot.
• Diagram below show the XS & longitudinal section of dicot stem

2. Xylem:

• fn? to transport water & dissolved mineral salts/ions from the roots upto the stem. And to provide mechanical support in woody plant.
  
• Consists of xylem vessels, tracheids, parenchyma, fibres.
  
• Question: How does the xylem vessels adapt to function efficiently in water transportation?

3. Phloem:

• fn? transport organic food substances (eg: glucose, sucrose, amino acids) both upwards & downwards to various parts of a plant.
  
• consists of sieve tube cells, companion cells, parenchyma cells, fibres.
  

4. Movements of water from roots up to the leaves are assisted by:

• (i) Root pressure:
  - Created by osmotic pressure of xylem sap which is created by dissoved minerals & sugars.
  - It is an upward force that push water (& mineral salts) up to a certain height in plants.
  
• (ii) Capillary action:
  - combine the forces of cohesion & adhesion of water molecule.
  - hold water column together in the capillary-sized xylem vessel.
  
• (iii) Transpirational pull
  - a pulling force/suction force that move water from leaves & stems & eventually from the xylem in the roots.
  - pulling force is created due to transpiration/evaporation of water vapour from the mesophyll cells & the cohesive property of water.

5. What is transpiration?

• It is the loss of water in the form of water vapour (evaporation) from a plant to the atmosphere.
• Through the stomata of leaves (main channel), the cuticles & lenticels (woody stem).
• Roles of transpiration? create tranpiration pull, produce cooling effect, supply water for photosynthesis, support through cell turgidity.

6. What is translocation?

• is the two-way transport (upwards & downwards) of dissolved organic solute in the phloem, from the leaves to other parts of the plant.

7. Opening & closing of stomata.

8. Factors affecting the RoT.

• Light intensity
• Temperature
• Air movement
• Relative humidity

9. Potometer experiment to study RoT.

• assumption made? rate of water uptake by the root = rate of transpiration.
• Precautionary steps? make sure all connections are airtight. the leafy shoot must be cut & connected in a basin of water.

A Gift of Life

A Gift of life - Organ donation

Do you know there are about millions of people in the world who die just because they fail to find a donor?

Donating organ is a big noble step, it will help SAVE lives.
Imagine this, your eyes can continue to see while your heart continues beating after your death. Isn’t that wonderful? You continue to live through someone else!

Frequently Asked Questions:

1. Who can be a donor?
   Anyone, young or old alike can sign up to be a donor. Individuals below 18 years of age will need parental/guardian consent.


2. What is organ donation?
   It is the gift of ones body parts after death for the purpose of transplantation. Transplantation is an operation which involves the replacement of diseased and defective organs and tissues with healthy ones from donors.
   This treatment helps save lives of people. Organ and tissues donation is the ultimate humanitarian act of charity.


3. What are the organs and tissues that can be donated?
   The commonly transplanted organs are kidneys, heart, liver, lungs and pancreas while transplantable tissues are eyes, bone, skin and heart valves.
   Thus a single donor can save the lives of a number of people.


4. How can i become a donor?
   Simply complete the donor pledge form and the donor card.
   Forward the form to the National Transplant Resource Centre and keep the donor card in your wallet. Inform your parents/family members.
   
   Useful links:
   1) Touching lives through precious gift.
   TransWeb.org – A resource on Transplantation and Donation, University of Michigan Transplant Center.
   
   2) Give Life, the transplant journey - animated
   
   3) National Transplant Resources Centre - Malaysia
   4) Sign up to be an organ donor - Malaysia
   
   More readings:
   1) Chiew Fong Neo donated a pair of kidneys, cornea, liver, lungs and heart valves after her death. click here or here.
   
   2) I believe my son’s heart beats on...
   
   3) More must take up this healthy practice
   
   4) 11,000 waiting for kidney transplants
   
   5) Heartbreaking wait in IJN

Form 4 Chapter 3 - Movement of sub across the PM (Part 1)

The plasma membrane (PM)

• PM is a boundary that separates the living cells from its surrounding.
  
• Function: to regulate the movement of substances in and out of the cell.
  
• It is selectively permeable/semi-permeable. Because it allows some substances to move across the PM easily/freely while others cannot.
  
• It is made up of Phospholipids (PL) bilayer & Proteins.

The PL bilayer:
i) Each PL molecule has a polar head (phosphate) and a pair of non-polar fatty acid tails.

ii) The polar head has hydrophilic property (“like water/attract water”), therefore both the heads of the lipid bilayer point towards the aqueous environments. One head pointing to the external environment (consists of interstitial fluid/tissue fluid) while the other head pointing towards the intracellular cytoplasm.

iii) The non-polar tails hv hydrophobic property (“dislike water/repel water”). The fatty acid tails of the PL bilayer point towards each other. This part form the selective barrier of the PM.

The proteins:
i) A few different types of protein can be found on the PM. Which include transmembrane protein, integral protein, peripheral protein.

ii) Transport protein is a transmembrane protein.


iii) 2 types of transport proteins are the carrier protein & pore protein.

• Besides, the PM also has cholesterol which makes the bilayer stronger, more flexible, more fluid.
  
• Glycoproteins are branching carbohydrate chains that attached to protein molecule while glycolipids consist of branching carbohydrate chain that attached to lipid molecule.
  

Fluid-mosaic model

1. which is proposed by Singer & G. Nicolson is used to describe the PM.
   
2. The model describes both the “mosaic” arrangement of proteins embedded throughout the lipid bilayers as well as the “fluid” movements of lipids & proteins alike.
   
3. The PM form a dynamic, flexible & fluid structure.
   
   
   
   

The Size & polarity of a molecule determine whether a molecule can or can’t pass through the PM easily.

• What is Polar & Non-polar molecule?
  The arrangement or geometry of the atoms in some molecules is such that one end of the molecule has a positive electrical charge and the other side has a negative charge. If this is the case, the molecule is called a polar molecule, meaning that it has electrical poles.
  Otherwise, it is called a non-polar molecule. Whether molecules are polar or non-polar determines if they will mix to form a solution or that they don't mix well together.
  Examples:
  i) Water & sucrose are both polar molecules, therefore they mix well to form sucrose solution.
  ii) Water (a polar molecule) & oil (a non-polar molecule) will not mix!
  To learn more about Polar & Non-polar molecules, click here.
  

What are the molecules that can move easily/ freely across the PM?
i) Lipid soluble molecules – eg: fatty acids, glycerols, steroids, vit. A,D,E,K.
ii) Water – small & polar
iii) Oxygen & carbon dioxide – small uncharged molecule.

What are the molecules that cannot move freely across the PM? It requires the use of transport proteins.
i) Large , polar & water-soluble molecule. eg: glucose, amino acid.
ii) Ionic/charged, small, water –soluble molecule. eg: sodium ions, calcium ions.

to be continued . . . see you again in the next lesson. take care.

Form 4 Chapter 2 - Cell structure & cell organisation (part 3)

this is the last part of chapter 2.

1) This part covers the cell organisation in both humans & animals as well as in plants.
a) You should know how to explain each level of cell organisation. Eg: what is a tissue? why the erector muscle is a tissue while skin is an organ?
b) What is differentiation process? it is a process of cell development that enables the cell to perform a specialised function.
c) Why multicellular organisatin needs cell organisation while unicellular organisation doesn't?
d) What are the 4 different types of tissues in humans/animals? Epithelial tissue, connective tissue, muscle tissue, Nerve tissue.
e) Examples of organs & systems in humans.
f) The 3 main types of tissues in plants? Epidermal tissue, ground tissue, vascular tissue.
g) The function of xylem & phloem.
h) The structural difference btw root hair cell & palisade mesophyll cell.
i) organs & systems in plants.

2) We also look at the importance of regulating the internal environment (eg: the temperature, pH value, osmotic pressure, glucose level, etc) with examples.
a) what is homeostasis?
b) You can refer to the table at the last page of your notes to learn more about this & other examples. For instance, when your body temperature (BT) drops below normal BT, one of the response is shivering, why?
c) you will learn more about negative feedback under chapter 3, form 5.


3) We end the chapter by looking at how different organelles involve in the production of enzyme (which is a protein) in the human body. Read note 7 (b), page 8.

A useful video is attached to help you understand the whole process of enzyme/protein synthesis.

Coronary artery bypass surgery

I hope this posting could answer some of your questions on bypass surgery.


The Coronary arteries (CA) supply blood, oxygen & nutrients to the heart/cardiac muscles. It extends over the surface of the heart & branches into smaller capillaries.

CA can become blocked due to a buildup of fatty deposits called plaques on the inner wall of these arteries (a condition known as atherosclerosis). This reduce the flow of blood causing cardiac muscles receiving less blood which can lead to coronary artery disease (CAD).

Partially blocked CA (can reduce blood flow) causing chest pain (angina). A total/complete blockage of CA (can stop blood flow) causing a heart attack (myocardial infarction).



Various drugs can be used to treat CAD. Sometime, heart patients might need to undergo surgery to restore & improve blood flow. What are the available options?

Option 1:
Coronary bypass surgery/Coronary artery bypass surgery/Coronary artery bypass graft.
This is normally used to treat patients with multiple narrowed/blocked coronary arteries. By using blood vessels taken from another part of the body (either artery from the chest or a vein from the leg), a heart surgeon creates a graft to bypass the narrowed/blocked arteries. This allow blood to flow around the narrowed/blocked artery.
Most conventional bypass surgery requires open-heart surgery which means the surgeon will cut open the sternum (ribcage) in order to gain access to the heart.

Minimal invasive bypass surgery such as keyhole heart surgery maybe used when only 1 or 2 coronary arteries need a bypass and they are located around the front of the heart. A heart surgeon will make a 3- to 5-inch-long incision (cut) in the left part of the chest between the ribs to allow the surgeon to reach the heart for grafting .



Option 2: Angioplasty & stent placement

watch video number 2.



Watch this video on Coronary artery bypass surgery





Video below is about Coronary artery angioplasty

Form 5 Chapter 1 - Transport (Part 3)

The Lymphatic System, the defence mechanism & AIDS.

The lymphatic system consists of lymphoid organs/tissues, lymphatic vessels (lymph capillaries, vessels, including the one-way valves), lymph, lymph nodes.





You shld know the followings:
1. How the interstitial fluid/tissue fluid is formed? Remember to include the high hydrostatic pressure!
2. The importance of IF?
3. How the lymph is formed?
4. The differences btw blood & lymph/IF.
5. What happens to the body parts if the lymph vessel is blocked?
6. What causes Elephantiasis/Lymphatic filariasis?
7. What are the functions of lymphatic system? The functions of lymph node?
8. How the lymph is returned back to the circulatory system? With the help of lymphatic valve and surrounding skeletal muscles.
9. Able to describe the pathway at which the lymph moves from the lymph cap. To the subclavian veins.
*refer to your notes/exercises to get the answers, if you still can’t, ask me during our lesson.

The formation of lymph








More pictures on Elephantiasis, click here.

Next, we shall look at our body’s defence mechanism, AIDS & CVD.

1. There are 3 lines of defence mechanisms in our body. First line & Second line of denfence being non-specific defence.
2. Second line of defence involves phagocytes (neutrophils & monocytes/macrophages) which can perform phagocytosis to kill & destroy invading pathogens.
3. Third line of defence is specific defence which involves the immune system where the lymphocytes produce antibodies.
4. You shld know what is antigen? Antibody?
5. The 4 different ways how antibody destroys the antigen. Remember L.O.A.N.
6. How the lymphatic system helps in the body’s defence mechanism.
7. The 4 different types of immunity. Active immunity? Passive immunity? Natural versus artificial? Including recognising the graphs.
8. Causes, transmission & prevention of AIDS. Click here.

9. CVD & steps to reduce the risk.

Second line of defence – Non-specific
Phagocytes carry out phagocytosis




Third line of defence - Specific Immunity
Lymphocytes producing Antibodies

Immune system, WBC, T-Cells, Cancer cells
If you can understand half of the content in this video, you are in A-level now.
Do not get discouraged if you could not understand this video, it is because the T-helper cells, T-cell, Natural Killer cells, B cells, etc. are not part of your SPM syllabus & i did not cover this as well. But it is good to learn & know more about your own body!

See you again.

The Known Universe - Best Video

Dear students,

this is a beautiful piece...developed by American Museum of Natural History. I got this video from Huffington post. The Milky Way is just a speck of dust in the universe....


About this film:
This film shows the known universe as mapped through astronomical observations. Every satellite, moon, planet, star and galaxy is represented to scale and in its correct, measured location according to the best scientific research to-date.
....... from the Himalayas through our atmosphere and the inky black of space to the afterglow of the Big Bang. Every star, planet, and quasar seen in the film is possible because of the world's most complete four-dimensional map of the universe, the Digital Universe Atlas that is maintained and updated by astrophysicists at the American Museum of Natural History.

Frequently Asked Questions on CANCER

Dear students,
We have many times discussed about cancer during our lessons, especially when we study cell division.

In Malaysia, according to the data released by Ministry of Health some years ago, 1 out of 4 Malaysians is suffering from one type of cancer, that work out to be 25%. While in the UK, 1 in 3 people develop cancer during their lives; and about 1 out of 2 people in the US had cancer. That's scary!

There are about 200 different types of cancer, many are rare cancer while 20 cancer are common cancer types. In Malaysia, the most common cancer among women are breast cancer followed by cervical cancer; for men, it is prostate cancer followed by lungs cancer.

I find this article useful to deal with many questions most of us have on CANCER topic. You can either read the article below or you can get this article from www.newscientist.com or click here.

1. What exactly is cancer?

Cancer is the uncontrolled growth and spread of abnormal cells. These rogue cells invade and destroy healthy tissues around them. Without treatment, cancer is likely to kill.

2. What causes cancer?

For cells to turn cancerous, some of their genes must be damaged through mutation. People may inherit mutations that predispose them to cancer, but damage to genes happens during life too - when cells are exposed to carcinogens such as tobacco, for example. But cells do not easily turn cancerous: at least three "hits", or different types of damage or mutation, are usually needed.

Three main gene groups are involved in changes that lead to cancer.
Firstly, proto-oncogenes normally instruct cells to grow and divide. If these are mutated, they can turn into oncogenes that instruct cells to continue dividing when they should not - imagine a car with the accelerator jammed down.
Secondly, tumour-suppressor genes normally stop cells from multiplying. If they are damaged however, like a car brake failing, cell division goes unchecked.
The third gene group normally helps in the repair of damaged DNA, but if they fail in their task, cells will copy damaged DNA into their daughter cells as they divide.

3. How does cancer develop in the body?

Once a cell has transformed into a cancerous state, it begins to divide and multiply. In most cancers, these cells form a lump, or tumour, that can invade surrounding tissue. The tumour puts pressure on healthy cells around it, and may also secrete enzymes to break down that tissue.

By the time a tumour is detected, it will contain billions of cells. Cancerous cells produce growth factors that stimulate blood vessels to grow near them, enabling the tumour to build itself a nourishing blood supply. At later stages of the disease, cells break off the tumour and spread via blood or lymph vessels to seed secondary tumours in other parts of the body.

4. How common are different types of cancer?

After heart disease, cancer is the second most common cause of death in Western societies. In your lifetime, the risk of developing some kind of cancer is greater than one in three. There are perhaps 200 different types of cancer, but many are rare.

The most commonly diagnosed are non-melanoma skin cancers, many of which are easily treated. For men, the next most common three types of cancer are prostate, lung and bowel. For women, breast cancer is most prevalent, followed by lung and bowel. The number-one killer among all these is lung cancer, for both men and women. Outside of the West, liver cancer and cervical cancer are among the most common types.


photo above shows breast cancer

5. What factors may increase my risk of developing cancer?

Cancer is rarely triggered by a single factor. It usually results from an interplay between environmental factors - such as carcinogens or viruses - on one hand, and factors within the body - such as hormones and inherited genes - on the other. Among numerous carcinogens, tobacco towers over the rest as the biggest killer. In the US, for example, it is responsible for 30% of all cancer deaths and 87% of lung cancer deaths. Researchers estimate that a further one-third of cancer deaths can be blamed on other "lifestyle" factors, such as diet and obesity.


The incidence of lung cancer is highly correlated with smoking. Source:NIH.

Viruses can cause cancer by interfering with the genetic instructions in cells. The worst culprits for this are the hepatitis B virus, which can cause liver cancer, and the human papilloma virus, which can cause cervical cancer. The risk of developing cancer increases with age, simply because cancerous changes in cells usually take years to occur. Two of every three people diagnosed with cancer in the UK each year are over the age of 65.

6. What are some of the most promising new treatments for cancer?

Twentieth-century treatments for cancer - which relied mostly on poisoning tumours through chemotherapy or burning them away with radiation - remain the major weapons in our arsenal. But newer, more sophisticated treatments are starting, slowly, to make an impact.

7. Why does cancer appear so much more common today than in history?

More people are surviving into old age - not only in industrialised countries but worldwide - so there are more cases of cancer. As non-Western nations such as China and India smoke ever-more tobacco, worldwide prevalence could soar to a projected 16 million cases per year by 2020 - compared with 11 million cases today.

8. Do experts believe we could ever have a universal cure for cancer?

No. There are so many different types of cancer, and so many causes, that the idea of a universal cure is too simplistic. However, many experts are hopeful that a combination of better treatments and earlier detection, could whittle down death rates significantly. Some experts talk about "managing" cancer so that it becomes a chronic long-term condition, and not a direct threat to life.

To read more on cancer, click the links below.

1) National Cancer Institute - US

2) Get the facts about tobacco & cancer.
* secondhand smoke

3) Cancer Research UK

4) Oprah - The Breast Cancer Monologue (+ real breast cancer stories)

5) How to perform a breast self-exam - (to detect lump)

Would you choose your child's gender?

this is one of the many interesting topics that many of us would like to debate on....

With the advancement in genetic screening techniques, now parents can choose the gender of their child more accurately. Many experts argue whether this technology should be used for non-medical reason.

Let's look at the very reason why it is important for some parents to choose their child's gender.
For parents who carry genetic diseases/defects in their genes (sex-linked genes - genes carry in the sex chromosome X), they wouldn't want their children to also inherit these genetic illnesses. Therefore, it is crucial to choose the gender of the child based on what we called medical reasons/purposes.


How can this be achieved?



About two decades ago, a method called pre-implantation genetic diagnosis (PGD) was originally developed which enabled embryos to be tested/screened for genetic diseases. This method has been used since then to prevent parents from passing down their defective genes to their offsprings.

In PGD, the embryos are tested for genetic disorders and only those that are free of disease are transferred to the mother's uterus. This method requires In vitro fertilisation (IVF) or more commonly known as 'test tube baby' method where ova are fertilised by sperms outside a woman's body. Using PGD for gender selection is banned in many countries, but it is legal in many states in the US. IVF is a costly method to overcome infertility in married couple.

The diagram below shows how IVF is done.

To learn more about IVF, click on video below.

To learn more about PGD, click here.

Now, should PGD be used in gender selection which is a non-medical reason? Some argue that it helps to create 'family balance' while others think that we should not be playing ' God'. Some argue that this might lead to gender imbalance in societies with a traditional preference for boys, such as China which has one-child policy imposed since 1980; or India which has an age-old bias for boys.

What is your view on this?



*China has 32 million more young men than young women, which experts say could trigger a slew of social problems. To read more on gender imbalance in China, go to link below.


For more reading, click the appropriate links.

1) The genetic promise - a must watch video!

2) 29 stories on IVF - click here

3) Designer babies - can babies be made-to-order? - click here

4) China's population imbalance - click here

5) IVF video (we will learn this in chapter 4 form 5).