- 1 Management and Prevention Strategies for Non-communicable Diseases (NCDs) and Their Risk Factors
- 1.1 (a) Cancer
- 1.2 Causes of Cancer
- 1.3 General Symptoms of Cancer
- 1.4 Ways of Cancer Spreads
- 1.5 Treatment of Cancer
- 1.6 Cancer Develops Because of DNA Changes
- 1.7 (b) Diabetes Incipidus
- 1.8 (c) Diabetes Mellitus (Blood Sugar)
- 1.9 General Symptoms of Diseases
- 1.10 Diseases Causing Pathogen
- 1.11 General Preventive Measures for Control of Disease
- 1.12 Parasites Causing Human Disease
Advances in technology have expanded the scope of Biology Topics we can investigate and understand.
Management and Prevention Strategies for Non-communicable Diseases (NCDs) and Their Risk Factors
Cell division is a gene-controlled process. It has been discovered that an enzyme telomerase controls cell division. Generally, the enzyme telomerase in active condition causes cells to divide and in its inactivity stops division. In multicellular organisms, normal cell division causes growth, development of various organs, and repair of wounds. However, in some cases, it was observed that some cells start dividing in an uncontrolled manner which ultimately leads to cancer. Therefore, an uncontrolled increase in the number of cells without differentiation is known as cancer.
These cells which divide rapidly without any control, are known as neoplastic cells. Unwanted organ growth due to the division of the neoplastic cell is known as neoplastic growth or tumour. Tumour may be benign or malignant. If the division of the neoplastic cells is limited at the site of origin and the tumour produced as such is called a benign tumour. On the other hand, if neoplastic cells are migrated from their site of origin and produced secondary tumours at sites other than the origin, it is called a malignant tumour.
In our body, normal cell due to genetic defect is converted into a cancer cell. The main criterion of these cells is to divide vigorously beyond control. However, when a normal body cell is converted into a cancer cell massive changes in its behavioural and morphological characteristics are observed.
Different Types of Cancers are Shown in the Table Below:
|Type||Generic Name||Example and Nature|
|1. Cancer of epithelial tissue||Carcinoma||Squamous carcinoma – Skin Cancer, Adenocarcinoma – Breast Cancer, Cancer of the urinary bladder|
|2. Cancer of connective tissue and mesenchyme||Sarcoma||Osteo Sarcoma – Bone Cancer, Chondro Sarcoma – Cartilage Cancer, Fibro Sarcoma – Fibroblast Cancer|
|3. Cancer of the reticuloendothelial system||(a) Leukemia
|Myeloid leukemia Hodgkin’s lymphoma|
|4. Cancer of nerve tissue||Neuroblastoma||Retinoblastoma – Cancer of the retina, Meningioma – Cancer of the meninges|
|5. Cancer of foetus tissue||Teratoma||Cancer of embryo|
Causes of Cancer
A normal healthy cell bears proto-oncogene in its gene complement for normal activities like cell division and growth. This proto-oncogene when mutated to oncogene causes cancer. A few kinds of DNA viruses, RNA viruses; carcinogenic chemicals like nicotine, benzopyrene, etc; Physical agents like X-ray, g-ray, etc., are believed to be responsible for causing cancer. Cancer is a group of diseases that can cause almost any sign or symptom. The signs and symptoms will depend on where the cancer is, how big it is, and how much it affects the organs or tissues. If cancer has spread (metastasized), signs or symptoms may appear in different parts of the body.
As cancer grows, it can begin to push on nearby organs, blood vessels, and nerves. This pressure causes some of the signs and symptoms of cancer. If the cancer is in a critical area, such as certain parts of the brain, even the smallest tumor can cause symptoms. But sometimes cancer starts in places where it will not cause any signs or symptoms until it has grown quite large. Cancers of the pancreas, for example, usually do not cause symptoms until they grow large enough to press on nearby nerves or organs (this causes back or belly pain). Others may grow around the bile duct and block the flow of bile. This causes the eyes and skin to look yellow (jaundice). By the time pancreatic cancer causes signs or symptoms like these, it’s usually in an
advanced stage. This means it has grown and spread beyond the place it started the pancreas.
Cancer may also cause symptoms like fever, extreme tiredness (fatigue), or weight loss. This may be because cancer cells use up much of the body’s energy supply, or they may release substances that change the way the body makes energy from food. Or the cancer may cause the immune system to react in ways that produce these signs and symptoms. Sometimes, cancer cells release substances into the bloodstream that cause symptoms that are not usually linked to cancer. For example, some cancers of the pancreas can release substances that cause blood clots in the veins of the legs. Some lung cancers make hormone-like substances that raise blood calcium levels. This affects nerves and muscles, making the person feel weak and dizzy.
Important Characteristics of Malignant Cell or Cancer Cell:
- Cancer cells are able to survive and divide for an indefinite period, while normal cells are able to divide approximately fifty times.
- In most cases, cancer cells become round-shaped.
- Normal cells when come in contact with one another stop growth and division. Cancer cells even after contact continue to grow and divide. This is called loss of contact inhibition.
- Apoptosis is the process of cell death according to a definite plan. This is not found in cancer cells.
- Generally, the gradual destruction of DNA is the only cause of cell death. But DNAs of malignant cells are not affected by various chemical substances and radioactive radiation. That is why apoptosis is not observed in cancer cells.
- Malignant cells lose the power of differentiation.
- Like normal cells, malignant cells are not dependent on various growth-promoting factors for growth.
- Invasiveness is the most important characteristic of malignant cells.
- Reduced cellular adhesion is observed in malignant cells. As a result, these cells fail to adhere to one another.
- The proto-oncogene of normal cells is converted into an oncogene in cancer cells. In some cases, tumour suppressor gene of the normal cells on mutation may produce cancer cells.
- Structural deformities of chromosomes are observed in cancer cells.
- Information received from neighboring cells can not produce any response in the cancer cell.
- The existence of cancer cells is noticed anywhere in the body because cancer cells break off from their source and spread throughout the body by blood and lymph circulation. This is called metastasis.
- Generally, cancer cell carries an abnormal number of chromosomes. In most cases, aneuploid condition is observed.
- These cells may influence the neighbouring normal cell and convert them into cancer cells.
Microscopic Characteristics of Cancer Cell:
- Nucleolus is prominent and may be more than one in number.
- Mitochondria and other cellular organelles are fewer in number.
- The nucleo-cytoplasmic ratio is more.
- The endoplasmic reticulum is less in number.
- Desmosomes of cancerous epithelial cells are abnormal.
- The same type of cells have different shapes and sizes.
- A tendency of reduced cohesion is observed in cancerous cells.
- Nucleolus may be large and hypersensitive to pigment.
- The structure of the nuclear membrane may be irregular.
- Cells adjacent to cell membranes may have reduced adhesion power.
Physiological Characteristics of Cancer Cell:
- Surfaces of plasma membrane have an excessive negative charge.
- The concentration of Ca2+ is reduced.
- Plasma membranes have abnormal glycoprotein and glycolipid.
- Excess microfilaments are found due to the changed structural process of the actin filament.
- Some enzymes secreted from malignant cells may split collagen and other protein such as proteoglycan.
Chromosomal Characteristics of Cancer Cell:
- Malignant cells are generally aneuploid cells having chromosomes more than or less than a diploid number and with various chromosomal defects in nature.
- Cells exhibit abnormal karyotypes.
- In the case of chronic granulocytic leukemia especially in some individuals long arm of the 22nd chromosome is shorter than the normal chromosome.
- This abnormal chromosome is called the Philadelphia chromosome. This is not only an example of general deletion because here translocation also occurs.
- The separated chromosomal segment is attached to the short arm of the ninth chromosome.
- In the case of one type of kidney cancer called Wilms tumour, the deletion takes place in the short arm of the eleventh chromosome.
- In the case of cancer called retinoblastoma, deletion is identified in the long arm of the thirteenth chromosome.
What are Some General Signs and Symptoms of Cancer?
You should know some of the general signs and symptoms of cancer. But remember, having any of these does not mean that you have cancer many other things cause these signs and symptoms, too. If you have any of these symptoms and they last for a long time or get worse, please see a doctor to find out what’s going on. The symptoms are usually caused by the effect of cancer on the part of the body where it is growing, although the disease can cause more general symptoms such as weight loss or tiredness. It is advisable that anyone experiencing unusual symptoms that are not normal for more than a few weeks should seek medical attention. There are more than 200 different types of cancer with a wide range of different signs and symptoms, making it difficult to produce a definitive list.
Typical Symptoms of Cancer Include:
- The presence of an unusual lump in the body.
- Changes in a mole on the skin.
- A persistent cough or hoarseness.
- A change in bowel habits, such as unusual diarrhea or constipation.
- Difficulty in swallowing or continuing indigestion.
- Any abnormal bleeding, including bleeding from the vagina or blood in urine or feces.
- A persistent sore or ulcer.
- Difficulty in passing urine.
- Unexplained weight loss.
- Unexplained tiredness or fatigue.
- Skin changes such as an unexplained rash or unusual texture.
- Unexplained night sweats.
General Symptoms of Cancer
1. Unexplained Weight Loss:
Most people with cancer will lose weight at some point. When you lose weight for no known reason, it is called an unexplained weight loss. An unexplained weight loss of 10 pounds or more may be the first sign of cancer. This happens most often with cancers of the pancreas, stomach, oesophagus (swallowing tube), or lung.
Fever is very common with cancer, but it more often happens after the cancer has spread from where it started. Almost all patients with cancer will have a fever at some time, especially if cancer or its treatment affects the immune system. (This can make it harder for the body to fight infection.) Less often, fever may be an early sign of cancer, such as blood cancers like leukemia or lymphoma.
Fatigue is extreme tiredness that does not get better with rest. It may be an important symptom as cancer grows. It may happen early, though, in some cancers, like leukemia. Some colon or stomach can cause blood loss that’s not obvious. This is another way cancer can cause fatigue.
Pain may be an early symptom of some cancers like bone cancer or testicular cancer. A headache that does not go away or get better with treatment may be a symptom of a brain tumor. Back pain can be a symptom of cancer of the colon, rectum, or ovary. Most often, pain due to cancer means it has already spread (metastasized) from where it started.
5. Skin Changes:
Along with cancer of the skin, some other cancers can cause skin changes that can be seen. These signs and symptoms include:
- Darker-looking skin (hyper-pigmentation)
- Yellowish skin and eyes (jaundice)
- Reddened skin (erythema)
- Itching (pruritus)
- Excessive hair growth
6. Signs and Symptoms of Certain Cancers:
Along with the general symptoms, you should watch for certain common signs and symptoms that could suggest cancer. Again, there may be other causes for each of these, but it’s important to see a doctor about them as soon as possible.
7. Change in Bowel Habits or Bladder Function:
Long-term constipation, diarrhea, or a change in the size of the stool may be a sign of colon cancer. Pain when passing urine, blood in the urine, or a change in bladder function (such as the need to pass urine more or less often than usual) could be related to bladder or prostate cancer. Report any changes in bladder or bowel function to a doctor.
8. Sores that do not Heal:
Skin cancers may bleed and look like sores that don’t heal. A long-lasting sore in the mouth could be oral cancer. This should be dealt with right away, especially in people who smoke, chew tobacco, or often drink alcohol. Sores on the penis or vagina may either be signs of infection or early cancer and should be seen by a health professional.
9. White Patches Inside the Mouth and White Spots on the Tongue:
White patches inside the mouth and white spots on the tongue may be leukoplakia. Leukoplakia is a pre-cancerous area that is caused by frequent irritation. It is often caused by smoking or other tobacco use. People who smoke pipes or use oral or spit tobacco are at high risk for leukoplakia. If it’s not treated, leukoplakia can become mouth cancer. Any long-lasting mouth changes should be checked by a doctor or dentist right away.
10. Unusual Bleeding or Discharge:
Unusual bleeding can happen in early or advanced cancer. Coughing up blood in the sputum (phlegm) may be a sign of lung cancer. Blood in the stool (which can look like very dark or black stool) could be a sign of colon or rectal cancer. Cancer of the cervix or the endometrium (lining of the uterus) can cause abnormal vaginal bleeding. Blood in the urine may be a sign of bladder or kidney cancer. A bloody discharge from the nipple may be a sign of breast cancer.
11. Thickening or Lump in the Breast or Other Parts of the Body:
Many cancers can be felt through the skin. These cancers occur mostly in the breast, testicles, lymph nodes (glands), and the soft tissues of the body. A lump or thickening may be an early or late sign of cancer and should be reported to a doctor, especially if you’ve just found it or noticed it has grown in size. Keep in mind that some breast cancers show up as thickened skin rather than the expected lump.
12. Indigestion or Trouble Swallowing:
Indigestion or swallowing problems that don’t go away may be cancer of the oesophagus (the swallowing tube that goes to the stomach), stomach, or pharynx (throat). But like most symptoms in this list, they are most often caused by something other than cancer.
13. Recent Change in a Wart or Mole or Any New Skin Change:
Any wart, mole, or freckle that changes colour, size, or shape or loses its sharp border should be seen by a doctor right away. Any other skin changes should be reported, too. A skin change may be a melanoma that, if found early, can be treated successfully.
14. Nagging Cough or Hoarseness:
A cough that does not go away may be a sign of lung cancer. Hoarseness can be a sign of cancer of the voice box (larynx) or thyroid gland.
15. Other Symptoms:
The signs and symptoms listed above are the more common ones seen with cancer, but there are many others that are not listed here. If you notice any major changes in the way your body works or the way you feel especially if it lasts for a long time or gets worse – let a doctor know. If it has nothing to do with cancer, the doctor can find out more about what’s going on and if needed, treat it. If it is cancer, you’ll give yourself the chance to have it treated early, when treatment works best.
How a Cancer Spreads:
This point tells you about how cancer spreads. There is information about
- Primary and secondary cancer
- How cancer spreads
- Local spread
- Through the blood circulation
- Through the lymphatic system
- Why do cancers spread where they do
Primary and Secondary Cancer:
The main reason cancer can be difficult to cure is that it can spread to a different part of the body from where it started. The cancer that grows where it first started in the body, is called the ‘primary cancer’. The place a cancer spreads to and then starts growing, is called the ‘secondary cancer’ or ‘metastasis’. Cancer that has spread to another part of the body, is called metastatic cancer.
Ways of Cancer Spreads
In order to spread, some cells from primary cancer must break away, travel to another part of the body and start growing there. Cancer cells do not stick together as well as normal cells do. They may also produce substances that stimulate them to move. But how do cancer cells travel through the body? There are three main ways cancer spreads Local spread, Through the blood circulation, Through the lymphatic system.
1. Local Spread:
The cancer grows directly into nearby body tissues.
2. Through the Blood Circulation:
In order to spread, the cancer cell must first become detached from the primary cancer. It must then move through the wall of a blood vessel to get into the bloodstream. When it is in the bloodstream, it is swept along by the circulating blood until it gets stuck somewhere, usually in a very small blood vessel, called a capillary. Then it must move back through the wall of the capillary and into the tissue of the organ close by. There it must start to multiply to grow a new tumour.
As you can see, this is a complicated journey. Most cancer cells do not survive it. Probably, out of many thousands of cancer cells that reach the blood circulation only one will survive to form a secondary cancer or metastasis. Some cancer cells are probably killed off by the white blood cells in our immune system. Other cancer cells may die because they are battered around by the fast-flowing blood. Cancer cells in the circulation may try to stick to platelets to form clumps to give themselves some protection. This may also help them to be filtered out in the next capillary network they can then move into the tissues to start a secondary tumour.
3. Through the Lymphatic System:
In this way a cancer spreads through the lymphatic system is very similar to the way it spreads through the bloodstream. The cancer cell must become detached from the primary tumour. Then it travels in the circulating lymph fluid until it gets stuck in the small channels inside a lymph node. There it begins to grow into secondary cancer.
Why Cancers Spread Where They Do?
Whether it is in the blood or the lymph, the moving cancer cell stops in the first place it gets stuck. In the bloodstream, this is often the first capillary network it comes across. The blood flow from most body organs goes from the organ to the capillaries in the lungs. So not surprisingly, the lungs are a very common place for cancer to spread to.
The blood from the organs of the digestive system goes through the capillaries of the liver before going back to the heart and then to the lungs. So it is common for digestive system cancers to spread to the liver. In fact, the liver is the second most common area of cancer spread. Some cancers show unexpected patterns of spread. For example, prostate cancer often spreads to the bones. Scientists are still investigating why this happens.
Cancer cells often get trapped in the group of lymph nodes closest to the tumour. During cancer surgery, the surgeon may remove the main lymph nodes close to the area of the cancer. For example, a surgeon operating to remove breast cancer will remove one or more of the lymph nodes from under the arm. These are the first lymph nodes that the lymph draining from the breast goes to and so are most likely to contain any escaping cancer cells.
The first nodes that lymph draining from a tumour reaches are called the sentinel lymph nodes. After removing sentinel nodes, the surgeon will send them off to the lab to see if they contain cancer cells. Finding out whether the cancer has spread into the lymph nodes gives the doctor some information about whether further treatment is needed.
Micrometastasis are areas of cancer spread (metastasis) that are too small to see. If there are individual cells or even small areas of growing cells elsewhere in the body, no scan is detailed enough to show them.
For a few types of cancer, blood tests can detect certain proteins released by the cancer cells. These may give a sign that there is metastasis too small to show up on a scan. But for most cancers, there is no blood test that can say whether the cancer has spread or not. For most cancers, the doctor can only say whether it is likely or not that a patient has micrometastasis. This ‘best guess’ may be based on the following factors.
- Previous experience of many other patients treated in the same way. Doctors naturally collect and publish this information to help each other.
- Whether cancer cells are found in the blood vessels in the tumour removed during surgery (for example in testicular cancer).
- If they are found then cancer cells are more likely to have reached the bloodstream and spread to somewhere else in the body.
- The grade of the cancer – the higher the grade, the more aggressive the cancer and the more likely that cells have spread.
- Whether lymph nodes removed during an operation contained cancer cells (for example in breast cancer or bowel cancer).
- If the lymph nodes contained cancer cells this shows that cancer cells have broken away from the original cancer.
- But there is no way of knowing whether they have spread to any other areas of the body or not.
This information is important. If the doctor thinks it is likely that are micrometastasis, they may offer further treatment such as chemotherapy, radiotherapy, biological therapy, or hormone therapy. Treatment after surgery is called adjuvant treatment. The aim is to kill the areas of cancer cells before they grow big enough to be seen on a scan. Some doctors call this ‘belt and braces treatment. In other words, the treatment is to try to make sure the cancer does not come back. But no one can know for sure if all the cancer cells have been destroyed when someone has finished treatment. Or if the cancer has spread in the first place. It is this uncertainty that can make cancer difficult to cope with for many people, even if they seem to have been successfully treated.
When cancer in one part of the body spreads to another part of the body, the outlook for a patient is rarely positive. Given how frequently this happens, it may come as a surprise to know that the spread of cancer from one person to another is actually incredibly rare.
“Generally, in good people who are not immune-suppressed, getting cancer from one individual to another via blood is very unlikely,” says Dr Ashley Ng from the cancer and hematology division of the Walter and Eliza Hall Research Institute.
Several large studies have been conducted to specifically examine this question.
“One study looked at about one-third of a million blood recipients, of which about 12,000 were at risk of being transfused blood from a donor with sub-clinical cancer and they found no increase in risk,” says Ng.
This evidence fits with what we know about how the immune system responds to foreign matter. In the case of blood transfusion, blood type (such as A, B, AB, and O) is carefully matched between the donor and recipient so the recipient’s immune system doesn’t see the red blood cells as foreign and destroys the red blood cells.
If there are cancer cells in that blood, there are other unique proteins on the surface of those cells that in the majority of cases, mark them out as foreign. The recipient’s immune system, therefore, identifies them and destroys them before they can settle in. Blood banks also carefully screen donors to rule out anyone who’s had cancer, just in case. But if the recipient’s immune system isn’t working well. for example, if they are immune-suppressed by illness or because they have had an organ transplant which requires immunosuppression of the recipient to prevent rejection of the donor organ then they are less likely to be protected by this mechanism.
“When we do blood transfusion into immunocompromised people, we can irradiate the actual red cell units,” says Ng. This is done already to reduce the risk of the transfused white blood cells attacking the recipient’s body something called graft versus host disease. This irradiation can also kill any sub-clinical cancer cells which may be circulating in the donor’s blood.
Organ Donation and Pregnancy:
In the case of solid organ transplants, such as liver or kidneys, there have been reports of cancer being unknowingly transmitted from the donor to the recipient. While donors and their organs are screened for cancer it can, on very rare occasions, slip through undetected. However, the risk is incredibly low around 0.015 percent, according to Australian guidelines. Finally, there is also evidence that cancer can be transmitted from a mother to her unborn child but again, this is very rare.
“In review back in 2003, there were only 14 reported cases in the literature where the mother had a type of cancer and the child also developed the same cancer, “says Ng. The cancers documented generally included aggressive types of cancer and unfortunately likely to be during advanced stages of disease in the mother. Such cancers included leukemia, melanoma, solid organ cancers such as lung, and sarcomas.”
Transmission between mother and foetus can occur because of the unusual immunological relationship that exists between the two during pregnancy – one in which the foetal immune system is still relatively immature and may tolerate foreign cells. However, the transmission of maternal cancer to the foetus is very unlikely as this requires the cancer cells to be traveling in the mother’s circulation, and in addition, cross the placental barrier to the foetus. In most pregnancies, unless this placental barrier is breached such as with accidental trauma, foetal circulation remains completely separate from the mother’s blood supply.
Then there are the very rare, very unusual cases of person-to-person transmission, such as the surgeon who contracted cancer from a patient after accidentally cutting himself during surgery and transmission of colon cancer through a needlestick injury. In the case of the surgeon, it turned out that the cancer itself had performed a genetic miracle and incorporated some of the surgeon’s genes into itself. Dr. Ng suggests that the explanation for these rare cases could also be related to immunological similarities between the donor and recipient or that the cancer cells somehow were able to evade immune detection.
Treatment of Cancer
The main treatments are
- Surgery: Cancerous tissue or tumour is removed by surgery.
- Radiation therapy: In this process, rays are used to kill tumour cells as they do not affect the nearby cells.
- Chemotherapy: Some anticancer drugs are used in chemotherapy. These drugs kill dividing cells and stop to divide.
- Most anticancerous drugs have side effects like hair loss, anaemia, vomiting, etc.
- Immunotherapy: In this technique, the immune system is induced against the tumour cells.
- A periodic checkup is required because the cancer may return sometime after treatment.
Is Cancer Contagious?
No, cancer is not contagious. A healthy person cannot “catch” cancer from someone who has it. There is no evidence that close contact or things like sex, kissing, touching, sharing meals or breathing the same air can spread cancer from one person to another.
Cancer cells from one person are generally unable to live in the body of another healthy person. A healthy person’s immune system recognizes foreign cells and destroys them, including cancer cells from another person. There have been a few cases in which organ transplants from people with cancer have been able to cause cancer in the person who got the organ. But there’s a major factor that makes this possible – people who get organ transplants take medicines that weaken their immune systems. This must be done so their immune system won’t attack and destroy the transplanted organ. This seems to be the main reason that cancer in a transplanted organ can, in rare cases, give cancer to the person who gets the organ. Organ donors are carefully screened to help keep this from happening.
But recent studies have shown that cancer is more common in people who get solid organ transplants than in people who don’t even when the donor doesn’t have cancer. This is also probably due to the drugs that are used to reduce the risk of transplant rejection. These drugs weaken the immune response and make the immune system less able to recognize and attack pre-cancer cells and the viruses that can cause cancer. Even if a woman has cancer during pregnancy, cancer rarely affects the foetus directly. Some cancers can spread from the mother to the placenta (the organ that connects the mother to the foetus), but most cancers affect the foetus itself. In a few very cases, melanoma (a form of skin cancer) has been found to spread to the placenta and the foetus.
Germs can be Contagious:
We know that germs (mainly bacteria and viruses) can be passed from person to person through sex, kissing, touching, and sharing or preparing food. Some can even be spread by breathing the same air. But germs are much more likely to be a threat to a person with cancer than to a healthy person. This is because people with cancer often have weakened immune systems (especially when they are getting treatment), and they may not be able to fight off infections very well.
Germs Can Affect Cancer Risk:
There are some germs that can play a role in the development of certain types of cancer. This may lead some people to wrongly think that “cancer is catching.”
Differences between Normal Cells and Cancer Cells:
|Normal Cell||Cancer Cell|
|1. Increase in cell number is within a limit.||1. Increase in cell number is beyond control.|
|2. The plasma membrane remains in a semi-liquid state due to the presence of glycoprotein and glycolipid in a definite amount.||2. The plasma membrane of cancerous cells remains in a more liquid state because the amount of glycoprotein and glycolipid is found in a changed ratio.|
|3. The cellular skeleton of normal cells remains in such a state that they are oval to look at.||3. Due to defective cellular skeleton cells are almost round-shaped.|
|4. Glycolysis takes place at a normal rate, as a result, energy production and energy loss is well balanced.||4. Glycolysis takes place at a higher rate, as a result, rapid loss of energy is observed.|
Cancer Develops Because of DNA Changes
Most cancers do not appear to be caused or affected by infectious agents. Cancer develops because of mutations (changes) that take place in a person’s DNA, the genetic blueprint in each cell. These changes are inherited or developed during life. Some changes happen for no known reason, while others are due to environmental exposures, such as sun (UV) damage or cigarette smoke, Some viruses are known to directly cause mutations in DNA that can develop into cancer. Other germs promote cancer indirectly by causing chronic (long-term) inflammation, or by weakening a person’s immune system.
Differences between Benign and Malignant Tumours:
|Benign Tumour||Malignant Tumour|
|1. This is restricted to a particular site of the body.||1. This spreads throughout the body from the source.|
|2. Rate of overgrowth is less.||2. Rate of overgrowth is high.|
|3. Benign tumour does not cause much harm for the body.||3. Malignant tumour is very much harmful and may lead to death.|
|4. Metastasis is not observed.||4. Metastasis is its characteristic feature.|
|5. Can be cured by surgical treatment.||5. Remedial measure is still unknown.|
(b) Diabetes Incipidus
Hyposecretion of ADH or vasopressin from the posterior pituitary caused diabetes insipidus. Deficiency of ADH cause less reabsorption of water from the renal tubule, which results in excess urine formation and excretion but glucose does not appear in the urine.
(c) Diabetes Mellitus (Blood Sugar)
Diabetes mellitus is one physiological abnormality in humans when the utilization and metabolism of glucose is impaired in the body. We get glucose from different food staff and that glucose is utilized in the cell for the production of energy that we need for the performance of different daily activities. If glucose level becomes high in the blood that glucose is stored in muscle cells and that stored glucose is utilized in necessity. In this storage of glucose one hormone, insulin, produced in our pancreas helps. But if somehow insulin becomes deficient in the body excess sugar cannot be stored in the muscle and glucose is secreted through urine. This is known as diabetes insipid. If a person is affected by diabetes his blood sugar level goes high. Then the affected person may be called a diabetic.
Symptoms of Diabetes:
- Increased thirst.
- Weak, tired feeling.
- Blurred vision.
- Numbness or tingling in the hands and feet.
- Slow healing sores or cuts.
- Weight loss.
- Frequent urination.
- Frequent unexplained infection.
- Dry mouth.
- Decreased sex drive.
- Erectile dysfunction.
- Decreased muscle strength.
Test for Detection of Diabetes:
Normally blood test is required to detect the condition for diabetes. In healthy adults normal blood glucose level is below 100 mg/dL of blood in fasting. If a person is diabetic this becomes 126 or higher. In normal cases, two hours after a meal the glucose level should be below 180 mg/dL of blood. Therefore, at fasting if the blood glucose level is more than 125/dL of blood and two hours after a meal blood glucose level is greater than 180 mg/dL of blood, the person is detected to be diabetic. It is to be mentioned here that if the blood glucose level goes below 70 mg/dL of blood it is called hypoglycemia.
Symptoms of Hypoglycemia:
- Moist skin and sweating.
- Fast heartbeat.
- Sudden hunger.
- Pale skin.
- Numbness of mouth and tongue.
- Irritability and nervousness.
- Blurred vision.
- Headache and seizures.
Sometimes due to hypoglycemia, the patient goes senseless and that why even leads to death.
Diabetes Associated Complications:
If diabetes is not properly treated and blood sugar level is maintained, this may lead to several other complications. These complications include:
- Cardiovascular issues such as coronary artery disease, chest pain, heart attack, stroke, high blood pressure, etc.
- Neural damage.
- Kidney damage.
- Eye damage.
- Foot damage.
- Skin infection.
- Hearing less.
- Dental problems.
Prevention and Treatment:
As diabetes is a physiological disorder, it is not infectious and it does not spread from an infected person to the normal individual. The disease needs some management for the well-being of the infected person. Good food, regular exercise, and proper medical advice can only manage the situation. Regular blood sugar levels are needed to be followed.
Differences between Diabetes Mellitus and Diabetes Insipidus:
|Characters||Diabetes Mellitus||Diabetes Insipidus|
|1. Causes||Lack of formation or lack of secretion of insulin or less susceptibility of tissue cells to insulin hormone.||Lack of ADH formation or low secretion or defective kidney tubules.|
|2. Blood Sugar Level||High||Normal|
|3. Urine Characters
(b) Specific Gr.
More than normal.
More than average.
Less than normal.
Much more than average.
Differences between Infectious and Non-infectious Diseases:
|Infectious Disease||Non-infectious Disease|
|1. The disease is communicable i.e., it may pass from one person to the other.||1. The disease is non-communicable, i.e., it cannot be passed from the infected person to the other individual.|
|2. The disease must be caused by a pathogen either virus or bacteria or other parasite.||2. The disease is not necessarily caused by a pathogen.|
|3. The disease is not congenital.||3. The disease may be congenital.|
|4. No gene is involved in developing such a disease.||4. Gene or genes may be involved in developing such a disease.|
|5. Public health is affected by such disease.||5. Public health remains unaffected by such disease.|
General Symptoms of Diseases
Commonly the following general symptoms in most of diseases.
- Rise of body temperature.
- An increase in the rate of respiration and heartbeat.
- Dryness of the tongue.
- Loss of appetite.
- Change in the WBC and RBC count.
Diseases Causing Pathogen
The pathogen causes disease by two methods:
1. Tissue Damage:
The pathogen causes disease by tissue damage e.g., rabies virus damages brain tissue, and bacteria of pulmonary tuberculosis damages lung tissue.
2. Toxin Secretion
Some pathogen secrets toxin that causes many diseases. It is of two types-
- Exotoxin: This is secreted by the bacterial cell to the outside environment, e.g., diphtheria, tetanus, etc.
- Endotoxin: This is kept within the bacterial body and secreted only after the bacteria die and dissolve, e.g., cholera, dysentery, plague, typhoid, etc.
General Preventive Measures for Control of Disease
Precautionary steps to be taken for the prevention and control of communicable diseases are as follows:
- Personal hygiene.
- Proper sanitation.
- Destruction of vectors and carriers.
- Provision of safe water supply.
- Sterilization of articles used by the patients.
- Isolation of patients.
Parasites Causing Human Disease
An organism that lives in or on another organism (its host) and benefits by deriving nutrients at the other’s expense is called a parasite. These are two types based on their interaction with their hosts and their life cycles.
1. Facultative Parasite:
These parasites are dependent on the host at any stage of the life cycle and are called a facultative parasite, e.g., glochidium larva of the oyster.
2. Obligate Parasite:
These parasites are totally dependent on the host to complete their life cycle, e.g., Taenia, Ascaris.
- Endoparasites: Those that live inside the host are called endoparasites (including all parasitic worms), e.g., Taenia, and Ascaris.
- Ectoparasite: Parasites that live on the outside of the host either on the skin or the outgrowths of the skin, are called ectoparasites, e.g., Lice, Fleas, etc.