What are Diseases ?

A disease is a particular abnormal condition that affects part or all of an organism not caused by external force ‘injury’ and that consists of a disorder of a structure or function, usually serving as an evolutionary disadvantage. The study of disease is called pathology, which includes the study of cause. Disease is often construed as a medical condition associated with specific symptoms and signs

In humans, disease is often used more broadly to refer to any condition that causes pain, dysfunction, distress, social problems, or death to the person afflicted, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injuries, disabilities, disorders, syndromes, infections, isolated symptoms, deviant behaviors, and atypical variations of structure and function, while in other contexts and for other purposes these may be considered distinguishable categories. Diseases can affect people not only physically, but also emotionally, as contracting and living with a disease can alter the affected person’s perspective on life

Types Of Diseases

Acquired disease : disease that began at some point during one’s lifetime, as opposed to disease that was already present at birth, which is congenital disease. “Acquired” sounds like it could mean “caught via contagion”, but it simply means acquired sometime after birth. It also sounds like it could imply secondary disease, but acquired disease can be primary disease.

Acute disease : disease of a short-term nature (acute); the term sometimes also connotes a fulminant natureChronic disease disease that is a long-term issue (chronic)

Congenital disease : disease that is present at birth. It is often, genetic and can be inherited. It can also be the result of a vertically transmitted infection from the mother such as HIV/AIDS.

Genetic disease : disease that is caused by genetic mutation. It is often inherited, but some mutations are random and de novo.

Hereditary or inherited : disease a type of genetic disease caused by mutation that is hereditary (and can run in families)

Iatrogenic : diseaseA disease condition caused by medical intervention.

Idiopathic : disease disease whose cause is unknown. As medical science has advanced, many diseases whose causes were formerly complete mysteries have been somewhat explained (for example, when it was realized that autoimmunity is the cause of some forms of diabetes mellitus type 1, even if we do not yet understand every molecular detail involved) or even extensively explained (for example, when it was realized that gastric ulcers are often associated with Helicobacter pylori infection)

Incurable disease : disease that cannot be cured

Primary disease : disease that came about as a root cause of illness, as opposed to secondary disease, which is a sequela of another disease

Secondary disease : disease that is a sequela or complication of some other disease or underlying cause (root cause). Bacterial infections can be either primary (healthy but then bacteria arrived) or secondary to a viral infection or burn, which predisposed by creating an open wound or weakened immunity (bacteria would not have gotten established otherwise).

Terminal disease : disease with death as an inevitable result

Diseases By Organ System


Cancer is an abnormal growth of cells. There are actually more than one hundred known types of cancer that can happen in the human body. Cancer can manifest as a tumor, but not all cancers cause tumors and not all tumors are even cancerous; some are benign. With cancerous cell growth also comes the possibility that the growth will spread to other organs or systems in the body. This is called metastasis. In this section you can explore many of the most common forms of cancer that make people sick.

  • Basal Cell Carcinoma »Basal cell carcinoma is a type of skin cancer that occurs in the basal cells of the epidermis – the outermost layer of the skin. Basal cells constantly divide to replace dead or damaged skin cells closer to the outer surface of the epidermis
  • Bladder Cancer »Bladder cancer is a cancer that occurs in the bladder – the balloon-shaped organ that collects urine until it is excreted. It is caused by an uncontrolled growth of cells that form lumps called tumors. While some tumors are harmless, others continue to grow and eventually invade other organs.
  • Breast Cancer »Breast cancer occurs when cells in the breast multiply out of control, forming an abnormal mass (tumor) that tends to invade surrounding tissues. Because cancer cells grow destructively, they are also called malignant.
  • Colon Cancer »Colon cancer (also called colorectal cancer) is cancer of the large intestine, including the colon and rectum. All cancers begin when cells grow uncontrollably to form a clump of cells referred to as a tumor
  • Liver Cancer »Liver cancer is a disease in which abnormal liver cells multiply uncontrollably and form a mass of cancer cells called a tumor. Cancerous tumors grow destructively and are described as malignant because they invade normal tissue and have a high mortality rate. Liver cancer is dangerous because the body depends on the liver to aid in digestion of food, eliminate toxins, and produce proteins for blood clotting function
  • Lung Cancer »Lung cancer develops when cells in the lung multiply abnormally, forming a mass (tumor) that grows destructively and invades normal tissues. Cancer can start in various parts of the lung such as the large air passages (bronchi), smaller airway branches (bronchioles), or tiny air sacs (alveoli). and many more like
  • Lymphoma »
  • Melanoma »
  • Prostate Cancer »
  • Squamous Cell Carcinoma (SCC) »
  • Stomach Cancer »

The adult human skeletal system consists of 206 bones, as well as a network of tendons, ligaments and cartilage that connects them. The skeletal system performs vital functions — support, movement, protection, blood cell production, calcium storage and endocrine regulation — that enable us to survive.

The amount of bones a person is born with isn’t the final tally later on. Human infants are born with about 300 bones, some of which fuse together as the body develops. By the time humans reach adulthood, they have 206 bones, according to Arizona State University’s School of Life Sciences. Human males grow until their late teens and females grow until two years after the beginning of their menstrual cycle, typically. This is when the growth plates on bones usually close, halting bone expansion.

Your bones help you move, give you shape and support your body. They are living tissues that rebuild constantly throughout your life. During childhood and your teens, your body adds new bone faster than it removes old bone. After about age 20, you can lose bone faster than you make bone. To have strong bones when you are young, and to prevent bone loss when you are older, you need to get enough calcium, vitamin D, and exercise. You should also avoid smoking and drinking too much alcohol.

Some Of The Bone Afected Diseases

  • Bone Cancer.
  • Bone Marrow 
  • Leukemia
  • Bone Density.
  • Bone Infections.
  • Osteogenesis Imperfecta.
  • Osteonecrosis.
  • Osteoporosis.
  • Paget’s Disease of Bone.
  • Rickets.

The muscular system is responsible for the movement of the human body. Attached to the bones of the skeletal system are about 700 named muscles that make up roughly half of a person’s body weight. Each of these muscles is a discrete organ constructed of skeletal muscle tissue, blood vessels, tendons, and nerves. Muscle tissue is also found inside of the heart, digestive organs, and blood vessels. In these organs, muscles serve to move substances throughout the body

  • Arthritis – Osteoarthritis, Rheumatoid Arthritis and Gout »Arthritis is defined as inflammation of the joints, and is characterized by pain and stiffness around one or more joints. The term arthritis may also be used broadly to describe a number of diseases associated with the breakdown of tissues surrounding the joints, as well as other connective tissues. Severe arthritis can impair limb function; cause deformity of the joints; and, in some cases, affect other organs in the body.
  • Water On the Knee »“Water on the knee” is common term for knee effusion, a condition in which excess fluid accumulates around the knee joint. Such effusions happen for many reasons. The most common ones are injury, overuse, and chronic health conditions like osteoarthritis. and many more like
  • Fibromyalgia »
  • Herniated Disc »
  • Hiatal Hernia »
  • Myoclonus »
  • Myositis »
  • Plantar Fasciitis »
  • Scoliosis »
  • Shin Splints »
  • Sleep Apnea – Central and Obstructive Sleep Apnea »
  • Stickler Syndrome »
  • Tendinitis and Tendinosis »
  • TMJ Disorders »

The digestive system is a group of organs working together to convert food into energy and basic nutrients to feed the entire body. Food passes through a long tube inside the body known as the alimentary canal or the gastrointestinal tract (GI tract). The alimentary canal is made up of the oral cavity, pharynx, esophagus, stomach, small intestines, and large intestines. In addition to the alimentary canal, there are several important accessory organs that help your body to digest food

  • Appendicitis »The appendix is a small, worm-shaped pouch extending from the beginning of the large intestine (cecum). A long time ago, this structure may have been useful in ancestral humans, but it probably no longer has a function, so it is classified as a vestigial organ.
  • Cirrhosis »Cirrhosis is a condition in which a chronically diseased liver gradually develops hard scar tissue (fibrosis) and grows lumps (regenerative nodules) in an attempt to repair itself.
  • Hepatitis »In the general sense, the term “hepatitis” refers to inflammation (swelling) of the liver. The liver’s main job is to filter harmful chemicals and toxins from the blood. It also converts proteins and sugars into useful substances, stores them, and releases them when your body needs them. Inflammation can make it difficult for the liver to perform these functions, leading to illness.and many more like
  • Encopresis – Stool Holding or Soiling »
  • Gallstones – Cholecystitis and Biliary Colic »
  • Gastroenteritis (Viral, Bacterial and Parasitic)  »
  • Gastroesophageal Reflux Disease (GERD) »
  • Halitosis – Bad Breath »
  • Hirschsprung’s Disease – Short-Segment and Long-Segment HD »
  • Inflammatory Bowel Disease (IBD) »
  • Irritable Bowel Syndrome (IBS) »

The health of our respiratory system is vital to our overall health; our body’s cells require oxygen and we also need a way to get rid of the carbon dioxide that our bodies produce as waste. Learn about some of the common diseases and conditions that affect the proper functioning of our respiratory system.

  • Asthma » Asthma is a chronic condition wherein the airways that deliver air to the lungs become swollen and narrowed. Certain substances in the environment act as “triggers” for increased inflammation and mucus production that further restrict airflow, causing shortness of breath, wheezing, and coughing.
  • Measles »Measles, also known as rubeola, is a serious childhood disease that is caused by a highly contagious virus. The common symptoms of measles include a high fever, cough, runny nose, red watery eyes and a signature red body rash.
  • Pneumonia »Pneumonia is a lung infection that causes inflammation of the air sacs (alveoli). This infection is commonly caused by bacteria, viruses, fungi, or mycoplasma. The severity of illness can range from mild to extremely severe.and many more like
  • Atelectasis »
  • Legionnaires’ Disease »
  • Parvovirus Infection (Fifth Disease) »
  • Scarlet Fever »

Diseases involving the blood vessels, heart and the movement of blood through the body are considered cardiovascular diseases. Beneath this umbrella we find some of the most common and deadly diseases, such as heart attack and stroke. Thankfully, the vast majority of cardiovascular disease is preventable. Time to get the facts about these diseases and the underlying conditions that lead to them!

  • Heart Attack (Myocardial Infarction) »The coronary arteries deliver nutrient- and oxygen-rich blood to the pumping muscles of the heart. A block in the flow of blood to the heart can lead to tissue damage and death – otherwise referred to as a heart attack
  • Aneurysm »An aneurysm is a balloon-like bulge in the wall of a blood vessel. It usually occurs in an artery, a type of blood vessel that carries oxygen-rich blood from the heart and lungs to the body.and many more like
  • Atherosclerosis »
  • Atrial Fibrillation »
  • Chilblains »
  • Deep Vein Thrombosis (DVT) »
  • Hemangioma »
  • Hemophilia »
  • Hemorrhoids »
  • Hypertension (High Blood Pressure) »
  • Myocarditis »
  • Stroke – Ischemic and Hemorrhagic Stroke »
  • Tachycardia »

Mental health and nervous system disorders affect people at all stages of life, from childhood to advanced age, and there’s never been a better time to study; scientists learn more about the incredibly complex human brain with each passing year.

  • Alzheimer’s Disease »Alzheimer’s disease is the most common type of dementia, a brain disease in which a person’s memory and thinking (cognitive) abilities progressively worsen over time.
  • Astigmatism »Astigmatism is a common eye condition that causes blurred vision at distances close and far. It happens when the cornea (clear front surface of the eye) or lens (a clear structure inside the eye) has an unusual shape. and many more like
  • Attention-Deficit/Hyperactivity Disorder (ADHD) »
  • Autism and Autism Spectrum Disorder (ASD) »
  • Bell’s Palsy »
  • Carpal Tunnel Syndrome »
  • Depression »
  • Obsessive-Compulsive Disorder – OCD »
  • Shingles »
  • Vasovagal Response and Vasovagal Syncope »
  • Viral Meningitis »

Did you know that the skin is the body’s largest organ? It’s also the outermost organ, so it interfaces constantly with our surrounding environment and naturally plays protective, exploratory and regulatory roles for us. But there are many diseases and conditions that can affect the normal functioning of our skin. Sometimes the symptoms are primarily cosmetic, but other times the effects of a skin condition are much more threatening.

  • Acne »Acne is a skin disorder that causes a variety of blemishes on the skin, including blackheads, whiteheads, pimples, nodules, and cysts
  • Atopic Dermatitis (Eczema) »Eczema is a catchall word for a number of skin conditions that cause a very itchy, red rash.
  • Impetigo – Bullous and Nonbullous Impetigo, and Ecthyma »
  • Molluscum Contagiosum »Impetigo is a skin infection caused by bacteria, resulting in a red rash, blisters, and a characteristic honey-colored crust on the skin. Impetigo most commonly occurs in infants and children age 2 to 6. and many more like
  • Psoriasis »
  • Scabies »
  • Vitiligo »

Diseases and conditions involving endocrine glands affect the balance of hormones in our bodies. These can profoundly disrupt our mood, physical health, body weight, metabolism, ability to reproduce and more. Learn all about diabetes, hyperthyroidism and other common diseases.

  • Hyperthyroidism »Hyperthyroidism occurs when the thyroid gland malfunctions and produces too much thyroid hormone. This condition is also known as overactive thyroid or thyrotoxicosis. An abnormal enlargement of the thyroid (goiter) develops in certain forms of hyperthyroidism.
  • Addison’s Disease and Addisonian Crisis – Adrenal Insufficiency »Addison’s disease is a rare disorder in which the adrenal glands fail to produce adequate amounts of certain hormones. The resulting low hormone levels impair a number of essential bodily functions.
  • Diabetes Mellitus »Diabetes mellitus (DM) is a common disease in which the blood sugar (glucose) is abnormally elevated. Normally, the body obtains glucose from food, and additional glucose is made in the liver. and many more like
  • Mittelschmerz »
  • Pituitary Adenoma »
  • PMS (Premenstrual Syndrome) »
  • Polycystic Ovary Syndrome (PCOS) »
  • Prostatitis »

Many conditions can affect the exocrine system including infections, an ulcer, cancer, tumors, some kind of obstruction, genetic conditions, and cysts.

The exocrine system and the endocrine system are closely linked and so some of the disorders seen in the endocrine system are also seen in the exocrine system.

  • Acromegaly: Too much growth hormone is produced in adults, causing an enlargement of bones and thickened skin. This is very rare.
  • Addisons Disease: The adrenal gland fails to produce enough corticosteroids.
  • Cretinism: An extreme form of hypothyroidism present prior to or soon after birth.
  • Cushing’s Disease: An over-production of cortisol.
  • Dwarfism: Too little growth hormone produced during childhood.
  • Gigantism: Too much growth hormone produced during childhood

The urinary system, also known as the renal system or urinary tract, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH. The urinary tract is the body’s drainage system for the eventual removal of urine.The kidneys have an extensive blood supply via the renal arteries which leave the kidneys via the renal vein. Each kidney consists of functional units called nephrons. Following filtration of blood and further processing, wastes (in the form of urine) exit the kidney via the ureters, tubes made of smooth

  • Bladder Cancer-Bladder cancer is a cancer that occurs in the bladder – the balloon-shaped organ that collects urine until it is excreted. It is caused by an uncontrolled growth of cells that form lumps called tumors.
  • Kidney Stones –Kidney stones (also known as renal lithiasis) are hardened material found inside the kidneys, and are made of crystallized minerals and salts. They can occur anywhere along the urinary tract, between the kidney and bladder. and more like
  • Bladder Diseases-
  • Interstitial Cystitis
  • Ostomy
  • Overactive Bladder
  • Urinalysis
  • Urinary Incontinence
  • Urinary Tract Infection

The lymphatic system is a network of tissues and organs that help rid the body of toxins, waste and other unwanted materials. The primary function of the lymphatic system is to transport lymph, a fluid containing infection-fighting white blood cells, throughout the body.

The lymphatic system primarily consists of lymphatic vessels, which are similar to the circulatory system’s veins and capillaries. The vessels are connected to lymph nodes, where the lymph is filtered. The tonsils, adenoids, spleen and thymus are all part of the lymphatic system.

  • Hashimoto’s Disease »Hashimoto’s disease is a condition that causes inflammation and destruction of the thyroid gland (thyroiditis). Hashimoto’s disease is also known as chronic lymphocytic thyroiditis, or Hashimoto’s thyroiditis.
  • HIV/AIDS »The human immunodeficiency virus (HIV) is a virus that infects humans and can lead to an advanced disease state called acquired immunodeficiency syndrome (AIDS). There are two types of the HIV virus: HIV-1 and HIV-2. HIV-1 is more virulent and the dominant strain seen globally.
  • Limited Scleroderma (CREST Syndrome) »Limited scleroderma (also known as CREST syndrome) is a type of scleroderma, which as the name implies is characterized by thick, hardened skin. In the more severe form, this connective tissue disorder can affect the function of internal organs
  • Lupus – Discoid and Systemic Lupus »Lupus (systemic lupus erythematosus) is a chronic disease of the immune system that causes inflammation throughout the body. Normally the immune system makes proteins called antibodies that protect the body against foreign invaders like viruses, bacteria, and cancers.
  • Sarcoidosis »Sarcoidosis is an inflammatory disease that can affect any bodily organ. It is characterized by the growth of tiny inflammatory cells called granulomas or nodules. The most commonly affected body parts are the lungs, lymph nodes, eyes, and skin

The most common gas symptoms include burping, passing gas, bloating, and pain or discomfort in your abdomen. Gas symptoms vary from person to person.


Burping, or belching, once in a while, especially during and after meals, is normal. If you burp a lot, you may be swallowing too much air and releasing it before the air enters your stomach.

Passing gas

Passing gas around 13 to 21 times a day is normal.


Bloating is a feeling of fullness or swelling in your abdomen. Bloating most often occurs during or after a meal.

When should I talk with a doctor about my gas symptoms?

You should talk with your doctor if

  • gas symptoms bother you
  • your symptoms change suddenly
  • you have other symptoms with gas—such as constipation, diarrhea, or weight loss