1. Circulatory Diseases

2. Stroke
A stroke occurs due to the blockage of a blood vessel within the brain reducing oxygenated blood supply and possibly causing permanent brain damage. It is most commonly caused by a blood clot that originated in another part of the body, such as the heart, then travelling through the arterial system to the brain and causing a blockage (embolic stroke) there. Strokes can also occur due to excessive bleed (hemorrhagic stroke), as seen in the case of brain aneurysms. Strokes are a serious condition, with every minute upon onset proving vital for reversing the symptoms of blood clots in the brain.

3. Atherosclerosis and coronary artery disease
Here, blood vessels narrow due to cholesterol plaque buildup  on the walls of your arteries, eventually restricting blood flow. This means greater force is required for blood to pass through these narrow areas to be able to deliver adequate blood supply, causing increased blood pressure. If this blood vessel narrowing occurs in the vessels supplying the heart, it can trigger a heart attack.

4. Heart Attack
This occurs when the heart does not receive enough blood due to a blocked coronary artery. If not remedied in time, the heart muscle can become permanently damaged and subsequently lead to heart failure or even sudden death. Typical symptoms of a heart attack include pain in the center or left side of the chest, pain that radiates to the jaw, shoulder, or arm, shortness of breath, nausea, sweating, irregular heartbeat, and/or loss of consciousness

5. AnginA Pectoris
Referring to pain in the chest, this condition is a specific type of chest pain that is related to the heart. It is often accompanied by shortness of breath, fatigue, and nausea. A diagnosis of angina signifies that not enough blood is reaching the heart muscles. Angina pain patients often take nitroglycerine pills, which help to dilate blood vessels, to relieve the pain.

6. HIV/AIDS
HIV is the virus that causes HIV infection. AIDS is the most advanced stage of HIV infection.
HIV is spread through contact with the blood, semen, pre-seminal fluid, rectal fluids, vaginal fluids, or breast milk of a person with HIV. In the United States, HIV is spread mainly by having anal or vaginal sex or sharing drug injection equipment with a person who has HIV.
Antiretroviral therapy (ART) is the use of HIV medicines to treat HIV infection. People on ART take a combination of HIV medicines (called an HIV regimen) every day. 
ART can’t cure HIV infection, but it can help people with HIV live longer, healthier lives. HIV medicines can also reduce the risk of transmission of HIV.

7. Hemophilia
Hemophilia is a rare disorder in which your blood doesn't clot normally because it lacks sufficient blood-clotting proteins (clotting factors). If you have hemophilia, you may bleed for a longer time after an injury than you would if your blood clotted normally.
Small cuts usually aren't much of a problem. The greater health concern is deep bleeding inside your body, especially in your knees, ankles and elbows. That internal bleeding can damage your organs and tissues, and may be life-threatening.
Hemophilia is an inherited (genetic) disorder. There's no cure yet. But with proper treatment and self-care, most people with hemophilia can maintain an active, productive lifestyle

8. Sickle Cell Anemia
Sickle cell anemia is an inherited form of anemia — a condition in which there aren't enough healthy red blood cells to carry adequate oxygen throughout your body.
Normally, your red blood cells are flexible and round, moving easily through your blood vessels. In sickle cell anemia, the red blood cells become rigid and sticky and are shaped like sickles or crescent moons. These irregularly shaped cells can get stuck in small blood vessels, which can slow or block blood flow and oxygen to parts of the body.
There's no cure for most people with sickle cell anemia. But treatments can relieve pain and help prevent problems associated with the disease.

9. PURPURA
Purpura, also called blood spots or skin hemorrhages, refers to purple- colored spots that are most recognizable on the skin. The spots could also be located on organs or mucous membranes, including the membranes on the inside of the mouth.
Purpura occurs when small blood vessels burst, causing blood to pool under the skin. This can create purple spots on the skin that range in size from small dots to large patches. Purpura spots are generally benign, but may indicate a more serious medical condition, such as a blood clotting disorder.

10. Thrombosis
Deep vein thrombosis (DVT) occurs when a blood clot (thrombus) forms in one or more of the deep veins in your body, usually in your legs. Deep vein thrombosis can cause leg pain or swelling, but also can occur with no symptoms.
Deep vein thrombosis can develop if you have certain medical conditions that affect how your blood clots. It can also happen if you don't move for a long time, such as after surgery or an accident, or when you're confined to bed.
Deep vein thrombosis can be very serious because blood clots in your veins can break loose, travel through your bloodstream and lodge in your lungs, blocking blood flow (pulmonary embolism).

11. SEPSIS
Sepsis is a potentially life-threatening complication of an infection. Sepsis occurs when chemicals released into the bloodstream to fight the infection trigger inflammatory responses throughout the body. This inflammation can trigger a cascade of changes that can damage multiple organ systems, causing them to fail.
If sepsis progresses to septic shock, blood pressure drops dramatically, which may lead to death.
Anyone can develop sepsis, but it's most common and most dangerous in older adults or those with weakened immune systems. Early treatment of sepsis, usually with antibiotics and large amounts of intravenous fluids, improves chances for survival.

12. Components OF blood Red blood cells = involved in carrying oxygen
White blood cells = involved in immune system
Plasma = liquid part of blood. A dilute solution of salts, glucose, amino acids, vitamins, urea, proteins, and fats
Platelets = involved in blood clotting

13. Blood types
Type “a”
Type “B”
Type “AB”
Type “O”
Positive vs negative

17. THE HEART