blood Flashcards
(11 cards)
composition of blood
Blood is made up of two main parts: plasma and blood cells. Plasma is the liquid part of blood, and blood cells are the solid parts. Together, they help the body work properly and stay healthy.
Plasma makes up about half of the blood. It is a pale yellow liquid that is mostly water. Plasma also contains proteins, salts, sugar, hormones, and waste products. It helps carry these substances around the body. Some of the important proteins in plasma include albumin, which keeps the right balance of fluid in the blood, and fibrinogen, which helps the blood to clot.
Red blood cells are the most common type of blood cell. They carry oxygen from the lungs to the rest of the body and bring carbon dioxide back to the lungs to be breathed out. Red blood cells contain a special protein called hemoglobin, which helps carry the oxygen. They are red in color and have a round, disc shape.
White blood cells help fight infections. They are part of the immune system and protect the body from germs like bacteria and viruses. There are different types of white blood cells, and each type has a special job in defending the body.
Platelets are small cell pieces that help the blood to clot. When you get a cut or injury, platelets stick together at the wound and help stop the bleeding by forming a clot or scab.
function of blood
- Transporting substances
One of the main jobs of blood is to carry important substances around the body. Blood transports oxygen from the lungs to the body’s cells and takes carbon dioxide back to the lungs to be breathed out. It also carries nutrients from food, hormones, and waste products like urea to where they need to go. - Protecting the body
Blood helps protect the body against infections. White blood cells in the blood fight off germs like bacteria and viruses. Blood also contains antibodies, which help the body recognize and destroy harmful invaders. - Clotting to stop bleeding
When you get a cut or injury, blood helps stop the bleeding. Platelets, which are tiny cell pieces in the blood, work with special proteins to form a clot. This creates a barrier (a scab) to protect the wound and help it heal. - Regulating body temperature
Blood helps control your body temperature by spreading heat around the body. If you’re too hot, blood vessels widen to release heat. If you’re too cold, they narrow to keep the heat in. - Maintaining balance
Blood helps keep the right balance of water, salts, and pH in the body. This is important for your organs to work properly and for your body to stay healthy
white blood cell functions
Neutrophils: Fight bacteria and are the first to respond to infection.
Lymphocytes: Make antibodies and help remember past infections (includes B cells and T cells).
Monocytes: Clean up dead cells and help fight long-term infections.
Eosinophils: Help fight parasites and deal with allergies.
Basophils: Help with allergic reactions and inflammation.
white blood cell functions more detail
- Neutrophils
Neutrophils are the most common type of white blood cell.
They are the first responders to infections, especially bacterial infections.
When germs enter the body, neutrophils rush to the site of infection and swallow and destroy the bacteria through a process called phagocytosis.
They work fast but don’t live long—only a few hours to a couple of days.
- Lymphocytes
Lymphocytes are responsible for the body’s immune memory and long-term defense.
There are two main types:
B cells: These make antibodies, which are proteins that attach to specific germs and help destroy them. Once the body has fought an infection, B cells can remember the germ and respond faster if it returns.
T cells: These have several jobs. Some help B cells make antibodies, while others kill infected or cancerous cells directly. T cells also play a role in regulating the immune response to prevent it from attacking healthy cells.
Together, lymphocytes help your body remember past infections and build immunity, such as after getting vaccines.
- Monocytes
Monocytes are the largest white blood cells and are part of the body’s clean-up crew.
They remove dead or damaged cells and digest harmful bacteria and viruses.
Monocytes can turn into macrophages when they move from the bloodstream into tissues. Macrophages stay in the tissues and continue to protect and clean the area.
They are especially useful in fighting long-lasting (chronic) infections like tuberculosis.
- Eosinophils
Eosinophils help the body fight parasites, such as worms, and play a big role in allergic reactions.
They can release chemicals that kill parasites, which are too big to be swallowed like bacteria.
They are also involved in asthma and allergy symptoms, such as sneezing or itching, by reacting to things like pollen, pet dander, or certain foods.
- Basophils
Basophils are the least common type of white blood cell, but they play an important role in inflammation and allergic responses.
They release chemicals like histamine, which causes swelling, redness, and itching during allergic reactions.
Histamine helps the immune system react quickly but can also cause symptoms like runny nose or hives in people with allergies.
Erythrocytes red blood cells
Red blood cells, also called erythrocytes, are the most common type of blood cell.
They make up about 40–45% of your blood. These cells give blood its red color and play a very important role in keeping your body healthy.
The main job of red blood cells is to carry oxygen.
They pick up oxygen from the lungs and transport it to all the cells and tissues in the body. This helps your body produce energy and carry out its daily functions.
Red blood cells contain a protein called hemoglobin.
Hemoglobin is what binds to oxygen and allows it to be carried in the blood. It also carries carbon dioxide—a waste gas—from the body’s cells back to the lungs, where it is breathed out.
Red blood cells have a special shape.
They are round and flat with a dip in the middle, like a doughnut without a hole. This shape helps them move easily through tiny blood vessels and carry as much oxygen as possible.
These cells are made in the bone marrow.
Bone marrow is the soft tissue found inside bones. Red blood cells are produced there and then released into the bloodstream. Your body makes millions of red blood cells every second.
Red blood cells have a limited lifespan.
They usually live for about 120 days. After that, they are broken down in the liver and spleen, and new red blood cells are made to replace them.
A low number of red blood cells can cause anemia.
Anemia makes you feel tired and weak because your body is not getting enough oxygen. It can happen due to poor diet, blood loss, or health conditions that affect red blood cell production.
platelets
Platelets, also known as thrombocytes, are tiny cell fragments found in the blood. They are not full cells like red or white blood cells, but they play a very important role in the body. The main function of platelets is to help the blood clot and stop bleeding. When you get a cut or injury, platelets quickly gather at the site of the damage. They stick together and form a plug, which helps seal the wound and prevents too much blood from being lost. Platelets also release special chemicals that help other clotting factors work properly. Without enough platelets, a person may bleed too much even from small injuries. Platelets are made in the bone marrow and have a short life—usually about 7 to 10 days—before they are removed from the body and replaced with new ones.
transport
Transportation
One of the main functions of blood is transportation. Blood carries oxygen from the lungs to all the cells in the body using red blood cells, which contain hemoglobin to bind the oxygen. At the same time, blood picks up carbon dioxide, a waste product made by cells, and takes it back to the lungs to be breathed out. Blood also transports nutrients such as glucose, amino acids, and vitamins from the digestive system to cells where they are needed for energy, growth, and repair. In addition, blood carries hormones from the glands that produce them (like the thyroid or adrenal glands) to different parts of the body where they control various functions, such as growth or metabolism. Finally, blood helps remove waste products, like urea, by carrying them to the kidneys, where they are filtered out and removed in urine. Without this transport system, cells would not get the materials they need and waste would build up, causing harm to the body
temp
Blood plays a key role in helping the body control its internal temperature. The human body needs to stay at a stable temperature (around 37°C) for enzymes and cells to work properly. When the body gets too hot, blood vessels near the skin widen (a process called vasodilation), allowing more warm blood to flow close to the skin’s surface. This helps heat escape through the skin, cooling the body down. On the other hand, when the body is cold, blood vessels narrow (vasoconstriction), reducing blood flow near the skin so that less heat is lost. Blood also spreads the heat produced by active organs like muscles to cooler parts of the body, keeping everything balanced. This temperature regulation is crucial for survival and is controlled automatically by the brain.
exchange of material with body tissue
Blood is responsible for exchanging materials between itself and the body’s tissues through capillaries. Capillaries are tiny blood vessels with very thin walls, which allow substances to pass through easily. As blood flows through capillaries, oxygen and nutrients diffuse out of the blood and into the tissue fluid and body cells. These materials are used by the cells for energy, repair, and normal function. At the same time, waste products like carbon dioxide and urea pass from the cells into the blood to be taken away and removed from the body. This constant exchange keeps the internal environment stable and allows every cell in the body to function properly.
prevent infection
Another vital function of blood is protecting the body from infections and diseases. This is mainly done by white blood cells, which are part of the immune system. Different types of white blood cells have different jobs. Some (like neutrophils) can attack and destroy harmful bacteria and viruses directly by swallowing them. Others (like lymphocytes) produce antibodies, which are special proteins that recognize and attack specific germs. Some white blood cells also help by remembering past infections so the body can respond faster if the same germ returns. Without white blood cells, the body would be very vulnerable to infections, even from small cuts or common viruses.
blood clotting
Blood helps prevent blood loss and protects the body by forming clots when there is an injury. This process begins when platelets, which are small cell fragments, gather at the site of a broken blood vessel. They stick to the damaged area and to each other, forming a temporary plug. At the same time, clotting proteins in the plasma, like fibrinogen, are activated and form a mesh-like structure that strengthens the clot and seals the wound. This clot prevents further bleeding and blocks germs from entering the body. Once the tissue is healed, the clot dissolves naturally. If blood did not clot properly, even a small cut could lead to dangerous blood loss or infection.
