blood from the heart gets around the body through blood vessels There are 3 types of blood vessels a. ARTERY شريان b. VEIN وريد c. CAPILLARY شعيرة دموية

Blood vessels There are three types of blood vessels الاوعية الدموية blood from the heart blood to the heart artery carries blood back into the heart يحمل الدم الى القلب carries blood away from the heart يحمل الدم من القلب carries blood to and from the body’s cells vein

The ARTERY thick muscle عضلات كثيفة and elastic fibres الياف مرنة Arteries carry blood away from the heart. the elastic fibres الالياف المرنة allow the artery to stretch يتمدد under pressure تحت الضغط the thick muscle العضلات can contract تنقبض to push لتدفع the blood along.

The VEIN Veins carry blood towards from the heart. thin muscle and elastic fibres veins have valves صمامات which act to stop the blood from going in the wrong direction الاتجاه الخاطئ.

The CAPILLARY Capillaries link تربط Arteries with Veins the wall of a capillary is only one cell thick they exchange تبادل materials between the blood and other body cells. The exchange of materials between the blood and the body can only occur through capillaries.

arteryvein capillaries body cell The CAPILLARY capillary bed A collection of capillaries is known as a capillary bed.

Blood Blood is the body’s means of transporting نقل substances المواد around. It transports ينقل : oxygen from the lungs to the heart and then to the body’s tissues carbon dioxide from the tissues to the heart and then to the lungs to be expiredلطرده للخارج materials like hormones from one organ to another nutrients (especially glucose) and minerals from the intestines to the tissues waste products to the kidneys.

The Blood plasma red blood cell white blood cell platelets

Red blood cells Also called erythrocytes. Disc-shaped قرصية الشكل. Made in the bone marrowنخاع العظم. Contain a red-coloured compoundمركب احمر called haemoglobin which bonds with oxygen to form oxyhaemoglobin. Transport oxygen to the tissues. Blood is made up of a number of different elements. The most common cell in blood is the red blood cell.

White Blood Cells there are many different types and all contain a big nucleus. the two main ones are the lymphocytes الخلايا اللمفية and the macrophages. some lymphocytes fight disease by making antibodies to destroy invaders by dissolving them. other lymphocytes make antitoxins to break down poisons. macrophages ‘eat’ and digest micro- organisms.

Platelets الصفائح الدموية They are formed in red bone marrow. Platelets are bits of broken cells. Platelets produce tiny fibrinogen fibres to form a net شبكة. This net react with other blood cells to form a blood clot الجلطة الدموية. Platelets help to repair tissues and close wounds غلق الجروح.