Circulatory System PDF

12 The Circulatory System  12.1 - Function of Circulation The circulatory system interacts with many other body systems, including the digestive system and the respiratory system to maintain homeostasis The Cardiovascular System: ❏ Delivers O2 (and nutrients) to cells and takes CO2 aw...

12 The Circulatory System  12.1 - Function of Circulation The circulatory system interacts with many other body systems, including the digestive system and the respiratory system to maintain homeostasis The Cardiovascular System: ❏ Delivers O2 (and nutrients) to cells and takes CO2 away from them ❏ Transports chemical messengers like hormones around the body ❏ Helps to maintain a constant body temperature ❏ Plays an active role in blood pressure control  12.1 - Function of Circulation There are three parts to any circulatory system: ❏ Pump – the heart ❏ Fluid – blood ❏ Vessels along which blood travels – arteries, veins, capillaries The body’s main extracellular (outside of cells) fluid is the blood - Adults have ~5-6L of blood running through our body at all times  12.1 - Function of Circulation When blood is centrifuged The buy coat is a small layer that (spun around very fast), two separates the plasma from the distinct layers are seen: lower layer. On top (the lightest layer) sits Contains the white blood cells the liquid component of blood, present in the sample plasma, and accounts for 55% of the blood volume On the boom (the heaviest layer) is made up of erythrocytes: Plasma is 90% water This thicker, heavy red layer Plasma dissolves salts, contains three separate parts: proteins, hormones, nutrients, red and white blood cells and waste products, and gases. platelets  12.1 - Function of Circulation Red Blood Cells The most abundant cells in the blood. Made in bone marrow and stored in the spleen Primary function is to carry O2 / CO2- contain hemoglobin molecules which bind O2 Iron is a key component and gives blood its bright red colour when exposed to oxygen Red blood cells (RBC’s) have a biconcave shape that allows them to move through areas of varying size and shape Blood becomes oxygenated in the lungs, and deoxygenated at the tissue level when they release their oxygen to cells Anemia occurs when there is a decreased amount of hemoglobin in the blood, most commonly caused by low blood iron. Genetic disorders or blood loss can lead to this decrease 12.1 - Function of Circulation White Blood Cells Also called leukocytes and are responsible for helping to defend the body from disease and infection by destroying and consuming invading bacteria and damaged body cells There are fewer white blood cells than red blood cells. A high level of white blood cells (WBC’s) indicate that an infection is present WBC’s will localize at a cut to fight bacteria Pus sometimes forms at the site of cuts and is a combination of living and dead WBC’s along with dead bacteria  12.1 - Function of Circulation Platelets These are important for blood cloing. They are actually cell fragments that have broken o from special cells in the bone marrow When platelets encounter damaged blood vessels, they break open and release chemicals called cloing factors into the blood, which make them stick together to form a platelet plug Shortly after, fibrin forms (at the ends of cut blood vessels) which makes a mesh like formation called a clot. Clots trap blood cells and prevent them from passing through the damaged blood vessel A scab occurs when fibrin, platelets and blood cells mesh together to seal a wound until new tissue can grow and repair the area  12.1 - Function of Circulation As multicellular organisms become larger and more complex, an eicient transport system is essential Open vs. Closed Circulation An open circulatory system consists of a body sinus that contains all the vital organs. Blood is pumped in here and “bathes” the body organs. It is then “drained” from the body sinus to allow new blood in. This is most common in insects. A closed circulatory system consists of vessels containing fluid and a pumping mechanism to circulate the fluid. HOMEWORK Read section 12.1 + pg 488 #2, 4, 12 - 14