Blood is the fluid that transports nutrients and oxygen to every cell in the body. It also transports wastes away from cells. Blood keeps our body temperature steady by carrying excess heat from regions of the body to the skin where it can be dissipated. It also fights infection and carries chemicals that regulate many body functions. Four major parts to blood are plasma, red blood cells, white blood cells, and platelets. Red blood cells – contain haemoglobin.
What are they?! Can anyone think of them...If so, what are there functions?!
Ask questions…what are arteries?! Check for learning – explain what an artery looks like!! Types of arteries: Biggest artery in the heart is AORTA, receives blood directly from the left ventricle of the heart via the aortic valve . Other arteries include pulmonary, systemic and arterioles. The pulmonary arteries carry deoxygenated blood that has just returned from the body to the heart towards the lungs , where carbon dioxide is exchanged for oxygen . Systemic arteries deliver blood to the arterioles , and then to the capillaries , where nutrients and gasses are exchanged. Arterioles , the smallest of the true arteries, help regulate blood pressure by the variable contraction of the smooth muscle of their walls, and deliver blood to the capillaries. Arterioles , the smallest of the true arteries, help regulate blood pressure by the variable contraction of the smooth muscle of their walls, and deliver blood to the capillaries. Arteries are elastic vessels that transport blood away from the heart. The largest artery of the body is the aorta . The aorta originates from the heart and branches out into smaller arteries. An artery actually has three layers: an outer layer of tissue, a muscular middle, and an inner layer of epithelial cells. The muscle in the middle is elastic and very strong. The inner layer is very smooth so that the blood can flow easily with no obstacles in its path.
Therefore, the veins transport waste-rich blood back to the lungs and heart. It is important that the waste-rich blood keeps moving in the proper direction and not be allowed to flow backward. This is accomplished by valves that are located inside the veins. Remember: Vein -> Atrium -> Ventricle -> Artery i.e. A V A V
Capillary walls are thin and are composed of endothelium (a single layer of overlapping flat cells). Oxygen, carbon dioxide, nutrients and wastes are exchanged through the thin walls of the capillaries. 5-10 microns in diameter.
Arterioles are like small arteries, branching off arteries and leading down to the capillary bed. They're not arteries because they're not the same, main vessels - but they still have a muscular tunica media, which is used for vasoconstriction in order to increase blood pressure .
Venules are a bit like arteriole-equivalents, as they lead from the capillary bed back into the veins. But they're quite simple things, with thinner and less-developed walls. They still have all the three layers which most blood vessels have, but they're not substantial, and venules aren't important for controlling blood pressure.
Bfd blood vessels session 3
The Structure and Function of Blood Vessels Session 3
Aims <ul><li>To describe the structure and function of blood vessels </li></ul><ul><li>Objectives </li></ul><ul><li>Learners will be able to explain the role of blood, veins, capillaries, arteries and blood vessels </li></ul>
Blood Contains.. <ul><li>Plasma: a watery liquid which contains calcium, salts and carbon dioxide. </li></ul><ul><li>Red blood cells: carry oxygen from the lungs to our body cells </li></ul><ul><li>White blood cells: are more plentiful than the red cells. Role is to fight infection and disease </li></ul><ul><li>Platelets: produce clots when blood is damaged </li></ul>
Types of Blood Vessels <ul><li>Arteries: are thick and elastic in texture. Carry blood AWAY from the heart. </li></ul><ul><li>Veins: these are two layers thick. Carry blood BACK to the heart. </li></ul><ul><li>Capillaries: narrow and thin. Connect arteries and veins. </li></ul><ul><li>Arterioles: smallest vessels in body. Direct blood from arteries to capillary network. </li></ul><ul><li>Venules: direct blood from capillary network to the veins. </li></ul>
Arteries <ul><li>Muscle action pushes the blood through the arteries to relevant stops. </li></ul><ul><li>Carry blood AWAY from the heart </li></ul><ul><li>Arteries carry bright red blood! The colour comes from the OXYGEN that it carries. </li></ul>
Veins <ul><li>Transport blood BACK to the heart from Upper and Lower sections of body </li></ul><ul><li>Receive blood from the capillaries after the exchange of oxygen and carbon dioxide has taken place </li></ul>
Capillaries <ul><li>Extremely small vessels </li></ul><ul><li>Transport blood from the arteries to the veins </li></ul><ul><li>Responsible for the exchange of oxygen & carbon dioxide between blood </li></ul>
Arterioles <ul><li>Are like small arteries </li></ul><ul><li>Branch out from arteries and lead to the capillary bed </li></ul>
Venules <ul><li>Allows deoxygenated blood to return from capillaries to veins </li></ul><ul><li>Quite simple things, with thinner and less-developed walls </li></ul>
Blood flow and body temperature The circulatory system plays an important role in regulating body temperature. If the body gets too hot , capillaries near the surface of the skin widen. Blood is diverted to the skin where the heat can easily radiate away. This is called vasodilation . Water from the blood is excreted as sweat to cool the body . Capillaries Sweat gland Thermoregulation
Blood flow and body temperature If the body gets too cold , capillaries near the surface of the skin get narrower. Blood is diverted away from the skin to limit heat loss. This is called vasoconstriction . Sweating stops. Capillaries Sweat gland