Higher Human Biology Subtopic 13 Circulatory system Physiology and Health Higher Human Biology Subtopic 13 Circulatory system

Learning Intentions To discuss the need for the cardiovascular system To state the different types of blood vessel and describe features of each. To explain what tissue fluid is To explain the function of the lymphatic system

Reminder What can you remember about the heart?

The Circulatory System Made up of : the heart, blood vessels and blood Important because : Substances need to be exchanged - the external environment and the organism - the cells and structures in the organism

Lungs Body cells the right side of the system deals with deoxygenated blood. the left side of the system deals with oxygenated blood.

Some key functions : Transport oxygen Remove carbon dioxide and wastes Transports nutrients Fight disease Transport hormone

Carotid artery Jugular vein Pulmonary vein Pulmonary artery aorta Vena cava Hepatic artery Hepatic portal vein Gut artery Renal vein Renal artery

Blood Vessels Vessels have a lumen – central cavity It is lined with epithelial cells There are 3 types of blood vessel…. - Artery - Vein - Capillary

The ARTERY Arteries carry blood AWAY from the heart under high pressure. The elastic fibres allow the artery to stretch and recoil under pressure Narrow lumen The thick muscle can contract to push the blood along.

Vasoconstrition and Vasodilation The smooth muscle of the arterioles : - contracts (vasoconstriction) to reduce blood flow - relax (vasodilation) to increase blood flow

The CAPILLARY Capillaries link arterioles to venules. They exchange materials between the blood and other body cells The wall of a capillary is only one cell thick to allow….. ……rapid exchange

Veins carry blood TOWARDS the heart under low pressure. The VEIN Veins carry blood TOWARDS the heart under low pressure. Veins have valves which act to stop the blood from going in the wrong direction. thin muscle and elastic fibres Wide lumen

Capillaries Arteriole Capillaries (capillary bed) Venule video Capillaries do not have such a complex structure as their role is to allow exchange of materials via diffusion. They have a capillary wall which is made up of one layer of epithelium cells and a lumen. video 17 17

Tissue Fluid and the Lymphatic System

Blood consists of rbc, wbc and platelets bathed in plasma. Plasma contains e.g : carbon dioxide glucose amino acids proteins ions

The CAPILLARY BED (tissue fluid) The squeezed out liquid is tissue fluid. It has little/no protein. Blood arrives at the capillaries under high pressure and is forced through. body cell Blood undergoes pressure filtration and plasma is squeezed out.

Exchange Tissue fluid has a HIGHER concentration of useful molecules e.g. oxygen than the cell….. ……these diffuse in The cells have a HIGHER concentration of waste e.g. carbon dioxide than the fluid… …..this diffuses out

Most of the tissue fluid returns to the blood at the venule side. Osmotic Return body cell Tissue fluid Most of the tissue fluid returns to the blood at the venule side. Some doesn’t return and enters lymphatic vessels and is now called lymph. 22

Lymph passes into lymphatic system Blood arriving in the arteriole high pressure Lymph vessel Blood leaving in venule low pressure Some tissue fluid enters capillary by osmosis capillary Some tissue fluid enters lymphatic system Some plasma forced out of capillary Tissue fluid

Lymph Lymph is moved through vessels due to the muscular contraction during breathing, locomotion and movement. They contain valves to prevent backflow. Lymph vessels eventually return their contents to the main circulation near the heart via osmosis.

Kwashiorkor and Elephantiasis

Learning Intentions To discuss the need for the cardiovascular system To state the different types of blood vessel and describe features of each. To explain what tissue fluid is To explain the function of the lymphatic system