Biology - circulatory system Flashcards
What are the four main components in blood?
red blood cells
white blood cells
platelets
plasma
What is the purpose of red blood cells?
Red blood cells transport oxygen. They absorb oxygen from the lungs and transport it through narrow blood vessels. The oxygen is released to the cells in the body which use it for aerobic respiration.
What adaptions do red blood cells have?
-They contain haemoglobin – a red protein that combines with oxygen
-They have no nucleus so they can contain more haemoglobin
-They are small and flexible so that they can fit through narrow blood vessels
-They have a biconcave shape (flattened disc shape) to maximise their surface area for oxygen absorption.
What is the purpose of white blood cells?
White blood cells defend the body against disease. The majority of the white blood cells are a type of cell called phagocytes. The phagocytes ingest and destroy pathogens such as bacteria.
How do white blood cells break down bacteria?
-The phagocyte engulfs the bacterial cell
-The bacterial cell is broken down by enzymes inside the phagocyte
What is the function of platelets?
Blood contains tiny fragments of cells called platelets. These platelets are involved in blood clotting and scab forming. The wound must be closed to prevent blood loss and the entry of pathogens.
How is a scab formed?
When skin is wounded, platelets are able to:
-Release chemicals that cause soluble proteins to form a mesh of insoluble fibres across the wound
-Stick together to form clumps that get stuck in the mesh
Red blood cells also get stuck in the mesh, forming a clot. This develops into a scab, which protects the wound as it heals.
What is plasma?
Plasma is a straw–coloured liquid that makes up just over half the volume of blood.
What are the functions of plasma?
-Transports carbon dioxide from respiring cells to the lungs
-Transports digested food from the small intestine to respiring cells
-Distributes heat all around the body
-Transports hormones from the glands where they are made to the target organs
How does blood go around the body starting at the vena cava(right)?
Deoxygenated blood in the VENA CAVA vein enters the heart through the RIGHT ATRIUM. The right atrium contracts forcing open the TRICUSPID VALVE and blood enters the RIGHT VENTRICLE. The right ventricle contracts forcing the tricuspid valve closed to prevent backflow. The blood pushes open the SEMILUNAR VALVE and moves into the PULMONARY ARTERY. The pulmonary artery moves the deoxygenated blood to the LUNGS to oxygenate the blood.
Oxygenated blood from the lungs enter the LEFT ATRIUM via the PULMONARY ARTERY. The left atrium contracts forcing open the BICUSPID VALVE and blood enters the LEFT VENTRICLE. The left ventricle contracts forcing the bicuspid valve closed to prevent backflow. The blood pushes open the SEMILUNAR VALVE and moves into the AORTA. The aorta moves the blood around the rest of the body.
What is the purpose and adaptions of the artery?
-Carry blood away from the heart (always oxygenated apart from the pulmonary artery which goes from the heart to the lungs).
-Have thick elastic and muscular walls.
-Have small passageways for blood (internal lumen).
-Contain blood under high pressure.
What is the purpose and adaptions of the vein?
-Carry blood to the heart (always deoxygenated apart from the pulmonary vein which goes from the lungs to the heart).
-Have thin, less muscular walls.
-Have larger passageways for blood (internal lumen).
-Contain blood under low pressure.
-Have valves to prevent blood flowing backwards.
What is the purpose and adaptions of capillaries?
-Microscopic – walls are one cell thick, this allows for the diffusion of substances into the cells from the capillaries and out of the cells into the capillaries.
-Very low blood pressure.
-Found near every living cell of the body.
What does the structure of an artery look like?
Small lumen, endothelium, thick muscle layer, tough outer coat
What does the structure of a vein look like?
Large lumen. endothelium, thinner smooth muscle layer, tough outer coat
