blood and vessels

• blood vessels are designed for...

  their function
• types of blood vessels

  arteries, veins, capillaries
• artery function


  transports oxygenated blood away from the left side of the heart at a high pressure to the body
• artery structure


  - thick wall

  - elastic walls

  - narrow lumen
• arteries carry blood away/to the heart


  away
• why do arteries have thick walls?

  to withstand the high pressure of the blood pumped by the heart
• how are arteries strong?

  they contain thick layers of muscle to make them strong
• capillary function


  forms a connection between arteries and veins and allows for diffusion of nutrients and wastes between cells and blood - they supply food and oxygen and take away waste like carbon dioxide
• why do arteries have a narrow lumen?

  to maintain high blood pressure
• to arteries carry oxygenated or deoxygenated blood?


  oxygenated
• how are arteries elastic?

  they contain elastic fibres to allow them to spring and stretch back
• capillary structure


  - one cell thick vessels

  - permeable walls

  - close to every cell in the body

  - thin lumen

  - branches from arteries

  - join up to form veins
• why do capillaries have thin walls?

  to decrease the distance of which diffusion occurs across
• why do capillaries have permeable walls?

  so substances can diffuse in and out
• why do capillaries carry blood closely to every cell?

  to exchange substances with them
• do capillaries carry oxygenated or deoxygenated blood?


  both
• vein function


  return deoxygenated blood to right side of heart
• vein structure


  - thin walls

  - have valves

  - wide lumen
• veins carry blood away/to the heart


  to
• why do veins have thin walls?

  because they carry blood under low pressure back to the heart
• why do veins have valves?

  to prevent back flow of blood as pressure in them are low
• why do veins have a wide lumen?

  to decrease resistance to blood flow
• do veins carry oxygenated or deoxygenated blood?


  deoxygenated
• what does blood contain?

  red blood cells, white blood cells, platelets, plasma
• red blood cell function

  carry oxygen
• red blood cell structure

  - biconcave disc shape

  - no nucleus

  - contain haemoglobin
• why are red blood cells a biconcave shape?

  the shape creates a large surface area, allowing rapid diffusion of oxygen
• why do red blood cells not have a nucleus?

  to increase the amount of space inside the cell for haemoglobin. they also do not need to have a nucleus because they have already made all the proteins they will ever need
• why do red blood cells contain haemoglobin?

  haemoglobin absorbs oxygen in the lungs and releases oxygen in the rest of the body
• haemoglobin


  the protein that carries oxygen in the red blood cells and also gives blood its red colour
• oxyhaemoglobin


  the molecule formed when haemoglobin binds to oxygen molecules in the lungs. the molecule is broken up again in body tissues to release oxygen into the cells
• white blood cell function

  fight infection
• white blood cell structure

  - can vary in structure

  - can produce antibodies/antitoxins

  - has nucleus
• why do white blood cells vary in structure?

  to engulf infectious microorganisms in a process called phagocytosis
• phagocytosis


  process in which a cell engulfs large particles or whole cells
• why do white blood cells produce antibodies?

  to fight microorganisms
• why do white blood cells produce antitoxins?

  to counter toxins produced by invading microorganisms
• antibodies


  specialized proteins that aid in destroying infectious agents
• antitoxins


  produced by the host body and neutralize toxins
• why do white blood cells have a nucleus?

  because they actively work to help protect the body from infections and they need to be able to make proteins to do this, and therefore must keep their nuclei