transport in animals

• Why don't single celled organisms need a transport system

  use processes such as diffusion, osmosis, active transport and endocytosis/exocytosis to supply everything
• Why do multi-cellular organisms need transport systems?

  - high metablic demands

  -small SA:vol ratio- SA to absorb is smaller

  -hormones/enzymes and food are needed in one place, but produced/digested in another

  - waste produced need to be removed
• why kind of stuff to transport systems carry

  oxygen carbon dioxide, nutrients and waste products
• 3 features of circulatory systems

  - liquid transport medium (blood)

  - vessels to carry around the liquid transport medium

  - pumping mechanism to move fluid around
• features of open circulatory systems

  - few vessels to contain the transport medium

  -pumped straight from the heart to the body cavity of an animal

  -transport medium is returned to the heart by open ended vessels
• where are open circulatory systems found

  Found in insects, many arthropods, mulloscs
• what is the body cavity of an animal called

  haemocoel
• haemocoel pressure


  low
• where does exchange take place in the haemocoel

  direct content between blood and cell
• gas exchange in an insect

  takes place in tracheal system
• What is a closed circulatory system?

  blood confined to blood vessels and has no direct contact with cells
• how does the heart pump blood around the body in a closed circulatory system?

  by pressure
• how do substances leave and enter the blood stream in closed circulatory system?

  diffusion through the walls of blood vessels
• how can the volume of blood going to a particular vessel be adjusted

  by the narrowing or opening of the vessels
• what is a single closed circulatory system

  Blood flows through the heart and is pumped out to travel all around the body and through two sets of capillaries before returning to the heart.
• why is pressure extremely low in single closed circulatory systems and what is the exception?

  blood travels through 2 sets of capillaries, fish
• why are fish the exception to having low pressure in exchange processes

  have a countercurrent gaseous exchange system, body weight is supported by water + they don't need to maintain their body temp = reduces metabolic demands
• what is the 1st capillary for in a single closed circulatory system

  exchanges oxygen and carbon dioxide
• what is the 2nd capillary for in a single closed circulatory system

  substances are exchanged between the blood and the cells
• Where are single closed circulatory systems found?

  fish and annelid worms
• how many capillary networks in a double closed circulatory system and pressure

  1, high pressure so flow is maintained
• what is a double closed circulatory system

  Blood passes through the heart twice for each complete circuit of the body
• where can double closed circulatory system be found

  birds and most mammals (all very active land animals which maintain their own body temperature)
• what is the most efficient circulatory system

  double closed circulatory system
• what are elastic fibres

  Composed of elastin and can stretch and recoil providing vessel walls with flexibility
• what is smooth muscle

  Contracts or relaxes which changes the size of the lumen
• what is collagen


  Provides structural support to maintain the shape and volume of the vessel
• what is the lumen


  central cavity through which the blood flows
• role of arteries


  carry (oxygenated) blood away from the heart
• pressure of blood in arteries

  high
• what do artery walls contain

  Elastic fibres, smooth muscle and collagen
• role of elastic fibre in arteries


  enable them to withstand the force of the blood and stretch to take larger volumes, in between heart contractions the elastic fibres recoil and return to their original length
• role of smooth muscle in arteries

  blood can easily Flow through arteries
• role of arterioles


  link arteries to capillaries
• amount of elastin and smooth muscle in arteriole walls and what does this mean

  more smooth muscle and less elastin in their walls = little pulse surge
• what can the arterioles do

  constrict and dilate to control to flow of blood into individual organs
• what is vasoconstriction


  the constriction of blood vessels, which increases blood pressure.
• what is vasodilation


  the dilatation of blood vessels, which decreases blood pressure.
• role of the capillaries

  link the arterioles with venules
• diameter of capillaries and what does this mean

  10um- substance scan be exchanged through gaps in the endothelial cells in the walls