9 - Transport in plants

• circulatory system


  system of blood vessels with a pump and valves to ensure one-way flow of blood
• Single circulation (of a fish):

  • fish has two chambers, one atrium & and one ventricle
  • it sends blood to the gills, where it is oxygenated
  • the blood then flows to all parts of the body before returning to the heart
  • known as single circulation because the blood goes through the heart once for each complete circulation of the body
  • pressure is lost as the blood passes through the capillaries of the gills and is not built back up again until the blood returns to the heart
  • this makes single circulation inefficient
• Pulmonary circuit - 

  • reference to the lungs
  • circulation between heart and lungs
  • collects oxygenated blood from the lungs and pumps it to the body
• Systemic circuit:

  • circulation between heart and whole body
  • the right side of the heart collects deoxygenated blood from the body and pumps it to the lungs
  • pressure needs to be high in order to be able to transport the blood throughout the entire body
• Advantages of double circulation:

  • lungs and heart are close together, so the pressure of the blood in the pulmonary circuit must be sent slower (in comparison to the systemic circuit) if it was faster, the blood veins would rupture
  • efficient as there’s separate pressures, high pressure for the systemic circuit, low pressure for the pulmonary circuit
• Comparison of two circulations:

  A) 1

  B) low

  C) fish

  D) absent

  E) 2

  F) 2

  G) high

  H) reptiles

  I) amphibians

  J) birds

  K) mammals

  L) present

  M) 4

  
• ventricle:

  • thickness of wall on the left> thickness of wall on the right
  • needs to build up enough pressure to pump the blood to all of the main organs
  • the right ventricle pumps blood only to the lungs, which is a shorter distance
• atria:

  • thickness of atria walls<thickness of ventricle walls
  • because the contraction of the atria only needs to be powerful enough to move blood down into the ventricles, while the ventricles are moving blood around the body and through all of the organs
• septum divides the left side of the heart from the right side

  • prevents the mixing of oxygenated and deoxygenated blood
• Flow of blood:

  1. right atrium (via vena cava)
  2. right ventricle (through atrioventricular valve)
  3. pulmonary artery (through semilunar valve)
  4. left atrium (via pulmonary vein)
  5. left ventricle (through atrioventricular valve)
  6. aorta (all around body)
• Blood flow - 

  • deoxygenated blood → right atrium via vena cava
  • heart gives a beat & blood is pushed through atrioventricular valve → right ventricle
  • walls of the ventricle contract, blood → pulmonary artery through semilunar valve
  • blood → lungs, moves through capillaries
  • has to be low pressure for this – capillaries which would burst under higher pressure
  • oxygenated blood → left atrium via pulmonary vein
  • passes through atrioventricular valve into the left ventricle
  • walls of the ventricle contract to push the blood into aorta and all the way around the body
• Effect of physical activity on heart rate:

  • heart rate increases from the resting rate and stays high until physical activity slows down or stop 
  • heart rate increases to supply the muscles with more oxygen and glucose a
  • needed to allow the muscles to respire aerobically, so they have sufficient energy to contract
  • after exercise, the heart rate gradually returns to normal
• Coronary artery disease:

  • coronary artery is the artery that transfers blood to the heart
  • coronary heart disease is caused by blockage of the coronary arteries, which supply the heart with oxygen and glucose
  • people get heart attack from lack of oxygen to part of heart
• How CHD forms:

  • fat deposits form plaque 
  • fat starts to narrow down the lumen 
  • the blood that can go through becomes limited 
  • eventually - causes a difference in pressure that causes the layer, plaque and wall to rupture
  • blood clot + fat blocks off the blood vessel
• RISK OF CHD: Poor diet with too much saturated (animal fat)


  Leads to fatty deposits (atheroma) in arteries, which eventually block the blood vessel or allow a blood clot to form
• RISK OF CHD: Obesity 


  Being overweight puts extra strain on the heart and makes it more difficult for the person to exercise
• RISK OF CHD: Smoking 

  Nicotine damages the heart and blood vessels
• RISK OF CHD: Stress 

  Tends to increase blood pressure, which can result in fatty materials collecting in the arteries
• RISK OF CHD: Lack of exercise


  The heart muscle loses its tone and becomes less efficient in pumping blood
• RISK OF CHD: Genetic predisposition 


  Heart disease appears to be passed from one generation to the next in some families
• RISK OF CHD: Age 

  Risk increases with age
• RISK OF CHD: Sex 

  Males are more at risk than females
• Treatment for Coronary heart disease -

  Stent:

  • is used to expand the blood vessel and allow good flow of blood

  Bypass surgery:

  • an alternate route is provided for blood to flow
• three blood vessels:

  • artery
  • vein
  • capillary
• Artery:

  • Thick, tough wall with muscles, elastic fibres and fibrous tissue
  • Carries blood at high pressure – prevents bursting and maintains pressure wave
  • Lumen quite narrow, but increases as a pulse of blood passes through
  • This helps to maintain blood pressure
  • Valves absent 
  • The high pressure prevents blood flowing backwards, so valves are not necessary
• Vein: 

  • The walls are mainly fibrous tissue, with little muscle and few elastic fibres
  • Carries blood at low pressure
  • Lumen large 
  • This reduces resistance to blood flow
  • Valves present 
  • To prevent backflow of blood
• Capillary 

  • Permeable wall, one cell thick, with no muscle or elastic tissue
  • Allows diffusion of materials between capillary and surrounding tissues
  • White blood cells can squeeze between cells of the wall
  • Lumen approximately one red blood cell wide
  • Red blood cells pass through slowly to allow diffusion of materials and tissue fluid
  • Valves absent
  • Blood is still under pressure
• Heart:

  A) pulmonary artery

  B) vena cava

  C) right atrium

  D) semilunar valve

  E) atrioventicular valve

  F) right ventricle

  G) muscular wall

  H) aorta

  I) pulmonary vein

  J) left atrium

  K) semilunar valve

  L) atrioventicular valve

  M) tendon

  N) left ventricle

  O) septum

  
• Kidney:

  A) vena cava

  B) renal vein

  C) right kidney

  D) aorta

  E) renal artery

  F) left kidney

  
• Functions:

  • red blood cells = transporting oxygen
  • white blood cells = phagocytosis and antibody reproduction
  • platelets = clotting
  • plasma = transport of blood cells, ions, nutrients, urea, hormones & carbon dioxide
• Lymphocytes -

  • are involved in the production of antibodies, which are needed to fight disease
  • antibodies can attach themselves to antigens (foreign proteins) and clump them together
• Phagocytes -

  • have the ability to change their shape 
  • move to engulf pathogens by a process called phagocytosis
• Blood Clotting:

  • platelets are essential for blood clotting
  • blood thinners oppose this and stop clotting from happening (people who take blood thinners usually have stents in their hearts) (blood thinners is also a type of medicine)
  • prevents blood loss
  • prevents entry of pathogens
• Process of blood clotting - 

  1. platelets clump together when tissues are damaged and block the smaller capillaries
  2. platelets and damaged cells at the wound produce a substance that acts on a soluble plasma protein called fibrinogen
  3. fibrinogen is changed into insoluble fibrin, which forms a network of fibres across the wound
  4. red blood cells become trapped in this network and so form a blood clot