Topic 5 - Blood and Organs

• Unicellular organisms need to exchange substances. Why don't they need transport systems?


  - Exchange things like food + waste products

  - Exchange across the cell membrane

  - Unicellular organisms do not have specialist exchange surfaces + transport systems because they have large SA to volume ratio (meaning diffusion/osmosis/active transport can occur at a sufficient rate)
• Why do multicellular organisms need transport systems?

  Organisms contain many layers of cells --> distance between the surface of organism to the centre is long = diffusion is too slow
• Example of unicellular organism

  amoeba
• Transport system in animals

  circulatory system - carries substances via blood (oxygen, glucose, water, waste, carbon dioxide)
• Transport system in plants


  vascular system - xylem carries mineral salts frm root to shoots + water, phloem carries amino acids + sugars
• Blood consists of?


  Plasma, white blood cells, red blood cells, PLATELETS
• Red Blood cells


  - Biconcave shape = large surface area for absorbing + releasing oxygen (diffusion)

  - no nucleus so there is plenty of space for haemoglobin to carry oxygen (reacts w oxygen in lungs to become oxyhemoglobin BUT in body tissues, it releases oxygen)
• White blood cells


  Large cells containing big nucleus. There are 2 types of white blood cells:

  1. Phagocytes -> carry out phagocytosis by engulfing and digesting pathogens. Once they sense a foreign pathogen (through its chemicals produced), it engulfs the pathogen and digests them with their digestive enzymes. They have a multi-lobed nucleus + granular cytoplasm (distorted).

  2. Lymphocytes -> Produce antibodies that are specific to one type of pathogen. They are Y-shaped proteins. IF however they come across a foreign antigen, anti-bodies will be made which lock onto the pathogen to mark them out. The anti-bodies cause the pathogenic cells to clump together = restrict movement and chemical signals are sent out to the phagocytes to be destroyed. Lymphocytes also produce anti-toxins to neutralise toxins released by pathogens. They have one LARGE round nucleus.
• Platelets


  Fragment of cells that clump together to form blood clots when blood vessels get damaged. Prevents you from losing a lot of blood
• Plasma


  Straw coloured, watery fluid in which holds all the components of blood flow. Transport substances like CO2, urea (breakdown of protein in liver), hormones (chemical messengers released into blood), heat energy (to areas of heat loss)
• Antigens


  Each pathogen has specific antigens on the surface of its cell. It is a molecule. it invades the body.
• Memory cells


  MEMORY CELLS are also produced as a response to foreign antigens, they reproduce quickly to mark out an antigen that has entered the body before and fight them off.
• Process of engulfing + digesting for phagocytes


  phagocytosis
• Where the left side of the heart?

  the RIGHT side of the page
• what is the atrium and ventricle separated by?

  valve
• what does the valve do?

  prevents blood from flowing backwards
• which ventricle has thicker walls?

  The left ventricle because blood is pumped out to the body meaning the blood is under higher pressure.
• Which blood vessel carries deoxygenated blood from the heart to the lungs?

  pulmonary artery
• The journey of blood around the body (heart)


  body tissues --> vena cava --> right atrium --> right ventricle --> pulmonary artery --> lungs --> pulmonary vein --> left atrium --> left ventricle --> aorta --> body tissues
• Which blood vessel carries oxygenated blood from the heart to the body?


  aorta
• The movement of blood between the ventricles and atria:


  1. The walls of the atria contract, pushing blood into the relaxed ventricles.

  2. The walls of the ventricles contract, pushing blood out of the heart. At the same time, more blood will enter the now-relaxed atria.

  3. The cycle repeats.
• Pacemaker cells are found in which chamber of the heart?

  right atrium
• What are pacemaker cells?


  Cells that send electrical impulses through the heart that keep it beating at a steady rhythm
• Arteries


  carry blood away from the heart

  - carry blood out at high pressure = artery walls strong + elastic (can expand and maintain blood pressure)

  - blood flows through at fast rate (blood needs to deliver nutrients to the rest of the body)

  - narrow LUMEN = maintain pressure

  - thick + strong muscular walls
• Veins


  carry blood to the heart

  - blood flow is slow + pressure is low = large lumen to maintain steady blood flow (reduce resistance)

  - contains valves = prevent blood flowing backwards
• What supplies the heart muscle with oxygen and nutrients?

  The coronary arteries
• Exercise + adrenaline ( the heart )


  During exercise, cells of muscle respire more rapidly in order to provide energy for muscle contraction.

  
  

  - Exercise --> cells of muscle respire more rapidly to provide energy for muscle contraction

  - respiration increases = more oxygen + glucose required + move waste products (CO2) must be removed =

  1. heart rate increases (rate at which heartbeats (beats per min)) = deliver more + remove more

  2. volume of blood pumped out of heart increases

  note: After exercise, heart rate continues to increase as extra oxygen is needed to break down the Lactic acid produced (oxygen debt)

  
  

  Adrenaline = hormone released by the adrenal gland that increases heart rate causing 'fight or flight' response

  - during times of fear or stress, adrenaline is produced by adrenal glands

  - adrenaline binds to specific receptors in heart so heart rate increases + heart pumps more blood = increase oxygen supply to tissues getting body ready for action
• Coronary heart disease


  Layers of fatty material (plaque) build up inside the coronary arteries

  - fatty deposits mainly formed from cholesterol (dietary + cholesterol synthesised by liver)

  - many layers of fatty material - the artery becomes blocked losing its ELASTICITY = cannot stretch to accommodate blood flow
• Risk factors increasing chances of coronary heart disease (4)

  1. obesity (diet high saturated fat) - extra weight = strain heart, type 2 diabetes can further damage blood vessels

  2. high blood pressure - increases force of blood against artery walls = damage of the vessels

  3. high cholesterol - speeds up build up of fatty plaques in coronary arteries = more build up

  4. smoking - an increase-in blood pressure = damage coronary artery walls + fatty material (plaque) builds up
• Blood vessels


  arteries, capillaries, veins
• Capillaries


  involved in exchange of materials at the tissues

  - ARTERIES branch into CAPILLARIES

  - speed of blood flow is SLOW

  - carries oxygenated + deoxygenate blood (nutrients to be delivered to cells in bodies + waste from those cells like CO2)

  - VERY SMALL

  - carries blood very close to cell to exchange substances

  ADAPTATIONS:

  - walls are once-cell thick to allow for fast DIFFUSION

  - permeable walls = diffusion of substances
• Circulatory system


  Closed network of blood vessels connected to the heart:

  - oxygenated blood carried away from heart from aorta and into organs (carried by arteries)

  - narrow to arterioles then capillaries as they pass through organs (exchange substances)

  - organs = respiring cells use oxygen from blood

  - capillaries widen to veins as they move away from organ and into heart (carrying deoxygenated blood) via the vena cava
• normally arteries carry _____ EXCEPT for the pulmonary artery


  oxygenated blood
• normally veins carry _____ EXCEPT for the pulmonary vein


  deoxygenated blood
• lymphatic system


  our body's 'sewerage system'. It maintains fluid levels in our body tissues by removing all fluids that leak out of our capillaries back to the circulatory system
• Blood vessels HEART


  towards organ --> vena cava, pulmonary vein

  away from organ --> pulmonary artery, aorta
• Blood vessels LUNG


  towards organ --> pulmonary artery

  away from organ --> pulmonary vein
• Blood vessels KIDNEY


  towards organ --> renal artery

  away from organ --> renal vein
• RENAL


  to do with kidneys
• PULMONARY


  to do with lungs