B4 Animal & plant organisation

• The circulatory system:

  deoxygenated blood > vena cava > pulmonary artery > lungs > oxygenated blood > pulmonary vein > Aorta > body
• The left side of the heart has a thicker muscular wall to pump blood around the body
• The purpose of the coronary arteries is to provide oxygen to the muscle cells of the heart. The oxygen is used in respiration to provide the energy for contraction
• Heart

  An organ that pumps blood around the body in a double circulatory system
• Parts of the lungs

  • Trachea
  • Bronchi
  • Alveoli
  • Capillary network surrounding the alveoli
• Natural resting heart rate

  Controlled by a group of cells located in the right atrium that act as a pacemaker
• Artificial pacemakers

  Electrical devices used to correct irregularities in the heart rate
• Types of blood vessels

  • Arteries
  • Veins
  • Capillaries
• Arteries

  • Pump blood AWAY from the heart
  • Thick elastic walls due to high pressure of blood flow
  • Narrow lumen maintains pressure in artery
• Veins

  • Pump blood TO the heart
  • wide lumen, less pressure
  • Thin wall lining
  • contains valves - to prevent back flow of blood due to low pressure
• Capillaries

  • a network connecting arteries to veins
  • one cell thick - semi permeable & short diffusion pathway
  • Narrow lumen
  • Exchange nutrients + oxygen with cells and tissue
• Components of the blood:

  • 55% Plasma
  • 1% Platelets/white blood cells
  • 44% Red blood cells
• Heart

  • Pump blood around the body
  • The walls of the heart are made of cardiac muscle
  • The muscle is supplied with oxygen by coronary arteries
  • The left and right side of the heart never mix (separated by the septum)
• Circulatory system

  • The main function is to get nutrients and oxygen to every cell in the body and remove waste products
  • humans have a double circulatory system
• White blood cells

  • Much larger than red blood cells
  • contains nucleus
  • function - to defend against pathogens
• Platelets

  • small fragments of cells
  • No nucleus
  • platelets causes blood to clot at site of a wound forming a scab
  • reduces blood loss and prevents harmful pathogens from entering
• Plasma

  • Blood plasma is a pale straw coloured liquid
  • plasma carries :
  • red blood cells
  • white blood cells
  • platelets
  • hormones
  • antibodies and antitoxins
  • nutrients
  • waste products (carbon dioxide, urea)
• donated blood :

  1. To replace blood lost during injury
  2. Platelets extracted from blood to help in clotting
  3. Proteins extracted from blood can also be useful ( antibodies)
• In a blood transfusion it is important to make sure that the donated blood is the same type as the patient otherwise the body’s immune system will reject the blood leading to death .
• cardiovascular disease are diseases of the heart and blood vessels
• Coronary heart disease

  • layers of fatty material build up inside the coronary arteries, narrowing them
  • This reduces the flow of blood through the coronary arteries
  • resulting in a lack of oxygen for the heart muscle
• Treating coronary heart disease:

  1. Stent - metal mesh that is placed in the artery which widens the artery to increase blood flow however does not treat underlying causes of disease
  2. Bypass surgery - replace narrow or blocked artery with parts of veins
  3. Statins - drugs which reduce the level of cholesterol slowing down the rate of fatty material build up in the arteries. Statins are effective however can cause unwanted side effects (liver problems)
• Heart transplants

  • long wait for a donor
  • requires open heart surgery (risk of infection + long recovery time)
  • immunosuppressant drugs to ensure the heart is not rejected by their own immune system
• Artificial hearts

  • mechanical devices that pumps blood for a person who's own heart has failed
  • temporary until donor is found
  • less likely to be rejected by the body
  • parts of the heart could wear out/motor could fail - required to take blood thinning drugs
• Damaged valves allow the blood to flow in both directions leading to less effective circulation
• Biological valves

  • valves that are taken from animals
  • work very well but not long lasting
  • chance of rejection by immune system
  • risk of infection
• Artificial valves

  • Made from titanium and polymers
  • very durable and last a long time (replacement not needed)
  • need to take blood thinning drugs for majority of life
  • risk of infection
• Pace makers

  • an artificial pacemaker is an electric device used to correct irregularities in the heart rate
  • sends electrical signals to the heart to stimulate it to beat properly
  • patients fitted with a pacemaker are in need of regular checkups
• Artificial blood is a blood substitute (eg salt solution) that gives patients enough time to produce new blood cells
• Plant organ contains leaf stem and roots
• Layers of a leaf

  • waxy cuticle - thin layer of lipids and reduces water loss by evaporation
  • upper epidermis - transparent to let light pass through
  • palisade mesophyll - many chloroplasts near the top so photosynthesis can take place
  • spongy mesophyll layer - air spaces increases the rate of diffusion
  • Lower epidermis - full of stomata , opening and closing controlled by guard cells in response to the environment
• xylem:

  • Continuous and hollow tube thats strengthened by a chemical called lignin
  • carry water and mineral ions from the roots to the stem and leaves (one direction)
• Phloem:

  • phloem Tubes transport food substances (glucose) made in the leaves to the rest of the plant
  • transport goes in BOTH directions (translocation)
  • companion cells provide energy for the movement of glucose/amino acids
• Osmosis = the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
• Plant cells placed in a solution of the SAME concentration will experience NO osmosis
• Plant cells placed in a LESS concentration solution will GAIN water by osmosis, causes cell to swell up and become turgid (firm)
• Plant cells placed in a MORE concentrated solution will LOOSE water by osmosis, causes the cell to become flaccid (soft)
• Root hair cells are adapted for the efficient uptake of water by osmosis and mineral ions by active transport
• Active transport The net movement of particles from an area of low concentration to an area of higher concentration using energy.
• Meristem tissue found at the growing tips of shoots and roots