lesson 4

• Xylem


  Transports water and phloem, transports food and other substances
• Vascular Bundle


  • Found in plants
  • Serves as transport channels
  • Comprises xylem
• Root hairs


  Increase the surface area for transport
• Absorption of water plus macronutrients and micronutrients

  1. Through the root system

  2. Epidermis

  3. Cortex

  4. Endodermis

  5. Pericycle

  6. Upwards by means of xylem vessels
• Phloem cells


  Transport substances such as products of photosynthesis, water and other compounds up and down the plant body
• Phloem tissues


  • Adjacent to companion cells
  • Give them support and nourishment
• Hypotheses on how substances can move up and down the plant body

  • Ascent of xylem sap
  • Pressure flow or bulk flow
• Ascent of xylem sap

  1. Push from below by water molecules gushing upwards through xylem vessels

  2. Pull from above by a combination of transpiration and cohesion of water molecules through hydrogen bonds
• Pressure flow or bulk flow

  In the plant there is a source cell (where photosynthesis occurs) and a sink cell (where nutrients are needed), materials accumulate in the source and flow down (or up) where they are needed
• Sink cells


  • Growing parts of the plants- buds, flowers, fruits, root tips
• Xylem lies adjacent to phloem tissues and water may easily diffuse from xylem to phloem
• Materials are transported up and down the plant body by a combination of the actions of phloem and xylem cells
• Protozoan circulation


  Food products and oxygen are taken into the cell and distributed, the waste products are eliminated by diffusion
• Poriferan circulation


  Used canal systems to carry the food-laden water throughout the cells
• Coelenterate and Platyhelminth circulation

  A gastrovascular cavity serves both for nutrition and circulation
• Mollusk, annelid and arthropod circulation


  Have a heart and a well-developed vascular system
• Vertebrate heart chambers


  • Fishes have 2 (1 atrium and 1 ventricle)
  • Amphibians and reptiles (except crocodiles) have 3 (2 atria and 1 ventricle)
  • Birds and mammals have 4 (2 atria and 2 ventricles)
• Vessels which act as channels for circulation and transport are present in all vertebrates
• The human circulatory system comprises of the blood, blood vessels, and the heart
• Blood components


  • Plasma (55% of blood, 92% water, 8% dissolved nutrients, mineral salts, antibodies and hormones)
  • Red blood cells (45% of blood, contain hemoglobin to carry oxygen)
  • White blood cells (help defend the body against infection)
  • Platelets (work with fibrinogen in the clotting process)
• Plasma proteins


  • Albumin (regulates blood pressure and water content)
  • Globulin (contains antibodies)
  • Fibrinogen (works with platelets in clotting)
• Circulatory system


  A closed system of tubes that blood moves through in the body
• Circulatory system


  • Blood moves through your body in tubes called VESSELS
  • There are three kinds of vessels: ARTERIES, VEINS, CAPILLARIES
• Arteries


  Carry blood away from the heart
• Veins


  Carry blood towards the heart
• Capillaries


  Very small tubes that connect the arteries to the veins
• The human body has 100,000 miles of blood vessels
• If a person's blood vessels were laid end to end, they would circle the earth twice
• Arteries


  • Have thick, muscular walls
  • Expand and contract with the force of the heart pumping
• Aorta


  The large artery that is the first entry leaving the heart to the body
• Veins


  • Have muscular walls but thinner than arteries
  • Have one-way valves to prevent blood flowing backwards
• When you move your muscles

  It squeezes the blood inside the veins and pushes it towards the heart
• Veins


  • Carry blood to the heart
  • The blood in veins is darker in colour because it lacks oxygen
• Capillaries


  • Are so small that red blood cells must pass through them in single file
  • The walls of capillaries are only one-cell thick
• The work of the circulatory system takes place at the capillaries, where the exchange of materials between the blood and the cells takes place
• Circulatory system


  Has two separate parts: one that pumps blood to the lungs, and one that pumps blood to the body
• Key components of the human heart

  • Two atria (smaller chambers near top of heart that collect blood from body and lungs)
  • Two ventricles (larger chambers near bottom of heart that pump blood to body and lungs)
• Heart Valves


  • Atrioventricular valves (between atria and ventricles)
  • Semilunar valves (between ventricles and arteries)
• Atrioventricular valves


  Bicuspid valve on left side, tricuspid valve on right side
• Semilunar valves


  Aortic valve on left side, pulmonary valve on right side