Lesson 8: PLANT AND ANIMAL ORGAN SYSTEMS AND THEIR FUNCTIONS

• All living organisms obtain energy by metabolizing compounds such as carbohydrates
• RespirationThe process by which organisms require oxygen for metabolism


  Respiration
• Carbon dioxide gas is produced and must be removed from the body of animals
• In plants, carbon dioxide, a waste product of respiration, is needed for photosynthesis
• Animals have to take in oxygen and expel carbon dioxide in order to survive
• Gas exchange


  One of the essential prerequisites for life to continue
• Diffusion


  A process by which molecules move from an area of higher concentration to an area of lower concentration in the direction following a concentration gradient
• Breathing


  Mechanical process by which oxygen is taken in and carbon dioxide is released
• Ways in which animals obtain oxygen

  • Through the moist surface directly into the body
  • Through a thin, moist body wall of blood vessels
  • Through spiracles (opening on the thorax) or a tracheal system to a system of ducts to the tissues
  • Through moist gill surfaces to blood vessels
  • Through moist lungs surface to blood vessels
• Respiratory system


  Its function is to exchange oxygen and carbon dioxide between the air and the cells
• In simple animals, exchange of gases directly occurs with the environment
• In some animals like mammals, breathing is done through the body's nasal passages
• The general body surface of most animals lacks sufficient area to exchange gases for the whole organism
• The solution is a respiratory organ that is extensively folded or branched, thereby enlarging the available surface area for gas exchange
• Air is a respiratory medium with plentiful O2. Water has much less oxygen and greater density and viscosity, making gas exchange more challenging in water than in air
• The respiratory surfaces (organs) where gas exchange with the respiratory medium occurs must be moist, thin, and large enough to supply the whole body
• Types of gas exchange systems used by animals


  • Skin system
  • Gills system
  • Tracheal system
  • Lung system
• Skin system


  • Animals that live in moist environments like worms and amphibians use their moist body surface to breathe in oxygen
  • Capillaries or tiny vessels lie just below the skin of worms to facilitate gas exchange between the external environment and the circulatory system
  • The skin of frogs is made up of very thin tissues, allowing smooth exchange of gases
• Gills system


  • Fish and other aquatic animals use their gills to take up the dissolved oxygen from water
  • Gills are thin tissue filaments that are highly branched and folded
  • When water passes over the gills, the dissolved oxygen in water rapidly diffuses across the thin membranes of the gills into the bloodstream
  • Carbon dioxide in the bloodstream of the animals leaves through the gills
• Tracheal system


  • Insects, such as grasshoppers and spiders, use their tracheae to facilitate gas exchange
  • Tracheae consist of air tubes called spiracles forming network in the bodies of insects
  • Spiracles connect to the tubular network allowing oxygen to pass into the body and regulate the diffusion of CO2 and water vapor
• Lung system


  • A pair of organs divided into small chambers filled with capillaries called lungs are found inside the cavity of land animals such as humans
  • The tube that connects the nose and mouth to the lungs is called trachea
  • The trachea divides into two main bronchi (the left and right) which further subdivides into bronchioles
  • The tip of each bronchiole is called alveolus wherein actual gas exchange occurs
  • Lying flat at the bottom of the chest cavity (under the lungs) is the diaphragm, a large muscle that aids in breathing by moving up and down
  • The rib cage encloses the lungs and protects the respiratory organs and the heart
• Inhalation


  1. The diaphragm contracts and the ribs move up making the size of the chest cavity larger, allowing for more space and less air pressure inside the lungs

  2. Air is pushed in from the outside where there is higher pressure and is pushed into the lungs where there is lower air pressure
• Exhalation


  1. The diaphragm relaxes and the ribs and chest cavity return to their original place, decreasing the space and increasing the air pressure inside the lungs

  2. Air is pushed to the outside where there is lower pressure
• Plants exchange their gases with the environment in a straightforward way
• In order to carry on photosynthesis, green plants need a supply of carbon dioxide and a means of disposing oxygen
• Contrary to animals, plants do not have specialized organs for gas exchange
• In aquatic plants, water passes among the tissues providing a medium for gas exchange, while in terrestrial plants, air enters the tissues and the gases diffuse into the moisture bathing the internal cells
• Diffusion is the only process through which much needed oxygen is supplied to all the cells of the plants
• Diffusion occurs in leaves, roots, and stems
• Leaves


  • Plant leaf consists of stomata that allow gas exchange between the surrounding air and the photosynthetic cells inside the leaf
  • Stomata regulate CO2 uptake for photosynthesis and are the major avenues for the evaporative loss of water
  • The mesophyll consists mainly of parenchyma cells specialized for photosynthesis
  • The palisade mesophyll consists of one or more layers of elongated parenchyma cells on the upper part of the leaf
  • The air spaces are particularly large in the vicinity of the stomata, where gas exchange with the outside air occurs
• Roots


  • Plant roots take oxygen from the air that is present in between the particles of soil
  • Root hair, an extension of the root epidermal cells, is in direct contact with the soil
  • Oxygen diffuses in the root hair, reaching all the other cells of the roots
  • It is through the root hairs that only carbon dioxide gets diffused into them and is expelled from the roots of a plant
• Roots absorb oxygen from air present in-between the soil particles through the root hair
• Stems


  • Lenticels are in the small area of a bark
  • Lenticels are loosely placed, allowing gaseous exchange of respiratory gases between air and living cells of the woody stem
• Organisms require food, water, and oxygen for survival
• The circulatory system functions to support life as it feeds our cells with food and oxygen, and removes waste products
• Open circulatory system


  There is no distinction between blood and interstitial fluid, this general body fluid is more correctly called hemolymph
• Closed circulatory system


  Blood is confined to vessels and is distinct from the interstitial fluid
• 3 main Parts of the circulatory system

  • Heart
  • Blood vessels
  • Blood
• Heart


  • It is a bundle of muscles about the size of the fist
  • It is located in the center of the chest in between the lungs and is tilted to one side and points downward to the left
  • It is divided into two chambers: the top chamber called atrium (plural: atria) and the bottom chamber called the ventricle
  • Between each atrium and ventricle is a valve that prevents the blood from flowing backwards
  • There are four blood valves in the heart: the tricuspid (right), bicuspid (left), pulmonary, and aortic valves
• Arteries


  They have thick muscular walls, are elastic and expand every time the ventricles contract, carry blood away from the heart, and the blood in the arteries is bright red because it contains much oxygen