module 1B

• Gas exchange


  The exchange of oxygen and carbon dioxide between an organism and its environment
• Gas exchange in plants

  • Carbon dioxide is used in photosynthesis, oxygen is released
  • Gases diffuse through moist cell membranes and stomata in leaves
• Gas exchange in animals

  • Oxygen diffuses into the bloodstream and carbon dioxide diffuses out
  • Exchange happens directly with the environment in simple animals, and between the environment and blood in complex organisms
• Gas exchange structures in animals

  • Skin (e.g. earthworms)
  • Spiracles and tracheae (e.g. arthropods)
  • Gills (e.g. fish)
  • Lungs (e.g. amphibians, reptiles, birds, mammals)
• Human respiratory system


  • Provides oxygen for cellular respiration and removes carbon dioxide
  • Includes airways (mouth, nose, sinuses, pharynx, trachea, bronchial tubes), lungs, and diaphragm
  • Gas exchange occurs in the alveoli of the lungs

  
• Functions of the respiratory system

  • Provide oxygen for cellular respiration to body tissues
  • Extract carbon dioxide from waste product
  • Help preserve acid-base balance
  • Used for non-vital purposes like odor detection, voice generation, and stress
• Parts of the respiratory system

  • Mouth and nose
  • Sinuses
  • Pharynx (throat)
  • Trachea
  • Bronchial tubes
  • Lungs

  
• Diaphragm


  Muscle that helps lungs pull in air and push it out
• Ribs


  Bones that surround and protect lungs and heart
• Components that work with lungs and blood vessels

  • Alveoli
  • Bronchioles
  • Capillaries
  • Lung lobes
  • Pleura

  
• Other components of the respiratory system

  • Cilia
  • Epiglottis
  • Larynx (voice box)

  
• Breathing in


  Air enters body through nose and mouth
• Cilia and mucous


  Work to trap dirt and germs before we inhale
• Diaphragm


  Helps draw air into the lungs
• Brain

  Controls the rate of breathing
• The structure where the respiratory system and the circulatory system meet is the alveoli

  
• Xylem


  Tissue composed of dead, hollowed-out cells that form a web of pipes to carry water and minerals up through the stem
• Lignin


  Substance that strengthens the walls of xylem cells to tolerate pressure changes as water flows through the plant

  
• Phloem


  Living cells that transport sugar formed by photosynthesis in the leaves up and down the plant to growing parts, storage organs, developing seeds, and for respiration
• Sieve tubes


  Specialized phloem cells for transport that contain no nuclei and have perforated end walls so cytoplasm binds one cell to the next
• Companion cells


  Supply the energy for the sieve cells in the phloem
• In the root, the xylem forms a central axis for support, with the phloem in the middle above the xylem. In the stem, the xylem and phloem are organized into vascular bundles.

  
• Water transport in plants

  1. Water enters root hair cells by osmosis

  2. Moves through root cortex by osmosis down a concentration gradient

  3. Enters xylem vessels in the center of the root

  4. Moves up xylem vessels to leaves

  5. Exits xylem and moves from cell to cell

  6. Some water evaporates from leaves through stomata in a process called transpiration
• Heterotrophs are species which cannot produce food on their own and rely on other sources/organisms
• Plants require transport mechanisms to carry water, dissolved food and other substances around their structures in order to remain alive
• Water is required by plants for photosynthesis and transport of minerals
• Unicellular organisms rely on simple diffusion for transport, while multicellular organisms have developed more complex circulatory systems
• Parts of the circulatory system

  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
  • Heart
  • Arteries
  • Veins
• The heart pumps blood through a network of arteries and veins called the cardiovascular system
• The network of arteries carries oxygenated blood from the heart to provide oxygen and nutrients to body cells, and the veins carry deoxygenated blood back to the heart
• Transpiration stream


  Flow of water through the plant
• Transport systems are crucial to survival
• Unicellular organisms rely on simple diffusion for transport of nutrients and removal of waste
• Multicellular organisms have developed more complex circulatory systems
• Parts of the Circulatory System

  • Plasma (fluid part of blood)
  • Red blood cells or erythrocytes (transports oxygen)
  • White blood cells (defense of the body)
  • Platelets (blood clotting)
• Heart


  Four-chamber muscular organ that pumps blood through the cardiovascular system
• Arteries


  Carry oxygenated blood
• Veins


  Carry deoxygenated blood
• Blood vessels


  Network of arteries and veins that bring oxygenated blood from the heart, provide oxygen and nutrients to the cells of the body, and then return deoxygenated blood back to the heart
• Open Circulatory System


  • Blood vessels carry all fluids to the cavity
  • Blood moves freely in both directions throughout the body
  • Blood bathes the body immediately, delivering oxygen and eliminating waste from the bloodstream
  • Blood moves at a very slow pace due to the lack of smooth muscles