LESSON 4

• Respiration


  The process by which organisms take in oxygen and release carbon dioxide

  
• Circulation


  The movement of blood, nutrients, gases, and other substances through the body
• Respiratory system


  Works with circulatory system to bring oxygen to cells and carry carbon dioxide back to the lungs where it can be expelled

  
• Circulatory system


  • Has to pump blood against gravity
  • Needs to prevent backflow
  • Must overcome these and other challenges to deliver needed materials to different cells
• Plants


  • Must work against gravity to bring water and minerals from the roots to the shoots where they are needed
  • Must supply sugar to organs that will break it down for energy supply and organs that will store it
• Gas exchange


  The process by which animals breathe in oxygen from the environment and expel carbon dioxide to the environment
• Cellular respiration


  The process through which the body takes in oxygen to break down sugar from food, producing energy and by-products such as water and carbon dioxide
• Gas exchange


  1. Oxygen enters the body as one breathes and reaches the respiratory surface where gas exchange with carbon dioxide occurs

  2. Oxygen is then carried by the circulatory system to different parts of the organism's body

  3. Carbon dioxide is carried by the circulatory system towards the respiratory surface

  4. After gas exchange, Carbon dioxide is expelled from the body

  
• Respiratory structures


  • Always moist
  • Have large and thin surface area, usually formed by single layers of cells
• Animals using skin for respiration


  • Amphibians
  • Some invertebrates
• Gills


  Outfoldings that extend from the body and are immersed in water, where gas exchange between water and blood occurs
• Tracheal system


  Land animals' respiratory system made up of highly branched tubes called tracheae, where gas exchange occurs directly between the smallest tracheae branches and body cells

  
• Lungs


  Internal sacs which are heavily subdivided and found in most land vertebrates, where gas exchange occurs in the moist epithelium lining the sacs

  
• Human respiratory system


  1. Air is inhaled through the nostrils and goes into the nasal cavity

  2. Air then moves to the pharynx

  3. Air then goes to the trachea which branch into two bronchi towards each lung

  4. Bronchioles become smaller as they extend further from the bronchi

  5. Alveoli are found at the tips of the bronchioles, where gas exchange occurs
• Alveoli


  • Very small air sacs where the exchange of oxygen and carbon dioxide takes place
  • Capillaries are blood vessels in the walls of the alveoli
  • Highly sensitive to contaminants found in polluted air and cigarette smoke
  • White blood cells are commonly found guarding these sacs

  
• Gas exchange in the respiratory system

  1. Oxygen moves to the lung as it is inhaled and diffuses down to the blood capillaries

  2. Oxygen-rich blood then travels to the heart and is pumped to the tissue cells

  3. Carbon Dioxide from the tissue cells diffuses to the blood and returns to the heart

  4. The heart pumps this oxygen-poor blood into the lungs where carbon dioxide diffuses into the alveolar air spaces and is exhaled out

  
• Hemoglobin


  The most important component of red blood cells, composed of a protein called heme that binds oxygen, causing the blood to turn red when carrying oxygen

  
• Circulatory system


  Helps organisms transport nutrients, gases, and waste materials necessary for life

  
• Animals with no circulatory system

  • Hydra
• Open circulatory system


  Found in invertebrates, mollusks, and arthropods, where the circulatory fluid flows out of the vessels into the tissues
• Closed circulatory system


  Found in animals such as earthworms, octopuses, and vertebrates, where blood is restricted inside the vessels and is different from the interstitial fluid

  
• Arteries


  Bring blood away from the heart to the different tissues
• Veins


  Carry blood back to the heart
• Capillaries


  Bring blood from arteries and veins to the tissues

  
• Heart


  • Has two atria that receive blood and two ventricles that pump blood
  • Has two valves to prevent backflow of blood: atrioventricular valves between atria and ventricles, and semilunar valve between left ventricle and aorta

  
• Blood flow through the heart and lungs

  1. Oxygen-poor blood from the body goes back to the heart, then is pumped to the lungs for gas exchange

  2. Oxygen-rich blood flows back to the heart to be pumped to the rest of the body

  3. Oxygen-poor blood from the upper and lower body goes to the right atrium, then the right ventricle, and is pumped to the lungs

  4. Oxygen-rich blood goes from the lungs to the left atrium

  
• Heart


  Has four chambers: two atria (receive blood) and two ventricles (pump blood to lungs and body)
• Heart


  • Has two valves: atrioventricular valves (between atria and ventricles) and semilunar valve (between left ventricle and aorta)
• Blood circulation


  1. Oxygen-poor blood from body goes to heart, then pumped to lungs for gas exchange

  2. Oxygen-rich blood flows back to heart to be pumped to rest of body

  
• Superior vena cava


  Carries oxygen-poor blood from upper body to right atrium

  
• Inferior vena cava


  Carries oxygen-poor blood from lower body to right atrium

  
• Blood circulation


  1. Right atrium pumps oxygen-poor blood to right ventricle

  2. Right ventricle pumps oxygen-poor blood to lungs through pulmonary arteries

  3. Oxygen-rich blood returns to left atrium through pulmonary veins

  4. Left atrium pumps oxygen-rich blood to left ventricle

  5. Left ventricle pumps oxygen-rich blood to body through aorta

  
• Blood vessels


  Main function is to transport materials to different parts of the body
• Blood


  Connective tissue composed of 55% plasma and 45% blood cells and other cells

  
• Plasma


  90% water with different types of molecules including ions, organic salts, proteins, carbon dioxide, gases, nutrients, hormones, and waste products
• Red blood cells


  • Adapted structure with depression in center and lack of nucleus to enhance oxygen transport capacity
  • Mature red blood cells eject nuclei and organelles to carry more hemoglobin
  • Red blood cells have a lifespan of 100-120 days

  
• White blood cells


  Several types associated with immunity
• Platelets


  Function in blood clotting to prevent and stop bleeding
• Cardiac cycle


  1. Hearth contraction (systole) and relaxation (diastole) occurs in a rhythmic cycle

  2. One cycle lasts 0.8 seconds at a normal heart rate of 72 beats per minute
• Blood pressure


  • Measured using a sphygmomanometer
  • Normal blood pressure for a healthy young adult is 120/70
  • Systolic pressure is the top number, diastolic pressure is the bottom number
  • Blood pressure higher than normal is indicative of cardiovascular disease