Bio

• Oxygen gas (O2)


  Needed for cellular respiration
• Getting oxygen


  Lungs create a pressure gradient, and the movement of O2 from higher to lower pressures and concentrations
• Carbon dioxide (CO2)


  Created through the process of cellular respiration as we oxidize food
• Getting rid of CO2

  Travels from high to low—from cells in tissues to the blood and then the lungs to be exhaled
• Breathing gets O2 in and allows CO2 out. The gases travel through the blood and the CO2 and O2 exchange actually happens at the capillary beds. This is driven by laws of high to low partial pressure.
• Gas exchange


  Passive transport, movement from high to low which doesn't require energy input
• Respiratory surfaces have to be thin and moist to allow for exchange
• Gas exchange in different organisms

  • Earthworm- exchange gases through their skin
  • Fish- use gills with capillaries that lie just below the gill surfaces
  • Insect- use a tracheal system of tubes (not lungs)
  • Mammal- mammals use lungs and have a closed circulatory system

  
• Tracheal system of insects

  Branching tubes that connect the outside air to the inside of the organism, allowing for gas exchange

  
• Gills


  Extensions of the body that have a high surface area for gas exchange

  
• Countercurrent exchange in gills

  Water travels across the gills in the OPPOSITE direction of blood flow, ensuring a concentration gradient the whole way across the gills so O2 can diffuse into gills the entire length
• Components of the respiratory system

  • Nasal cavity
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi
  • Bronchioles
  • Alveoli
  • Diaphragm
• Alveoli are directly associated with capillaries in the lungs, where gas exchange occurs
• Cilia and mucous in the respiratory system

  Mucous traps stuff and cilia sweep that stuff out, cleaning the system and protecting the lungs
• Surfactants


  Chemicals that line the alveoli to keep them from collapsing, preventing the moist surfaces from sticking shut
• COPD (chronic obstructive pulmonary disease)

  Chronic bronchitis and emphysema, with emphysema being damage to the walls of the alveoli causing the lungs to lose their elasticity
• Negative pressure breathing


  A system in which air is pulled into the lungs as the chest cavity expands
• Hemoglobin


  A protein complex in red blood cells that binds oxygen, with the iron molecule causing the oxygen to stick
• Hemoglobin transports oxygen and CO2, and buffers blood
• Fetal hemoglobin


  A form of hemoglobin found in fetuses
• Additional functions of the circulatory system

  • Defense (immune system)
  • Temperature regulation
  • Hormone distribution
• Open circulatory system


  Interstitial fluid that bathes the tissues, with vessels that are opened ended
• Closed circulatory system


  Blood stays in blood vessels, in a closed loop
• Animals with an open circulatory system: Gastrovascular cavity (only 4 animals with tissues layers a few cells thick)

  Animals with a closed circulatory system: Most animals
• Types of blood vessels

  • Arteries (arterioles = smaller arteries)
  • Veins (venules = smaller veins)
  • Capillaries
• Single circulation


  One pump
• Double circulation


  Two pumps (ventricles)
• Animals with a 2-chamber heart have single circulation, animals with a 4-chamber heart have double circulation
• Ventricles


  Pump blood out

  Right ventricle- pumps blood to the lungs

  Left ventricle – pumps blood to the rest of the body
• AV valves


  Separate atria and ventricles, open during diastole
• Semilunar valves


  Separate the ventricles from the arteries they feed, closed during diastole
• Systole


  When the heart contracts, higher pressure phase of the cardiac cycle
• Diastole


  When the heart relaxes, lower pressure phase of the cardiac cycle
• Coronary arteries feed the heart muscle itself with blood. In a heart attack, heart muscle is deprived of blood (usually due to a blockage) and the muscle tissue dies.
• Atherosclerosis


  Buildup of plaque in the artery walls, causing a narrowing of the arteries and potentially leading to heart attacks and strokes
• Hypertension


  Negative health effects include making the heart work harder, rupturing artery walls due to increased pressure, and increasing the likelihood of stroke, heart attack, kidney disease, and heart disease
• Artery and vein structure

  Arteries and veins are made of connective tissue, smooth muscle, and epithelium, while capillaries are made of only 1 thin layer of epithelial cells wrapped in a thin layer of connective tissue
• Arteries need more elastic connective tissue to handle the high blood pressure from blood being pumped out of the heart
• What capillaries bring and take away

  Capillaries bring O2 and nutrients, and take away CO2 and other wastes
• Venous blood flow


  Skeletal muscles and one-way valves assist in moving venous blood back to the heart against the flow of gravity, as blood pressure is low in the veins