Respiration Pre IB

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  • Remember, oxygen is the final electron acceptor in cellular respiration (O 2 combines with H + & electrons to form H 2 O).
  • Diffusion can effectively distribute substances over about 0.5 millimeters. Earthworms & amphibians have circulatory systems that transport gases between cells & the body surface.
  • Gills are not suited to a terrestrial environment because they tend to collapse in air. Problem with external gills is that they are easily damaged. Sea stars & sea urchins have dermal gills that project from body wall. Gills are ventilated by ciliated epidermal cells. Parapodia of polychaetes function as gills & in locomotion.
  • Countercurrent flow maximizes amount of oxygen extracted from the water.
  • Atmospheric
  • A First lungs appeared in lobe-finned fishes (smooth-walled sacs associated with capillary beds). Lungs of lobe-finned fishes & lungfishes (bichir) supplemented gills in breathing air. B & C Amphibian lungs have few subdivisions. Gills &/or skin supplement lungs. Lungs of reptiles (D), birds (E) & mammals (F) are highly subdivided & are used exclusively for respiration. Turtles are an exception - rigid shell restricts ventilation, so they supplement lung breathing with gas exchange across moist surfaces in mouth & cloaca. Note: bird lungs are unusual in that they contain air sacs that enable them to move air through the lungs in a one-way direction.
  • Air leaving pharynx enters larynx. Food leaving pharynx enters esophagus. Larynx is composed of 9 cartilages, one of which is the epiglottis. When you swallow, the larynx rises up as the epiglottis curves downward. These actions combine to close the opening to the larynx (glottis), causing food to enter the esophagus. Males begin producing relatively large amounts of testosterone during puberty. Testosterone causes the vocal cords to lengthen & thicken - results in deepening of voice.
  • Note dome shape of relaxed diaphragm. When diaphragm contracts it flattens. Contraction of external intercostal muscles causes rib cage to expand. The action of both these muscles increases the volume of the thoracic cavity. When volume increases, pressure decreases. Air rushes inward because the air pressure inside the thoracic cavity is less than that of the atmosphere. Air will stop rushing in when the 2 air pressures equalize.
  • Normal exhalation is a passive process because it occurs without contracting any muscles. Muscles relax & lungs recoil, returning to their original shape. Air is pushed out because air pressure inside the thoracic cavity is greater than that of the atmosphere. Air will stop rushing outward when the 2 air pressures equalize. Once you have taken your first breath, you can never force all of the air out of your lungs. The air remaining after a maximal exhalation is called residual air.
  • At rest, most adults breath an average of 12 times/ minute. Thus, the medulla sends out 12 impulses/minute.
  • To a lesser degree, the increase in arterial CO 2 is detected by chemoreceptors in the carotid arteries & aorta. [Chemoreceptors in the carotid arteries & aorta mediate 30% of the response]

Transcript

  • 1. Respiration
  • 2.
    • What is respiration?
    • External respiration - exchange of O 2 & CO 2 between respiratory surfaces & the blood [breathing].
    • Internal respiration - exchange of O 2 & CO 2 between the blood & cells.
    • Cellular respiration - process by which cells use O 2 to produce ATP .
  • 3. Gas Exchange in Animals Describe the 4 functional processes involved in most animal respiration. Compare to gas exchange in plants.
  • 4.
    • Types of Respiratory Surfaces
    • All respiratory surfaces MUST be:
      • moist
      • thin
      • large enough to meet metabolic needs of organism
    • Challenges:
      • Aquatic organisms - H 2 O contains only 1/30 of the O 2 present in air.
      • Terrestrial organisms - must prevent desiccation of respiratory surface.
  • 5. Respiratory Organs Respiratory adaptations, as it relates to lifestyle.
  • 6.
    • 1. Body surface
      • simplest gas exchange mechanism
      • adapted to moist environment
      • may be associated with circulatory system
    • protista
    • cnidaria
    • flatworms
    • earthworms
    • amphibians
  • 7.
    • 2. Tracheae - highly branched system of internal tubules.
      • adapted to terrestrial environment
      • NOT associated with a circulatory system
    • Terrestrial arthropods
    • Large, active arthropods use abdominal & flight muscles to ventilate tubules.
  • 8. Tracheal System in Insects Each cell has a nearly direct means of gas exchange via the tracheal system (2-4 spiracles on the thorax, 6-8 on abdomen). (May serve as storage reserve)
  • 9.
    • 3. Gills - featherlike extensions of the body surface.
      • adapted to aquatic environment
      • may be external or internal
    • some echinoderms
    • some annelids
    • aquatic mollusks
    • crustaceans
    • amphibian larvae; some adult salamanders
    • fish
  • 10. Diversity in gills
    • Describe the dual function of gills in bivalves and polychaetes.
    • Two of these animals utilize structures for body movement in gas exchange as well. Describe.
    p. 983
  • 11.
    • In fish:
      • protects gills & pumps water over their surfaces
      • water flow is countercurrent to blood flow
  • 12. Countercurrent Mechanism for Gas Exchange Draw a similar picture showing blood flow and water flow in the same direction. How would oxygen diffusion change? Nearly 80% of the O 2 is removed from the water as it passes over the gills. Is this more or less efficient than gas exchange at the lungs? Why ? p. 984
  • 13. Ventilation in Birds p. 987
  • 14.
    • 4. Lungs - paired internal sacs lined with moist epithelium.
      • adapted to terrestrial environment
      • interact with circulatory system
    • vertebrates
  • 15. Human Respiration
    • Involves the process of cellular respiration and gas exchange.
    • a) cellular respiration :
    • glucose + O2  H2O + CO2 + 36 ATP’s
    • b) gas exchange :
    • exchange of gases between the internal and external environment with the use of lungs.
  • 16. Blood Transports Gases Between Lungs and Tissues
  • 17. (I) Human Respiratory System
    • Functions :
      • Works closely with circulatory system, exchanging gases between air and blood:
        • Takes up oxygen from air and supplies it to blood (for cellular respiration).
        • Removal and disposal of carbon dioxide from blood (waste product from cellular respiration).
    • Homeostatic Role :
      • Regulates blood pH.
      • Regulates blood oxygen and carbon dioxide levels.
  • 18.
    • 1 - nasal cavity 2 - pharynx (throat) 3 - (blue) alveoli or air sacs 4 - (yellow) bronchioles 5 - (pink) lung 6 - (red) diaphragm 7 - nostril 8 - (orange) larynx or voice box 9 - (green) trachea 10 - (light green) bronchus
  • 19. Nasal Cavity
    • The nose
    • Lined with a ciliated mucus membrane .
    • The cilia and mucus :
    • 1. Filters air
    • 2. Warms air
    • 3. Moistens air
  • 20.
    • Pharynx & Larynx
    nasal cavity pharynx larynx
    • Pharynx (throat)
    • muscular tube
    • conducts air & food
    • Larynx (Adam’s apple)
    • cartilaginous structure
    • contains vocal cords; conducts air
    What prevents food from entering larynx? epiglottis What causes deepening of male voice during puberty ? testosterone
  • 21. Epiglottis
    • A cartilaginous flap
    • It “covers” the trachea when swallowing food.
  • 22. Trachea
    • Known as the windpipe
    • Kept open by rings of cartilage
    • Lined with a ciliated mucus membrane.
    • One cigarette paralyzes the cilia for 20 minutes .
                                       
  • 23. Bronchi
    • Bronchus = singular
    • Trachea divides into two major divisions known as bronchi.
    • The bronchi contain cartilage rings as well.
    • The bronchi subdivide many times forming smaller tubules known as bronchioles .
  • 24. Bronchioles
    • Lack cartilage rings
    • Tiny bronchioles subdivide and terminate (end) with structures known as alveoli.
  • 25.  
  • 26. Alveoli
    • Are thin, moist and surrounded by capillaries
    • Are the functional units for gas exchange between the lung and the blood
    • Alveoli increase surface area for gas exchange
    • O2 diffuses into the blood from the alveoli and CO2 and water diffuse out of the blood and into the alveoli
                             
  • 27. Structure of Lung Alveoli
  • 28. http://www.digitalfrog.com/resources/archives/respirat.mov
  • 29.  
  • 30.
    • Path of air flow in external respiration:
    • nose 
    • pharynx 
    • larynx 
    • trachea 
    • bronchi 
    • bronchioles 
    • alveoli
  • 31.
    • II. Breathing Process
      • Occurs in response to pressure differences between lungs & atmosphere.
    • Inhalation (active process)
    • diaphragm & external intercostal muscles contract
    • thoracic cavity volume  & air pressure 
    • air pulled inward; lungs expand
    External intercostal muscles
  • 32.
    • Exhalation (passive process)
    • diaphragm & external intercostal (rib) muscles relax ; lungs recoil
    • thoracic cavity volume  & air pressure 
    • air pushed outward; lungs deflate
    Forced exhalation is active - caused by contraction of internal intercostal muscles & abdominal muscles.
  • 33. Human Breathing: Inhalation and Exhalation
  • 34.
    • Control of Breathing
      • Breathing is regulated by the rhythmicity center in
      • the medulla of brain.
    Medulla stimulates inspiratory muscles (diaphragm & external intercostal muscles). rhythmicity center
  • 35.
    • The most important factor affecting the rhythmicity center is CO 2
    •  in arterial CO 2 causes  in acidity (below 7.4) of cerebrospinal fluid (CSF).
    •  in CSF acidity is detected by pH sensors in medulla.
    • medulla  rate & depth of breathing.
  • 36. Human Breathing is Automatically Controlled
  • 37. (III.) Gas Exchange
    • Hemoglobin Functions:
      • Transports oxygen (binds in the alveoli to form oxyhemoglobin .
      • Transport carbon dioxide carried in the plasma forms bicarbonate ions.
      • Helps buffer blood
    • As carbon dioxide is picked up from tissues it is converted into carbonic acid:
    • CO 2 + H 2 O <-----> H 2 CO 3 <----> H + + HCO 3 -
    • Carbon Carbonic acid Carbonate ion
    • dioxide
    • Hemoglobin picks up most H + ions, so they don’t acidify the blood.
  • 38. Hemoglobin Loading and Unloading of Oxygen
  • 39.  
  • 40.  
  • 41. IV. Diseases of the Respiratory System
  • 42.
    • Respiratory rate: 10 to 14 inhalations/minute.
    • In one day, an average human:
      • Breathes 20,000 times
      • Inhales 35 pounds of air
    • Most of us breathe in air that is heavily contaminated with solid particles, ozone, sulfur oxide, carbon monoxide, nitrogen oxides, and many other damaging chemicals.
    • Breathing contaminated air can cause a number of diseases including asthma, bronchitis, emphysema, and lung cancer.
  • 43.
    • Cigarette smoke is one of the worse air pollutants.
      • Over 1 million people start smoking every year.
      • Kills about 350,000 people every year in U.S.
      • Contains 4000 different chemicals.
      • Each cigarette smoked subtracts about 5 minutes from life expectancy.
      • Cigarette smoke paralyzes cilia in airways, preventing them from removing debris and from protecting delicate alveoli.
      • Frequent coughing is the only way airways can clean themselves.
      • Cigarette smoke also causes fetal damage, which can result in miscarriage, premature birth, low birth weight, and poor development.
  • 44. Bronchitis
    • Inflammation of the membrane of the bronchial tubes.
  • 45. Asthma
    • An allergic response characterized by constriction of the bronchial tubes.
  • 46. Emphysema
    • Disease in which the walls of the alveoli breakdown, decreasing surface area for gas exchange.
    • Characterized by shortness of breath, difficulty in breathing, and decreased lung capacity.
  • 47.  
  • 48. Pneumonia
    • The alveoli become filled with fluid, preventing gas exchange between the alveoli and the capillaries .
  • 49.
    • Lung Cancer
    • Cancerous growth that invades and destroys lung tissue. Very high fatality rate.
    • Symptoms include bloody sputum, persistent cough, difficulty breathing, chest pain, and repeated attacks of bronchitis or pneumonia.
    • Causes: Smoking (50% of all cases) and pollution (radon, asbestos). Smokers are 10 times more likely to develop lung cancer than nonsmokers.