| Slide 1 |
| Goals for the next few weeks... |
| Respiratory physiology | ||||
| gasex basics 2/15 | ||||
| gasex extreme 2/17 | ||||
| Temperature and metabolism | ||||
| vertebrate metabolism/temp. regulation 2/22 | ||||
| supercooling/freeze tolerance in phibs 2/24 | ||||
| guest lecture by Mr. Mark Mandica | ||||
| Environmental Endocrinology | ||||
| Hormones and feedback 3/1 | ||||
| Stress response 3/3 | ||||
| Endocrine disruptors 3/8 | ||||
| Midterm Exam 3/10 |
| 4 essay questions | |
| 2 from January to now | |
| 2 from 2/15-3/8 |
| Today's Lecture |
| Gas exchange overview | |
| Gases: Oxygen and Carbon Dioxide | |
| Energy conversion | |
| Importance of blood pH | |
| Respiratory surfaces | |
| Comparative respiratory physiology | |
| Neuronal control |
| Respiratory Physiology |
| Goals of GasEx |
| Exchange | ||
| O2 in | ||
| CO2 out | ||
| Circulation | ||
| O2 in | ||
| CO2 out | ||
| Gasses |
| Oxygen | ||||
| aerobic respiration | ||||
| most efficient | ||||
| yield = 38 ATP | ||||
| most cellular energy needed in 2 phosphate bonds | ||||
| each = 12 kcal PE/mole | ||||
| about 2300 kcal used/ day | ||||
| = 128 moles ATP | ||||
| = average person (2500 KCal diet) = 125 moles ATP | ||||
| Glycolysis? | ||||
| (glycolysis) |
| Anaerobic respiration | |||
| no Oxygen required | |||
| first step in aerobic respiration | |||
| low ATP yield (2) | |||
| dangerous waste products | |||
| pyruvate → lactic acid (→ ethanol) | |||
| lactic acid buildup = yeeeouch! | |||
| Gasses |
| Carbon Dioxide | ||
| waste product of aerobic respiration | ||
| must be transported away from cells | ||
| build-up may change blood pH | ||
| Energy Conversion |
| Oxygen for energy conversion | |
| What's ATP used for ? |
| Gasses and Blood pH |
| Blood pH tightly connected to CO2 levels | ||
| 2 effects of CO2 Δ | ||
| 1. Respiratory Acidosis | ||
| pCO2 > 40 mm Hg | ||
| pH < 7.4 (mammalian) | ||
| causes: ↓ gasex across alveoli, impaired gas diffusion | ||
| compensation: renal | ||
| CO2 + HCO3- (bicarbonate) ↔ H2CO3 |
| Resorption--puts bicarb back into the system. | |
| Why is resorption of bicarb by the kidney an important compensatory mechanism for respiratory acidosis? | |
| GasEx and pH |
| 2. Respiratory Alkalosis | ||
| PCO2 < 40 mmHg | ||
| pH > 7.40 | ||
| causes: hyperventilation | ||
| compensation: renal | ||
| pH control |
| changes in blood pH that result from respiratory problems | ||
| compensation through renal system | ||
| acidosis = elevation of plasma bicarb (to buffer) | ||
| result = ↓ carbonic acid (CO2), ↑ pH | ||
| alkalosis = decrease in plasma bicarb | ||
| result = ↑ carbonic acid (CO2), ↓ pH | ||
| Acidosis/Alkalosis |
| 2 types | |||
| Respiratory | |||
| cause limited to gasex problems | |||
| compensatory mechanism is renal | |||
| Metabolic | |||
| cause is nutrient metabolism-related (could be secondary to infection) | |||
| main compensatory mechanism is respiratory (immediate in acute phases of disease) | |||
| Respiratory Surfaces |
| Thin for gasex | |
| Ability to transport gases to other cells |
| Respiratory Surfaces |
| Lungs | ||
| mammals | ||
| amphibians | ||
| Gills | ||
| neotinic amphibians | ||
| fish | ||
| Skin | ||
| phibs | ||
| Mammalian Lungs |
| Anatomy | ||
| series of tubes (bronchi) | ||
| thin air sacs (alveoli) | ||
| adjacent to capillaries (blood stream) | ||
| Slide 19 |
| Slide 20 |
| Alveoli |
| Perfect respiratory surface | ||
| Air sacs | ||
| thin | ||
| moist | ||
| compliant | ||
| in close proximity to circulatory system | ||
| Slide 22 |
| Why is the respiratory surface so close to the circulatory system? |
| Respiratory Pigments |
| How is Oxygen carried to cells? | |||
| Hemoglobin | |||
| present in some form in all vertebrates | |||
| protein + O2-binding pigment | |||
| Oxygen binding/affinity varies with environ | |||
| Affected by: | |||
| pH | |||
| PCO2 | |||
| pO2 | |||
| temperature | |||
| Driving force behind GasEx |
| Diffusion | |||
| Must take several factors into account: | |||
| Partial Pressure of O2 or CO2 in blood/tissues | |||
| " in atmosphere | |||
| Other inside or outside environmental factors | |||
| temperarure | |||
| pH | |||
| At rest |
| Pressure inside chest cavity | |
| diaphragm at rest |
| Slide 27 |
| Carbon Dioxide Out |
| Diaphragm relaxes | |
| Positive pressure | |
| CO2-rich air out |
| Slide 29 |
| How Do We Know When to Breathe? |
| Main control in respiratory centers in medulla | ||
| motor out to diaphragm and intercostals | ||
| Mechanoreceptors | ||
| in chest wall and lungs | ||
| monitor ms. effort and lung volume changes | ||
| Chemoreceptors | ||
| arterial blood oxygenation detected at carotid artery and aortic arch | ||
| CO2 levels detected on medulla-sense CO2 tension within brain tissue | ||
| I didn't inhale |
| inhalation = active breathing | |||
| requires energy (ms) | |||
| stimulus from receptors | |||
| mechano | |||
| chemo | |||
| motor output from CNS | |||
| exhalation = passive | |||
| air out with elastic recoil | |||
| Thinking Questions |
| If the chest cavity is punctured? | |
| If lung compliance (stretchability) is compromised | |
| If blood pH is low | |
| If blood pH is high |
| Amphibian Lungs |
| Phib Lungs |
| no chest muscles | ||
| no diaphragm | ||
| same lung anatomy | ||
| gulps air--positive pressure | ||
| gular pumping | ||
| contraction of gular ms. (floor of mouth/throat) | ||
| forces air down to lungs | ||
| Slide 35 |
| Slide 36 |
| GasEx through Skin |
| Gills |
| Fish, neotinic & larval amphibians | |
| note key components to respiratory surface |
| Slide 39 |
| Sum It Up |
| Why? | |
| How? | |
| Factors that affect gasex | |
| Does the animal compensate internally or change its environment? | |
| Thursday |
| GasEx in extreme conditions: | |||
| High altitude | |||
| O2/CO2 partial pressures | |||
| Mammalian fetal gasex | |||
| pigments | |||
| GasEx through an eggshell | |||
| EWL and...you're breathing through a shell! | |||
| Antarctic sea fish (brrrr) | |||
| what's temperature got to do with it? | |||