Bio 182- Ecology Unit Outline 1

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1 Bio 182- Ecology Unit Outline 1 Respiration Introduction 1. Multicellular organisms require oxygen to generate E using cellular respiration 2. Wastes released as CO2 3. Summary equation for cellular respiration: a. C6H12O6 + 6O2 ----à 6CO2 + 6H2O + E 4. General functions: a. Gas exchange b. Control of blood ph 5. Processes: a. Movement of air into and out of the lungs is called pulmonary ventilation (= breathing) b. Exchange of gases between alveoli of the lungs and blood is called external respiration c. Transport of gases by circulatory system d. Exchange of gases between body cells and blood is called internal respiration 6. Organs of respiratory system a. Nose 1) External protrusion from center of face supported by nasal & maxilla bones & cartilage 2) Functions: a) Opening for air entry b) Moistens & warms entering air c) Filters & cleans air d) Olfaction e) Resonating chamber for speech 3) Openings to nasal cavity are nostrils or external nares 4) Vestibule-chamber just superior to nostrils; loaded with guard hairs 5) Nasal septum divides cavity; formed by: a) Hyaline cartilage anteriorly b) Vomer posteriorly & inferiorly c) Perpendicular plate of ethmoid superiorly 6) Paranasal sinuses are spaces found in frontal, sphenoid, ethmoid, & maxillary bones a) These sinuses lighten the skull, warm & moisten air, mucus linings trap debri, and are important resonating chambers 7) Rhinitis-inflammation of nasal mucosa that releases excessive mucus; caused by viruses, bacteria, or allergens 8) Sinusitis-inflammation of the mucosa lining the sinuses; similar causes as rhinitis

2 Bio 182- Ecology Unit Outline 2 9) Nasolacrimal duct-duct that runs from medial canthus of eye and drains fluids into nasal cavity 10) Nasal concha bones a) Superior & middle are part of ethmoid b) Inferior nasal concha is a separate bone c) These bear highly vascular mucosal linings that warm & moisten air 11) Epithelium a) Mostly goblet cells that secrete mucus for trappng dust, bacteria & debri b) Pseudostratified epithelium with cilia c) Olfactory-sensory nerve endings that become olfactory nerve (I) 12) Nasal cavity ends at internal nares (choanae) leading into pharynx b. Pharynx 1) Nasopharynx-posterior to nasal cavty & superior to soft palate a) Lined by pseudostratified epithelium b) Auditory (Eustachian) tubes open on each side of internal nares c) Adenoids present d) Uvula folds upward & blocks nasal cavity during deglutition 2) Oropharynx-posterior to oral cavity; from soft palate to epiglottis a) Involuntary phase of deglutition starts here b) Fauces-narrowed area separating oral cavity from pharynx c) Palatine & lingual tonsils here d) Stratified squamous epithelium 3) Laryngopharynx-lowermost portion; from hyoid bone to larynx a) Respiratory & digestive systems separate b) Glottis-opening to larynx c. Larynx 1) Also called the voice box 2) Supported by 9 cartilages: a) Thyroid (= Adam s apple)-largest & most prominent, especially in males; ligaments anchor to hyoid b) Cricoid-below thyroid; ring connects to trachea c) Arytenoid-support vocals cords d) Epiglottis-flap of elastic cartilage that folds down over glottis during deglutition 3) Epithelium: stratified squamous to pseudostratified inferiorly 4) Vocal cords a) Paired strips of stratified squamous epithelium supported by arytenoid cartilages b) Produce sound by vibration

3 Bio 182- Ecology Unit Outline 3 c) Pitch-caused by increasing/decreasing tension and size of cords/larynx and movement of arytenoid cartilages d) Loudness-amt of air passing over cords; abdominal and thoracic muscles influence e) Quality-added by accessory structures: lips, tongue, palate, etc. 5) False vocal cords or vestibular folds-protrude into vestibule of larynx a) Keep glottis closed during defecation; allows increase in abdominal pressure b) Vocalists can modify movements to get different sounds 6) Laryngitis-inflammation of the larynx or cords a) Caused by overuse, bacteria, dryness, or irritating chemicals d. Trachea 1) Also called windpipe 2) Tube that leads from inferior end of larynx to top of lungs 3) Support by C-shaped cartilage rings; rings connected by smooth muscle & elastic CT 4) Lined by pseudostratified ciliated epithelium & globlet cells a) Mucus entraps debri and cilia move away (ciliary escalator) from lungs towards pharynx where debri is (usually) swallowed e. Bronchi 1) Trachea divides into 2 major branches called primary bronchi 2) Each primary bronchus branches towards R & L lungs 3) Primary bronchi divide into secondary bronchi; these enter lobes of each lung 4) Both 1 o & 2 o bronchi are supported by cartilage & lined by pseudostratified ciliated epithelium 5) Secondary bronchi split into tertiary bronchi; these divide further 6) Once cartilage support is gone at ~ 1 mm diameter, tubes are called bronchioles f. Bronchioles 1) Splitting of bronchioles continue each with a specific name 2) Terminal bronchioles end in a grape-like cluster of sacs called alveoli 3) Epithelium-now simple ciliated columnar (bronchioles)-simple squamous (alveoli) g. Lungs 1) Fills thoracic cavity except for mediastinum; found in pleural cavity 2) Pointed at apex and concave at base 3) R lung has 3 main lobes: superior, middle, & inferior 4) L lung has 2 lobes: superior & inferior a) Also has medial concavity called cardiac notch-what structure resides in this space?

4 Bio 182- Ecology Unit Outline 4 5) Serous membranes a) Pleurae-serous membranes associated with lungs b) Visceral pleurae-on surface of lungs c) Parietal pleurae-lines wall of thoracic cavity d) Pleural cavity-space between parietal & visceral pleurae e) Functions: i. secrete a lubricating serous fluid ii. pressure changes created here iii. isolates lungs from other organs (heart & thymus) 6) Alveoli a) Grape-like clustered sacs at end of terminal bronchioles b) million/lung providing a total SA of 70 m2/lung c) Surrounded by a network of capillaries and elastic fibers d) Membrane epithelium: simple squamous e) Distance between capillary wall & membrane = 0.1 um f) Alveolar cell types: i. Type I alveolar cells-simple squamous cells for gas exchange ii. Type II alveolar or Septal cells-scattered among squamous cells; secrete an oily mixture of PPL called surfactant reducing surface tension preventing collapse of alveoli (5% of cells) iii. Alveolar macrophages (dust cells)-patrol epithelium and phagocytize small particles that escape ciliary escalator g. Disorders 1) Pneumothorax-introduction of air into thoracic cavity 2) Hemothorax-entry of blood into one of pleural cavities 3) Pleurisy-inflammation of pleurae; caused by decreased secretion of serous fluid creating rough & dry membranes 4) Respiratory distress syndrome-deficiency of surfactant in premature infants; alveolar fluid enters space; breathing becomes more and more difficult with each breath 7. Pulmonary ventilation a. Also know as breathing-movement of air into and out of lungs for gas exchange b. Divided into 2 phases: 1) Inhalation (inspiration)-movement of air into lungs 2) Exhalation (expiration)-pushing of air out of lungs c. Lungs in air tight cavity d. Atmospheric pressure at sea level = 760 mmhg e. Pressure changes in pleural cavity are the key f. Boyles Law

5 Bio 182- Ecology Unit Outline 5 1) Pressure of a gas in a closed container is inversely proportional to the volume of the container 2) P1V1 = 3) If container size decreases: P1 = 1; V1 = 1; V2 = ½; P2 =2 4) If container size increases: P1 = 1; V1 = 1; V2 = 2; P2 = ½ g. Inspiration 1) Caused by expansion of thoracic (pleural) cavity 2) External intercostals push sternum forward 3) Diaphragm changes from dome to flat shape 4) Labored breathing aided by: sternocleidomastoids, scalenes, & pectoralis major 5) Intrapleural pressure-pressure between visceral & parietal pleurae; always subatmospheric = 756 mmhg 6) Expansion of thoracic cavity causes intrapleural pressure to decrease from 756 to 754 mmhg 7) Pleural linings aide expansion a) As parietal pleurae are forced out by thoracic cavity expansion, they pull on the visceral pleurae covering lungs b) Outer surfaces of lungs are pulled out c) Intrapulmonary pressure, or pressure in alveolar space, changes from 760 to 758 mmhg 8) Air moves from high to low pressure h. Expiration 1) Passive 2) Elastic tissue of lungs recoil 3) Diaphragm & external intercostals relax 4) Results in decrease in size of thoracic cavity 5) Intrapulmonary pressure increases to 763 mmhg (from 758) 6) Surfactant insures that alveolar membranes don t stick because of high surface tension 7) Labored breathing aided by abdominal and internal intercostals muscles i. Respiratory volumes 1) Spirometer-device a subject breathes into that measures ventilation 2) Tidal volume-air inhaled or exhaled in one quiet breath (~ 500 ml) 3) Inspiratory reserve volume-air in excess of tidal inspiration that can be inhaled with maximum effort (~3100 ml) 4) Expiratory reserve volume-air in excess of tidal expiration that can be exhaled with maximum effort (~1200 ml) 5) Residual volume-air remaining in lungs after maximum expiration; keeps alveoli inflated (~1200 ml)

6 Bio 182- Ecology Unit Outline 6 6) Vital capacity-amt of air that can be exhaled with maximum effort after maximum inspiration; asses strength of thoracic muscles and pulmonary function 7) Total lung capacity-max amt of air lungs can contain (~6000 ml) 8. Exchange of respiratory gases a. Dalton s Law of partial pressures-total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gas in the mixture b. Atmospheric pressure at sea level = 760 mmhg c. Partial pressure (pp or p) of a gas is directly proportional to its per cent in the total gas mixture 1) N2 is 79%; ppn2 =.79 X 760 = 597 mmhg 2) O2 is 21%; 0.21 X 760 = 159 mmhg 3) CO2 is 0.04%; X 760 = 0.3 mmhg 4) Water vapor averages 0.5%; X 760 = 3.7 mmhg d. At higher altitudes, pp s decrease in direct proportion to atmospheric pressure e. Henry s Law-when a mixture of gases (w/ ~ = solubilities) is in contact with a liquid, each gas will dissolve into the liquid in direct proportion to its pp 1) Ex: If O2 & CO2 had equal solubilities, O2 would diffuse faster because its pp is 159mmHg while CO2 pp is only 0.3 mmhg 2) Key in the direction of gas movement between tissues & blood f. Alveolar gas has more CO2 & H2O, but less O2 and N2 than the atmosphere 9. Factors that affect diffusion rate a. pp difference 1) po2 atmosphere = 160 mmhg 2) po2 alveoli = 105 mmhg 3) po2 alveolar capillary (arteriole end) = 40 mmhg 4) Difference between alveolus & capillary = 65 mmhg 5) Direction of movement: from alveolus into blood 6) pco2 atmosphere = 0.3 mmhg 7) pco2 alveoli = 40 mmhg 8) pco2 alveolar capillary (arteriole end) = 45 mmhg 9) Difference between alveolus & capillary = 5 mmhg 10) Direction of movement: from the blood into alveolus 11) Based ONLY on pp, O2 would move 13X faster b. Surface area-increased SA increases diffusion rate c. Membrane thickness-increased membrane thickness decreases diffusion rate 1) Respiratory diseases, such as pneumonia or emphysema, increase membrane thickness d. Gas solubility

7 Bio 182- Ecology Unit Outline 7 1) CO2 is 20X more soluble than O2 2) Therefore, despite large pp difference between gases, CO2 diffuses at a similar rate to O2 e. Temperature 1) Charles Law-increased temperature, increases molecular motion; increased molecular motion, increases diffusion rate (and gas expansion) 2) Therefore, ambient air at 80 F entering nasal cavity and passing inward along rest of respiratory tract will warm and expand as it reaches alveoli 3) The expansion helps lungs inflate making inhalation easier (body expends less E to inflate lungs) 4) When air is at 98 F, there is no warming and therefore no aide to inspiration f. Molecular wt-as MWt increases, the rate of diffusion will decrease 1) O2 = 32 Daltons (AMU) 2) CO2 = 44 Daltons 3) Therefore, O2 diffuses a little faster than CO2 10. External respiration a. Also known as pulmonary gas exchange b. Inspired air: po2 = 160 mmhg; pco2 = 0.3 mmhg c. Expired air: po2 = 120 mmhg; pco2 = 27 mmhg d. Shows a pp decrease for O2 because this is used as a result of cellular respiration 1) C6H12O6 + 6O2 -à 6CO2 + 6H2O + E e. Shows a pp increase for CO2 because this gas is formed by cellular respiration and exhaled f. Comparison between alveolus and blood 1) pp Blood: po2 = 40 mmhg; pco2 = 45 mmhg 2) pp Alveoli: po2 = 105 mmhg; pco2 = 40 mmhg g. Oxygen diffuses from alveolus to blood h. Carbon dioxide diffuses from blood into alveolus i. Equilibrium is reached in capillary in 0.25 s j. RBC s reside in pulmonary capillaries for 0.75 s 11. Internal respiration a. Also known as systemic exchange b. Comparison between alveolus and blood 1) pp arteriole Blood: po2 = 105 mmhg; pco2 = 40 mmhg 2) pp venule blood: po2 = 40 mmhg; pco2 = 45 mmhg g. Oxygen diffuses from blood into tissue cell h. Carbon dioxide diffuses from tissue cell into blood i. Equilibrium is reached in capillary in 0.25 s j. RBC s reside in systemic capillaries for 0.75 s

8 Bio 182- Ecology Unit Outline 8 Oxygen Transport Oxygen Transport 1. Carried in 2 ways: a. Bound to Hb as O2Hb (oxyhemoglobin; ~ 98% b. Dissolved in plasma ~ 1-2% 2. 1 Hb binds 4 O2 s 3. Reaction: HbH+ + O2 --à O2Hb + H+ 4. Conformational change in Hb makes loading & unloading easier (picking up 1 st O2 alters Hb conformation making it easier to pick up 2 nd O2) 5. Affinity-state of attraction of Hb for O2 a. High-strong state of attraction in lungs b. Low-weak state of attraction in tissues 6. Analysis of Hb Dissociation Curve a. X axis is po2 b. Units of X axis are mmhg c. Range of value on x axis is 0 to 105 d. Y axis is per cent saturation of Hb e. Units of y axis is per cent (%) f. Range of values for y axis is 0 to 100% g. Curve shape is sigmoid h. Slope comparision: 1) Between 0 & 40-very steep slope 2) 40 & 70-less steep slope 3) 70 & 105-little if any slope i. Hb is over 90% (93%) saturated at only 70 mmhg pp; therefore gas exchange is till very efficient at high altitudes and in people with emphysema j. Venous reserve 1) Hb is 100% saturated before entering capillaries (arteriole end at tissues) 2) Hb is 75% saturated after leaving capillaries (Venule end) 3) Hb is 50% saturated after leaving venule end of capillaries during exercise 4) How many O2 s, on average, does a Hb have if the blood is 50% saturated? Answer 2 5) Deoxygenated Hb still has a lot of oxygen! 7. Factors that affect O2-Hb dissociation curve a. Temperature 1) Hb is 85% saturated at a pp of 70 mmhg & temperature of 43 C 2) Hb is 95% saturated at a pp of 70 mmhg & temperature of 38 C 3) Hb is 98% saturated at a pp of 70 mmhg & temperature of 20 C 4) The relationship between temperature & oxygen saturation is: As temperature increases, the saturation of Hb decreases 5) Human body temperature is 38 C 6) Hb loads oxygen slower at 43 C than at 38 C

9 Bio 182- Ecology Unit Outline 9 7) When temperature is increased, the affinity of Hb for O2 will decrease 8) During exercise, the tissue temperature in skeletal muscle will increase 9) During exercise, Hb entering the capillaries of skeletal muscle will have a lower affinity for oxygen compared to a condition of no exercise 10) Under exercise conditions, Hb will unload more O2 to muscle cells than it would during nonexercise conditions 11) Under warmer conditions the O2-Hb dissociation curve shifts to the right b. ph 1) Normal blood ph is ) Hb is 96% saturated at a pp of 70 mmhg & ph of 7.6 3) Hb is 93% saturated at a pp of 70 mmhg & ph of 7.4 4) Hb is 90% saturated at a pp of 70 mmhg & ph of 7.2 5) The relationship between ph & oxygen saturation is: As ph decreases, the saturation of Hb decreases 6) Hb loads oxygen faster at 7.6 compared to normal ph 7.4 7) When ph is decreased, the affinity of Hb for O2 will decrease 8) During exercise, the tissue ph in skeletal muscle will decrease 9) During exercise, Hb entering the capillaries of skeletal muscle will have a lower affinity for oxygen compared to a condition of no exercise 10) Under exercise conditions, Hb will unload more O2 to muscle cells than it would during nonexercise conditions 11) Under lower ph conditions the O2-Hb dissociation curve shifts to the right c. Fetal Hb 1) Fetal Hb is 97% saturated with O2 at a pp of 70 mmhg 2) Maternal Hb is 92% saturated with O2 at a pp of 70 mmhg 3) Therefore, Fetal has a stronger affinity for O2 than maternal Hb 4) O2 needs to move from mother to fetus through placenta d. Diphospholgycerate (DPG) 1) Also known as Biphosphoglycerate or BPG 2) RBC s lack mitochondria; metabolism is entirely anaerobic a) Important in preventing trillions of RBC s from using carried O2 3) DPG is an unique intermediate compound of glycolysis that enhances release of O2 from Hb 4) Increased metabolism, more DPG produced 5) DPG binds to Hb and enhances O2 unloading to tissues e. Carbon monoxide (CO) 1) CO has 200X the affinity for O2 compared to Hb s affinity for O2

10 Bio 182- Ecology Unit Outline 10 2) Therefore, every CO molecule that contacts a Hb molecule will displace an O2 and not be released from the Hb at any time under normal atmospheric pressures 3) Requires a hyperbaric chamber at very high pp s to drive CO s off the Hb Carbon Dioxide Transport Carbon Dioxide Transport 1. CO2 has only a 5 mmhg difference in pp between alveolus and blood or between blood and tissue cell 2. Transported in 3 ways: a. Dissolved in plasma (~ 5-10%) b. Bonded to Hb as carbaminohemoglobin, but binds to an aa, not the Fe++ where it would compete with the O2 (20-30%) c. As the bicarbonate ion (HCO3-) in plasma (60-70%) 3. Bicarbonate transport of CO2 a. Reaction: CO2 + H2O --à H2CO3 ---à HCO3- + H+ b. Catalyzed by carbonic anhydrase (CA), an EZ in RBC s c. CA makes reaction go 1000X faster than without the EZ d. Release of H+ binds to Hb and triggers the Bohr effect (forces unloading of O2 due to lowered ph) e. Summary equations: 1) C6H12O6 + 6O2 --à 6CO2 + 6H2O + E (Cellular respiration, CR) 2) CO2 + H2O --à H2CO3 ---à HCO3- + H+ (Carbonic acid reaction) 3) HbH+ + O2 --à HbO2 + H+ (Hb picks up O2) f. Internal respiration (Systemic Gas Exchange) 1) Defined as the exchange of gases between the blood and the tissue cell 2) As CR forms CO2, the higher pp (45 mmhg) in cell causes diffusion of CO2 out of cell into capillary 3) Inside RBC, CO2 reacts with H2O forming carbonic acid 4) Carbonic acid dissociates into HCO3- and H+ a) To keep diffusion of CO2 going into RBC, the HCO3- has to diffuse out of RBC b) Electrical problems are created if too many negative charges exit cell c) To compensate, the cell brings in Cl-, an event called the Chloride shift 5) H+ binds to Hb and forces Hb to unload O2 (Bohr effect) 6) O2 diffuses into cell because of high pp (105) in capillary compared to low pp (40) in cell; CR is using O2 to break down glucose and keeping pp low 7) The O2Hb circulates back to lungs g. External respiration (Alveolar Gas Exchange)

11 Bio 182- Ecology Unit Outline 11 1) Defined as the exchange of gases between the blood and the alveolus in the lungs 2) Arriving in the lungs, the high (105) pp of O2 in alveolus diffuses into RBC and forces H+ off Hb forming O2Hb 3) The release H+ combines with HCO3- to form H2CO3; the EZ CA breaks H2CO3 into CO2 + H2O a) When HCO3- s are depleted in cell, they are brought in from plasma b) An electrical problem is again created by too many negative charges c) To compensate, the RBC moves Cl- out into plasma, also called the Chloride Shift 4) The higher pp (45) of CO2 allows diffusion into alveolus with pp of CO2 is only 40 mmhg 5) The oxygen-rich blood now circulates back to tissues where internal respiration again occurs Neural Control of Respiration 1. Basic pattern set in reticular formation of pons & medulla 2. Medulla sets rate and basic pattern of breathing a. Inspiratory center (=Dorsal Respiratory Group, DRG) 1) Nerves: phrenic & intercostal 2) These nerves transmit AP s to diaphragm & external intercostals 3) Involved in every cycle to help expand thoracic cavity 4) Neurons are myogenic where their activity increases over a 2 sec period until air brough in; DRG turned off for 3 s allowing diaphragm & ext intercostals to relax 5) Rate: ~ breaths/min 6) Passive expiration occurs via elastic recoil b. Expiratory Center (=Ventral Respiratory Group, VRG) 1) Active during forced expiration 2) Both inspiratory & expiratory neurons present 3) As DRG increases firing, neurons stimulate VRG which activates accessory muscles for inhalation 4) Expiratory component activated after inhalation complete 5) Expiratory component stimulates internal intercostals & abdominals in forced expiration 3. Pons a. Cut connections between pons & medulla causes abnormal breathing: rhythmic, but in deep gasps b. Seems to adjust depth of each breath; smooth s out transitions between inspiration & expiration c. Pneumotaxic center 1) Superiorly located

12 Bio 182- Ecology Unit Outline 12 2) Continuously sends inhibitory signals to DRG in medulla increasing rate as end of inspiration nears 3) If connection is severed between pneumotaxic & apneustic centers, lungs inflate to max for s each cycle 4) Fine-tunes breathing rhythm modifying pace and prevents overinflation of lungs d. Apneustic center 1) Continuously signals DRG 2) After 2 s, apneustic center is inhibited by pneumotaxic center 3) Prolongs inspiration for holding breath Factors that Influence Breathing Factors that Influence Breathing 1. Irritants in lungs 2. Strong emotions & pain via hypothalamus 3. Chemicals a. Monitored in aortic & carotid bodies by chemoreceptors b. pco2-most potent because it affects ph of brain causing hypercapnia and hyperventilation c. po2-has little effect until pp decreases to 60 mmhg 4. Respiratory Terminology a. Eupnea-normal quiet breathing b. Apnea-cessation of breathing c. Hypernea-abnormal increase in rate & depth of breathing d. Dyspnea-painful or labored breathing e. Asphyxia-unconsciousness due to interference with oxygen supply to blood f. Hypocapnia-below normal CO2 plasma levels g. Hypercapnia-above normal CO2 plasma levels h. Hypoxia-a low tissue oxygen concentration i. Hyperventilation-an increase in the breathing rate without a corresponding increase in metabolism 1) Increase CO2 removal; therefore decreases pco2 in the blood (hypocapnia) 2) Causes alkalosis (in brain) j. Cheyne-Stokes-a repeated cycle of irregular breathing beginning with shallow breaths that increase in rate & depth, then decrease and cease for s 1) Normal in infants 2) Indicator of various diseases in adults: pulmonary, cardiac, cerebral, kidney

13 Bio 182- Ecology Unit Outline 13

UNIT 9 - RESPIRATORY SYSTEM LECTURE NOTES

UNIT 9 - RESPIRATORY SYSTEM LECTURE NOTES 9.01 GENERAL FUNCTIONS OF THE RESPIRATORY SYSTEM A. Brings oxygenated air to the alveoli B. Removes air containing carbon dioxide C. Filters, warms, and humidifies