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Respiratory System Chapter 22.

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Presentation on theme: "Respiratory System Chapter 22."— Presentation transcript:

1 Respiratory System Chapter 22

2 Role of Respiratory System
Supplies body w/ O2 and disposes of CO2 Four part process Pulmonary ventilation Moving air in and out of lungs External respiration Exchange of gases between lungs and blood Transport of respiratory gases Moving air to and from tissues via blood Internal respiration Exchange of gases between blood and tissues

3 Functional Respiratory System
Conducting zone: carries air Cleanses, humidifies, and warms air Nose  terminal bronchioles Respiratory zone: site of gas exchange Respiratory bronchioles Alveolar ducts Alveoli

4 Nose and Nasal Cavity Normal air entry, why not mouth?
Moistens, warms, and filters air Superficial capillary beds Vibrissae filter particulates Respiratory epithelium (what is that?) Mucus traps debris and moves posterior to pharynx Defensins and lysozymes Turbinate bones and meatuses enhance Olfaction Olfactory epithelia through cribriform plates Nerve endings irritated = sneezing Resonation for speech

5 Pharynx Nasopharynx Oropharynx Laryngopharnx Air mov’t only
Closed off by uvula w/ swallowing Giggling prevents = nose expulsion Respiratory epithelium (why?) Pharyngeal tonsil (adenoids) Oropharynx Food and air mov’t Stratified squamous (why?) Palatine and lingual tonsils Laryngopharnx Stratified squamous Branches to esophagus and larynx

6 Larynx Keep food and fluid out of lungs Transport air to lungs
Epiglottis (elastic) covers glottis Coughing/choking when fails False vocal cords Transport air to lungs Supported by 8 hyaline cartilages Voice production True vocal cords (elastic) vibrate as air passes Pitch from vibration rate (more tension = faster = higher) Loudness from force of expelled air (whisper = little/no vibration) Additional structures amplifies, enhances, and resonates Pseudostratified ciliated columnar again (why?) Mucus up to pharynx

7 Trachea Transports air to lungs Mucosal layer Submucosal layer
Respiratory epithelium Mucus trapped debris to pharynx Submucosal layer Mucus glands Adventita Connective tissue supported by C-rings of hyaline cartilage

8 Bronchial Tree Table 2:  Divisions of the Bronchial Tree.  Taken from Ross et al., Histology, a text and atlas, 10th edition, p. 589, Table 18.1.

9 The Respiratory Membrane
Walls of the alveoli where actual exchange occurs Simple squamous cells (type I cells) surrounded by capillaries Surface tension resists inflation Cuboidal epithelia (type II cells) produce surfactant to counter Macrophages patrol Dead/damage swept to pharynx

10 Lung Anatomy Paired air exchange organs
Right lung Superior, middle, and inferior lobes Oblique and horizontal fissures Left lung Superior and inferior lobes Oblique fissure Cardiac notch contributes to smaller size Costal, diaphragmatic, and mediastinal surfaces Hilum where 1° bronchi and blood vessels enter

11 Pleura Serous membrane covering Reduces friction w/ breathing
Parietal pleura Visceral pleura Pleural fluid in cavity Reduces friction w/ breathing Surface tension binds tightly Expansion/recoil with thoracic cavity Creates 3 chambers to limit organ interferences

12 Pressure Relationships
Relative to atmospheric pressure (Patm) Sea level = 760 mmHg Intrapulmonary pressure (Ppul): pressure in alveoli Intrapleural pressure (Pip): pressure in pleural cavity Always negative to Ppul Surface tension b/w pleura Lung wall Atmosphere Patm Intrapleural fluid Chest wall Ppul Pip (Ppul – Pip) (Patm – Ppul) Pressure of gases around the body

13 Transpulmonary Pressure (Ptp)
Difference b/w intrapulmonary and intrapleural pressure (Ppul – Pip) Influences lung size (Greater diff. = larger lungs) Equalization causes collapse Keeps lungs from collapsing (parietal and visceral separation) Alveolar surface tension and recoil favor aveoli collapse Recoil of chest wall pulls thorax out

14 Pulmonary Ventilation
Patm – Ppul R F = Ppul < Patm inspiration Ppul > Patm expiration Inspiration and expiration change lung volume Volume changes cause pressure changes Gases move to equalize Boyle’s Law P1V1 = P2V2 Increase volume = decrease pressure Decrease volume = increase pressure

15 Breathing Cycle Inspiration Expiration Thoracic cavity increases
Pip decrease  Ptp increase Lung volume increases Ppul < Patm Air flows in till Ppul = Patm Inspiratory muscles relax Thoracic cavity decreases Pip increase  Ptp decrease Lung volume decreases Ppul > Patm Air flows out till Ppul = Patm

16 Influencing Pulmonary Ventilation
Airway resistance Flow = pressure gradient/ resistance (F = P/R) Diameter influences, but insignificantly Mid-sized bronchioles highest (larger = bigger, smaller = more) Diffusion moves in terminal bronchioles (removes factor) Alveolar surface tension Increase H20 cohesion and resists SA increase Surfactants in alveoli disrupt = less E to oppose Lung compliance ‘Stretchiness’ of the lungs Stretchier lungs = easier to expand

17 Pulmonary Volumes Tidal volume (TV): air moved in or out w/ one breath
Inspiratory reserve volume (IRV): forcible inhalation over TV Expiratory reserve volume (ERV):forcible exhalation over TV Residual volume: air left in lungs after forced exhalation

18 Respiratory Capacities
Inspiratory capacity (IC) Inspired air after tidal expiration TV + IRV Functional residual capacity (FRC) Air left after tidal expiration RV + ERV Vital capacity (VC) Total exchangeable air TV + IRV + ERV Total lung capacity (TLC) All lung volumes TV + IRV + ERV + RV

19 Non-Respiratory Air Dead space Reflex movements
Anatomical: volume of respiratory conducting passages Alveolar: alveoli not acting in gas exchange Total: sum of alveolar and anatomical Reflex movements Cough: forcible exhalation through mouth Sneeze: forcible exhalation through nose and mouth Crying: inspiration and short expirations Laughing: similar to crying Hiccups: sudden inspiration from diaphragm spasms Yawn: deep inspiration into all alveoli

20 Properties of Gases Dalton’s Law Henry’s Law
Pressure exerted by each gas in a mix is independent of others PN2 ~ 78%, PO2 ~ 21% , PCO2 ~ .04 Partial pressure (P) for each gas is directly proportional to its concentration O2 at sea level  760mmHg x .21 = 160mmHg 10,000 ft above  523mmHg x 0.21 = 110mmHg Henry’s Law In contact w/ liquid, gas dissolves proportionately to partial pressure Higher partial pressure = faster diffusion Equilibrium once partial pressure is equal Solubility and temperature can influence too (concentration)

21 External Respiration Gas exchange Respiratory membrane
Partial pressure gradients drive Alveoli w/ higher PO2 and tissues w/ PCO2 PO2 gradients always steeper that PCO2 PCO2 more soluble in plasma and alveolar fluid than PO2 Equal amounts exchanged Respiratory membrane Thin to allow mov’t Moist to prevent desiccation Large SA for diffusion amounts

22 External Respiration (cont.)
Ventilation and perfusion synchronize to regulate gas exchange PO2 changes arteriole diameter Low  vasoconstriction  redirect blood to higher PO2 alveoli PCO2 changes bronchiole diameter High  bronchiole dilation  quicker removal of CO2

23 Oxygen Transport 98% bound to hemoglobin as oxyhemoglobin (HbO2)
Review structure Deoxyhemoglobin (HHb) once O2 unloaded Rest dissolved in plasma Affinity influenced by O2 saturation 1st and 4th binding enhances Previous unloading enhances Hemoglobin reversibly binds O2 Influenced by PO2, temp., blood pH, PCO2, and [BPG] HHb + O2 Lungs Tissues HbO2 + H+

24 PO2 Influences on Hemoglobin
Hb near saturation at lungs (PO2 ~ 100mmHg) and drops ~ 25% at tissues (PO2 ~ 40mmHg) Hb unloads more O2 at lower PO2 Beneficial at high altitudes In lungs, O2 diffuses, Hb picks up = more diffusion Hb bound O2 doesn’t contribute to PO2

25 Controlling O2 Saturation
Increase in [H+], PCO2, and temp Decrease Hb affinity for O2 Enhance O2 unloading from the blood Areas where O2 unloading needed Cellular respiration Bohr effect from low pH and increased PCO2 Decreases have reverse effects

26 Carbon Dioxide Transport
Small amounts (7 – 10%) dissolved in plasma As carbaminohemoglobin (~20%) No competition with O2 b/c of binding location HHb binds CO2 and buffers H+ better than HbO2, called the Haldane effect Systemically, CO2 stimulates Bohr effect to facilitate In the lungs, O2 binds Hb releasing H+ to bind HCO3-

27 Carbon Dioxide Transport (cont.)
Primarily (70%) as bicarbonate ions (HCO3-) CO2 + H2O H2CO H+ + HCO3- Hb binds H+ = Bohr effect and little pH change HCO3- stored as a buffer against pH shifts in blood Bind or release H+ depending on [H+] CO2 build up (slow breathing) = H2CO3 up (acidity) Faster in RBC’s b/c carbonic anhydrase Fig 22.22

28 Neural Control of Respiration
Medullary respiratory centers Dorsal respiratory group (DRG) Integrates peripheral signals Signals VRG Ventral respiratory group (VRG) Rhythm-generating and forced inspiration/expiration Excites inspiratory muscle to contract Pontine center ‘Fine tunes’ breathing rhythm in sleep, speech, & exercise

29 Regulating Respiration
Chemical factors Increase in PCO2 increases depth and rate Detected by central chemoreceptors (brainstem) CO2 diffuses into CSF to release H+ (no buffering) Greater when PO2 and pH are lower Initial decrease in PO2 enhances PCO2 monitoring Peripheral chemoreceptors in carotid and aortic bodies Substantial drop to increase rate b/c Hb carrying capacity Declining arterial pH increases depth and rate Peripheral chemoreceptors increase CO2 elimination

30 Regulating Respiration (cont.)
Higher brain center influence Hypothalamic controls Pain and strong emotion influence rate and depth Increased temps. increases rate Cortical controls Cerebral motor cortex bypasses medulla Signals voluntary control (overridden by brainstem monitoring) Pulmonary irritant reflexes Reflexive constriction of bronchioles Sneeze or cough in nasal cavity or trachea/bronchi Inflation reflex Stretch receptors activated w/inhalation Inhibits inspiration to allow expiration

31 Homeostatic Imbalances
Sinusitis: inflamed sinuses from nasal cavity infection Laryngitis: inflammation of vocal cords Pleurisy: inflammation of pleural membranes, commonly from pneumonia Atelectasis: lung collapse from clogged bronchioles Pneumothorax: air in the intrapleural spaces Dyspnea: difficult or labored breathing Pneumonia: infectious inflammation of the lungs (viral or bacterial) Emphysema: permanent enlargement of the alveoli due to destruction Chronic bronchitis: inhaled irritants causing excessive mucus production Asthma: bronchoconstriction prevents airflow into alveoli Tuberculosis: an infectious disease (Mycobacterium tuberculosis) causing fibrous masses in the lungs Cystic fibrosis: increased mucus production which clogs respiratory passages Hypoxia: inadequate O2 delivery Anemic (low RBC’s), ishemic (impaired blood flow), histotoxic (cells can’t use O2), hypoxemic (reduced arterial PO2)


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