Ch 22 The Respiration System *ASSIGNMENT: Please read the ppt

IV. Gas Exchange Between the Blood, Lungs, and Tissues A. Basic Properties of Gases 1. Total Pressure: the percentages of all the gases = 100% Partial Pressure = pressure of gas due to is % of the total 2. Gas in Contact with Liquid Gas dissolves into liquid proportional to its partial pressure At equilibrium: partial pressures in gas & liquid same b) Chemical Nature of Gas CO2 is 20 times more soluble in water than O2 Figure 11.10: Gas exchange between blood in pulmonary capillaries and air in alveoli.

2. Gas in Contact with Liquid Basic Properties of Gases … 2. Gas in Contact with Liquid a) Gas dissolves into liquid proportional to its partial pressure At equilibrium: partial pressures in gas & liquid same b) Chemical Nature of Gas CO2 is 20 times more soluble in water than O2 c) Other Factors that increase Pp Temperature Pressure

B. Composition of Alveolar Gas Alveoli gas mix is slightly different from that in the atmosphere due to solubility differences O2 CO2

Blood from Pulmonary Artery C. External Respiration Inside the alveoli, gas exchange is driven by simple diffusion O2 diffuses to blood & Co2 diffuses to Alveoli Low CO2 in air; High O2 Alveolar Air Figure 11.10: Gas exchange between blood in pulmonary capillaries and air in alveoli. High CO2 in blood; Low O2 Blood from Pulmonary Artery RULE: Intuitively, one knows which way O2 moves, so remember CO2 always goes the opposite way

External Respiration– AT THE LUNGS 1. In LUNGS a) O2 Partial pressure gradient: Alveolar Po2 = _________ Venous blood: Blood returning from body cells and going to lungs via Pulmonary Artery Po2 = __________ RESULT: b) CO2 Partial pressure gradient: Alveolar Pco2 = _________ Venous blood Pco2 = ___________ Low CO2 in air; High O2 40 104 45 40 High CO2 in blood; Low O2 Pulmonary A.

c) Blood leaving Lungs via Pulmonary Veins PO2 = ______________ PCO2 = _____________ Equal numbers of molecules of oxygen and carbon dioxide have exchanged - Aerobic Cellular Respiration: Alveoli of lungs: P 104 mm Hg P 40 mm Hg O2 CO2 External respiration Pulmonary arteries Pulmonary veins (P 100 mm Hg) O2 Blood leaving tissues and entering lungs: P 40 mm Hg P 45 mm Hg Blood leaving lungs and entering tissue capillaries: P 100 mm Hg P 40 mm Hg O2 CO2 O2 CO2 Heart Systemic veins Systemic arteries Figure 22.17 . 6O2 + Glucose 6H2O + 6CO2 + 32ATP Enzymes

Respiratory membranes 0.5 to 1 m thick Large total surface area 2. Thickness and Surface Area of Respiratory Membrane effects gas exchange Respiratory membranes 0.5 to 1 m thick Large total surface area Capillary O2 Alveolus CO2

3. REGULATION– Ventilation-Perfusion Coupling at Lungs a) Equilibrium between getting proper air into alveoli (Ventilation) and having proper blood flow for diffusion (Perfusion). These are coupled for efficient gas exchange by altering blood vessel and bronchiole diameter. This happens at the local level so individual arterioles & bronchioles serving certain alveoli are independently regulated from each other. B) DIFFERENCE BETWEEN BODY TISSUE AND ALVEOLI i) Body Tissues O2 content: When O2 is low in the body tissues and their arterioles/capillary beds, the smooth muscle relaxes and more blood flows through the arteriole to the tissue to deliver more O2. ii) Lungs: Lungs arterioles operate in the opposite because the movement of O2 is in the opposite direction. The Pulmonary Capillaries are there to pick up O2, not deliver it.

D. Internal Respiration At Body Cells: 1. Active tissues use up O2 which is diffusing in from the blood. PO2 100 (blood)  PO2 40 (body cells) 2. Also the tissues are producing CO2 as they use the O2. So there is high CO2 in the body cells and low amounts in the blood just coming to the body cells. PCO2 45 (body cells)  PCO2 40 (blood) CO2 = 45 CO2 = 40 O2 on Hb Body Cells O2 = 40 O2 in Blood Plasma = 100

D. Internal Respiration at the body cells … 3. O2 and CO2 levels in blood leaving Body Cells (systemic circuit) and going back to the heart O2 = 40 as the oxygen has been used by body cells CO2 = 45 as the blood has picked up the CO2 the cells have produced while using Aerobic Respiration This blood then in Pulmonary Arteries to Lungs Alveoli of lungs: P 104 mm Hg P 40 mm Hg O2 External respiration CO2 Pulmonary arteries Pulmonary veins (P 100 mm Hg) O2 Blood leaving tissues and entering lungs: P 40 mm Hg P 45 mm Hg Blood leaving lungs and entering tissue capillaries: P 100 mm Hg P 40 mm Hg O2 CO2 O2 CO2 Heart Systemic veins Systemic arteries Internal respiration O2 CO2 Figure 22.17

V. Transport of Respiratory Gases by Blood A. Introduction: V. Transport of Respiratory Gases by Blood A. Introduction: CellularRespiration is occurring in active tissues: ACTIVE  . 6O2 + Glucose 6CO2 + 6H2O + 32ATP H+ + HCO3  INACTIVE 1. Active vs. Inactive Tissues a) Active Tissues: O2 CO2 H+ Temp b) Inactive Tissues: O2: CO2, H+, Temp: c) Hemoglobin– four 02 per Hb Loading: Hemoglobin’s ability to take up O2 (Load) at the lungs (relatively inactive tissues) Unloading: Hemoglobin gives off O2 (unload) at the body cells (active tissues)

1.5% is dissolved in plasma as gas V. Transport of Respiratory Gases by Blood … B. O2 Transport & Loading/unloading Hemoglobin 98.5% O2 is on Hemoglobin 1.5% is dissolved in plasma as gas Reduced hemoglobin oxyhemoglobin Alveolus Fused basement membranes CO2 Red blood cell O2 + HHb HbO2 + H+ O2 O2 O2 (dissolved in plasma) Blood plasma (b) Oxygen pickup and carbon dioxide release in the lungs

1. Hb Affinity for O2 is Related to how Active Tissue is Reversibly binds O2: Loading & Unloading As O2 binds at lungs: ppO2 is high, ppCO2 is low, and (H+ is low) these factors enhance Loading = Inactive tissue As O2 is released at body cells: ppO2 is low, ppCO2 is high, and (H+ is high)  enhances Unloading => Active tissues Due to Hb shape changes

2. Ability to add or subtract O2 (four 02 per Hb) also depends in part on how many O2 already attached a) At Lungs: O2 diffuses from: alveoli Plasma TO Hemoglobin on RBC in blood plasma  As a O2 is added to hemoglobin at the lungs, the hemoglobin changes shape which facilitates the next O2 addition, etc… RESULT IN LUNGS: keeps adding O2 until Hemoglobin is Saturated = has all 4 O2 - Unsaturated if hemoglobin has only 3 O2 Hb in RBC Alveolus Blood Plasma O2 O2 O2 (dissolved in plasma, is HIGH)

active tissues are using up O2 O2 on Hb Body Cells O2 O2 in Blood Plasma b) At Body Cells: active tissues are using up O2 As one O2 comes off the hemoglobin this facilitates the removal of the next O2, etc… - Result: At rest, still have much O2 on hemoglobin (75%) eventhough blood is considered unsaturated b. Hb Affinity for O2 -- Loading & Unloading Loading– As O2 binds at lungs: ppO2 is high, ppCO2 is low, and H+ is low these factors enhance Loading Unloading– As O2 is released at body cells: ppO2 is low, ppCO2 is high, and H+ is high  enhances Unloading Due to Hb shape changes

2. Association of Oxygen and Hemoglobin … Oxygen-Hemoglobin Dissociation Curve Influence of PO2 dissolved in plasma on Hb saturation AT LUNGS: have high Po2 in blood leaving the Lungs and Hb is saturated iii) At Rest: when blood arrives at the body cells, it gives off approx. 25% of its O2 and the change in PO2 is large (60 mmHg) The amount of O2 left on Hb is 75% = Reserve of O2 iv) Exercising: Need more O2 and and PO2 is low in muscle tissue = 18; An additional 50% O2 can be unloaded with a small drop in PO2 (22 mmHg) iv) Importance: If PO2 of inspired air is below normal unloading can still be adequate; At PO2 of 80 have 97% O2 in blood Lungs O2 given off to cells at rest 75 O2 given off in exer- cise Change in PO2 at rest Change in PO2 Exercise O2–Hb Saturation Curve

e. Other Factors Influencing Hb Saturation Increases in Pco2 causes a slight increase in H+ (decrease in pH) and curve shifts to right  more O2 unloaded = Bohr Effect Due to Modifying structure of Hb, so has ↓ affinity for O2 Example: Normal curve from 60 to 40 mm, unload 15% O2 For ↑ CO2: 60 to 40 releases 21% O2 Decreased carbon dioxide (P 20 mm Hg) or H+ (pH 7.6) CO2 Normal arterial carbon dioxide (P 40 mm Hg) or H+ (pH 7.4) CO2 Increased carbon dioxide (P 80 mm Hg) or H+ (pH 7.2) CO2 P (mm Hg) O2

e) Other Factors Influencing Hb Saturation … ii) Increases in temperature Modify structure of Hb, affinity for O2   unloading) Saturation curve shifted to the right with higher temperatures 10°C 20°C 38°C 43°C Normal body temperature

C. CO2 Transport 7 - 10% : dissolved in plasma 3 ways 7 - 10% : dissolved in plasma 20% : on Hemoglobin attached to certain amino acids = Carbaminohemoglobin 3. 70% : as bicarbonate = HCO3- CO2 + H2O  H2CO3 H+ HCO3– Carbon dioxide Water Carbonic acid Hydrogen ion Bicarbonate ion

C. CO2 Transport … 3. As Bicarbonate … a) At Body Cells: CO2 diffuses into plasma, then into RBC In RBC: carbon dioxide reacts with water to form a weak acid with aid of the enzyme Carbonic Anhydrase The Carbonic Acid, then becomes: H+ and bicarbonate which diffuse into plasma This reaction is reversible. AT BODY CELLS Interstitial fluid Plasma Tissue cell CO2 (dissolved in plasma) CO2 CO2 CO2 HCO3– Carbonic anhydrase Fast CO2 + H2O H2CO3 HCO3– + H+ CO2 CO2 Red blood cell

b) IN LUNGS: reaction reverses to unload CO2 3. As Bicarbonate … b) IN LUNGS: reaction reverses to unload CO2 Bicarbonate diffuses from plasma to RBC and reverse reaction occurs and produces CO2 Dissolved CO2 in plasma diffuses to Alveoli Alveolus Fused basement membranes Blood plasma CO2 CO2 (dissolved in plasma) Slow CO2 CO2 + H2O H2CO3 HCO3– + H+ HCO3– Chloride shift (out) via transport protein Fast Cl– CO2 CO2 + H2O H2CO3 HCO3– + H+ Carbonic anhydrase RBC Cl–

c) Carbonic Acid-Bicarbonate Buffer System i) Alkaline Reserve: the HCO3- in plasma is a Buffer Sys b. Changes in pH (usually via metabolic factors) If H+  in blood: equation goes to the left and forms more Carbonic Acid If H+ : reaction goes to right to form more H+ 4. Influence of CO2 and Blood pH on Breathing Rate c. Respiratory Sys Regulation: If CO2 is low in blood, then Respiratory System causes Slow Breathing Rate and Shallow inhalation/exhalation If CO2 is high in blood  Respiratory System causes Rapid Rate of breathing & deep inhalation/exhalation: H2CO3  H+ + HCO3– Carbonic acid Hydrogen ion Bicarbonate ion

VI. Control of Respiration Neural Mechanisms Involves neurons in reticular formation of medulla and pons Medulla Oblongata Respiratory Centers Ventral Respiratory Group Inspiration: Certain neurons send impulses to breathing muscle Pons Medulla Pons Medulla Pontine respiratory centers interact with the medullary respiratory centers to smooth the respiratory pattern. Pontine respiratory centers interact with the medullary respiratory centers to smooth the respiratory pattern. Ventral respiratory group (VRG) contains rhythm generators whose output drives respiration. Ventral respiratory group (VRG) contains rhythm generators whose output drives respiration. Pons Medulla Pons Medulla Dorsal respiratory group (DRG) integrates peripheral sensory input and modifies the rhythms generated by the VRG. Dorsal respiratory group (DRG) integrates peripheral sensory input and modifies the rhythms generated by the VRG. To inspiratory muscles To inspiratory muscles Diaphragm Diaphragm External intercostal muscles External intercostal muscles

b. Dorsal Respiratory Group 1. Medulla Oblongata … a. Ventral Respiratory Group ... Normal Rhythm generated = Eupnea b. Dorsal Respiratory Group Integrates information from peripheral stretch receptors & chemoreceptors  sends to VRG to modify rhythm Pons Medulla Pons Medulla Pontine respiratory centers interact with the medullary respiratory centers to smooth the respiratory pattern. Pontine respiratory centers interact with the medullary respiratory centers to smooth the respiratory pattern. Ventral respiratory group (VRG) contains rhythm generators whose output drives respiration. Ventral respiratory group (VRG) contains rhythm generators whose output drives respiration. Pons Medulla Pons Medulla Dorsal respiratory group (DRG) integrates peripheral sensory input and modifies the rhythms generated by the VRG. Dorsal respiratory group (DRG) integrates peripheral sensory input and modifies the rhythms generated by the VRG. To inspiratory muscles To inspiratory muscles Diaphragm Diaphragm External intercostal muscles External intercostal muscles

2. Pons– Pontine Respiratory Centers 1. Medulla Oblongata… 2. Pons– Pontine Respiratory Centers Fine tunes rhythm for smoothing out Transition from: a) Inspiration to Expiration b) Vocalizing c) Exercising: rate can ↑ by 20 fold Pons Medulla Pons Medulla Pontine respiratory centers interact with the medullary respiratory centers to smooth the respiratory pattern. Pontine respiratory centers interact with the medullary respiratory centers to smooth the respiratory pattern. Ventral respiratory group (VRG) contains rhythm generators whose output drives respiration. Ventral respiratory group (VRG) contains rhythm generators whose output drives respiration. Pons Medulla Pons Medulla Dorsal respiratory group (DRG) integrates peripheral sensory input and modifies the rhythms generated by the VRG. Dorsal respiratory group (DRG) integrates peripheral sensory input and modifies the rhythms generated by the VRG. To inspiratory muscles To inspiratory muscles Diaphragm Diaphragm External intercostal muscles External intercostal muscles

Peripheral chemoreceptors in carotid and aortic bodies B. Factors Influencing Breathing Depth and Rate - modification for changing body demands’ Arterial P CO2 Chemical Factors a. CO2 and H+ are most important Factors: CO2 diffuses across blood- brain barrier and forms ↑HCO3- + ↑H+ in brain i) Brain pH Stimulates: Central Chemoreceptors in medulla ventillation ii) Arterial pH stimulates: peripheral chemoreceptors ↑ Ventilation H in brain extracellular fluid (ECF) CO2 Central chemoreceptors in medulla respond to H+ in brain ECF (mediate 70% of the CO2 response) Peripheral chemoreceptors in carotid and aortic bodies (mediate 30% of the CO2 response) Afferent impulses Medullary respiratory centers Efferent impulses So Both types of chemoreceptors increase ventilation Respiratory muscle Ventilation (more CO2 exhaled) Initial stimulus Arterial P and pH return to normal Physiological response CO2 Result

c. PO2 is NOT a common stimulus Only if arterial PO2 < 60mm, peripheral chemoreceptors  ventilation Brain Carotid body Cranial nerve X (vagus nerve) Aortic bodies in aortic arch Aorta Heart Figure 22.26

2. Other Influences i) Emotions and Hyperventilation: Emotional stimuli via hypothalamus: if ↑ Ventilation when more O2 not needed  too much Blood CO2 removed  BREATH IN PAPER BAG = Are rebreathing exhaled CO2 which increases blood CO2 levels and stops loss of consciousness

END OF PPT REVIEW QUESTIONS

Review A. ID B. ID C. What type of E.T. is found here?

Review Questions The _____________ ______ ________ epithelium of the nasal cavity helps move _________ and gives way to ________ _________ epithelium in the oropharynx to protect against ___________ from food. How many lobar bronchi are there? pseudostratified ciliated columnar mucus stratified squamous friction 5 = 3 right + 2 left lobes

Review Questions The ___________ ________ is where respiratory gases diffuse from air in the ________ to the blood plasma. Intrapleural (Pip) pressure is always _____ than _____________(Ppul) pressure, otherwise the lungs would do what? respiratory membrane alveoli less intrapulmonary Collapse (atalectasis)

Review Questions Which of the following physical factors would negatively effect pulmonary ventilation? Increased resistance to flow Increased lung compliance Decreased alveolar surface tension D. A and C only E. All of the above _______ _______ is the portion of gas in the lungs that does not participate in active gas exchange. Dead space Figure 11.17: A child in Mexico City who is already adept at smoking cigarettes—a behavior that, if continued, will one day endanger her capacity to breathe. 34

Review Questions In a mix of gases, the ________ _________ of each gas and its ___________ in the liquid determine the direction and quantity of diffusion. How does rapid, shallow breathing effect alveolar respiration rate, i.e. actual gas exchange? partial pressures solubility Reduces it.

Review Questions What brain regions have primary control over respiration? The primary stimulus for regulating respiration rates is the concentration of _____ and its eventual production of ___ ions. Long term acclimation is regulated by what organs? Pons and Medulla CO2 H+ kidneys

Review Questions As CO2 enters the blood, what happens to blood pH? What happens to the ability of Hb to hold onto O2 as CO2 levels increase? The Haldane effect describes the influence of ____ on the capacity of blood to carry _____. Decreases (H+ increases) Decreases (Bohr effect) O2 CO2