Chapter 22: The Respiratory System

Question 1

General Function of the Respiratory System:

Answer 1

o 1. Filters inspired air.
o 2. Provides for gas exchange.
o 3. Helps regulate blood pH.
o 4. Olfaction (sense of smell).
o 5. Produces sounds and resonance for vocalization.
o 6. Way of getting rid of small amounts of water and heat.

Question 2

Nasal Cavity:

Answer 2

o External and internal nares.
o Nasal septum.
o Warms, humidifies, filters incoming air (rich network of capillary plexuses and thin-walled veins).
o Nasal conchae and nasal meatuses increase surface area of internal nose.
o Nasal mucous membrane = First line of defense! (ciliated pseudostratified columnar epithelium).

Question 3

Paranasal Sinuses:

Answer 3

o Drain into nasal cavity.
o Resonance for speech.
o Cavities lined by mucous membranes that drain into.

Question 4

Epistaxis:

Answer 4

Nosebleed

Question 5

Rhinitis:

Answer 5

Excessive mucus production with inflammation of nasal mucosa, leads to a runny nose.

Question 6

Rhinoplasty:

Answer 6

Plastic Surgery of the Nose.

Question 7

Pharynx:

Answer 7

o Extends from CHOANAE = INTERNAL NARES = POSTERIOR NASAL APERTURES to the level of the cricoid cartilage of the larynx.
o Moves air and food to distal locations.
o Contains openings for Eustachian tubes.
o Houses our tonsils.
o Wall = mostly skeletal muscles lined by mucous membranes.
o Divisions:
o Nasopharynx.
o Oropharynx.
o Laryngopharynx.

Question 8

Larynx:

Answer 8

o 1.5 inch passageway connecting the laryngopharynx to the trachea.
o Primary function: patent airway!
o Keep food and ingested fluids out of airways.
o Another function: produce sound!
o 9 separate pieces of cartilage
o Thyroid cartilage = “Adam’s apple”
o Cricoid cartilage = “ring” shaped
o Epiglottis = leaf-shaped “trap door”
o GLOTTIS:
o True vocal cords —inferior.
o Rima glottis = space between the true vocal folds, this closes when we swallow.
o FALSE VOCAL CORDS = vestibular folds.
o LARYNGITIS = inflammation of larynx.
o CANCER OF LARYNX = almost entirely in people who smoke.

Question 9

Trachea:

Answer 9

o Extends from larynx to superior border T5.
o 4 to 5 inch long windpipe, three-quarters an inch in diameter.
o C-shaped hyaline cartilage rings = maintains patency of airway = 16 to 20 partial rings.
o Trachealis muscle on posterior side (smooth muscle).
o Carina = inferior trachea at bifurcation = generates a very strong cough reflex.
o Tracheostomy = incision into trachea inferior to cricoid cartilage, must suction frequently!

Question 10

Primary Bronchi:

Answer 10

o PRIMARY BRONCHUS = division of the trachea into the hilum of each lung.
o RIGHT primary bronchus is shorter, wider, and more vertical, things more likely to get stuck!
o Supported by hyaline cartilage, histology includes ciliated pseudostratified columnar epithelium, elastic c.t., and smooth muscle.
o As you go deeper down the “bronchial tree,” there is less and less cartilage, more and more smooth muscle, but ALWAYS elastic c.t. and an epithelial membrane of some type!

Question 11

“Trends” in Histology from Upper to Lower Conducting Zones:

Answer 11

o Decreasing amounts of: Cartilage, Glands, Goblet cells, Height of columnar epithelial cells, Size of lumen.
o Increasing amounts of: Smooth muscle, Elastic tissue.

Question 12

Bronchioles:

Answer 12

o	Bronchiole tree = 20 to 25 orders of branching, blood supply from bronchial arteries that come off thoracic aorta.
o	Once they get less than 1 mm in diameter, then there is no cartilage.
o	BRONCHOCONSTRICTION (smooth muscle contraction with narrowing of airways).
o	BRONCHODILATION (smooth muscle relaxation with lumen of airways increasing in size… sympathetic nervous system stimulation with beta two adrenergic receptors!).

Question 13

Narrowing of Bronchioles:

Answer 13

o	1.  Bronchoconstriction.
o	2.  Obstruction.
o	Inflammation:
o	Infection.
o	Irritation (pollution, allergens).
o	Cystic fibrosis
o	Genetic defect in Chromosome #7
o	Abnormal Chloride pump
o	Cl- stays inside surface cell
o	Na+ stays with it
o	Water comes in, leaving mucus in lumen thick, viscous, and dry, clogs the airways.

Question 14

Terminal Bronchioles:

Answer 14

o Less than 0.5 mm in diameter.
o Over 65,000 terminal bronchioles between the two lungs (one bronchiole may divide into 50 to 80 terminal bronchioles!!!).
o No mucous glands, no goblet cells, very few cilia if any = great need for MACROPHAGES.
o Each one divides into 2/more respiratory bronchioles.

Question 15

Respiratory Bronchioles:

Answer 15

o Beginning of RESPIRATORY ZONE (vs. the “conducting zone”), where gas exchange can begin.
o Each respiratory bronchiole divides into 2 to 10 alveolar ducts.
o Alveolar ducts end in alveolar sacs.
o Alveolar sacs are clusters of individual alveoli (one alveolus, several alveoli).

Question 16

Alveolus:

Answer 16

o Air pouch 0.2 to 0.5 mm in diameter; may contain alveolar pores.
o Specialized cells:
o Squamous (Type I) alveolar cells (simple squamous epithelial cells for gas exchange)(95 percent of surface area of alveolus).
o Great (Type II) alveolar cells = septal cells (secrete surfactant).
o Alveolar macrophages = dust cells.
o Outer surface = network of blood capillaries branching off the pulmonary arteries.
o Fibroblasts produce reticular and elastic fibers that surround alveoli.

Question 17

Respiratory Membrane:

Answer 17

o Consists of 4 layers of tissue = 0.5 microns thick (tissue paper is 15X thicker).
o Alveolar wall with 3 cell types.
o Basement membrane underlying alveolar wall.
o Capillary basement membrane.
o Capillary wall = simple squamous = endothelium.
o Estimated that the two lungs contain 300 million alveoli with a combined surface area of 750 square feet = size of a racquetball court!

Question 18

Ventilation-Perfusion Coupling:

Answer 18

o Pulmonary BLOOD VESSELS have a weird feature = they CONSTRICT in response to localized hypoxia (remember: most blood vessels would reflexively vasodilate with hypoxia).
o This diverts pulmonary blood from poorly ventilated areas to better-ventilated regions of the lungs!
o Too much vasoconstriction can cause pulmonary hypertension leads to right-sided CHF!

Question 19

Lungs:

Answer 19

o Located on either side of mediastinum.
o Right lung is broader but shorter (3 lobes).
o Left lung is 10 percent smaller (2 lobes only).
o Apex of lungs is just superior to clavicles.
o Base of lungs sits on top of the diaphragm.
o R and L Phrenic nerves innervate the diaphragm (C3, C4, C5 keeps the diaphragm alive).
o Lungs surrounded by pleural membrane (visceral pleura, parietal pleura, pleural cavity in between).

Question 20

Pleuritis:

Answer 20

Inflammation of pleura. Not enough fluid= pleural friction rub. Too much fluid= pleural effusion.

Question 21

Thoracentesis:

Answer 21

Removal of excess fluid in pleural cavity.

Question 22

Atelectasis:

Answer 22

collapse of a portion/all of lung.

Question 23

Pneumothorax:

Answer 23

Air in the pleural space.

Question 24

Hemothorax:

Answer 24

Blood in the pleural space.

Question 25

RDS:

Answer 25

Respiratory distress syndrome= deficiency of surfactant in infants.

Question 26

Physiology of Breathing:

Answer 26

o 1. Pulmonary ventilation = “breathing” (atmospheric air enters/leaves alveoli). o 2. Alveolar gas exchange = gas exchange at the respiratory membrane (external respiration). o 3. Transport of gases in the blood. o 4. Systemic gas exchange = gas exchange between the systemic capillaries leads to interstitial fluid leads to cells (internal respiration).

Question 27

Basic Facts About Pulmonary Respiration:

Answer 27

o Airflow is governed by the same principles of flow, pressure & resistance that govern blood flow: o FLOW = difference in pressure between 2 points divided by resistance. o Air always diffuses FROM areas of higher pressure TO areas of lower pressure. o Atmospheric pressure: A column of air 100 km high exerts 1 atmosphere of pressure = enough to force a column of mercury up a tube 760 mm at sea level. o Intrapulmonary pressure: The pressure of air inside the alveoli of the lungs o What matters to the FLOW of air is the DIFFERENCE between atmospheric pressure and intrapulmonary pressure. o VOLUME changes can cause changes in the PRESSURE of gases. o Boyle’s Law: The pressure of a given quantity of gas is inversely proportional to its volume (assuming a constant temp).

Question 28

Pulmonary Ventilation:

Answer 28

o Pulmonary ventilation refers to the flow of air from the atmosphere INTO and OUT OF the alveoli of the lungs. o Inhalation: Air flows INTO the lungs if the atmospheric pressure (760 mm) is greater than the intrapulmonary pressure (758 mm). o Exhalation: Air flows OUT of the lungs if the atmospheric pressure (760 mm) is LESS than the intrapulmonary pressure (762 mm).

Question 29

Primary Muscles of Inhalation:

Answer 29

o Depression of diaphragm accounts for 75 percent of quiet inspiration. o Depression of diaphragm by 1 to 1.5 cm causes a 1 to 3 mm pressure difference. o Contraction of External intercostal muscles account for 25 percent of quiet inspiration.

Question 30

Quiet vs. Force Inhalation:

Answer 30

o When the diaphragm descends 1 – 1.5 cm, about 500 mL of air comes into the lungs = TIDAL VOLUME. o Stronger contraction of the diaphragm (descending down 7 to 10 cm) & accessory muscles can allow for forced inhalation of 2000 -3000 mL of air! o Accessory muscles of forced inhalation include: scalene muscles, pectoralis minor, sternocleidomastoid, serratus anterior.

Question 31

Steps for Inhalation:

Answer 31

o 1. Inspiratory muscles contract (diaphragm descends; rib cage rises). o 2. Thoracic cavity volume increases. o 3. Lungs are stretched; intrapulmonary volume increases. o 4. Intrapulmonary pressure drops (to -1mm Hg). o 5. Air (gases) flow into lungs down its pressure gradient until intrapulmonary pressure is 0 (equal to atmospheric pressure).

Question 32

Steps for Exhalation:

Answer 32

o 1. Inspiratory muscle relax (diaphragm rises; rib cage descends due to recoil of costal cartilages). o 2. Thoracic cavity volume decreases. o 3. Elastic lungs recoil passively; intrapulmonary volume decreases. o 4. Intrapulmonary pressure rises (to +1 mm Hg.) o 5. Air (gases) flows out of lungs down its pressure gradient until intrapulmonary pressure is 0.

Question 33

Quiet (Passive) Exhalation:

Answer 33

o In a healthy person, the relaxation of the diaphragm and external intercostal muscles leads to exhalation. o This is a PASSIVE process which depends primarily on the natural elasticity of the lungs and the elasticity of the chest wall.

Question 34

Muscles of Forced Exhalation:

Answer 34

``` o Internal intercostal muscles are active in FORCED exhalation. o Other accessory muscles: o Abdominal muscles. o Latissimus dorsi. o Quadratus lumborum. o Serratus posterior inferior. ```

Question 35

Valsalva Maneuver:

Answer 35

o When the diaphragm contracts, it INCREASES abdominal pressure. o If we take a deep breath, then close the rima glottidis and contract our abdominal muscles, we increase abdominal pressure even more = Valsalva Maneuver o We use the valsalva maneuver in defecation, childbirth, and even urination. o This decreases heart rate via stimulation of the Vagus nerve (CN X).

Question 36

Factors Affecting Pulmonary Ventilation:

Answer 36

o FLOW = difference in pressure between 2 points divided by resistance. o Note: Air pressure differences determine the DIRECTION of the flow of air. o RESISTANCE to air flow can affect the RATE of airflow and the EASE of air flow. o 1. obstruction of airways. o 2. pulmonary (lung) compliance. o 3. surface tension of the alveoli. o 4. changes in pressure of pleural cavity.

Question 37

Obstruction of Airways:

Answer 37

o The walls of airways create (insignificant) friction to the flow of air. o OBSTRUCTION can cause significant resistance to the flow of air: o Inflammation of respiratory epithelium. o Increased mucus secretion. o Severe BRONCHOCONSTRICTION via contraction of smooth muscles in walls of airways.

Question 38

Etiology of Bronchoconstriction:

Answer 38

``` o Inhaled irritants. o Smoke and pollutants. o Histamine and other inflammatory chemicals. o Cold air. o Respiratory infections. o Allergies. o Drug reactions. o COPD. ```

Question 39

Treatment of Asthma:

Answer 39

``` o Beta-2 agonists: o e.g., Albuterol, Ep, Serevent. o Anticholinergics: o e.g., Atrovent inhalers. o Anti-inflammatory meds: o Systemic Steroids (e.g., prednisone). o Inhaled steroids (e.g., Aerobid, Pulmicort, Nasarel, Flovent). o Leukotriene inhibitors (e.g., Accolate & Singulair). o Combination meds: o e.g., Advair, Symbicort. ```

Question 40

Pulmonary (Lung) Compliance:

Answer 40

o Refers to how much effort is required to STRETCH the lungs and EXPAND the chest wall. o High compliance: lungs/chest expand easily. o Low compliance: lungs/chest resist expansion. o Compliance affected by 2 major things: o Elasticity of lung and chest wall structures. o Mechanical things (weakening/paralysis of . inspiratory muscles, arthritis). o Fibrosis (scar tissue from burns, TB, toxic chemicals). o Dz (emphysema, alpha-1 antitrypsin deficiency). o Surface tension of the alveoli.

Question 41

Abnormal Alveolar Surface Tension:

Answer 41

o If surface tension in the alveoli is too high, compliance will be lowered. o If lung tissue accumulates fluid, this also decreases compliance.

Question 42

Pleural Cavity Pressure Changes:

Answer 42

o Normally, pressure in the pleural cavity is negative compared to intrapulmonary pressure. o Anything increasing pleural cavity pressure will interfere with expansion of the lung. o Atelectasis: collapse of all or part of a lung. o Pneumothorax. o Hemothorax . o Pleural effusions.

Question 43

Measuring Pulmonary Ventilation:

Answer 43

o Respiratory Rate: Breaths/Min. Normal: 12 to 15 at rest. | o Respiratory Volumes and Capacities: Instrument used is a spirometer.

Question 44

Respiratory Volumes:

Answer 44

o Tidal Volume: air exchanged in single breath at rest o Inspiratory Reserve Volume: Amount of air that can be forcefully inhaled after a normal tidal volume inhalation. o Expiratory Reserve Volume: Amount of air that can be forcefully exhaled after a normal tidal volume exhalation. o Residual Volume: Amount of air remaining in the lungs after a force exhalation. o Vital Capacity: Maximum amount of air that can be expired after a maximum inspiratory effort. TV+IRV+ERV. o Total Lung Capacity: Maximum amount of air contained in lungs after a maximum inspiratory effort. TV+IRV+ERV+RV.

Question 45

Pulmonary Function Tests:

Answer 45

``` o MINUTE VENTILATION = total volume of air inhaled/exhaled in one minute. o MV (mL/min) = TV (mL/breath) X Resp. rate (breaths/min). o FORCED VITAL CAPACITY = amt. of air expelled after taking a deep breath followed by a forced exhalation. o FEV1 = Percent of vital capacity that can be exhaled in 1 second. ```

Question 46

Eupnea:

Answer 46

Normal pattern of quiet breathing.

Question 47

Hyperpnea:

Answer 47

Increased rate and depth of breathing.

Question 48

Dyspnea:

Answer 48

Shortness of breath (SOB).

Question 49

Orthopnea:

Answer 49

Difficult breathing unless upright.

Question 50

Apnea:

Answer 50

Temporary cessation of breathing. (Sleep apnea)

Question 51

Respiratory Arrest:

Answer 51

Permanent cessation of breathing without medical intervation.

Question 52

Kussmaul Breathing:

Answer 52

Deep, rapid breathing seen in acidosis.

Question 53

Hyperventilation:

Answer 53

Increased ventilation in excess of demand.

Question 54

Hypoventilation:

Answer 54

Decreased ventilation relative to metabolism.

Question 55

Regulation of Respiration:

Answer 55

o Control of respiration is primarily through the nervous system…significant differences from regulation of the heart (which was also greatly influenced by hormones).

Question 56

Laws Associated with Respiration:

Answer 56

o Boyle’s Law: o The higher the volume, the lower the pressure of the gas o Charles Law: o The volume of a given quantity of gas is directly proportional to its temperature o Dalton’s Law of Partial Pressures: o The total pressure of a mixture of gases is the sum of the pressures exerted by each gas. o Each gas exerts its own pressure, regardless of other gases present.

Question 57

Dalton's Law of Partial Pressures:

Answer 57

o The pressure exerted by each gas—its partial pressure—is directly proportional to the percentage of that gas in the gas mixture.” o Atmospheric air is a MIXTURE of gases, which (at sea level) exerts a total of 760 mm Hg pressure: o 78.6% nitrogen gas. o 20.9% oxygen gas. o 0.04% carbon dioxide gas. o 0.5% water vapor (varies).

Question 58

Partial Pressure Gradients Involved in O2 and CO2:

Answer 58

o Individual gases will diffuse down their own pressure gradient! o The greater the pressure gradient, the FASTER the diffusion of the gas! o We need to know what the pO2 and the pCO2 are in the arteries, in the veins, in the tissues, and in the lungs in order to know which direction gases are going to diffuse!

Question 59

Henry's Law:

Answer 59

o When a gas interfaces with a liquid at a specific temp, the amount of the gas that ends up in the liquid is proportional to the partial pressure of that gas. o How much gas that can dissolve in the liquid also has to do with its intrinsic solubility quotient in that liquid. o In the watery medium of blood plasma, CO2 is 20 to 24X more soluble than O2. o In the watery medium of blood plasma, O2 is twice as soluble as N2. o At sea level, very little N2 gas dissolves in our plasma or in our tissues. o However, when you scuba dive (below sea level), pressure INCREASES and the diver is breathing in air under higher pressure. o More N2 dissolves in our plasma and in our tissues, especially lipid-soluble tissue like myelin! o This causes NITROGEN NARCOSIS (“rapture of the depths”), every 15 to 20 meters down is said to be equivalent of one martini on an empty stomach!

Question 60

Diffusion:

Answer 60

o All gas exchanges are made according to the laws of diffusion, the DIRECTION of gas flow is determined by the pressure gradient. o Always from an area of higher partial pressure to an area of lower partial pressure. o You will have a FASTER rate of diffusion when: o There is a greater difference in the partial pressures between 2 areas. o There is a greater surface area available for diffusion. o The smaller the diffusion distance. o The greater the temperature. o The higher the solubility in water (for humans).

Question 61

pO2 and pCO2 in Blood Vessels:

Answer 61

``` o Atmospheric Air: o pO2 = 160 mm Hg. o pCO2 = 0.3 mm Hg. o Alveolar Air: o pO2 = 104 mm Hg. o pCO2 = 40 mm Hg. o Systemic Arteries: o pO2 = 100 mm Hg. o pCO2 = 40 mm Hg. o Systemic Veins: o pO2 = 40 mm Hg. o pCO2 = 45 mm Hg. ```

Question 62

Alveolar Gas Exchange (External Respiration):

Answer 62

What happens in the pulmonary capillaries.

Question 63

Healthy Efficiency of Alveolar Gas Exchange:

Answer 63

o It takes about 0.25 seconds for gas exchange to occur. o At rest, it takes a RBC about 0.75 seconds to get through the pulmonary capillary bed (plenty of time for equilibration). o With vigorous exercise, it still takes a RBC 0.30 seconds to go through the capillary bed.

Question 64

Systemic Gas Exchange (Internal Respiration):

Answer 64

Refers to what happens in the peripheral (tissue) capillaries.

Question 65

Factors Affecting Rate of Alveolar and Systemic Gas Exchange:

Answer 65

o 1. Magnitude of the DIFFERENCE in partial pressure of the gas. o In which example is diffusion the fastest: • From pO2 of 100 mm Hg to pO2 of 35 mm Hg. • OR • From pO2 of 85 mm Hg to pO2 of 40 mm Hg. o 2. Surface area available for gas exchange. o 3. Diffusion distance. o 4. Solubility of the gas in body fluids.

Question 66

Effect of Increasing Altitude on Partial pressures of Oxygen in Atmosphere and Alveolus:

Answer 66

o At higher altitudes, the rate of diffusion of O2 will be slower in external respiration, may create altitude sickness.

Question 67

Altitude Sickness:

Answer 67

o Roughly 20% of humans who go higher than 8530 feet experience altitude sickness: o SOB, Headache, Dizziness/light-headed, Insomnia, Nausea, Disorientation, Cerebral edema, Pulmonary edema.

Question 68

Decrease in Surface Area:

Answer 68

o In healthy person, alveolar surface area = 750 sq feet (size of racquetball court). o SMOKING causes destruction in alveoli. o EMPHYSEMA results in a breakdown of alveolar walls. o Decreased surface area SLOWS the rate of diffusion of gases in external and internal respiration!

Question 69

Increase in Diffusion Distance:

Answer 69

``` o Pulmonary edema is abnormal accumulation of fluid in the interstitial fluid between alveoli. o Tissue (peripheral) edema is too much fluid surrounding cells. o The greater the distance, the SLOWER the rate of diffusion! ```

Question 70

Effect of Slow Diffusion:

Answer 70

o A slow rate of diffusion in external or internal respiration can result in HYPOXIA. o HYPOXIA = inadequate oxygen is available to tissues. o Many types of hypoxia (anemic hypoxia, ischemic hypoxia, histotoxic hypoxia--don’t worry about these). o What signs and symptoms will you see? o Cyanosis (unless CO poisoning). o SOB, DOE, orthopnea, cough. o Hypoxemia. o Hypercapnia.

Question 71

Transport of Oxygen:

Answer 71

o O2 is non-polar; only 1.5% dissolved in plasma. o 98.5% of blood O2 is carried bound to Hb inside RBCs. o O2 attaches to the IRON ion of the HEME portion of Hb, over 1 billion O2 molecules carried by one RBC!

Question 72

Bond Between Hemoglobin and Oxygen:

Answer 72

o Bond between Hb and O2 is REVERSIBLE. o Several factors affect how tightly O2 is bound to Hb (the affinity of O2 for Hb). o Concept of O2 Saturation: o If 4 molecules of O2 are bound = 100% saturated. o If 3 molecules of O2 are bound = 75% saturated. o If 2 molecules of O2 are bound = 50% saturated. o If 1 molecule of O2 is bound = 25% saturated.

Question 73

Oxygen-Hemoglobin Dissociation Curve:

Answer 73

o The higher the partial pressure of oxygen, the tighter the O2 is bound to Hb. o The lower the partial pressure of oxygen, the less tightly O2 is bound to Hb.

Question 74

High pO2 Environments VS. Low pO2 Environments:

Answer 74

o At the higher levels of pO2, fairly big changes in pO2 don’t change the Hb saturation to any great degree: o pO2 of 100 mm Hg: 98 percent saturation. o pO2 of 80 mm Hg: 95 percent saturation. o At the lower levels of pO2, big changes in pO2 dramatically change the Hb saturation: o pO2 of 40 mm Hg: 75 percent saturation. o pO2 of 20 mm Hg: 40 percent saturation.

Question 75

Things Affecting Binding of Hemoglobin to O2:

Answer 75

o pH: o The lower the pH, the less tightly O2 is bound to Hb (curve shifts to the right, O2 dissociates more readily). o Under acidic conditions, Hb acts like a buffer and binds H+, changing the shape of Hb leads to more likely to release O2. o Remember: Metabolically active tissues produce lactic acid and carbonic acid. o pCO2: o CO2 can also bind to Hb leads to shape change so that O2 doesn’t bind as tightly. o As pCO2 goes up, curve shifts to right and gives up O2 more easily. o Temperature: o As temp goes up, curve shifts to right and gives up O2 more easily. o As temps go down, curve shifts to left and Hb holds more tightly to O2. o BPG: o As BPG goes up, curve shifts to right and gives up O2 more easily. o As BPG goes down, curve shifts to left and Hb holds more tightly to O2. o 2,3-bisphophoglycerate is a chemical that goes up in RBCs when glucose is broken down by anaerobic glycolysis leads to goes up when increase in T3/T4, hGH, catecholamines. o CO: o Carbon monoxide binds to IRON 200 times more tightly than O2à O2 is displaced leads to Hypoxia. o Increased CO from car exhaust, faulty gas furnaces and space heaters. o Cherry red skin!

Question 76

Transport of Carbon Dioxide:

Answer 76

o Exchangeable CO2 is transported 3 ways in the blood: o Dissolved in blood: About 7- 10 percent. o Attached to Hb: About 20 – 23 percent. o Attached to globin as carbamino compound o Bicarbonate ion: About 70 percent.

Question 77

Important CO2-O2 Exchange Equation:

Answer 77

o CO2 + H20 ßà H2CO3 ßà HCO3- + H+ o H2CO3 = carbonic ACID, which can dissociate into bicarbonate ion and H+ . o Requires the enzyme carbonic anhydrase, which is abundant in RBCs and important other body tissues.

Question 78

Regulation of Respiration:

Answer 78

o Conscious control: o Singing, talking, holding your breath, crying. o Unconscious control at several brain levels: o Medulla oblongata. o Pons. o RF.

Question 79

Medullary Respiration Centers:

Answer 79

``` o Ventral Respiratory Group (VRG): o Rhythm generator. o Output to muscles of inspiration. o Dorsal Respiratory Group (DRG): o Receives sensory input related to breathing needs. o Receives input from pons. ```

Question 80

Chemoreceptor Input:

Answer 80

``` o Peripheral Chemoreceptors: o Monitor O2, CO2, H+. o Carotid bodies. o Aortic bodies. o Central Chemoreceptors: o Mediates 70 percent of response! o Monitor CO2—most potent. o Monitor H+ (from increase in CO2). o Monitor O2 (not as potent). ```

Question 81

Importance of CO2:

Answer 81

o Central chemoreceptors in medulla oblongata account for at least 70 percent of our respiratory drive! o Medulla oblongata is strongly stimulated by changes in pH.

Question 82

Hyperventilation and Hypocapnia:

Answer 82

o Increased rate and depth of ventilation in excess of metabolic demand. o Creates hypocapnia (low CO2 in the blood)). o Causes cerebral blood vessels to constrict. o Tingling and tetany. o Syncope o Therapy: breath into a paper bag!

Question 83

Role of Oxygen:

Answer 83

o A drop in arterial O2 has little effect on respiration unless it drops below 60 mmHg. o Low O2 primarily augments any CO2 effects. o An increase in arterial CO2 of even 10% will double the respiratory rate! o High O2 diminish the effectiveness of CO2 stimulation!

Question 84

Baroreceptor Input:

Answer 84

o Low blood pressure detected in carotid sinuses and aortic sinuses will increase minute ventilation. o High blood pressure decreases minute ventilation.

Question 85

Hering-Breur Reflex:

Answer 85

o Stretch receptors located in the smooth muscle of bronchi and bronchioles and visceral pleura sense an increased stretch of lungs. o Inhibits inspiratory neurons of VRG.

Question 86

Irritant Receptors:

Answer 86

o Sensory receptors in the epithelial cells of the respiratory airways can be sensitive to: o Smoke, dust, pollen. o Chemical fumes. o Cold air. o Excessive mucus. o Medulla oblongata can initiate a variety of reflexes that result in bronchoconstriction, coughing, sneezing, etc.

Question 87

The 2 Issues That Lead to Asthma:

Answer 87

``` o Bronchoconstriction: o Allergens, smoke, pollution. o Pathogens. o Exercise induced. o Inflammation with excess mucus production. ```

Question 88

The 3 Types of Lung Cancer:

Answer 88

o Squamous-cell carcinoma: o Cancer of stem cells of respiratory epithelium. o Adenocarcinoma: o Cancer of mucous glands of lamina propria. o Oat-cell carcinoma: o Typically originates in primary bronchi, rapidly metastasizes.

Question 89

Tuberculosis:

Answer 89

o Infection from Mycobacterium tuberculosis. o 1/3 of world is infected. o In 1930s, 1/3 of all deaths in the 20-45 year age group were from TB. o Resistant strains huge global concern.

Question 90

Sleep Apnea:

Answer 90

o Pt. temporarily stops breathing more than 5X in one hr or more than 30X in a 6-hour sleep period. o Two types o Central: o Airways stay open, but chest muscles and diaphragm don’t contract. o Obstructive: o Enlarged pharyngeal tonsil or uvula. o Reduced muscle tone in throat muscles. o Increases risks for: o CVD, including HTN, cardiac arrhythmias, MI, CVAs, and dilated cardiomyopathies. o DM. o Mood disorders, ability to focus, memory issues. o Treatment: o Weight loss. o Uvulectomy and tonsillectomy. o CPAP = Continuous Positive Air Pressure.

Question 91

Unilateral Rhinorrhea:

Answer 91

o 6-month hx of “halo” stain on pillow, with more drainage when she coughed/sneezed. o Bending forward caused drops of clear fluid to fall only from her right nostril. o Fluid contained beta2-transferrin, consistent with presence of CSF.