Respiratory System Flashcards

Question

What expands the thoracic cavity?

Answer 1

Release of ACh at neuromuscular junctions of the diaphragm and external intercostal muscles

Answer 2

Passive: elastic recoil of lungs and thoracic cage return ribs and diaphragm to original position Active: contraction of intercostals and abdominal muscles forces air out

Answer 3

1. contraction of diaphragm and external intercostals 2. chest wall expands 3. decreased intrapleural pressure 4. Increased transpulmonary pressure (Palv-Pip) 5. Decreased Palv 6. Increased Patm - Palv 7. Air flows into alveoli until Palv = Patm

Answer 4

1. lung compliance 2. airway resistance

Answer 5

how easily the lungs expand when exposed to a change in pressure, dependent on stretchability and surface tension within alveoli CL = ∆ lung volume / ∆Tp

Answer 6

Chronic inhalation of fine particulate matter deep into the lungs. Results in inflammatory process that builds collagen in lung tissue that. decreases lung compliance, impairing inspiration, and slow diffusive gas exchange.

Answer 7

Attractive forces between H2O molecules resist alveolar expansion, increasing work for inspiration. This is avoided with amphipathic phospholipid surfactant that decreases cohesive forces on the alveolar surface, increasing lung compliance.

Answer 8

Deficiency of surfactants in premature infants causes lung compliance to decrease, which is treated with artificial ventilation and aerosol administration of artificial surfactant.

Answer 9

Transpulmonary pressure and lateral traction

Answer 10

during inhalation, Pi increases, and thus Tp increases, which increases airway radius and decreases resistance.

Answer 11

small airways are physically connected to surrounding alveolar tissue by elastic connective tissue fibers, so when alveolar sacs expand outward, they pull the small airways more open, decreasing resistance.

Answer 12

- Parasympathetic stimulation: release of ACh causes bronchioconstriction - Paracrine agents: mast-cell histamine release causes contraction of bronchiolar smooth muscle and stimulates mucus secretion - CO2: high PCO2 = dilation, low PCO2 causes constriction

Answer 13

bronchioconstriction and inflammation due to hyper-responsiveness of smooth muscle to irritants

Answer 14

Elastin in lung tissue is degraded, reducing elastic recoil, which causes collapse of alveoli and small airways. Lung compliance increases but impairs expiration by trapping air in lungs. (high residual volume)

Answer 15

Partial pressure = fraction of gas x total pressure

Answer 16

O2: 105 mmHg in alveoli > 40 mmHg in pulmonary vein = O2 moves INTO vein CO2: 40 mmHg in alveoli < 46 mmHg in pulmonary vein = CO2 moves OUT of vein

Answer 17

Increased PCO2: bronchiodilation, pulmonary arteriole constriction, systemic arteriole dilation Increased PO2: bronchioconstriction, pulmonary arteriole dilation, systemic arteriole constriction

Answer 18

Respiratory pigment found INSIDE red blood cells composed of two alpha globin and two beta globin protein chains. Each is bound to a Fe2+ containing heme group for O2 binidng.

Answer 19

Monomeric respiratory pigment that facilitates O2 delivery within skeletal and cardiac muscle

Answer 20

Oxyhemoglobin (HbO2): closed/relaxed/high affinity state Deoxyhemoglobin (dHb): open/tense/low affinity state

Answer 21

Tense: allosteric effector binding creates salt bridges (H+) that stabilize the protein's tense state and keep the O2 binding sites shut. Relaxed: Effector release breaks salt bridges, causing the protein state to relax, revealing the O2 binding sites.

Answer 22

Four subunits of hemoglobin are connected in a way that the conformational change in one subunit is rapidly transferred to the other three subunits.

Answer 23

Spans PO2 in alveoli/pulmonary capillaries; ensures that hemoglobin is >90% saturated over a wide range of PO2 values

Answer 24

Spans PO2 in systemic capillaries; venous blood is saturated creating a large O2 reserve that can be tapped into during exercise

Answer 25

Plasma PO2 at which 50% of hemoglobin molecules are saturated with oxygen (50% T, 50% R state)

Answer 26

Low: it takes less PO2 for hemoglobin to be saturated (high affinity for O2) High: it takes more PO2 for hemoglobin to be saturated (low affinity for O2)

Answer 27

H2, DPG, CO2, inorganic ions bind to hemoglobin to stabilize the T-state and increases P50. This shifts OEC to the right, allowing offloading of O2 by lowering affinity.

Answer 28

surface exposed histidine residues and N terminus of four globin chains can reversibly bind to protons from acidification of CO2. This creates positive charges that form salt bridges with anionic residues, stabilizing T state, increasing blood P50, and decreasing O2 affinity.

Answer 29

The harder a tissue works (producing more CO2 and H+), the more O2 gets released.

Answer 30

DPG can form up to five bonds with cationic residues of beta chains (B1Val, B2His, B82Lys, B143His) which strongly stabilizes the T-state, decreases oxygen affinity to promote oxygen offloading.

Answer 31

Chronically undersaturated arterial blood increases DPG production, increasing blood P50 above 28mmHg. This allows more O2 to be extracted from Hb at systemic capillaries with relatively little effect on O2 uptake in the lungs.

Answer 32

Carbon dioxide binds to amino group of the 1st residue of each alpha and beta chain, forming a carbamino protein (NHCOO-) which forms salt bridges with cationic residues which stabilizes the T state, unless dominated by DPG.

Answer 33

As pH declines and Hb cavity becomes progressively more cationic, chloride ions can cross bridge certain cationic residues (cation-Cl-cation) and stabilize the T state.

Answer 34

Increasing temperature increases free energy that can be used to weaken the Hb-O2 bonds, lower O2 affinity and promote offloading of O2, especially during exercise.

Answer 35

CV: increased cardiac output and capillary recruitment at exercising muscles Hemoglobin: - increased temp lowers blood affinity - increased PCO2 and [H+] decrease blood pH and increase bohr effect - decreased pH creates more binding sites for DPG and Cl-

Answer 36

Hemoglobin facilitates endocrine transport of nitric oxide. When RBC senses low PO2 at working tissues, Hb releases NO to vasodilate the vessel and increase blood flow to allow for more opportunity to offload and deliver oxygen.

Answer 37

oxygenated myoglobin and hemoglobin lower [NO] by converting it to nitrate.

Answer 38

Fetal hemoglobin uses gamma globin chains instead of beta, which have 4 out of 8 adult DPG sites uncharged, so only 3 bonds can be made, lowering P50, increasing affinity for O2.

Answer 39

CO binds to heme groups with 200x higher affinity than O2, lowering blood O2 content at any given PO2, and resisting release.

Answer 40

1. dissolved in blood plasma (5-10% during exercise) 2. Bound to amino groups of plasma proteins (less than 1% in normal proteins, 5% in hemoglobin) 3. Bicarbonate ions catalyzed by carbonic anhydrase (90%)

Answer 41

1. CO2 from tissues enters the RBC via concentration gradient 2. CO2 + H2O are turned to HCO3- by carbonic anhydrase 3. HCO3- gets transported back to blood in exchange for one Cl- ion, via band 3 antiport exchanger protein 3. Cl- is given to oxyhemoglobin (HbO2), assisting DPG in stabilizing T state, offloading oxygen which follow concentration gradient into tissues.

Answer 42

1. emotions and voluntary control: send signals to cerebral cortex which sends signals to medulla 2. chemoreceptors: peripheral and central, signal to medulla 3. muscle and joint receptors: sense exercise, signals to medulla 4. pulmonary stretch receptors: senses overinflation of lungs and signals to medulla

Answer 43

Glomus cells of carotid and aortic bodies are strongly activated when plasma PO2 drops below 60mmHg. They release neurotransmitters onto sensory neurons projecting to the medulla, primarily increasing RATE of ventilation.

Answer 44

1. High CO2 in capillaries cross blood brain barrier and enter cerebrospinal fluid. 2. CO2 is converted into bicarbonate and a proton. 3. Bicarbonate stays in the CSF, but the protons cross the blood brain barrier and enter the medulla interstitial fluid. 4. H+ trigger sensory neurons of the medulla, increasing the depth of ventilation.