The Respiratory System PDF

The Respiratory System Structure and properties mechanics of breathing gas exchange transport of gases regulation of breathing  mammalian lung Fig. 3.28  J the oura lines iline ener...

The Respiratory System Structure and properties mechanics of breathing gas exchange transport of gases regulation of breathing  mammalian lung Fig. 3.28  J the oura lines iline ener [ Loading…  mammalian lung Fig. 13.21  2 airway zones 1. Conducting zone: conditions warmed humidified Loading… filtered (mucus and ciliated cells) 2. Respiratory zone (respiratory bronchiole and alveoli) gas exchange  pulmonary venule respiratory bronchiole pulmonary arteriole alveolar sac alveola capillary network on surface r of alveolus duct picks up Oxygen drops of CO2 as Waste  physical properties of lungs compliance: stretchable elasticity: return to original size surface tension: Air-water interface at the inner surface of the alveoli. Offset by surfactants secreted by some alveolar cells. Prevents alveolar collapse.  proteins DPPC: depalmitoyl phosphotidyl choline, a PL Matalon et al. 2006  Mechanics of breathing 2 phases: inspiration and expiration driven by changes in the volume of the thoracic cavity neural control motor neurons evade these muscles  Inspiration: expansion of the thoracic cavity diaphragm external intercostals others for deep breathing  Expiration: passive insp. muscles relax muscle relaxation remaining air: residual volume Loading… amount expired: tidal volume force more out with internal intercostals, others respiratory muscles Gas Exchange: Driven by gradients of partial pressures of individual gasses direction of movement from high pressure to low pressure. components of air H2O variable (will displace gasses) PN2 ~590 mm Hg PO2 ~160 mm Hg PCO2 ~ 10 mm Hg total 760 mmHg atmospheric pressure alveolar air: saturated with H2O removes CO2 as waste PO2 ~ 105 mm Hg PCO2 ~ 40 mm Hg (from cellular respiration) Vs. components of air (external) H2O variable (will displace gasses) PN2 ~590 mm Hg PO2 ~160 mm Hg PCO2 ~ 10 mm Hg total 760 mmHg atmospheric pressure  transport of respiratory gasses (O2) 3% dissolved in plasma (controls diffusion direction) 97% bound to hemoglobin in RBCs  hemoglobin protein is globin: 4 subunits (2 alpha and 2 beta) pigment molecule is heme: 1/subunit, each contains and Fe++, binds 1 O2  hemoglobin iron binding ↓ figure 13.2  Hb +O2 Hb(O2)4 deoxy- oxy- hemoglobin hemoglobin contains 4 subunits environmental factors controls the direction of equation  low temp high Hb +O2 Hb(O2)4 PO2 deoxy- high pH oxy- hemoglobin hemoglobin  low temp high Hb +O2 Hb(O2)4 PO2 deoxy- high pH oxy- hemoglobin > - hemoglobin low PO2 low pH high temp binding of organic phosphate compounds  O2 release is favored at tissues because: low PO2 low pH – blood, CO2: carbonic acid – muscle activity: lactic acid – Bohr effect: H+ binds Hb and lowers its O2 affinity  Bohr Effect -- it takes more pind Oxygen to hemoglobin to & 50 %  O2 release is favored at tissues because: (cont.) metabolically active cells produce heat binding of organic phosphate compounds DPG 2,3 –diphosphoglycerate DPG binds AAs in beta chains and decreases O2 affinity.  Carbon Monoxide binds Hb ~ 250X better than O2 decreases O2 transport Hb(CO)4 = carboxy hemoglobin  transport of CO2 in blood 10% dissolved in plasma 20% binds amine groups on alpha and beta chains (carbaminohemoglobin) 70% converted to bicarbonate-mostly in RBCs does not need a Catalyst , ⑰ COn + HO HiLO , -HCO ; high CO2 will cause low PH die , ↓ M to the H+ protons it is converted , bicarbonate needsthic losing a to picarbonate after ↑ CO2 - fPH in the plasma proton premains anhydrase instead  CO2 entering at tissues/ O2 leaving CO2 moves across its gradient A little CO2 stays bit of in ↓ - ↑ On diffuses out of cell in to the longs the plasma I converted to bicarbonate drivin radieni ↑ Dand O out Transporter Bicarbonate made (passive antiporter) , in the RBS exits the cell through the PONNsed kinds to Hb band III transporter in of C1- exchange > CO2 can bind to Ho a displace O2 as well  CO2 leaving at lungs/O2 entering CO2 exits out the O enters the lungs longs some carbonate & enters Cell through pand III to form d HeOCOn O & CO2 goes its down gradient ↑ ↓ gradient drige one & diffuses out On in favorable of the lungs H2O formed conditions blo anhydrase Carponic an hydrase O carbonic works in the drives the diffusion Other direction Of CO2 out of the lungs  regulation of breathing (neural control) medulla oblongata: rhythmicity center generates pattern of activity of: I neurons activate motoneurons that innervate breathing muscles: inspiration E neurons inhibit inspiratory motor neurons: expiration  mechanisms that determine the length of inspiration (1) hering breuer reflex: stretch receptors in bronchi and bronchioles activated Loading… signals via vagus nerve to inhibit inspiration cut vagus, inspiration lasts longer  mechanisms that determine the length of inspiration (2) pons pneumotaxic center – Can regulate transition from I to E – without center, inspiration lasts longer pons apneustic center promotes inspiration higher brain centers can also adjust breathing  where signals come from to change breathing Stimulateis E neurons I neurons (and some I neurons) sneurons neuron a regulation of breathing: influence of pH (CO2) high low pH is related to concentrations of CO2 two groups of chemoreceptors; – central chemoreceptors – peripheral chemoreceptors  central chemoreceptors in medulla oblongata sensitive to pH in CSF reports small changes in PCO2 $ breathing required for breathing peripheral chemoreceptors O  peripheral chemoreceptors aortic bodies carotid bodies both sensitive to pH increased CO2/decreased pH: $ breathing ↑ CO.& LpH = breathing  CO NOT detected by chemoreceptors Changes in PO2 levels cannot be detected except in very low O2 conditions (carotid body)