BIOL 252 1st Edition Lecture 20 Outline of Last Lecture I Poll Everywhere Outline of Current Lecture I Poll Everywhere Current Lecture I Capillary Exchange a What moves across capillaries Water nutrients wastes ions antibodies hormones i Example of waste urea ii Ions sodium chloride iii Transcytosis through endothelial cells iv Diffusion v Intercellular clefts vi Fenestrations filtration reabsorption vii Bulk flow 1 Movement of fluid component of blood plasma to leak out of capillary wall b Filtration and reabsorption i Fluid filters out of arterial end of capillary ii Fluid leaving capillary filtration 1 Opposing forces a Hydrostatic pressure drives fluid out of capillary 33 out b Osmotic pressure drives fluid into capillary 20 in i Force of water moving c Net filtration pressure 13 out iii Fluid has forces causes it to be pulled back in 1 On venous side 2 Fluid reabsorbed at venous end reabsorption 3 Net hydrostatic pressure drops 13 out a Lower blood pressure 4 Net osmotic pressure drives fluid into capillary 20 in 5 Net reabsorption pressure 7 in technically 7 iv Capillaries reabsorb about 85 of filtered fluid These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute II III v Other 15 is absorbed by lymphatic vessels and returned to the circulation vi Edema 1 Capillary filtration capillary reabsorption lymphatic absorption Respiratory System a Alveoli i Squamous alveolar cells ii Shared basement membrane 1 Where O2 must traverse to get from air to blood iii Capillary endothelial cell b What are the factors that affect the rate of diffusion i Temperature ii Surface area greater SA greater diffusion rate iii Partial pressure 1 Substitute for concentration 2 High concentration of O2 on one side versus the other concentration gradient a Greater the difference greater diffusion rate iv Molecule size 1 Bigger harder to move v Diffusion distance vi Solubility 1 O2 versus CO2 solubility CO2 more soluble c Respiration exchange of gases at respiratory membrane d Ventilation movement of air to and from respiratory membrane Ventilation a Only diaphragm is needed for relaxed ventilation b Inhalation inspiration contracted diaphragm c Expiration relaxed diaphragm d Other muscles there for active ventilation e Control of ventilation i VRG ventral respiratory group ii Has reverberating circuits that alternate between stimulating muscular contraction inspiration and allowing relaxation expiration iii Can receive signals that tell it to speed up down iv Inspiratory neurons have spontaneous action potentials 1 Trigger other neurons to cause integrating centers to cause muscle contraction 2 Besides stimulating muscles sends another signal to expiratory neuron that has effect of turning off inspiratory neuron 3 Called reverberating circuit a Why diaphragm contracts and then relaxes v Rate factors DRG dorsal and PRG pontine influence rate of ventilation IV 1 Central chemoreceptors pH a In CNS 2 Peripheral chemoreceptors CO2 O2 3 Stretch receptors Hering Breuer reflex a Prevents over inflation of lung 4 Irritant receptors a Breathe more shallow when irritants present 5 Hypothalamus and motor cortex f Principles of ventilation i How do we breathe ii Boyle s law pressure of given quantity of gas is inversely proportional to its volume iii Greater volume lesser pressure iv Atmospheric pressure outside vs alveolar pressure inside 1 Flow outward is pressure inside pressure outside v How do we increase volume of our lungs 1 Balloons lungs expand when pressure differential 2 When hand pulls down volume increases and pressure decreases pulling balloons open 3 Applied to lungs a Drop pressure around the lungs causes lungs to get larger b Key to inflating lungs is space around the lungs g What connects lungs to thoracic wall i Pleural cavity between parietal and visceral pleura 1 Adhere lungs to thoracic wall ii Visceral pleura covering organ iii Parietal pleura iv Plural membranes enclose pleural cavities and secrete pleural fluid Expiration is easy a Around each alveolus elastic fibers b Unopposed elastic recoil of lungs and thorax produces a positive pressure w in lungs c Ribcage is ridged providing resistance to lungs tendency to collapse Which also prevents inward collapse of lungs i Elastic fibers surrounding alveoli 1 Inward force ii Surface tension w in alveoli 1 Force on inside of alveoli pulls water toward itself 2 Inward force iii Atmospheric air pressure iv Alveolar air pressure 1 Pressure inside alveoli 2 Depends upon plural cavity v Pleural cavity 1 Holds lungs outward