Respiratory System II Gas Exchange in the Lungs Control of Breathing Defense and Interesting Stuff

Blood and Respiratory System each blood cell contains 280 million hemoglobin molecules  each of those can carry four oxygen molecules a single cell can carry ~ one billion molecules of oxygen the chemical combination of oxygen and hemoglobin is loose and reversible

Alveoli a network of capillaries surrounds each alveolus – capillary and alveolus each is only one cell thick alveoli are small but very numerous (several hundred million) surface area is 100 m2 – the size of a tennis court gases dissolve in warm, moist, mucus lining (In contrast, the surface area of the body is 2 m2.)

DIFFUSION – the movement of molecules from an area of high concentration to one of lower concentration Image from: http://upload.wikimedia.org/wikipedia/commons/f/f9/Blausen_0315_Diffusion.png

AIR air is nearly 80% nitrogen – we can’t use this and it is exhaled ~20% is oxygen – much higher concentration in air than in blood carbon dioxide is at a higher concentration in blood than in air (due to cellular respiration) differences in concentration cause diffusion across alveoli in both cases http://www.ccmtutorials.com/rs/oxygen/page03.htm Normal blood oxygen levels in humans are considered 95-100 % Image from: http://www.woolsnz.com/_resx/assets/en-US/benefits/assets/4-2-CleanAir8248175istock.jpg

Image from: http://3. bp. blogspot

CO2 and O2 recall: CO2 is mostly transported as carbonic acid, which dissociates into bicarbonate ions and hydrogen ions in the capillaries of the lungs, the bicarbonate and hydrogen ions combine to reform carbon dioxide, which diffuses into the alveoli  EXHALE O2 from air diffuses into alveoli  INHALE where it is picked up by RBCs (hemoglobin)

Image from: http://4. bp. blogspot

Overview of diffusion oxygen diffuses across the membrane of the alveolus from air ____________into the RBC ___________ carbon dioxide diffuses from the plasma ____________to the alveolus ____________

HEALTHY SMOKER Image from: http://2.bp.blogspot.com/-pUzDwO8UN-g/UBi2joUxLjI/AAAAAAAAB-4/IZMvxvyypNQ/s1600/Tips+To+Clean+The+Lungs+Of+Smokers+%282%29.jpg

Consequences? Above: bacteria allowed to colonize alveoli Image from: http://hyperphysics.phy-astr.gsu.edu/hbase/imgmec/alveoli.gif Image from: https://www.biofilm.montana.edu/files/CBE/images/Alveoli_B_11-04.preview.jpg Above: bacteria allowed to colonize alveoli Right: emphysema Consequences? Image from: http://upload.wikimedia.org/wikipedia/commons/a/ac/Centrilobular_emphysema_865_lores.jpg

and Control of Breathing Homeostasis and Control of Breathing Image from: http://brainmadesimple.com/uploads/7/8/8/5/7885523/1801071.jpg?269

Homeostasis Recall: homeostasis is the maintenance of a balanced internal environment ability of the body to maintain levels of CO2 and O2 breathing movements are controlled by muscles, not by lungs muscles are stimulated by nerve impulses from the brain nervous feedback from the muscles to the brain tells it that inspiration or expiration has occurred

Negative feedback mechanism the muscles contract because of the nerve impulses, and stop contracting when the nervous system detects the contraction motor neurons of the respiratory centre of the brain (medulla oblongata) carry impulses to the respiratory muscles (diaphragm and intercostals), causing contractions sensory neurons carry impulses from the respiratory muscles to the medulla, shutting off motor impulses, and stopping the contractions  is a repeating cycle [Positive feedback is more rare – in those cases, the phenomena will build as the signal loops (e.g. ovulation – the signal builds until the follicle bursts).]

chemoreceptors in the aorta and carotid arteries medulla oblongata chemoreceptors in the aorta and carotid arteries diaphragm and intercostal muscles contract blood pH decreases breathing rate increases and CO2 released blood pH returns to normal EXERCISE

Control of Breathing Rate usually, breathing movements supply enough O2 as rapidly as required, and remove enough CO2 at the same time occasionally, CO2 can accumulate and O2 may be needed in greater supply (often these events are simultaneous) either condition can increase the rate and/or depth of breathing

the body is more sensitive to increased CO2 breathing rate is controlled by medulla oblongata, which monitors blood CO2 O2 is monitored by sensory cells in the aorta and common carotid arteries change in breathing hastens the removal of CO2 and brings in more O2 CO2 causes the formation of carbonic acid in the blood increased H+ ions cause pH to decrease. the change in pH is detected, not the actual CO2 levels CO2 +H2O  H2CO3 H2CO3  H+ + CO3–

Defense Mechanisms AND OTHER COOL STUFF

Effects of Elevation on Breathing higher elevations have less oxygen in the air you must breathe faster and deeper in the mountains people who live there have more alveoli and blood vessels in the lungs, as well as a higher red blood cell count (70% vs. 45-50%)  acclimatization

Image from: http://shelledy. mesa. k12. co

Coughing a reflex action in response to irritation of the throat, trachea, lungs, or pleural membrane rapid contraction of the chest, causing rapid intake of air epiglottis closes as the chest relaxes – a build up of pressure occurs epiglottis suddenly opens and the air blows out, taking harmful particles with it

Sneezing sudden expulsion of air through the nose air is taken in normally the soft palate closes off the mouth air is forced out the nose carrying particles during a sneeze, the heart stops momentarily

Hiccoughing result of stimulation of the vagus nerve impulse is relayed from the spinal cord to the diaphragm causes an involuntary spasm of all or a part of the diaphragm sudden closing of the epiglottis makes the sound

Yawning and Snoring Yawning: combination of psychological and physical reactions, resulting in an involuntary stretching of the mouth and a large intake of air air is exhaled as the mouth closes result of decrease in breathing rate (oxygen) due to tiredness, boredom, or drug action Snoring vibrations of the soft palate during sleep