Respiration Physiology External Respiration vs Internal Respiration exchange

Respiration Physiology

External Respiration vs. Internal Respiration �exchange of O 2/CO 2 btwn. fluids & environment (organ level) vs. btwn cells (cellular level)

Four major Steps of Respiration 1. Pulmonary Ventilation (breathing) air into & out of lungs 2. Gas Diffusion Across Respiratory Membrane from alveolar to alveolar capillaries 3. Storage and Transport of O 2/ CO 2 from alveolar caps to caps in tissues 4. Exchange of O 2/ CO 2 btwn blood and tissues

�The last two will be referred to as Gas pickup & delivery. �If any of these steps is affected hypoxia occurs ( tissues are starved of O 2) �If O 2 is completely shut off anoxia

Hypoxia

Boyle’s Law-

Pulmonary Ventilation air into and out of aveoli (continual supply of O 2 prevents build up of CO 2) �Boyle’s Law inverse relationship btwn volume & pressure of a gas. As one increases, the other decreases. �Inhalation/expiration changes the size of the lungs which changes the pressure

�Pressure gradients move air into & out from hi to low �Pleural cavity / fluid slide easily side to side but creates a suction when you try to separate Ex. wet glass on table �Surface of each lung sticks to wall of chest and top of diaphragm

�This fluid bond is actually what keeps lungs inflated! �Vol. of thoracic cavity changes when diaphragm or ribs move �When diaphragm is relaxed, it curves upward in a dome shape, when it contracts, it moves downward and increases the volume of cavity. Pg. 453 Fig. 16. 2

�Inhalation = ribs elevate, diaphragm contracts, size of cage increases, pressure decreases & air goes into the lungs. �The opposite occurs upon Exhalation = rib cage gets smaller, volume decrease, pressure increases, & air moves out of lungs.

Respiratory Cycle = 1 single inhalation & exhalation �Tidal volume = amt. of air into & out of lungs in a single respiration; avg. 500 ml --- but only 350 ml. enters aveoli; the other 150 ml. keep alveoli inflated. �Collapsed lung = when pleural fluid bond is broken

�Respiratory Muscles internal and external intercostals ( ribs) 25% of work diaphragm 75 % of work

�Mouth to mouth after each breath, contact is broken to permit passive exhalation, meets temporary O 2 demands of cells. �CPR cardiopulmonary resusitation �Pregnant women rely on costal breathing b/c diaphragm can’t move a lot

�Respiration rate = # of breaths per minute; avg. adult = 12 -18 � Air in alveoli always contains less O 2 and more CO 2 than outside air. This ensures that O 2 is constantly flowing INTO the aveoli.

Respiratory volumes �Resting tidal volume = amt. of air into/out of lungs during a quiet resp. cycle �Expiratory Reserve Vol. = amt. of air that COULD BE voluntarily expelled; 1000 ml! �Residual vol. = amt. left after maximum exhalation

�Inspiratory Reserve Vol. = amt. that can be taken in over & above the tidal vol. �Total Lung capacity = ( ER + TV + IR) + RV; 6 L in males; 4. 2 L in females �Spirometer = used to measure lung volumes �Wheezing = air whistling thru.

Henry’s Law

Gas exchange @ Resp. Membrane � � � Henry’s Law = gas molecules go from liquid into air easily ex. open can of soda Decompression sickness = decrease in pressure causes N 2 to come out of soln. & collect in joints; ex scuba divers Diffusion is efficient b/c -Difference in partial pressures is great - the greater the gradient, the faster the diffusion - if the pressure of O 2 decreases, that the diffusion into the blood decreases which makes people light headed @ altitudes of 3000 m or more. Fig. 16. 21 pg. 462 As blood goes from heart to lungs, there is more CO 2 than O 2; picks up O 2 and drops off CO 2 Goes to heart to get pumped systemically Goes to cells where O 2 is low and CO 2 is high; both are exchanged

BOHR Shift �O 2 transport �Hb saturation 1 heme can hold 4 O 2 �normally, heme is 50% saturated; only holds 2

Gas Pickup and Delivery �CO poisioning CO competes with O 2 for binding sites; CO usually wins b/c it has a higher affinity (liking) for Hb * treatments = breathe pure O 2 or transfuse RBC’s

Hb/p. H THE BOHR SHIFT pg. 463 �when p. H drops to 7. 2, Hb molecules change shape and release O 2 (lose affinity) � CO 2 combines with the water in the blood to make carbonic acid �H+ ionizes and lowers the p. H

�Hb and temp. as temp. increases, Hb releases more O 2, and vice versa; �ensures that skeletal muscles generating heat get the O 2 they need

�Fetal Hb has a much higher affinity for O 2 than adult Hb; ensures that fetus gets O 2 across placenta �CO 2 transport opposite reaction of BOHR SHIFT occurs; as p. H increases, heme gains affinity for O 2