Anatomy Chapter 22; Part 4

Factors that Increase Release of O2 by Hemoglobin

( Bohr effect ) As cells metabolize glucose and use O2: - *Pco2 and H+ increase in capillary blood* - *Declining blood pH and increasing Pco2* Heat production increases ---> *directly and indirectly decreases Hb affinity for O2* ----> increased oxygen unloading to active tissues

Simultaneous Cortical Motor

*Activation of skeletal muscles and respiratory centers.*

Haldane Effect

*Amount of CO2 transported affected by Po2* - Reduced hemoglobin (less oxygen saturation) forms carbaminohemoglobin and buffers H+ more easily ---> - Lower Po2 and hemoglobin saturation with O2; more CO2 carried in the blood. https://www.youtube.com/watch?v=dHi9ctwDUnc

Psychological Stimuli

*Anticipation of exercise.*

Apnea

*Breathing cessation (ending, being brought to an end) from abnormally low Pco2.*

Hyperventilation

*Increased depth and rate of breathing that exceeds body's need to remove CO2.* - Leads to decreased blood CO2 levels (hypocapnia) - And cerebral vasoconstriction and cerebral ischemia ---> dizziness, fainting.

Hypercapnea

*Increased ventilation (10 to 20 fold) in response to metabolic needs.*

Acclimatization

*Respiratory and hematopoietic adjustments to long-term move to high altitude.* - Chemoreceptors become more responsive to Pco2 when Po2 declines. - Substantial decline in Po2 directly stimulates peripheral chemoreceptors. *Result---minute ventilation increases and stabilizes in few days to 2-3 L/min higher than at sea level.*

Respiratory,

*Rising CO2 levels is the most powerful ________________ stimulant.*

60, Respiration,

*When arterial Po2 falls below ____ mm Hg, it becomes major stimulus for _____________.*(via peripheral chemoreceptors)

Respiratory Adjustments: Exercise

- Adjustments geared to both intensity and duration of exercise - *Hypercapnea* ---> Increased ventilation (10 to 20 fold) in response to metabolic needs - Pco2, Po2, and pH remain surprisingly constant during exercise

Factors Influencing Hemoglobin Saturation

- Increases in temperature, H+, Pco2 - Modify structure of hemoglobin; decrease its affinity for O2 ----> Occur in systemic capillaries ----> *Enhance O2 unloading from blood* ----> Shift O2-hemoglobin dissociation curve to right - *Decreases in these factors shift curve to left* (Decreases oxygen unloading from blood).

3 Neural Factors that Cause an Increase in Ventilation as Exercise Begins

1.) *Psychological Stimuli* 2.) *Simultaneous Cortical Motor* 3.) *Excitatory Impulses* https://www.youtube.com/watch?v=9j6BpanhpKY

Bohr Effect

A decrease in the amount of oxygen associated with hemoglobin and other respiratory compounds in response to a lowered blood pH resulting from an increased concentration of carbon dioxide in the blood..

Increase,

Acclimatization to High Altitude *RBC numbers ____________ slowly to provide long-term compensation.*

Haldane Effect at Tissues

As more CO2 enters blood: - More oxygen dissociates from hemoglobin (Bohr effect) - As HbO2 releases O2, it more readily forms bonds with CO2 to form carbaminohemoglobin

Chloride Shift

Bicarbonate leaving RBCs in place of Cl-

Influence of CO2 on Blood pH

Carbonic acid-bicarbonate buffer system-resists changes in blood pH. - If H+ concentration in blood rises, excess H+ is removed by combining with HCO3- = H2CO3 - If H+ concentration begins to drop, H2CO3 dissociates, releasing H+

Transport and Exchange of CO2 in Pulmonary Capillaries

HCO3- moves into RBCs (while Cl- move out); binds with H+ to form H2CO3 H2CO3 split by carbonic anhydrase into CO2 and water CO2 diffuses into alveoli https://www.youtube.com/watch?v=W7egri8t-iE

Excitatory Impulses

Impulses to respiratory centers from *proprioceptors* in moving muscles, tendons, joints.

Ventilation

Is the movement of a volume of gas into and out of the lungs.

Peripheral Chemoreceptors

Located in aortic and carotid bodies. They are *arterial O2 level sensors.* When excited, cause respiratory centers to increase ventilation

Indirectly,

Normally blood Po2 affects breathing only _______________ by influencing peripheral chemoreceptor sensitivity to changes in Pco2

Influence of Po2 on Hemoglobin Saturation

PO2 heavily influences binding and release of O2 with hemoglobin. - *Oxygen-hemoglobin dissociation curve* - Hemoglobin saturation plotted against Po2 not linear; *S-shaped curve.* https://www.youtube.com/watch?v=StpQmmuVnTA

Respiratory Adjustments: High Altitude

Quick travel to altitudes above 8000 feet (2400 meters) may produce *symptoms of acute mountain sickness* (AMS) - *Headaches, shortness of breath, nausea, and dizziness* - *Atmospheric pressure & PO2 levels are lower.*

Declining Po2 Effect on Ventilation

Slight effect... - *Huge O2 reservoir bound to Hb* - *Requires substantial drop in arterial Po2 (to 60 mm Hg) to stimulate increased ventilation.*

Encourages, Tissues, Lungs,

The *Haldane Effect* ______________ CO2 exchange in ___________ and ________.

Respiration

The exchange of oxygen and carbon dioxide across a membrane either in the lungs or at the cellular level.

Influence of CO2 on Blood pH; *Changes in Respiratory Rate & Depth*

This affects blood pH: - Slow, shallow breathing leads to increased CO2 in blood which results in a drop in pH. - Rapid, deep breathing leads to decreased CO2 in blood resulting in a rise in pH. Changes in ventilation can adjust pH when disturbed by metabolic factors

CO2 Transport

Transported in blood in three forms: 1.) 7 to 10% *dissolved in plasma* 2.) 20% *bound to globin of hemoglobin* 3.) *70% transported as bicarbonate ions (HCO3-) in plasma* https://www.youtube.com/watch?v=W7egri8t-iE