EXSC 329 Blood Transport, Capillary Diffusion, and Regulation

What does hemoglobin binding depend on?

blood PO2 and the affinity between hemoglobin and O2

What can shift the oxyhemoglobin curve and in what direction?

pH: decrease shifts curve to the right

temperature: increase shifts curve to the right

How does exercise benefit hemoglobin loading and unloading? What mechanism causes this?

more O2 is unloaded at a given PO2 at the tissues, increasing O2 loading at the lungs

increased acidity due to H+ accumulation and higher core body temperature during exercise

What is O2 carrying capacity? What does it depend on?

the maximal amount of O2 the blood can transport

hemoglobin concentration

How does anemia, blood doping, and dehydration have an effect on O2 carrying capacity?

anemia → less RBC lowers carrying capacity

blood doping → more RBC increases carrying capacity

dehydration → higher % of hematocrit can increase carrying capacity

How can O2 content of the blood be calculated?

ContentO2 = [Hb](g/dL of blood) O2 capacity of Hb (mL/g) % saturation

In what three ways can CO2 be transported through the body? What percentage is each?

as bicarbonate ions 60-70%

bound to hemoglobin 20-30%

dissolved in blood plasma 7-10%

How does CO2 become bicarbonate?

increasing CO2 levels also increases the PCO2 in tissues, speeding up the reaction that produces bicarbonate and H+ ions, where bicarbonate is dissolves into the plasma and H+ binds to Hb

How is CO2 released from the lungs?

by recombining with H+ to form CO2 that can be exhaled from the lungs

CO2 binding with Hb creates ___?

carbaminohemoglobin

What determines CO2 binding to Hb?

blood PCO2 and the affinity between Hb and CO2

Which effects occur at the tissues and lungs to determine O2 and CO2 transport?

at tissues → Bohr effect increases O2 delivery and number of CO2 and H+

at lungs → Haldane effect increases O2 delivery and CO2 removal at the lungs

What is the a-vO2 difference?

the difference in O2 content between arterial and venous blood

What can be assumed about O2 use based on the a-vO2 difference?

the amount of O2 taken up at the tissues

At rest, what would O2 content at the lungs be in a normal healthy adult? a-vO2 difference? % saturation used?

O2 content at the lungs: 20 mL O2/dL of blood

a-vO2 difference: 4-5 mL O2/dL of blood

% saturation: about 25% used at the tissues

During exercise, what would O2 content at the lungs be in a normal healthy adult? a-vO2 difference? % saturation used?

O2 content at the lungs: 20 mL O2/dL of blood

a-vO2 difference: 10-15 mL O2/dL of blood

% saturation: about 65% used at the tissues

What factors impact O2 delivery and uptake?

oxygen content of blood

blood flow

pH

temperature

What involuntary centers are responsible for regulation of pulmonary ventilation?

the medulla oblongata and the pons

Where are the VRG, DRG, and PRGs located?

medulla: VRG and DRG

pons: PRG

What centers determine respiratory rate at rest?

regular stimulation from DRG to inspiratory muscles

What centers determine respiratory rate during exercise?

regular stimulation from DRG to inspiratory muscles AND VRG to expiratory muscles

How does the PRG determine respiratory rate?

pneumotaxic: inhibits the DRG, slowing respiratory rate

apneustic: stimulates the DRG, increasing respiratory rate

What can cortex control do for respiratory rate?

override involuntary mechanisms to allow voluntary control of breathing

How do chemoreceptors determine rate and depth of breathing?

central chemoreceptors in the medulla respond to changes in H+ and PCO2, while peripheral chemoreceptors in the aortic arch and common carotids respond to changes in PO2 levels

What blood characteristics are primarily responsible for rate and depth of breathing?

PCO2 and pH of blood

What is the Hering-Breuer reflex?

when stretch receptors in the lungs protect against over-inflation by restricting duration of breath

What is true of afferent feedback from exercising limbs and ventilation?

greater frequency of limb movement can stimulate an increasing in ventilation during exercise

Emotional distress and abrupt changes in temperature can impact respiratory rate and depth? T/F

true