Chapter 11 - exam 2

Question 1

H+ production depends on what three things

Answer 1

1. exercise intensity
2. amount of muscle mass involved (need more E and higher H+)
3. duration of exercise

Question 2

what pH declines more dramaticlaly than blood pH

Answer 2

muscle pH – b/c source of H+ production

Question 3

What are the sources of hydrogen ions in skeletal muscle

Answer 3

1. aerobic metabolism of glucose –> carbonic acid –>
2. anaerobic metabolism (glycolysis) of glucose –> lactate
3. ATP breakdown and release of H+ ions

hydrogen ions (H+) increase

Question 5

What are the three sources of H+ ions during exercise

Answer 5

1. production of carbon dioxide
2. production of lactic acid
3. ATP breakdown

Question 6

Explain how CO2 adds to H+ ion production during exercise

Answer 6

Because it is the end product of oxidative phosphorylation

CO2 + H2O <-> H2CO3 <-> H+ + CO3-

Question 7

How does the production of lactic acid add to the amount of H+

Answer 7

due to glucose metaoblism via glycolysis

lactic acid <-> lactate + H+
* dissociate = extra H+ ions = number of H+ ions is relatively low

Question 8

How does ATP breakdown result in more H+ during exercise

Answer 8

release of H+

• ATP + H2O <-> ADP + HPO4- + H+

Question 9

How does high [H+] impair performance (2 ways)

Answer 9

1. inhibits enzymes in aerobic and anaerobic ATP production
2. [H+] impair muscle contraction by competing w/ Ca2+ for binding sites on troponin

• w/o Ca2+ binding no contraction/force production
• H+ can also bind to hemoglobin – effect distribution/availability of O2

Question 10

the binding of H+ to hemoglobin causes what

Answer 10

confirmation change of hemoglobin when bind to H+ that causes offloading of O2

Question 11

What are the effects of graded exercise on arterial concentrations of bicarb, lactate, and pH

Answer 11

bicarb: decreases w/ graded exercise
lactate: increases w/ graded exercise (more conversion from lactic acid –> lactate + H+
pH: decreases w/ graded exercise (H+ is increasing = more acidic)

Question 12

what is the acid-base balance maintained by

Answer 12

maintained by buffers
* release H+ ions when pH is high
* accept H+ ions when pH is low

Question 13

What are the lines of defense against pH change during intense exercise

Answer 13

1. cellular buffer systems: primary b/c its the source of H+ formation
2. blood buffer systems

Question 14

What are the four types of defense from cellular buffering systems

Answer 14

1. bicarbonate (convert strong acid to weak acid)
2. phosphates
3. proteins
4. carnosine

3 + 4 = accept H+ and able to get rid of H+ in blood

Question 15

How do hydrogen ions transport in skeletal muscle

Answer 15

use the

1. NHE (Na+ in and H+ out)
2. MCT (Lactate out and H+ out)

Question 16

What type of muscle have a higher buffering capacity

Answer 16

type 2 muscle fibers have a higher buffering capacity than slow type 1 muscle fibers

• b/c high intensity = improve muscle buffering due to higher carnosine and H+ ion transporters in trained muscle fibers

Question 17

What type of training improves muscle buffering capacity…why?

Answer 17

high intensity exercise training improves muscle buffering capacity due to increase in carnosine and H+ ion transporters in trained muscle fibers

• upregulate transporters that move H+ out of muscle = trained better than untrained

Question 18

What is the second line of defense to change in pH and what are the factors that effect it

Answer 18

blood buffering system (get H+ from inside muscle) –>

respiratory compensation for metabolic acidosis (as produce high CO2 use bicarb to help buffer) –>

• bicarbonate = major % of buffering blood
• phosphates – accept H+
• proteins – accept H+

Question 19

What are the two factors of regulation of acid-base balance during exercise

Answer 19

1. bicarb buffering system
2. when pH decreases –> [H+] increases

• reaction moves to the left
• CO2 is “removed” by the lungs, eliminating H+ and increasing pH –> push rxn other way

Question 20

Elevated CO2 levels push the equilibrium equation to the ________ creating more ________ and a ________ blood pH

Answer 20

right, H+, lower

Question 21

as the blood pH decreases what happens to the respiratory system

Answer 21

low pH –> more acidic –> respiratory system activated –> ventilation increases

Question 22

What is the ventilatory threshold caused by (2 things)

Answer 22

1. increaseing blood PCO2 and H+
2. increases in blood K+, rising body temp, elevated blood catecholamines, and neural influences

Question 23

Patients with McArdle’s disease indicates what w/ LT vs VT

Answer 23

they dont have LT b/c they cannot produce lactate but still have a VT becuase H+ comes from CO2 production during graded exercise

Question 24

Explain how arterial PO2, PCO2, and pH and ventilation is effected with grade exercise in untrained subjects

Answer 24

arterial PO2= remains unchanged
arterial PCO2 = unchanged until almost VO2max when ventilation increases rapidly (b/c exhaling more CO2)
arterial pH = unchanged until almost VO2 max when ventilation increases rapidly = more H+
Ventilation = linear increase up to 50-75% VO2max –> exponential rise

Question 25

how does venous PO2 decrease during graded exercise

Answer 25

• deliver more O2 to tissue b/c gradient is larger at higher intensity
• decrease in muscle pH = allow more O2 to be deliered

Question 26

why does arterial PCO2 decrease at max ventilation during graded exercise

Answer 26

hit respiratory limit = hyperventilate == and increase CO2 output

Question 26

what is the precursor for carnacine

Answer 26

beta alanine

Question 27

What are th two ways there is regulation of acid-base via the kidneys

Answer 27

1. kidneys are important in long-term acid base balance – regulate pH but very slow in buffering (best at rest) –bloodflow cut off b/c not essential
2. kidneys contribute to acid-base balance (at rest) by regulating blood bicarb concentration

Question 28

hwo do the kidneys balance acid-base by regulating the blood bicarb concentration

Answer 28

• when blood pH decreases (high H+) bicarb excretion is reduced
• When blood pH increases (low H+) bicarb excretion is increased

Question 29

what are the 3 ways that lactate is removed following exercise

Answer 29

1. 70% of lactic acid is oxidized - used as substrate by heart and skeletal muscle
2. 20% converted to glucose (via Cori cycle)
3. 10% converted to Amino acids

Question 30

Lactic acid is removed more rapidly with what and why

Answer 30

light exercise in recovery

• optimal intensity of recovery exercise = 30-40% Vo2 max
• bloodflow increases to the area of need = liver –> clearing lactate