Exam 2

Question 1

Phosphocreatine in the muscle

Answer 1

donates a phosphate group to make ATP quickly

Question 2

Glycogen in the muscle

Answer 2

can generate ATP both aerobically and anaerobically

Question 3

Bucking horses work for, at most 8 seconds. To power this effort for ATP would be synthesized

Answer 3

predominantly anaerobically

Question 4

To facilitate powerful movements such as going over a fence or breaking out of a head horse box or turning a barrel the horse would use

Answer 4

large motor units (large number of muscle fibers controlled by one motor neuron)

Question 5

Lactic acid in the muscle

Answer 5

is the product of anaerobic synthesis if ATP using glycogen

Question 6

There are breed differences in the proportion of Type I, Type IIA, and typer IIX muscle fibers expressed in the gluteal muscles of the horse. The quarter horse is known for its speed and power in the short distance. It would be expected that the quarter horses would have proportionally increased expression of

Answer 6

Type IIX fibers

Question 7

Muscles in the shoulder are important to maintain posture and help hold the neck and head up. Because of this role these muscles have to work for a long time without fatigue. It would be expected that most of the ATP used for theses activities would be derived from the

Answer 7

Aerobic ATP production using fatty acid

Question 8

Horses which suffer from mitochondrial myopathy are unable to move protons from the mitochondrial matrix to the inter-memebrane space (the mitochondria are dysfunctional). A filly with this disorder could not trot for more than 10 min and was unable to exceed 7 m/sec (slow lope). Which best accounts for these symptoms

Answer 8

high lactic acid synthesis since ATP cannot be made anaerobically

Question 9

Mutation of the glycogen synthase 1 gene (GLY1) is one cause of polysaccharide storage myopathy (PSSM). Mutation of this gene causes an increase in muscle glycogen and limits its exercise. What best accounts for theses symptoms

Answer 9

metabolic stress limits exercise since aerobic metabolism of glycogen (pyruvate) is dysfunctional

Question 10

In the first few seconds of any exercise ATP will be synthesized predominantly from

Answer 10

anaerobic pathways

Question 11

Muscle capillary density increases with increasing fitness. This increase in density would facilitate exercise by

Answer 11

increased surface are, increasing oxygen delivery

Question 12

With increased fitness, more ATP will be generated aerobically at any given speed. This will improve performance and delay fatigue because

Answer 12

aerobic pathways spares muscle glycogen

Question 13

With training and increased fitness, the muscle has an increase in aerobic and a decrease in aerobic ATP synthesizing enzymes. This change in enzymes would facilitate exercise by

Answer 13

increasing the capacity of aerobic ATP synthesis

Question 14

With training and increased fitness, number of IIA and IIX muscle fibers increase. This change delays fatigue since

Answer 14

These fibers derive more of their ATP from aerobic (oxidative) pathways

Question 15

Packed cell volume is a measure of RBC content of blood, and increases from resting values of 0.3 to a 0.6 at exercise. This increase in RBC reflects

Answer 15

The increased O2 carrying capacity at exercise

Question 16

Ventilation increases linearly with speed (or effort). This increase in ventilation is accomplished by

Answer 16

increased breath frequency at low speeds and greater tidal volume at high speeds

Question 17

In 2012 I’ll have another raced with a nasal strip, but was intending to run in the Belmont without it-the nasal strip was considered illegal at the Belmont. This nasal strip decreases nasal resistance which accounts for

Answer 17

approx. 50% of the airway resistance

Question 18

In a fit horse at intense exercise, supply of oxygen limits exercise capacity. Venous return blood is more deoxygenated and there is a decreased transit time in the pulmonary system compared to at rest. What causes these limitations

Answer 18

More O2 is consumed and increased pulmonary pressure decreases transit time

Question 19

The increase in VO2 with training is most likely influenced by

Answer 19

increased numbers of mitochondria

Question 20

If a horse had recurrent airway obstruction (RAO) developed from exposure to dusty stables or moldy hay, what would be the exercise limitation

Answer 20

limited gas exchange at the alveoli

Question 21

cross sectional are occupied by capillaries is much greater than that of arteries or veins training increases the number of capillaries which increase exercise capacity by

Answer 21

increased area for gas exchange

Question 22

V4, or the velocity a horse is going when it reaches 4 mmole lactate/ liter of blood, is an important measure of fitness because

Answer 22

V4 is the velocity after which most of the ATP must be synthesized anaerobically

Question 23

At exercise there is an increase in the number of RBC. There is not an additional increase in RBC with training. What is the best explanation for this

Answer 23

A further increase is packed cell volume would increase blood viscosity and pressure

Question 24

With training lung capacity

Answer 24

remains unchanged

Question 25

Horses suffer from mitochondrial myopathy are unable to move protons from the mitcochondrial matrix to the inter-membrane space. A filly with this disorder couldn’t trot for more than 10 min

Answer 25

high lactic acid synthesis since ATP cannot be made aerobically

Question 26

Mutation of the glycogen 1 gene is one cause of PSSM. Mutation of this gene increase in muscle glycogen and limits exercise. What best accounts for this

Answer 26

Metabolic stress limits exercise since aerobic metabolism of glycogen (pyruvate) is dysfunctional

Question 27

V200 is

Answer 27

the velocity at which heart rate is 200 bpm

Question 28

glycogen in the muscle

Answer 28

can be used to generate ATP both aerobically and anaerobically

Question 29

lactate in the muscle

Answer 29

is the ned product of aerobic metabolism of glycogen

Question 30

packed cell volume (RBC) increases in horses at exercise by about 60%. This increase in packed cell volume is from

Answer 30

Adrenaline causes release of RBC from the spleen

Question 31

If a horse has a recurrent airway obstruction (heaves) developed from exposure to air contamination, what would be the consequence

Answer 31

decreased gas exchange at the alveoli