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Equine Final > Physiological Adaptation > Flashcards

Flashcards in Physiological Adaptation Deck (22)
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1
Q

Exercise physiology of the horse encompasses:

A
  • the cardiovascular system
  • the respiratory system
  • the muscular system
  • the neurological system
  • the endocrine system
  • metabolic pathways
2
Q

Why is oxygen uptake of the most importance?

A

Required to harvest energy and produce work

3
Q

List the channels of heat transfer

A
  • infrared thermal radiation from vegetation
  • sunlight (direct & reflected)
  • infrared thermal radiation from atmosphere
  • wind
  • evaporation
  • thermal radiation
  • infrared thermal radiation from ground
4
Q

Factors affecting heat exchange

A

Conduction, convection, radiation, evaporation

5
Q

What is conduction

A

two things beside each other exchanging heat

6
Q

What is convection

A

how heat is dissipated

- wind may increase this by increasing movement of air from animal

7
Q

What is radiation

A

Controlled by surface-environment exchange

Different levels of heat:

  • inside vs. outside
  • concrete (cooler) vs. brick/rubber
  • straw (warmer) vs. shavings
8
Q

What is evaporation

A

vapor pressure gradient is the major controlling mechanism

- hair can help dissipate heat or keep heat in

9
Q

What is the LCT?

A
lowest temp (-15) when a horse has to up regulate energy expenditure in order to maintain body heat
- when wet --> LCT is decreased  (feels colder at warmer temperatures)
10
Q

What is UCT?

A

highest temp (+15) when horse must use energy to dissipate energy (e.g. sweat, seek cover)

11
Q

What mechanisms are used to change body temperature

A
  • postural (turn butt to wind, huddle, seek shelter/shade/water)
  • vasoconstriction/vasodilation
  • piloerection (raise hairs = winter coat –> provides air barrier)
  • behavioural adjustments (walk/eat)
  • shivering (muscular movements to generate heat)
  • feed intake to change heat increment of feeding/fermentation (more heat when fermenting hay in cecum/colon)
12
Q

Which is more adaptable, LCT or UCT

A

LCT

  • lowering LCT = horse feels colder at same temperature
  • increased win, rain, cloud cover = increased energy requirement
13
Q

Factors affecting LCT include:

A

Insulation

  • body size
  • hair thickness
  • fat
  • posture

Regulating metabolic rate

  • age is inversely related
  • feed/fiber intake
  • thyroid status
  • pregnancy/lactation

Prior thermal history
- insulate capacity changes (individual variability)

Wind speed
- lowers LCT

Rain
- lowers LCT

Cloud cover

  • lowers LCT
  • sun –> thermoregulation
14
Q

What guidelines should be taken for cold weather?

A
  1. growing horses have higher LCT than mature horses and need additional DE
    - ~1.3% addition for each degree drop in lCT in young horses (~2.5% in mature horses) - doesn’t count for foals
  2. provide heated water (2-10 degrees C)
    - to maximize consumption
  3. Well bedded run in with sufficient room for all horses, facing south or east
    - horses should all be able to lie in recumbent position)
  4. if transporting, horses need to be protected from wind chill (especially foals)
15
Q

What guidelines should be taken for hot and humid weather?

A
  1. water and salt must always be provided
  2. shelter from radiant sun
  3. ventilation will help to facilitate maintenance of BT through evaporative cooling
  4. no blankets/hoods
  5. if possible, avoid periods of the day where there is a lot of sunlight (whether riding and certainly for transport)
16
Q

To make ATP, nutrients need to be oxidized, therefore, the increased energy demand of exercise demands:

A
  • myoglobin has greater affinity for oxygen than Hb –> facilitating its movement into muscle
  • increased oxygen consumption which is accompanied by an increase in lung volume and respiratory rate
  • increased circulation/blood pressure which is accompanied by increase in heart rate and stroke volume
  • increased oxygen carrying capacity which is accompanied by an increase in RBC due to spleen concentration and increased generation of RBC during exercise
  • increase in oxygen saturation of Hb (increases the release of oxygen to tissues) –> further mediated by lactate production, increased p CO2 and increased temperature which decreases pH, increases oxygen dissociation which facilitates oxygen release
17
Q

Storage energy used during exercise

A

Muscle + ADIPOSE –> triglyceride
MUSCLE and Liver –> glycogen
- aerobic exercise

18
Q

Describe Type I muscle fibers

A
  • slow twitch
  • high oxidative capacity
  • intermediate glycolytic capacity
  • high lipid content
  • intermediate glycogen content
  • low fatigability
19
Q

Describe type IIa muscle fibers

A
  • fast twitch
  • high oxidative capacity
  • high glycolytic capacity
  • intermediate lipid content
  • high glycogen content
  • intermediate fatiguability
20
Q

Describe type IIb muscle fibers

A
  • fast twitch
  • high oxidative capacity
  • high glycolytic capacity
  • low lipid content
  • high glycogen content
  • high fatiguability
21
Q

Explain the role of the spleen in the horse and how it satisfies exercise demands

A

The spleen stores RBC

  • During exercise increased RBC’s are produced
  • When the spleen contracts it releases RBCs –> increases oxygen carrying capacity
22
Q

How does digestible energy relate to the feedstuff fed?

A
  • foods with a higher GI (corn) will have a faster and higher DE compared to low GI feed (hay)
  • Low glycemic index feed will have a more sustained digestible energy