Environmental Factors Flashcards
The TMZ is bound by what two limits?
The lower and upper critical temperature.
Why is the TMZ for rodents so narrow?
Large body surface to volume ratio and meager body insulation.
Why are mice particularly prone to cold stress?
Increased surface area to mass.
What temperature of cage do mice prefer when inactive and active?
Warmer cage when inactive, no preference when active.
What amount of nesting material improves energy balance?
12 grams of nesting material
What is phototransduction?
Information from the eyes is transmitted via the non-visual retinohypothalamic tract to the suprachiasmatic nuclei. SCN is master biologic clock in hypothalamus and signals pineal gland to regulate melatonin production
Does light above 550-600 nm disrupt circadian rhythm?
Previously though not, but nonvisual neural pathway of retinohypothalamic tract relies on the intrinsically sensitive retinal ganglion cells.
What is the recommended light levels in rodent housing rooms? What are these levels based on?
130-325 lux (30 ft candles) at cage level. Measured in center of room 1 meter off the floor. Levels based on light intensity known to cause phototoxic retinopathy in albino rats.
What wavelengths are the strongest inciters of neuroendocrine and circadian responses?
450-484 (blue light)
What is the impact of the switch from incandescent to fluorescent lighting?
Has an enriched blue light spectrum. Increase in peak melatonin in dark phase with positive effect on wellbeing.
Which mice do not produce melatonin?
C57 and BALB/c mice.
What condition is associated with immobilizing restraint in mice?
Severe bradyarrhythmias. Characterized with ventral neck fold and forelimbs abducted dorsally.
What type of noise is more concerning for rodents?
Sudden loud noise, especially at high frequencies, instead of low background noise
What are known effects of vibration?
Decreased breeding efficiency, decreased food and water intake, and behavior changes.
Define resonance frequency range.
Range of frequencies at which an object most readily vibrates and the range over which an animal may sense, respond to, and suffer adverse effects from vibration.
Mice: 30-110 Hz at 0.3-1 m/s2
