Chronicboilogy Flashcards
Biological rhythms
Ulradian (less than 24h) -appetite
Circadian (24h) -cortisol
Infradian (more than 24h) - menstrual cycle
Chronobiology is the study of
Timescales and cycles in bio
Height charts over years alert them of possible osteoporosis development and increased risk of bone fracture
Loss of 2cm or more in one year
Height changes throughout the day
1.5 cm variation in height due to compression and expansion of disk of spinal column
Change in height as a bio marker of osteoporosis
Varies durning day time of measurement needs to be standard
Measure over time
Doesn’t change much during disease process
Doesn’t directly precede or predict the disease state
DEXA to determine BMD
Done on lower spine and hip
Normal t score 0
Below -2.5 is osteoporosis
Normal bone vs osteoporotic bone
Changes occur in both tubercular and cortical bone
Bone diminishes
Peak bone mass
Increase density between age 20-30
Age and gender is factor of density lost women are less then males (menopause)
Maximize bone density
Consume calcium through teen to early adulthood
Vitamin d
Weight bearing exercise
Minimize bone density Smoking alcohol caffeine Coke Drugs corticosteroids High po4
Bones serve as a functional calcium store in the body
Acts as a buffer for plasma calcium levels
Plasma calcium must be maintained over narrow range
Cell signalling and generation of actions potential
pTH - prevents a decrease in plasma calcium
Calcitonin prevents an increase in plasma calcium
Sure
Circadian rhythms
Involve physiological process
Controlled by peripheral clock governed by a master clock
Control gene expression of enzymes proteins that affect metabolic processes
Disruption in experimental animals causes spectrum of health probs Metabolic syndrome Obesity Gastrointestinal function Elevated inflammatory cytokines
The master clock in a region called the suprachiasmatic nucleus keeps time based on light signals from retina even works in blinded ppl
Nearly every cell in body has subsidiary clock which coordinates it’s metabolism with the rest of the body
Controlling clock
Entrained by light /dark cycles
Chemical signals involved not clear (melatonin is somehow involved)
Blue spectrum light inhibit melatonin release
Shift workers tend to experience a greater incidence of
Heart attacks
Obesity diabetes cardio complications
Cancer
Alzheimer’s
Late chronotypes
More likely to suffer from mental stress and to smoke
Circadium rhythms to human health
Glucose tolerance greater in morning in normal weight ppl
Greater insulin release greater sensitivity
No rhythm in overweight ppl
Eat biggest meal in morning
