Chronobiology - Lecture 7 Flashcards
1
Q
Chronobiology
A
Study of timescales and cycles in biology (Natural physiological rythmes)
2
Q
Ultradian
A
- Less than 24h
- ex. Appetite (ghrelin and cortisol)
3
Q
Circadian
A
- 24 hours
- Controlled by peripheral “clocks” that are governed by a “central clock”
- Coordinate sleep, nutrient supply and activity patterns required at different stages of the day
- ex. Cortisol
4
Q
Infradian
A
- More than 24h
- ex. Menstrual cycle
5
Q
Disruption of Circadian Rythms
A
- Shift workers (heart attacks, obesity, cancer, Alzheimer’s)
- Late chronotypes (Suffer from mental stress and to smoke)
- Daylight Savings Time (incidence of heart attack proven to be increased)
6
Q
The Central “Clock” of Circadian Rythms
A
Suprachiasmatic Nucleus (SCN) which keeps time based on signals from the retina
7
Q
Peripheral “Clock”
A
Every cell in the body has a peripheral clock that coordinates its metabolism with the rest of the body
8
Q
Controlling of Molecular Clock
A
- Light/Dark cycles (even blind individuals)
- Chemical signals involved are not clear; involves Melatonin
9
Q
Melatonin
A
Hormone produced by pineal gland
(Blue spectrum light inhibits melatonin release)
10
Q
Height Biomarker - Osteoporosis development
A
- 2 cm variation in height throughout day
- most effect of compression occurs in the first hour of getting out of bed
11
Q
How to Maximize Bone Density
A
- Consumer sufficient calcium and vitamin D
- Participate in weight baring physical activity/exercise most days of the week
- maintain a stable body mass that is not too thin
- get sleep
12
Q
Age Related loss of bone density
A
- Peak bone density between 20 and 30
- +1.0T is healthy
- -2.5 or lower is when osteoporosis is diagnosed
13
Q
DEXA to determine bone mineral density
A
- amount of calcium in hip and spine
- non invasive
- T-score
- estimates the amount of x-ray absorbing dense material, hydroxyapetiite, that is packed in the extracellular space of the bone
