Bio 432 Final Exam Questions with 100% Correct Answers

Bio 432 Final Exam Questions with 100%
Correct Answers
Light at night (LAN) & eating: Correct Answer Increase in ghrelin
Decrease in leptin
Leads to more eating and possible obesity

Experiment with LAN, rats & sugar water: Correct Answer Chronic low light at night
Rats preferred normal water > sugar water

Need ____ to make melatonin Correct Answer Serotonin

Need _____ light to make 5-HT Correct Answer Blue

Blue light = _____ nm Correct Answer 480

Need ____ to make vitamin D Correct Answer UVB

UVB = _____ nm Correct Answer 295

To have a good, healthy sleep, we need 2 things: Correct Answer 1. Exposure to sun
during the day (not artificial light)
2. No exposure to light at night (esp blue light)

Why is LAN bad? Correct Answer Low levels of melatonin released

The study of circadian rhythms is called _____ Correct Answer Chronobiology

Light acts on body via 2 pathways: Correct Answer 1. Optic tract
2. Retinohypothalamic tract

Optic tract: Correct Answer Visual perception

Retinohypothalamic tract: Correct Answer Circadian, endocrine & neurobehaviour
Sensitive to blue light
Both acute & long-term

Light causes a chemical change in _____, which then causes a signal to be sent to
ganglion cells Correct Answer Melanopsin

5 main effects of light dysregulation: Correct Answer 1. Cardiovascular
2. Obesity
3. Depression
4. Insomnia

,5. Cancer (breast, prostate, colon)

Melatonin is secreted by the _____ to initiate sleep Correct Answer Pineal gland

The _____ controls melatonin production Correct Answer Suprachiasmatic nucleus

Suprachiasmatic nucleus: Correct Answer Once exposed to the first light of day, raises
body temp and releases stimulating hormones (ex. cortisol)
Delays release of melatonin until darkness

Melatonin & estrogen relationship: Correct Answer Melatonin is a regulator of ER and
estrogen production

5-HT is a ____ and a _____ Correct Answer NT
Hormone

Most 5-HT is produced in the _____; rest in the ____ Correct Answer Gut
CNS

Serotonin functions: (4) Correct Answer 1. Mood
2. Appetite
3. Memory
4. Sleep

5-HT is derived from _____ Correct Answer Tryptophan

Highest levels of 5-HT are seen during the morning/afternoon/night Correct Answer
Afternoon

5-HT acts as a *local regulator* of ______ Correct Answer Mammary gland epithelium

Vitamin D: Correct Answer Maintains *calcium & phosphorus* blood levels
Imp effects on cell differentiation & development
Metabolite of cholesterol, which is present in the skin when exposed to UVB (then
processed in liver & kidneys)
10% eaten
Structurally related to steroids, so uses a *nuclear receptor*
Signals for *anti-proliferation* (imp for understanding cancer)

_____ is the active form of vitamin D Correct Answer Calcitriol

Receptors of vit D found in 6 places: Correct Answer 1. Bone
2. Kidneys
3. Gut
4. Immune cells
5. Testes

,6. Breasts

Low levels of ____ & _____ associated with breast cancer (BC) Correct Answer
Melatonin
Vit D

Exposure to light is also dependent on ____ & _____ Correct Answer Latitude
Season

Not only does a lack of 5-HT during the day lead to a lack of melatonin at night, but so
does a lack of _____ Correct Answer Vit D

LAN is correlated with _____ & _____ cancer Correct Answer Breast
Prostate

Changes in exposure to light affects biological rhythms. Alters metabolism of 6
hormones: Correct Answer 1. GnRH
2. Estrogen
3. Progesterone
4. Testosterone (DHEA)
5. Vit D
6. Melatonin

Changes in exposure to light affects biological rhythms. Alters micronutrients, including
_____ Correct Answer Iron

Changes in exposure to light affects biological rhythms. Alters NTs including ____ &
____ Correct Answer DA
5-HT

Melatonin synthesis: (3) Correct Answer 1. Tryptophan is made into 5-HT by
*tryptophan-5-hydroxylase*
2. 5-HT is made into N-acetylserotonin by *serotonin-N-acetyltransferase*
3. N-acetylserotonin is made into melatonin

Melatonin can also be called ______ Correct Answer N-acetyl-5-hydroxytryptamine

For melatonin synthesis, what is the rate limiting step? Correct Answer 5-HT being
made into N-acetylserotonin

Vit D is circadian: Correct Answer Short half-life
Peaks after 12 pm (same with 5-HT & body temp)
Secosteroid hormone

*Seco*steroid hormone: Correct Answer "Broken" ring structure
Produced in liver

, _____ drugs reduce BC risk Correct Answer SSRIs

_____ is low in those with seasonal affective disorder (SAD) Correct Answer 5-HT

Synergy between melatonin, 5-HT & vit D: Correct Answer Need UVB to get Vit D
Vit D activates transcription of gene for *tryptophan-5-hydroxylase*
So need Vit D to get 5-HT to get melatonin

Pathway of LAN → BC risk: (6) Correct Answer 1. Lack of UVB
2. Low vit D
3. Low 5-HT
4. Low melatonin at night (esp if LAN)
5. Higher estrogen levels
6. Increased BC risk

5-HT & its role in lactation: Correct Answer Regulates lactation and initiates the
transition into the earliest phases of *involution* (apoptosis at end of menstruation)
Induces another hormone to allow mammary gland to drive the *mobilization of calcium*
from skeleton
*BC cells are resistant to apoptosis*

Progesterone & its role in lactation: Correct Answer If pregnant, high levels for milk
production

Shift work increases/decreases progesterone levels Correct Answer Increases

Melatonin & GnRH: Correct Answer Melatonin acts on GnRH neurons in hypothalamus
Effects GnRH expression & G-coupled melatonin receptors
*Melatonin suppresses GnRH release*

Melatonin suppresses GnRH release: Correct Answer Involves PKC and *extracellular
signal-related kinase 1&2*
Used GT1-7 cell line model

5 approaches to experimentally studying LAN: Correct Answer 1. Shift work
2. Epidemiology in different areas of world
3. Direct evidence that light INH melatonin
4. Animal models
5. Melatonin signalling pathways

BC risk in night-shift workers: Correct Answer Urinary MEL metabolite low in both nights
(working & not working)
Nurses who reported less tolerance to long shifts (ex. depression, insomnia, etc) had
lower melatonin levels
Possibly a genetic predisposition