Enogenous Pacemakers (CR)

Question 1

What is the primary function of the SCN (suprachiasmatic nucleus)?

Answer 1

Regulates the internal body clock

The SCN sends signals to the pineal gland to influence melatonin production and is sensitive to light.

Question 2

What did Ralph et al. discover about genetically abnormal hamsters and their SCN?

Answer 2

Their circadian rhythms were shortened to 20 hours

This study showed that the SCN is pivotal in regulating the internal body clock.

Question 3

What happens to the circadian rhythms when the SCN is removed from normal hamsters?

Answer 3

The rhythms disappear

Morgan’s research indicated that transplanting SCN cells back restored the rhythms.

Question 4

What is considered one of the best indicators of the circadian rhythm?

Answer 4

Core body temperature

Core body temperature is a reliable measure for assessing circadian rhythms.

Question 5

Fill in the blank: Endogenous _______ are factors inside and outside the body that influence rhythms.

Answer 5

pacemakers

Endogenous pacemakers can function without environmental cues but may vary as a consequence.

Question 6

Where is the SCN located in the brain?

Answer 6

Hypothalamus

The SCN acts as the master clock, communicating with other brain regions to control sleep and arousal.

Question 7

What role does light play in melatonin production?

Answer 7

Inhibits melatonin production

Blue light exposure is particularly effective in reducing melatonin secretion.

Question 8

True or False: Circadian rhythms can become out of sync with each other.

Answer 8

True

Research by Folkard showed rhythms can differ under controlled environments.

Question 9

What was the outcome of Folkard’s study on university students in a controlled environment?

Answer 9

Core body temperature rhythms remained 24 hours, but sleep-wake cycles extended to 30 hours

This indicated that environmental cues significantly affect sleep-wake cycles.

Question 10

Fill in the blank: The SCN regulates the manufacture and secretion of _______.

Answer 10

melatonin

Melatonin is crucial for sleep regulation and is influenced by light exposure.

Question 11

What are external factors that can influence circadian rhythms?

Answer 11

Light, social cues, and environmental changes

These factors can affect the timing and synchronization of internal biological clocks.