Module 9.1

When studying disruptions to the biological clock in animals, what did Curt Richter find?

The biological clock is insensitive to most forms of interference.

What happens if people are put in an environment that is constantly light?

They complain that they cannot sleep.

What happens if people are put in an environment that is constantly dark?

They complain that they have difficulty waking up.

When traveling across time zones, adjustments are easier when traveling which direction?

Travel to the west is easier.

The PER and TIM proteins accumulate during the day until they cause sleepiness. What prevents them from continuing to accumulate at night?

When the proteins reach a high level, they turn off the genes that produce them.

When do the secretions of melatonin begin?

a couple of hours before a person naturally falls asleep

If you wanted to go to sleep at 11 pm, the best time to take melatonin would be:

about 9 pm.

If a migratory bird is kept in a laboratory room with constant temperature and 12 hours of light each day, when does it show migratory restlessness?

at approximately the correct time of year for migration

The proteins PER and TIM, originally discovered in insect but now found in mammals also, influence circadian rhythms by:

building up during the day and declining during sleep.

If suprachiasmatic nucleus neurons are disconnected from the rest of the brain, they:

continue to produce activity that follows a circadian rhythm.

Circadian cycles are to ____ as circannual cycles are to ____.

daily; yearly

A "zeitgeber" is a(n):

environmental cue that resets a biological clock.

What does "endogenous" mean?

generated from within

The suprachiasmatic nucleus is found in the:

hypothalamus.

A disruption of circadian rhythms due to crossing time zones is known as:

jetlag

Based on research, it has been determined that the human circadian rhythm appears to be:

just over 24 hours.

Which of the following would most likely help someone adjust to jet lag?

keeping the room light when you need to stay awake

What is the principal zeitgeber for land animals?

light

The retinohypothalamic path to the SCN comes from a special population of retinal ganglion cells that have their own photopigment, called:

melanopsin.

A human's body temperature over the course of 24 hours is usually highest:

mid to late afternoon.

The SCN is located just above the:

optic chiasm.

The SCN produces circadian rhythms by altering:

production of proteins.

Suppose you fell into a cave and lost your watch. Without any time cues, your circadian rhythm would:

remain relatively stable.

A small branch of the optic nerve, known as the ____ extends directly from the retina to the SCN.

retinohypothalamic path

After damage to the suprachiasmatic nucleus, the body:

still has rhythms, but they are less consistent.

The surest way to disrupt the biological clock is to damage the:

suprachiasmatic nucleus.

Social stimuli - that is, the effects of other people - are weak ____, unless they induce exercise or other vigorous activity.

zeitgebers