Exam 2-Chronobiology

Question 1

biological clock

Answer 1

physiological mechanism that gives an organism an endogenous capability to keep track of the passage of time (internal, independent of environ., comparison with nonendogenous rhythms)

Question 2

endogenous rhythm

Answer 2

• free run (measured without environ. cues)
• period: amount of time for one cycle of an endogenous rhythm
• entrainment: process of synchronizing endogenous rhythm to environ. stimulus
• phasing factor: environ. cue capable of entraining a biological rhythm (light, temp.)

Question 3

(physiological mechanism)
suprachiasmatic nucleus (SCN)

Answer 3

• hypothalamus, mammals
• input from inertia, absolute light
• Alzheimer
• bimodial free cycling
• E/M oscillator (begin to move apart when removing light cues)

Question 4

E oscillator

Answer 4

evening
sensitive to light, starts when light goes away
initiate beginning of darkness rhythms

Question 5

M oscillator

Answer 5

morning
light sensitive, when light appears (shuts off)
in terms of seasons

Question 6

(physiological mechanism)

pineal gland

Answer 6

• nonmammalian, senses light, “second clock”
• melatonin: released by pineal gland; receives/gives info to SCN coordinating the two clocks; involved with darkness
• mammals: controlled by SCN; melatonin is darkness hormone released at night

Question 7

(physiological mechanism)

biological clock

Answer 7

• involving genes
• circadian oscillator (time keeping mechanisms within cells’ alternating expression of key clock genes; temperature independent)