Circadian Rhythm

Question 1

in order to “find the rhythm” one must sample how often?

Answer 1

frequently across the span of a rhythm, enough to see the fluctuation in the variable being studied.

Question 2

therapy for seasonal affective disorder

Answer 2

bright artificial light phototherapy between Jan-March

Question 3

examples of human events that are not “random” but rather the result of circadian rhythms

Answer 3

natural child birth, natural death, suicide attempts, blood variables, heart attacks

Question 4

what is the time when significantly more myocardial infarcts and strokes occur? What are the contributing circadian reasons for this?

Answer 4

9 AM

increased autonomics, blood pressure, heart rate, vascular tone, platelet aggregation, blood coagulability; decreased coronary flow and fibrinolytic activity

Question 5

where is the master body clock located?

Answer 5

SUPRACHIASMATIC NUCLEUS OF THE HYPOTHALAMUS

Question 6

how does light information reach the master clock?

Answer 6

retinal hypothalamic tract takes light to the suprachiasmatic nucleus

Question 7

where/what cells does the SCN get its info from?

Answer 7

the ganglion cells in the retina that have melanopsin (which is only 3% of the ganglion cells)

Question 8

how does the master clock/SCN influence everything? (aka what connections does it have)

Answer 8

connections to pineal gland, pituitary gland, intermediolateral spinal column

Question 9

how does SCN influence sympathetics?

Answer 9

it has direct connections to intermediolateral spinal column, the location of preganglionic sympathetic neurons, which innervate adrenal glands.

Question 10

how does the SCN influence GI tract function?

Answer 10

SCN projects to the dorsal motor nucleus of the vagus

Question 11

is the SCN composed of homogeneous or heterogeneous neurons?

Answer 11

heterogeneous; the different neurons reside in different anatomical locations