Circadian Rhythm Flashcards
What is required to see circadian rhythym?
Many samples over a long period of time
One cycle every year is called ___________.
Circannual
One cycle every 30 days is called ____________.
Circatrigintan
One cycle every 7 days is called ____________.
Circaseptan
One cycle every 24 hours is called ____________.
Circadian
Cycles that occur at a higher frequency than circadian are referred to as ____________.
Ultraradian (HR, BP, etc.)
What is a good example of a circannual disorder? What is the treatment?
- Seasonal affective disorder (SAD)
- Blast with a high intensity light (Phototherapy)
What time do most myocardial infarctions and strokes occur?
9am
Why do most myocardial infarctions and strokes occur around 9am?
Circadian Rhythm
- That is when the ANS is most active and the following are at their peak:
- Blood pressure
- Heart rate
- Vascular tone
- Platelet aggregation
- Blood coagubility
- The following are at the least during this time of day:
- Coronary blood flow
- Fibrinolytic activity
What nucleus is responsible for the circadian rhythm?
Suprachiasmatic nucleus of (SCN) of the hypothalamus
What is the tract that gives input to the SCN nucleus?
-
Retino-hypothalamic tract
- Also recieved input from thalamus and raphe nucleus of brain stem (SCN is composed of heterogeneous population of neurons)
What cells are responsible for SCN input? What neurotransmitter?
3% of ganglion cells in ganglion layer that have melanopsin (Layer 8)
What is the output of the SCN nucleus?
Direct connection to pituitary and pineal gland →
- Central sympathetic intermediolaterl cell column (IML) of the spinal cord → Adrenal gland → Body through hormones (glucocorticoids)
- Central parasympathetic dorsal motor nucleus of the vagus (DMV) → Body (via CN X)
What is rheostasis?
When “homeostasis” is obtained when all of the biological rhythms in an animal are fluctuating normally
