Pattern of hormone secretion Flashcards
(16 cards)
What is a circadian rhythm?
Biological process that displays an endogenous oscillation around 24 hours
What drives the circadian rhythm?
The circadian clock
What does the circadian clock do?
Tells the body what time it is
What does the circadian rhythm describe?
The pattern of hormone secretion - important for integral control of the body
What is the peak of cortisol?
The beginning of the day
What is the peak of melanin?
The middle of the night
Does insulin follow a circadian rhythm?
No - it has three peaks. One after every meal.
The release is driven by another stimulus to complete its physiological role
What type of release does GnRH, FH and LSH follow?
Pulsatile release
What does pulsatile release of hormones entail?
Don’t have continuous increase or decrease in secretion
They are oscillatory
Need both positive and negative feedback loops to work
What is LH, FSH and GnRH used for>
Regulate menstrual cycle
Regulate steroid hormone synthesis
What is a feedback loop?
Deviation from a desired condition set off a series of events that amplify the original change
Don’t return the value back to normal
When is a positive feedback loop used by the body?
In childbirth
Oxytocin is released from the pituitary gland during contraction of thre utrerus
This is carried to the uterus via the bloodstream
In the uterus, the oxytocin triggers more contractions
When head of the baby pushes against the cervix - nerve impulses from the cervix travel to the brain and cause the pituitary to release more oxytocin
More contractions = more oxytocin, more oxytocin = more contractions
What is negative feedback?
Control systems operate so that any deviation from the desired condition will be counteracted
What is negative feedback useful for?
Generation of stability
What happens during the negative feedback loop?
Body senses perturbation
Ensures the system is stable
This is counteracted by an appropriate mechanism
What is an example of a negative feedback loop?
Increase in blood glucose after consuming a meal
B cells in the pancreas sense the increase in serum glucose
They release insulin
Insulin targets cells in the liver, adipose and muscle - cause deposition of glucose in tissue with insulin receptors
