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Flashcards in Pattern of hormone secretion Deck (16)
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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