Stress and Circadian Rythms Flashcards
Cortisol
Stress hormone released by adrenal cortex
Diurnal cortisol
Daily rhythm of cortisol (12 hours)
What is the differences between circadian rhythm and diurnal rhythm?
Circadian rhythm = 24 hours
Diurnal rhythm = 12 hours
Neuroendocrine system
Is the central nervous system and endocrine system
Endocrine system
Is the system that produce and release hormones
Function of neuroendocrine system
- is how brain communicates with the rest of the body.
- maintain regular functioning of organs
What are the glands in the brain that are part of the neuroendocrine system ?
Pituitary gland
Pineal gland
Pineal gland
Secretes melatonin (sleep hormone)
HPA axis
Hypothalamic pituitary adrenal axis. It is the body’s response to stress.
Hypothalamus
Is made up of clusters of nuclei
What is the function of hypothalamus?
Controls bodily functions e.g. sleep, mood, appetite, stress response.
What is the hpa?
It is the interaction between the hypothalamus, pituitary gland and adrenal cortex.
CRH
Corticotrophin-releasing hormone.
How is the hypothalamus and pituitary gland connected?
The hypothalamus and pituitary Gland are connected by a structure called infundibulum.
What is the blood supply in hypothalamus
Hypothalamus has a blood supply called portal blood supply.
CRH
corticotrophin releasing hormone is released by the paraventricular nucleus in the hypothalamus and travels in the portal blood stream to the pituitary gland. CRH stimulates the anterior pituitary gland to release ACTH.
Explain the HPA
The paraventricular nucleus in the hypothalamus releases CRH, which goes into the portal blood stream to the pituitary gland. CRH stimulates the release of ACTH from the anterior pituitary gland. The ACTH goes into the general blood stream and is detected by the adrenal cortex which produces cortisol
What does Adrenal gland consist of?
Adrenal gland consist of adrenal medulla (centre) and adrenal cortex (outer part)
ACTH
adrenocorticotropic hormone is produced by the anterior pituitary gland and it stimulates the production and release of cortisol from the adrenal cortex
Adrenal medulla
Inner part of adrenal gland. Adrenal medulla secretes Adrenaline.
Adrenal cortex
Outer part of adrenal gland. Adrenal cortex secretes cortisol when stimulated by ACTH
What does the HPA axis do?
The hypothalamic pituitary adrenal axis secretes cortisol and plays an important role in the stress response
What happens when stress occurs?
Stress activates brain monoamines, which stimulates the paraventricular nucleus in the hypothalamus to secrete CRH. The CRH goes through the portal blood supply to the the anterior pituitary gland. The anterior pituitary gland secretes ACTH. ACTH goes into the general blood supply and is detected by the adrenal cortex which releases cortisol. Cortisol goes everywhere.
Why is cortisol important?
Cortisol is necessary for survival. But too much or too little leads to problems.
What occurs when you are chronically stressed?
excessive cortisol secretion and enlarged adrenal glands.
Cortisol awakening response
Cortisol levels are highest in the morning and decreases during the day.