Hypothalamic Pituitary Adrenal Pathway Flashcards
What is the hypothalamic pituitary adrenal axis?
The interaction between the hypothalamus, pituitary gland and the adrenal gland
What are the steps of the hypothalamic pituitary adrenal axis?
- Hypothalamus detects stimulus and releases CRH
- The anterior pituitary is activated by CRH to release ACTH
- The adrenal gland is activated by ACTH and the zona fasciculata produces cortisol
Where is the pituitary gland?
In a protected pocket of bone directly connected to the pituitary gland
What is the innfundibulum?
The stalk that connects the pituitary to the brain
What is the posterior pituitary?
An extension of the neural tissue
What is the anterior pituitary?
A true endocrine gland
What does CRH stand for?
Corticotrophin Releasing Hormone
What does ACTH stand for?
Adrenocorticotrophic Hormone
What are tropic hormones?
Hormones which activate another endocrine gland
What are non-tropic hormones?
Hormones which target cells or organs
How are the hormones regulated in HPA?
Either long loop negative feedback or short loop negative feedback
What does ACTH do?
Acts on the adrenal cortex to promote the synthesis and release of cortisol
How does cortisol influence the negative feedback loop?
It inhibits ACTH secretion
What does cortisol do?
Activates the liver to produce glucose via gluconeogenesis
What does CRH do?
The anterior pituitary is activated to produce ACTH
Where is the adrenal gland?
On the kidney
What are the two parts of the adrenal gland?
Outer cortex and inner medulla
What is the largest part of the adrenal gland?
The cortex
How many zones is the cortex divided into?
3
Where is cortisol produced?
In the zona fasciculata in the cortex of the adrenal gland
What does the adrenal medulla do?
Secrets catecholamines
What are catechomalines?
Adrenaline, noradrenaline and dopamine
What does cortisol increase?
- Appetite
- Blood pressure
- Insulin resistance
- Gluconeogenesis
What does cortisol decrease?
- Wound healing
- Inflammatory activity
- Bone formation
What is the usual pattern of cortisol levels?
Highest at the beginning of the day and slowly decreasing until the lowest at the end of the day returning to highest during night
What is hyper-cortisolism?
Production of too much cortisol
What can cause hyper-cortisolism?
- Cushing’s syndrome
- Tumors on the adrenal gland or pituitary
- Exogenous administration
What does exogenous administration mean?
Something taken in from outside an organism ie medication, insulin, vitamins
What is hypo-cortisolism?
Not enough production of cortisol
What can cause hypo-cortisolism?
Addison’s disease
Congenital adrenal hyperplasia
What is cushing’s disease?
When cortisol levels are constantly elevated
What impacts does cushing’s disease have?
- Severe muscle, bone and skin breakdown
- Dampens the inflammatory and immune response
- Increases blood pressure, blood glucose and obesity
What are some signs and symptoms of cushing’s disease?
- Weight gain
- Slow healing cuts
- Increased risk of infections
- Fatigue
- Glucose intolerance
