21. The HPA Axis

What is the HPA Axis?

Coordinated endocrine activity of the hypothalamus, pituitary, and cortex of the adrenal glands

What is the structure of the adrenal gland? Which part of the adrenal gland is part of the sympathetic nervous system. and which is part of the HPA axis?

Cortex and medulla

Adrenal medulla is part of the sympathetic

Adrenal cortex is part of the HPA axis —> cortisol

HPA activity upregulates what? What is the important sequence of these hormoens?

Physiological processes for coping with stressful environments

CRH —> ACTH —> gluccorticoids (cortisol)

The stress response has been hypothesized to …

enhance short-term physiological performance; chronic long-term stress is clearly detrimental

acute effects:

• increased availibility of fuel for respiration and wound healing

• enhanced immune response

chronic effects

• tissue wasting due to high catabolism

• cardiovascular disease

• immunosuppression (suppression of immune functions)

  

Corticosteroids are commonly used to …

reduce inflammation or auto-immune symptoms through immunosuppressive effect

Nervous and endocrine system integration

-

Communication between nervous and endocrine systems goes …

both ways

Hypothalamic cells that trigger hormone release in the pituitary are themselves…

embedded in complex neural circuits in the brain

What is another control system related to stressful situations?

Sympathetic autonomic

Stress activates release of hormones or the sympathetic autonomic?

Activates both at the same time

• either both up or both down

  

Draw out the general pathways of posterior and anterior