Endocrine system: Adrenal Glands

What makes up the adrenal glands?

1. adrenal medulla

2. adrenal cortex

What is the adrenal medulla?

deep central region of the gland

• contains nervous tissue and functions as part of the SNS

• preganglionic neurons stim chromaffin cells→ release cataecholamine hormones (epinephrine, norepinephrine)

What are the properties of epinephrine/norepinephrine?

1. once released by chromaffin cells, bind to G-protein coupled adrenergic receptors

2. The receptors activate 2nd messengers to regulate enzyme activation→ response depends on tissue type

What are the properties of beta-adrenergic receptors in the liver?

Stimulate glycogenolysis

What do beta-adrenergic receptors do in cardiac muscle?

Increase heart rate and force of contraction

What do beta adrenergic receptors do in bronchioles?

Causes smooth muscle relaxation (bronchiodilation)

What do alpha-adrenegic receptors in blood vessels do?

Causes smooth muscle contraction→ vasoconstriction

• redirects blood flow to essential organs and skeletal muscle

What are the 3 zones of the adrenal cortex?

1. zona gloerulosa

2. zone fasciculata

3. zone reticularis

What is zona glomerulosa responsible for?

Releasing mineralcorticoids (regulate mineral balance)

• aldosterone

What is the zona fasciculata responsible for?

Releasing glucocorticoids (regulates metabolism)

• cortisol, corticoesterone, cortisone

What is the zona reticularis responsible for?

Androgens (stitmulates masculization)

• Dehydroepiandrosterone (DHEA)

What type of hormone is DHEA?

Androgen Gonadocorticoid

What are the effects of aldosterone?

Mineralcorticoid→ increases sodium reasorption and potassium secretion in kidneys

• increase blood volume and blood pressure (Na+)

What is cortisol?

Glucocorticoid that stimulates gluconeogenesis to inc blood glucose levels

What are corticoids?

Steroids that are produced by the adrenal cortex

What is the cortisol response mechanism?

1. Cortisol diffuses from capillary through lipid-soluble membrane→ enters targett cells

2. cortisol then binds to glucocorticoid receptor (GR) within cell

3. GR then enters nucleus and regulates gene transcription

4. Proteins are then produced that prepare the body for prolonged stress

What is thet effect of cortisol on blood glucose?

PEPCK produced by hepatocytes increase gluconeogenesis

What enzyme is involved in gluconeogenesis?

Phosphoenolpyruvate Carboxykinase (PEPCK)

What is the effect of cortisol on blood pressure?

Stimulates upregulation of adrenergic receptors in target cells (cardiac/smooth muscle) to inc response to catecholamines

What is the effect of cortisol on the hypothalamus?

Stimulates protein production in neurons that promote hunger

What is the effect of cortisol on inflammation?

Leukocytes produce proteins that decrease inflammation

What is Cushing’s syndrome (disease)?

Excess glucocorticoid signaling→ negative feedback to hypothalamus to stop producing CRH and ACTH

• hypertension

• hyperglycemia

• muscle atrophy