Chapter 16: The Adrenal Glands

Explain the causes of adrenocorticol defficiency

Primary: Addison's disease; all layers of the adrenal cortex are under secreting as a result of autoimmune disease. Erroneous antibodies destroy the adrenal cortex. Secondary: A hypothalamic or pituitary abnormality exists that results in an insufficient ACTH release; only effects cortisol secretion as aldosterone is not under the influence of ACTH

What are the symptoms of adrenocorticol defficiency?

Primary: Potassium retention, and excessive loss of sodium; Excessive potassium results in an abnormal cardiac rhythm, while reduced sodium disrupts the ECF/Plamsa volumes, thereby significantly reducing blood pressure. This can be fatal. Secondary: Poor response to stress, lack of gluconeogenic activity in the liver, hypoglycemia, and the lack of permissive action for both metabolic activities AND the vasocontrictive effects of catecholamines

Explain the causes of aldosterone hyper secretion

Primary: Referred to as Conn's syndrome, primary hyperaldosteronism is caused by an adrenal tumor that results in excessive secretion of the hormone aldosterone Secondary: A person exhibits hyperactivity of the renin-angiotensin-aldosterone system (caused by reduced blood flow to the kidneys)

Explain the causes of cortsiol hyper secretion?

Referred to as Cushing's Syndrome; Cause by excessive ACTH and CRH release, OR tumors in the adrenal cortex that release cortisol independent of ACTH

Sex hormones produced by the adrenal cortex include:

Small amounts of both estrogen and testosterone, but of primary concern is the dehydoepiandrosterone, which causes the manifestation of masculine characteristics

What type of hormones are released by the adrenal cortex?

Steroid hormones

Define stress

Stress is the non-specific response of the body to any factor that overwhelms or threatens to overwhelm the body's ability to maintain homeostasis

What is unique about sex hormones production by the adrenal cortex, relative to all other hormones produced by this gland?

The adrenal cortex is not the only site for sex hormone production in the body (i.e. estrogen and testosterone), where as mineralcorticoids and glucocorticoids are exclusively produced in the adrenal cortex. That being said, dehydroepiandrosterone is the exception to this, as it is only produced in the adrenal cortex.

What are the two endocrine glands that make up each adrenal?

The adrenal cortex, and the adrenal medulla

Describe the effects of adrenal androgen hyper secretion

Adult females: begin to exhibit male hair growth patterns (called hirsutism) Newborn females: pseudohermaphroditism (female genitalia enlarge and take on the form of a penis) Young males: early maturation, deepening of the voice, enlarged penis, increased sex drive, and growth spurts Adult males: no apparent effect

In what layers of the arenal cortex are aldosterone and cortisol synthesized, respectively?

Aldosterone production is limited to the zona glomerulosa, whereas cortisol is produced by both of the inner portions of the adrenal cortex: the zona fasciculata and the zona reticularis

Briefly describe the integrated stress response

All of the following activities are coordinated by the hypothalamus: 1. The sympathetic nervous system is activated, and as a result epinephrine is released from the adrenal medulla. 2. The hypothalamus secretes Cortiotropin Releasing Hormone (CRH) which acts on the anterior pituitary gland to release Adrenocortiotropin Hormone (ACTH). This activates the release of cortisol from the adrenal cortex. 3. This activation of cortisol enables energy stores in the body to change; recall that cortisol inhibits tissues from taking in glucose to save this nutrient for the brain. Furthermore, fats are broken down to provide energy to these tissues as an alternate source to glucose. 4. Epinephrine and glucagon stimulate both glucogenolysis (break down of glycogen into glucose for use by the brain) AND gluconeogenisis (production of new glycogen molecules to replenish those used during the stress response). At the same time insulin, which prevents the break down for glycogen, is decreased. 5. Finally, the activation of the renin-angitensin-aldosterone system AND the release of vasopressin by the posterior pituitary gland increase fluid retention by the body to maintain blood volume and pressure.

What type of hormones are released by the adrenal medulla?

Catecolamines

What precursor molecule do hormones released from the adrenal cortex all share?

Cholesterol

Describe the effects of epinephrine

Epinephrine reinforces the fight or flight response of the sympathetic nervous system during stressful situations by acting to increase cardiac output, increase the rate and strength of cardiac contractions, and raise arterial blood pressure by acting as a peripheral vasoconstrictor. Furthermore, it dilates the respiratory airways, and the blood vessels supplying skeletal and cardiac muscle.

Describe the function, location of action, and activation of glucocorticoids

Function: Glucose, protein, and lipid metabolism during the stress response, permissive hormone to epinephrine's vasocontrictive properties, and stimulates gluconeogenisis Location: Liver, muscle tissue, and adipose tissue Activation: Either stress or diurnal rhythms; Hypothalamus > CRH > Anterior Pituitary > ACTH > Adrenal Cortex

Describe the function, location of action, and activation of mineralocorticoids.

Function: Primarily play a role in electrolyte balance (i.e Aldosterone) Location: The distal and collecting tubules of the kidney Activation: The Renin-Angiotensin-Aldosterone system, that results from reduced flow of blood to the kidneys when blood is being allocated to other areas of the body

What are the symptoms of aldosterone hyper secretion?

High sodium retention and potassium depletion; as a result of salt retention, water is also retained. This leads to high blood pressure.

What are the symptoms of cortisol hyper secretion?

Hyperglycemia, abnormal fat distribution, and glucosuria (otherwise known as adrenal diabetes)

List the three different hormones released from the adrenal cortex, and provide one example of each.

Mineralcorticoids - Aldosterone Glucocorticoids- Cortisol Sex hormones- Dehydroepiandrosterone