The Pituitary Gland

Posteriorpituitary

The hypothalamus significantly influences the pituitary gland

The hypothalamus makes and releases the hormonesof the posterior pituitary

Hypothalamic releasingand inhibiting hormones are delivered to the anterior pituitary

Pituitary (Hypophysis)

• Anterior Pituitary – “adenohypophysis”

• Posterior Pituitary – “neurohypophysis”

Oxytocin

Antidiuretic Hormone (ADH)

• Anterior Pituitary – synthesizes 6 hormones.

Growth Hormone (hGH)(also called Somatotropin)

Adrenocorticotropic Hormone (ACTH)(also called corticotropin)

Thyroid Stimulating Hormone (TSH)

Follicle Stimulating Hormone (FSH)

Luteinizing Hormone (LH)

Prolactin (PRL)

hGH – is the primary hormone that regulates overall body growth, also important in general metabolism.

ACTH – stimulates cortisol secretion from the adrenal cortex (the stress hormone!). Also promotes growth of adrenal cortex.

TSH – stimulates secretion of thyroid hormone and the growth of the thyroid gland. Important regulator of metabolic activity in the body.

FSH – a) in females: stimulates growth and development of ovarian follicles, and promotes estrogen secretion.

LH – a) in females: responsible for ovulation and for luteinization. Regulates estrogen and progesterone.

PRL – enhances breast development and milk production in females.

b) in males: it is required for sperm production.

b) in males: stimulates interstitial cells (in testes) to secrete testosterone.

* called interstitial cell stimulating hormone (ICSH)

7ft 7in tall, died at age 22.

Thyroid Goiter.

Adrenal disorders in Females:• Hirsutism (male hair) • Oligomenorrhea (infrequent menstruation) • Deepening of voice • Hypertrophy of clitoris (resemble penis)

Pituitary Gland has enormous impact on entire Body.

Negative Feedback Loop of Hypothalmic-Adenohypophysisand the Thyroid Gland

Normal Growth

• Growth hormone and other hormones

• An adequate diet

• Absence of stress

• Genetics

Acetyl CoA

Hydroxymethyl Glutaric Acid (HMG-CoA)

Mevolaonate

Mevolaonate Pyrophosphate

Isopentenyl Pyrophosphate

Geranyl Pyrophosphate

Famesyl Pyrophosphate

Squalene

CholesterolUbiquinone(CoQ10)

Dolichol

Statin = HMG-CoA reductase inhibitors

Cholesterol

Vitamin D

Cortisone

Glucocorticoids

Mineralcorticoids

Bile Salts

Steroid Hormones(testosterone, estrogen,

progesterone)

Wow, what a “Life Saver”.

Growth Hormone

• Severe hGH deficiency leads to dwarfism

• Over secretion of hGH in children leads to gigantism

• Over secretion of hGH in adults leads to acromegaly

Pathway of Growth Hormone Control

The Cortisol Connection

The Hypothalamus-Pituitary-Adrenal Axis(HPA)

CRH = Corticotropin Releasing HormoneACTH = Adrenocorticotropic Hormone

The many functions of cortisol in the body:

Cortisol

• Promotes gluconeogenesis

• Breakdown of skeletal muscle proteins

• Enhances lipolysis (prevents glucose use)

• Suppresses the immune system

• Permissive – needed for NE vasoconstriction

• Response to stressors – protective?

Circadian Rhythm of Cortisol Secretion

Hyper-Cortisolism• Adrenal tumor that ↑ cortisol

• Pituitary tumor that ↑ ACTH

e.g., Cushing’s Disease

↑ glucose and ↓ protein

Loss of muscle mass

Characteristic fat deposits

"Moon" face, "Buffalo" humpProtruding abdomen High Blood Pressure Weakness, Acne, Backache Excessive thirst & urination Easy Bruising

Normal Hyper-Cortisolism

Hypo-Cortisolism

e.g. Addison’s Disease

• Under secretion of adrenal steroid hormones

• Autoimmune destruction of adrenal cortex

↓ glucose (hypoglycemia)

Poor response to stress

Lack of vasoconstriction (permissive NE action)

Symptoms and Clinical Signs

Fatigue and muscle weakness.

Low Blood Pressure (Orthostatic Hypotension).

Headache, sweating, joint and muscle pains.

Increased Melanocyte-Stimulating Hormone (MSH).

Growth Hormone