THE PITUITARY GLAND

Jaclyn Monaco&

Kristina Vukaj

The Pituitary Gland Is In Your Brain It is also known as the

Hypophysis!

The Pituitary Gland Is…• the size of a pea!

• behind the bridge of the nose,

between the optic nerves.

• found in a bony hollow

beneath the base of the brain,

in the sella turcica, and

beneath the hypothalamus.

• divided into two major lobes,

the anterior lobe and the

posterior lobe.

Chemical ActivityLet’s Talk Hormones:

POSTERIOR LOBE

1. Oxytocin

2. Anti-diuretic hormone

ANTERIOR LOBE

1. Growth hormone

2. Luteinizing hormone

3. Adrenocorticotrophic hormone

4. Prolactin

5. Follicle stimulating hormone

6. Thyroid stimulating hormone

The different lobes of the pituitary gland produce entirely different hormones. The hormones have an impact on all of the other glands of the body.

What do these hormones regulate?

• Growth • Breast milk production• Contractions during

birth• Water retention/removal

by the kidneys• Egg production by the

ovaries• Stress hormone

production by the adrenal glands

• Activity of the thyroid gland

Facts about hormones:• All anterior pituitary hormones are proteins, that act through

secondary messenger systems and are regulated, in most

cases, by negative feedback.

• The prolactin and growth hormones exert their major effects on

nonendocrine targets.

• The remaining four are tropic hormones which stimulate their

endocrine gland targets to secrete their hormones, which in

effect will stimulate other body organs and tissues.

• THIS IS WHY THE PITUITARY GLAND IS THE MASTER

GLAND!!!

Molecular Make-Up

• Anterior Lobe: GLANDULAR TISSUE

– Types of cells:

– 1) acidophils

– 2) basophils

– 3) chromophobes

• Posterior Lobe: NERVOUS TISSUE

Functions of the Pituitary Gland (and its hormones!)

• The major function of the pituitary gland

is to secrete hormones.

• HOWEVER, the activity of these

hormones is what’s important because

they affect multiple other parts of the

body.

Anterior Lobe Hormone Functions:

• Growth Hormone (GH):– Effects growth of skeletal muscles

and long bones.– Causes amino acids to be built

into proteins and stimulates target cells to grow and divide.

– Causes fat to be broken down and used for energy.

– Helps to maintain blood sugar homeostasis.

• Prolactin (PRL):– Stimulates and maintains milk

production by the mother’s breasts after childbirth.

• Adrenocorticotropic Hormone (ACTH):

– Regulates endocrine activity of adrenal cortex.

• Thyroid Stimulating Hormone (AKA thyrotropic hormone) (TH):

– Influences growth and activity of thyroid gland.

• Gonadotropic Hormones:

– Regulate the hormonal activity of the

gonads (ovaries and testes).

• Follicle Stimulating Hormone

(FSH):

– Stimulates follicle

development in ovaries in

women. As they mature, they

produce estrogen.

– Stimulates sperm

development by the testes in

men.

• Luteinizing Hormone (LH):

– Triggers ovulation of an egg

from the ovary in women.

– Stimulates testosterone

prudction by the interstitial

cells of testes in men.

Posterior Lobe Hormone Functions:

• The posterior lobe does not

create its own hormones.

These two hormones are

formed by the

hypothalamus.

• The posterior lobe acts as a

storage area for these

hormones.

• Oxytocin:– Released in significant amounts

during childbirth and nursing in women.

– Stimulates powerful contractions of the uterine muscle.

– Causes milk ejection (“let-down reflex”) during nursing.

• Anti-diuretic Hormone (ADH): (diuresis = urine production)

– Inhibits or prevents urine production.

– Causes kidneys to reabsorb more water from urine.

• Urine volume decreases; blood

volume increases.

– Increases blood pressure (in large amounts).

Pituitary Gland= MASTER GLAND:

• Pituitary-Hypothalamus Relationship:– Pituitary gland controls

activity of many other endocrine glands

– Its removal or destruction would cause the adrenal glands and thyroid glands and gonads atrophy

– Release of hormones is controlled by the releasing and inhibiting of hormones produced by the hypothalamus.

– The hypothalamus releases these regulatory hormones into the blood of a portal circulation (two capillary beds connected by veins) which connects the blood of the hypothalamus with the blood of the anterior pituitary.

What if something goes wrong?• Pituitary Tumors:

– When the cells that make up the pituitary gland grow too much or create small growths.

– Interfere with the normal production and release of hormones.– Common in adults.

• Two types of tumors: Secretory & Non-Secretory– Secretory= produce too much of a hormone.– Non-Secretory= large size interferes with normal functions of the gland.

• The consequences include:– Hypersecretion= over-production of any hormone.– Hyposecretion= under-production of hormones (usually caused by non-secretory

tumor).– Tumor mass effects= as a tumor grows and presses against the gland and other

parts of the brain, head aches, vision problems, or other health issues may occur.

Specifically:• Cushing’s Disease:

– A secretory tumor associated with the hypersecretion of ACTH, causing too much cortisol by the adrenals.

– Affects 4,000+ people in the U.S. per year.

– Symptoms include:• Muscle weakness

• Purple stretch marks

• Rapid weight gain

• Memory loss

• Menstrual cycle disorders

• Skin changes & red cheeks

• Depression

• High blood sugar/pressure

– Treatment= personalized, but may include medication, surgery, and

radiation.

• Non-functioning Adenoma:– A non-secretory tumor often associated

with head injury. – May cause headaches and vision

problems and also hyposecretion.– Symptoms/Effects:

• Loss of appetite• Weight loss/gain• Fatigue• Irregular menstrual cycle• Infertility• Frequent urination at night• Joint pains• Dizziness• Low blood pressure

– Treatment may include transsphenoidal microsurgery through the nasal sinuses, hormone replacement, or radiation.

Molecular Images:

• Slides A-C: normal pituitary obtained at autopsy.

• Slides D-F: pituitary adenoma in Cushing disease.

Pituitary Tumor Images

• Image 1: MRI image

showing a large

nonfunctioning

pituitary

macroadenoma

• Image 2: illustrated

image of pituitary

tumor.

Gigantism and Dwarfism…YES they are diseases!

• Hyposecretion of GH in childhood= pituitary dwarfism. – Although body proportions are fairly normal, the person as a whole is a living miniature (Max adult height=

4ft)

• Hypersecretion of GH in childhood= Gigantism – 8 to 9 ft is usual. Most usually caused by tumors of affected gland, which begin to secrete hormones like

the normal glandular cells do.

• If hypersecretion occurs after long bone growth has ended (how can we tell??):

– Acromegaly= Facial bones including lower jaw and bony ridges under eyebrows and also feet and hands, enlarge tremendously.

– Malformed facial features because of thickening of soft tissues.

• **Today, pharmacological doses of GH are used to reverse some of effects of aging. Although it is proven to help children with dwarfism grow normally, help stop the aging process, and even help prevent AIDS patients from dying, when abused, GH can be fatal.

– This is what you hear about on the news when all the baseball players are taking dangerous STEROIDS!

Dwarfism & Gigantism Images:

SOURCES:• http://2.bp.blogspot.com/_8Dln2xkR7y8/SEobigknUcI/AAAAAAAAA

Mc/LrgNcExIywg/s400/mayo+pituitary+gland.jpg• www.enotes.com/nursing-encyclopedia/pituitary-gland • http://www.webhealth.co.uk/a_to_z_of_health/pituitary.asp• http://www.suite101.com/content/the-pituitary-gland-a68589• http://www.encyclopedia.com/topic/pituitary_gland.aspx• http://www.answers.com/topic/pituitary-gland• http://www.thehormoneshop.com/pituitarygland.htm• http://www.ajmc.com/media/image/A102_04S424_F2.gif• http://www.hormone.org/Pituitary/overview.cfm• http://instruction.cvhs.okstate.edu/histology/histologyreference/hrendo.htm• ANATOMY TEXTBOOK