Pituitary Gland

A. Location

1. in Sella Turcica of sphenoid bone
   

2. attached to Hypothalamus by a stalk called Infundibulum

B. Structure

1. Anterior lobe – [glandular part] – Adenohypophysis

2. Posterior lobe – [neural part] - Neurohypophysis
   
   

C. Anterior Pituitary - (Adenohypophysis)

1. Hormone secretions controlled by secretions from the hypothalamus

- produced by nerve cells and control the release of hormones by

Endocrine glands; these hormones are called releasing factor

2. Growth Hormone (GH) – Somatotrophic Hormone (STH)

1. Increases Growth and Maintenance of Organs by:
   

1. stimulating protein anabolism

2. promotes fat catabolism (use of fat rather than sugars for energy)

2. Abnormal Secretions of STH

1. Gigantism -- hypersecretion during childhood ( before epiphyseal plates close)

2. Acromegaly -- hypersecretion durion adulthood

3. Dwarfism -- hyposecretion during childhood

4. Cachexia (Simmond’s Disease) – hyposecretion during adulthood

causes premature ageing and

atrophy of organs

B. Prolactin - (Lactogenic Hormone)

1. promotes breast development during pregnancy

2. stimulates mammary glands to produce milk after delivery

C. Thyriod Stimulating Hormone (TSH) - (Thyrotropin)

1. promotes growth of the Thyroid Gland

2. stimulates the secretion of the Thyroid Hormone

D. Adrenocorticotropin -- (ACTH)

1. promotes growth of the Adrenal Cortex

2. stimulates the secretion of Cortical Hormones

3. stimulates Fat Catabolism & Glycogenesis

E. Gonadotropins – FSH and LH

1. Follicle Stimulating Hormone (FSH)

a. female - stimulates the Ovarian Follicles to Develop and produce ova

- stimulates the Ovarian Follicles to secrete Estrogens

b. male - stimulates the production of sperm

- stimulates the secretion of Testosterone

2. Luteinizing Hormone (LH)

   1. female - associated with FSH in development of the Ovarian Follicles

- stimulates development of the Corpus Luteum following ovulation

- stimulates Corpus Luteum to secrete Progestrone

2. male - stimulates the Inerstitial Cells to secrete Testosterone

(also called Interstitial Cell Stimulating Hormone [ICSH])

D. Posterior Pituitary Lobe (Neurohypophysis)

1. Antidiuretic Hormone (ADH) - produced in the hypothalamus and collected and secreted by the posterior lobe

a. increases the permeability of the kidney tubules to water

b. promotes the reabsorption of the water from the urinary filtrate resulting in a smaller volume of urine

c.Diabetes insipidus - condition resulting in larger volumes of urine produced - may be treates with vasopressin

2. Oxytocin

1. stimulates powerful contractions of the pregnant uterus at the time of delivery

2. causes milk ejection from the lactating breast

Category: Physiology Notes