Penn State University College of Medicine PULSE Lecture 2, September 23, 2009 Mitchell Sternlieb, First year medical student

Outline Learning Objectives Review hormonal regulation and homeostasis Discuss normal pituitary function Discover what occurs when the pituitary gland does not function Discuss presentations of associated diseases

Objectives and Agenda Objectives: SWBAT… Describe the basic function and regulation of the endocrine system Discuss the outcomes of normal and abnormal function of the pituitary gland Discover the disease states that result from pituitary malfunction Go home and brag to your families about your expertise on pituitary disorders and how awesome Hershey medical students are. Agenda Key paradigms in life sciences: homeostasis and structure/function. Review endocrine system: neurosecretory and feedback control Review pituitary function Discover disease states and incidences I do You help I help Leave me alone Mitch, I got this! Questions?

Key Paradigms: Homeostasis

Key Paradigms: Form fits Function a

Form Fits Function and Homeostasis: Combined

Organs of the Endocrine System Critical Thinking Question 1: In groups of two, choose two of the endocrine organs shown on the left and describe why their location in the body makes sense. Write down your responses.

Regulation & Communication  Animals rely on 2 systems for regulation  endocrine system  ductless gland which secrete chemical signals directly into blood  chemical travels to target tissue  slow, long-lasting response  nervous system  system of neurons, central nerve system  transmits “electrical” signal to target tissue  fast, short-lasting response

Critical thinking question 2: What about the location of the pituitary gland might suggest why it is sometimes referred to as the “master gland”? Some questions to guide you: 1. What systems are involved in communication and regulation? 2. Where are these systems most likely to cross paths?

Endocrine Control

The Pituitary Gland  Particulars  Size: about the size of a pea and weighing 0.5 g  Location: protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica)  Anterior Pituitary  From glandular tissue - synthesizes its own products  Posterior Pituitary  projection of tissue from the hypothalamus - stores hypothalamic products

Structure of Pituitary Gland

Major Hormones secreted by the pituitary gland GlandHormoneActionsRegulated By Posterior PituitaryOxytocinStimulates contraction of uterus and mammary gland cells Nervous system Posterior PituitaryAntidiuretic homone (ADH)Promotes water retention by kidneys osmolarity Anterior PituitaryGrowth Hormone (GH)Stimulates growth and metabolism Hypothalamic hormones Anterior PituitaryProlactin (PRL)Stimulates milk production/secretion Hypothalamic hormones Anterior PituitaryFollicle Stimulating Hormone (FSH) Stimulates production of ova and sperm Hypothalamic hormones Anterior PituitaryLuteinizing Hormone (LH)Stimulates ovaries and testes (ovulation and androgens) Hypothalamic hormones Anterior PituitaryThyroid Stimulating Hormone (TSH) Stimulates thyroid glandHypothalamic hormones Anterior PituitaryAdrenocorticotropic Hormone (ACTH) Stimulates Adrenal cortex to secrete glucocorticoids Hypothalamic hormones

Additional hormones

When things go wrong!

Ok my young doctor friends, it is now your turn to put the pieces together Directions: Answer the following questions for each type of pituitary adenoma based on the types of described on the previous slide. I will model one of these cases first. 1. Which hormone will be secreted in excess? 2. Trace the impact of this over-secretion on other target organs in the body. 3. With what symptoms might a patient with this condition present? Types Corticotrophic adenoma Somatotrophic (GH- secreting) adenoma Thyrotrophic adenoma Gonadotropic adenoma Lactrotrophic adenoma

Cushing’s Disease

Acromegaly and Gigantism

Most importantly! Be compassionate! Be thorough! Be compassionate!

Bringing it full circle In 3-5 sentences, reflect on how pituitary adenomas disrupt the body’s ability to maintain homeostasis. Explain why this is potentially a bad thing.

Questions?

Facts about adenomas Can be small ( 10 mm) Often undiagnosed, 14.4% prevalence in autopsy studies* Actively secrete hormone in about 75% of cases Types Corticotrophic adenoma Somatotrophic (GH-secreting) adenoma Thyrotrophic adenoma Gonadotropic adenoma Lactitrophic adenoma

Acromegaly and gigantism Acromegaly is due to high Growth Hormone levels after adolescence when major bone growth has ceased. Soft tissues grow disproportionately Rare (1 in 25,000 people) Gigantism is due to excess of growth hormone during years of major bone growth Rare (0.6% prevalence)

Clinical Manifestations of acromegaly Pressure on cranial nerves III, IV, and VI Mandibular Prognathism Hypertension Shortness of breath Retinal hemorrhage Laterally shifted, elevated and sustained PMI IGF (insulin –like growth factor) [normal ng/mL] Chest X-ray Brain MRI with Gd contrast Oral glucose tolerance test (GH-test)

Cushing’s Disease High cortisol (adrenal glands) AND high ACTH