Penn State University College of MedicinePULSE Lecture 2, September 23, 2009

Mitchell Sternlieb, First year medical student

OutlineLearning ObjectivesReview hormonal regulation and homeostasisDiscuss normal pituitary functionDiscover what occurs when the pituitary

gland does not functionDiscuss presentations of associated diseases

Objectives and AgendaObjectives: 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 SystemCritical 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 glandGland Hormone Actions Regulated ByPosterior Pituitary Oxytocin Stimulates contraction

of uterus and mammary gland cells

Nervous system

Posterior Pituitary Antidiuretic homone (ADH)

Promotes water retention by kidneys

osmolarity

Anterior Pituitary Growth Hormone (GH) Stimulates growth and metabolism

Hypothalamic hormones

Anterior Pituitary Prolactin (PRL) Stimulates milk production/secretion

Hypothalamic hormones

Anterior Pituitary Follicle Stimulating Hormone (FSH)

Stimulates production of ova and sperm

Hypothalamic hormones

Anterior Pituitary Luteinizing Hormone (LH)

Stimulates ovaries and testes (ovulation and androgens)

Hypothalamic hormones

Anterior Pituitary Thyroid Stimulating Hormone (TSH)

Stimulates thyroid gland Hypothalamic hormones

Anterior Pituitary Adrenocorticotropic 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?

TypesCorticotrophic adenomaSomatotrophic (GH-

secreting) adenomaThyrotrophic adenomaGonadotropic adenomaLactrotrophic adenoma

Cushing’s Disease

Acromegaly and Gigantism

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

Bringing it full circleIn 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 adenomasCan be small (< 10 mm) or large (>10 mm)Often undiagnosed, 14.4% prevalence in

autopsy studies*Actively secrete hormone in about 75% of

casesTypes

Corticotrophic adenomaSomatotrophic (GH-secreting) adenomaThyrotrophic adenomaGonadotropic adenomaLactitrophic adenoma

Acromegaly and gigantismAcromegaly 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 growthRare (0.6%

prevalence)

Clinical Manifestations of acromegalyPressure on cranial

nerves III, IV, and VIMandibular

PrognathismHypertensionShortness of breathRetinal hemorrhageLaterally shifted,

elevated and sustained PMI

IGF (insulin –like growth factor) [normal 110-160 ng/mL]

Chest X-rayBrain MRI with Gd

contrastOral glucose

tolerance test (GH-test)

Cushing’s DiseaseHigh cortisol (adrenal glands) AND high

ACTH