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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