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1、ENDOCRINE PHYSIOLOGY AND PATHOPHYSIOLOGY,Barb Bancroft, RN, MSN, PNP ,General Anatomy,Limbic system (Temporal lobe) Hypothalamusthe “big cheese” Pituitary glandanterior and posterior lobes”the Master Gland” TARGET GLANDS Thyroid gland Parathyroid glands (4) Adrenal glandscortex and medulla Endocrin
2、e portion of the pancreasIslets of Langerhans (Insulin, Glucagon) Endocrine portion of the kidneyerythropoietin (EPO) Ovaries and testicles Your NEWEST ENDOCRINE ORGAN? BELLY FAT (visceral obesity),Lets start at the top,Hypothalamus is the link between the brain (temporal lobe/limbic system) and the
3、 “master gland”the pituitary gland The hypothalamus sends messages to the anterior and posterior pituitary gland which in turn send their message to target organs Once the target organ receives the message and performs the appropriate action, it sends a message BACK to the pituitary and hypothalamus
4、 to TURN OFF the messagethis is known as “negative feedback”,Analogystart at the topthe BIG CHEESE,Chief Nursing Officer, Director of Nursing, Dean of the Nursing School (the hypothalamus)-Sends her MEMO via EMAIL to,Analogythe “Middle woMan”,The MEMO can be either “DO something” or “STOP doing some
5、thing This memo goes to the: Heads of the Departments, Nursing Supervisors (the pituitary gland)relay the message to,Analogythe “worker bee”,Floor Nurses, student nurses (the TARGET ORGANS)that do all of the work “Ok, OK, OKIll get it done”,Enough already!,When you have performed the required work,
6、you (the target organ) send a message back to TURN OFF the messages from the “higher ups” This is known as NEGATIVE feedback,Who are the memos/messengers?,Releasing factors/hormones (DO IT!) or inhibiting factors/hormones (STOP DOING IT) from the hypothalamus via a capillary network to the The anter
7、ior pituitary gland which in turn releases either a stimulating or inhibiting hormone which in turn interacts with a receptor on the target organ to perform a certain task The hypothalamus sends a direct message via neuronal axons to the posterior pituitary to release hormones that interact with tar
8、get tissues,Example:,The Hypothalamus sends thyrotropin (an affinity for) releasing hormone (TRH) to The anterior pituitary which in turn sends thyroid stimulating hormone (TSH) to The thyroid. The thyroid releases thyroxine (T4) and tri-iodothyronine (T3) Once enough T4 and T3 are released to boost
9、 metabolismthe message returns to the pituitary and hypothalamus to TURN OFF NEGATIVE FEEDBACK,TRH - Hypothalamus + TSH - negative (off) Pituitary - + Thyroid T3, T4,What if something goes wrong?,Lets start at the bottom with the TARGET ORGAN, thyroidhypthyroidism Decreased T3, T4 feeds back to the
10、pituitary gland and hypothalamuspump out more TRH and TSH to stimulate a thyroid as the thyroid continues to “die” and T3, T4 are not being produced, the TRH and TSH continue to rise,Too much or too littlehyper- or hypo-,If the problem is in the TARGET organits a PRIMARY disorderPRIMARY HYPOTHYROIDI
11、SM (Hashimotos thyroiditis is an example) If the problem is in the pituitary its a SECONDARY disorderSECONDARY HYPOTHYROIDISM (removal of pituitary/radiation) If the problem is with the hypothalamus its a TERTIARY disorderTERTIARY or CENTRAL HYPOTHYROIDISM (Pituitary and hypothalamic dysfunction may
12、 also be referred to as CENTRAL dysfunction),So, to diagnose thyroid problems,If its primary hypothyroidism, the thyroid will not be able to produce thyroid hormonesdecreased circulating T, T This feeds back to the pituitary gland and saysI NEED A LITTLE HELPso the pituitary ramps up the production
13、of TSH and the hypothalamus ramps up the production of TRH TSH and thyroid measurements will show decreased thyroid hormones and an increased TSH,So, to diagnose thyroid problems,If the problem is in the pituitary, ie. Secondary hypothyroidism The pituitary will NOT be able to produce TSH to stimula
14、te the thyroidso Thyroid hormones will be low or non-existent AND TSH will be low since the pituitary gland is NOT WORKING.,Lets prepare an egg in the ovary for ovulationeggs live in follicles, follicles produce estrogen,The Hypothalamus releases gonadotropin releasing hormone (GnRH)message to the T
15、he Anterior pituitary gland to release follicle stimulating hormone (FSH) FSH stimulates the target organ, the ovary, to prepare a follicle/ egg/estrogen Egg prepared? Estrogen released? Job done. Feedback to turn off the system,SO then, what is PRIMARY ovarian failuremenopause!,Over the years the o
16、varies have a preprogrammed dropout of eggs /estrogen/and follicles-less and less estrogen, the negative feedback to the pituitary gland saysSomething is wrong, I need MORE estrogen The pituitary RAMPS up its production of FSHthinking that will helpmore FSH, more FSH FSH is a diagnostic marker of menopausemore later,Historical highlight,An Italian medical student, Bruno Lunenf
