BIO 212 Endocrine Anatomy and Physiology(Laboratory #1)

This exercise is designed to correlate with and reinforce endocrine system knowledge gained in lecture. It is usually helpful for you to have your textbook in lab, to help identify glands on models and diagrams, to help you discern the histology of select glands, and to help you answer questions about specific hormones, their targets, and their actions. You are expected to read the current week’s lab handout before arriving in lab; often there simply isn’t enough time in our 2 hr labs to thoroughly review concepts and conduct the lab activities. Plan to also spend several hours per week, minimum, in open lab sessions. All information presented in the lab handouts, as well as all questions in the handout pertaining to the day’s activities are fair game as future test questions.

The basic format for this and future labs is a brief recap of the day’s topics and goals (which you should already have familiarized yourselves with before class), including experimental protocols that we will employ in lab. Following this introduction, you will work in groups of 2-4 students and collaborate on the assigned topics. It’s a good idea to quiz one another periodically. Your lab instructor is there to facilitate your learning, but not to lecture to you. He/she will be available to answer questions only after you and your group have discussed and have made a concerted effort to come up with the answer, and cannot do so or remain confused on the topic. Consider your instructor to be a last resort resource person and not the first person that you turn to for an answer. Your laboratory instructor will periodically circulate and ask you questions about the material under study. Self-motivated mastery of the subject will stay with you much longer than simple memorization of answers given to you.

Endocrine System Learning Goals Overview:

1) Be able to locate and identify all assigned endocrine glands on anatomical models and charts, and, where applicable, on the cadaver.

2) Be able to identify and differentiate histological (i.e., microscopic) sections of the pituitary gland, adrenal gland, thyroid gland, pancreas, ovary, and testes. Be able to identify specific regions, structures, and cell types contained within these glands, and describe the hormones that are produced and/or released from these specific locales.

3) Describe the specific hormones produced by all assigned endocrine glands, the physiological stimuli that causes their release, their target organs, and their primary effects on target tissues. You should be extremely familiar with the table of hormones on page 645 (Table 17.4) and pages 657-658 (Table 17.5); this will prove essential for both laboratory and lecture success.

4) Be able to describe pathological states that occur with abnormal secretion of select hormones (Section 17.7, pp.671-676 in text).

Part I. Gland Gross Anatomy: Torso Model, Skull and Brain

Torso model:  All the structures may not be visible on every model, but you will find all of them on at least one or more of the models.  Locate these structures: Pituitary gland, adrenal gland, thyroid/parathyroid glands, pancreas, pineal gland, kidney, testes, ovaries, liver, and mammary glands. Skull: Locate the sella turcica on the floor of the sphenoid bone. What two-part endocrine organ lies in this indented pocket (sella turcica means “Turkish saddle” Brain: Review the location of the hypothalamus, pituitary gland (usually torn off during brain removal, but you should know its general location—models will help), and the general location of the pineal gland (again, models will be helpful).

Part II. Endocrine Glands of the Female Cadaver

Try to locate the pancreas, kidneys, adrenal glands, thyroid gland, ovaries, liver, mammary glands, and uterus on the female cadaver.

Identify a kidney. What hormone from the posterior pituitary gland increases water permeability of the collecting ducts of the kidney’s nephrons when you are dehydrated, thereby reducing urine output and further water loss __________________________________?

Name an endocrine hormone produced by the kidney that stimulates the formation of erythrocytes (red blood cells) ____________________.

What gland would be located on the superior aspect of each kidney? (Look at the right kidney of the cadaver for a fragment of this gland which remains)____________________________. Name two catecholamines (________________________________ and ______________________________), and three steroid hormones (______________________________, and______________________________, and __________________________produced in this gland.

While the regions of this gland on this cadaver cannot be identified (but will be examined histologically), which of these five hormones are produced in the outer cortex, and which are produced by the inner medulla?

Identify the pancreas. Name two endocrine hormones that are produced here which regulate blood glucose levels. Which hormone causes an increase (_____________________), and which causes a decrease (___________________________) in blood glucose respectively? Name one exocrine secretion of the pancreas (__________________________). What is the difference between the exocrine and endocrine function?

Identify the thyroid gland. What are two hormones produced by the thyroid gland (______________________, and _____________________) ? Identify the location of the parathyroid glands. What is one hormone produced by the parathyroid glands (__________________________)? What is the function of this hormone___________________________________________________? Where would you expect to locate the thymus if you could find the vestige that remains in an adult?

On the female cadaver identify the bladder and ureters that carry urine from the kidneys to the bladder. Identify the thick-muscular uterus which lies superior to (on top of) the bladder. The kidney has endocrine functions, too, but we’ll discuss this in more detail later in the semester. What endocrine hormone of the posterior pituitary causes uterine contractions during parturition (childbirth)_________________? While both right and left uterine tubes are present on the uterus, look mostly at the uterine tube on the right side of the body where it is easier to see. The uterine tube ends at what pinkish structure_______________? This woman was in her 80s at death, would you expect to find follicles and ovulation of ova from this ovary? What steroid hormone is produced by the ovarian follicle leading up to ovulation_________________________?

Part III. Endocrine Histology

Make drawings for this section. Please draw what you actually see on the slide, not what is pictured in the textbook.  Also, some slides may be missing details or may just be of poor quality, so be sure to look at more than one slide.  Borrow a slide from another tray, but be sure to return it to the appropriate tray when you are done.  There are excellent histology websites available online.  Also have your textbook open to the right page to view the diagrams.

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Pituitary gland slide #34 (Text p. 644-647; Fig.17.4 and Fig. 17.5)   Find this slide in your tray and look at the slide first with your naked eye.  Put it on a piece of white paper and notice that it has two distinct parts.  The darker part is the anterior portion of the pituitary gland called the adenohypophysis.   (The hypophysis is another name for the pituitary gland).   The prefix adeno- means glandular, so this is the glandular, epithelial, secreting part of the pituitary and is formed embryologically as an invagination of oral epithelium from the roof of the mouth).  Use your textbook to find out which six hormones are secreted by the adenohypophysis.   The lighter colored part of the pituitary gland is the neurohypophysis, containing lighter colored nervous tissue. This tissue develops embryologically from neural tissue.  It stores and releases two hormones that are made in the hypothalamus.  What are the hormones released from the neurohypophysis ? ______________________________, and _________________________________.

Now, under the microscope, scan the whole slide at low power of magnification (text: Fig. 17-5). Note the adenohypophysis has a cuboidal epithelial-like appearance, while the neurohypophysis has more open spaces and stringy-looking, fibrous structures.  That is because the neurohypophysis is composed of neural tracts from the hypothalamus.  Define what is meant by tract.  Draw a picture of the overall appearance of a section through the pituitary gland.  Shade the neurohypophysis and adenohypophysis different colors and label them.  Remember the pituitary is connected by the stalk (the infundibulum) to the hypothalamus and that hypothalamic neurons release oxytocin and ADH (antidiuretic hormone, or vasopressin) from axonal endings in the posterior pituitary. Also remember that anterior pituitary activity is controlled by a set of releasing hormones and inhibiting hormones that are dumped into a “portal” system of blood vessels at the hypothalmus (e.g., Growth Hormone-Releasing Hormone, Prolactin-Inhibiting Hormone, Prolactin-Releasing Hormone). These regulating hormones diffuse into the blood of the hypothalamus, travel via the hypothalamo-hypophyseal portal vessels to the pituitary, and then diffuse out of fenestrated capillaries (containing large gaps in the wall) into the anterior pituitary. These releasing hormones tell the anterior pituitary to release its specific hormones (e.g., growth hormone) into the blood for delivery to the body. They are called tropic hormones.

Thyroid gland slide #4 (Text 650-651; Fig.17.9) Examine it under the microscope at low power.  The thyroid gland helps control your metabolic rate and this tissue has a distinctive appearance in that it consists of numerous round "sacs" containing a clear, pink or purple substance.  Each sac is called a thyroid follicle and the colored substance inside is called colloid.   As you look at the slide under higher power notice that the outer border of each follicle is made up of a single layer of cells called follicular cells.  This layer of tissue is simple cuboidal epithelium.  This epithelium can be quite flattened if the cells are physiologically inactive and not producing thyroglobin. (Be sure and go back and review what an epithelial tissue is and where it is found in the body.)  The follicular cells make two of the hormones produced by the gland, both of which function similarly.  What are they? 

Look carefully at the spaces between some of the follicles.  You may see cells in-between the follicles that are not part of any follicle.  These in-between cells are parafollicular cells because they are between, and next to, the follicular cells.  These cells are called C-cells because they produce the hormone called ___________________. Hint: it begins with a “C”. What is the function of this hormone? _________________________________________________

Draw a picture of the histology of the thyroid gland.   Label a single follicle, the follicular cells, the parafollicular/C cells, and the colloid. What is the importance of this colloid? _______________________________________ 

Adrenal gland slide #36 (Text 652-653; Fig. 17.11).  Find this slide in the tray labeled number 36.  As you did with the pituitary slide, look first at this slide with your naked eye.  Put it on a piece of white paper and notice that it has a thicker, darker outer region around a thin, lighter inner region.  The outer part, the adrenal cortex (cortex means "bark") surrounds an inner adrenal medulla.  The histological/ embryological situation for the adrenal gland is similar to that of the pituitary gland.  The darker-colored cortex is derived from an epithelial tissue and produces many different hormones all of which belong to

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the same major chemical type of hormone.  What chemical type are these hormones____________________?  The lighter-colored adrenal medulla is modified nervous tissue innervated by sympathetic fibers which stimulate the secretion of two different hormones from the adrenal medulla.  What are these hormones? __________________________and _________________________________. 

Draw a picture of a section of the adrenal gland.   Shade the cortex and medulla different colors.  Label them clearly.   Attempt to identify the three layers of the adrenal cortex; from outside in, the zona glomerulosa, zona fasciculate, and zona reticularis—this may be difficult, depending on the slide quality. Try to find region of the adrenal gland where it is sectioned through the middle of the gland, and you can see from the adrenal capsule all the way to the medulla See Fig. 17.11 in your text. Probably the most prominent feature is between the zona reticularis and medulla where one sees numerous capillaries and venules with blood cells.) What hormones are produced by each of the 3 layers of the adrenal cortex? Why would you expect endocrine gland

Pancreas slide #20 (Text 654; Fig 17.12).  Find this slide in your slide tray as slide number 20.  The pancreas is a double organ in the sense that it has exocrine parts and endocrine parts.  The exocrine part of the pancreas makes up most of the organ. It has a clumpy appearance of small units, or collections of cells called exocrine acini.  It supplies digestive fluid through the pancreatic ducts to the digestive system.  (Recall that exocrine glands have ducts and secrete their products out to a surface of a structure through these ducts as per the definition of “exo” crine.)  The endocrine part consists of small islands of tissue that secrete hormones directly into the blood.  The endocrine parts are called pancreatic islets.   Scan the slide on low power looking for lighter-colored pancreatic islets among the exocrine acini.  Some slides do not show the pancreatic islets well.  If yours does not, borrow a slide from another tray. What are the two major glucose-controlling hormones that the pancreatic islets secrete?

Draw a picture of a small section of the pancreas showing both of the above features (exocrine acini and pancreatic islets).  Label the pancreatic islet and exocrine acinus. 

Ovary slide #40 (Text 655; Fig. 17.13a), find this slide in a tray at the front of the room.  The ovaries used to make these slides came from cats that were mature and ready to produce eggs.  Scan the slide at low power.  In the outer part of the ovary you will find a number of round structures called ovarian follicles.  They will range in size from small to large.  The larger ones have a fluid-filled space.  In many of the follicles you will be able to see a developing ovum or egg cell.  At the time of ovulation the follicle ruptures and releases the mature ovum.  The wall of the ovarian follicle consists of granulosa cells.  After a mature follicle releases its ovum it develops into a yellow structure called a corpus luteum.  These slides do not have corpora lutea (pleural form of corpus luteum) on them, but note its scalloped structure in the textbook. What is the main hormone produced by the granulosa cells of the ovarian follicle?  (This hormone belongs to the estrogen group of hormones.)   What hormone is produced by the corpus luteum, hint: this hormone is produced after ovulation and is potentially involved in maintaining pregnancy?  Draw a picture of a whole ovary.  Show small and large ovarian follicles.  Draw a circle around one and label it.  Label granulosa cells and an ovum.  On this diagram, only, "cheat" and draw a picture of a corpus luteum out of the textbook.

Testis slide #12 (Text 655; Fig. 17.13b), it consists of many tiny, coiled structures called seminiferous tubules.  Most of the tubules are cut in cross section.  The tubules produce sperm cells from spermatogonial stem cells located at the outer part of the tubule. Spermatocytes produced by the spermatogonia become embedded in sustentacular (Sertoli) cells and divide to eventually for sperm cells. Mature sperm cells are released into the lumen (cavity) of the tubule. Recall that spermatogonia divide by mitosis and spermatocytes divide by meiosis, not mitosis. You may be able to see some of the sperm cells with very small heads and long flagella for tails.  The endocrine cells we want to look at are in the spaces between the seminiferous tubules.  They are called interstitial cells. Notice that the cytoplasm of these cells appears “foamy”, which is characteristic of cells that secrete steroids. What hormone do these interstitial cells produce?   Draw a picture of a section through the testis.   Label a seminiferous tubule.  Also label developing sperm cells and interstitial cells. 

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Part IV. Histology In-class Questions and Exercise Sheet

When you make drawings of tissues and organs in this section, please draw what you actually see on the slide, not what is pictured in the textbook.  Also, some slides may be missing or of poor quality.  If so borrow a slide from another tray, just remember to put them back. 

A. Pituitary gland slide (# 34 for human hypophysis). Use your textbook to find out which six hormones are secreted by the adenohypophysis? List the hormones and their primary functions:

1.________________________________________________________________________

2._________________________________________________________________________

3._________________________________________________________________________

4._________________________________________________________________________

5._________________________________________________________________________

6._________________________________________________________________________

The lighter colored part of the pituitary gland is the neurohypophysis, containing lighter-colored nervous tissue.  It stores and releases two hormones made in the hypothalamus.  What are they and what are their primary functions?

1._____________________________________________________________________________

2._____________________________________________________________________________

B. Thyroid gland slide (slide #4).  The follicular cells make two of the hormones produced by the gland.  What are they?_____________________ and _________________________ . According to the readings in your text, these hormones are responsible for what action in the body?

_____________________________________________________________________________

What dietary mineral is required for proper thyroid function ? ____________________________

There are some cells located between the follicles that are called parafollicular cells.  These cells are called C-cells because they produce the hormone:___________________________. Is the function of this hormone different from the ones above? Explain your answer.

______________________________________________________________________________

______________________________________________________________________________

C. Adrenal gland slide (slide # 36). The darker-colored adrenal cortex is epithelium and produces many different hormones all of which belong to the same major chemical classification.  What is this classification type? ___________________________

What are the three major groups of hormones produced by the different regions of the adrenal cortex, and what are their primary functions ?

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1._________________________________________________________________________________

2._________________________________________________________________________________

3._________________________________________________________________________________

The lighter-colored adrenal medulla is modified nervous tissue which secretes two different hormones.  What are they?  _________________________ and ________________________________. What is their primary function ?

D. Pancreas slide (slide #20).  What are the two major glucose-regulating hormones that the pancreatic islets secrete, and what are their primary functions ?

1.________________________________________________________________________________

2.________________________________________________________________________________

E. Ovary slide (slide up at front of lab).  What is the main hormone produced by the granulosa cells of the ovarian follicle?  (This hormone belongs to the estrogen group of hormones.) _________________________ 

If you look at the graph associated with the physiology instructions you will see that this hormone is the dominant one during the follicular phase of the ovarian cycle and is responsible for causing the LH surge.

What hormone is produced by the corpus luteum? ____________________________ . This is the hormone of pregnancy.  hCG from the physiology exercise is responsible for keeping these endocrine structures functional during the first weeks of pregnancy while the placenta is growing.  Later the placenta will secrete most of the hormones associated with pregnancy. We will cover this in much greater detail when we study the reproductive system.

Draw a picture of a whole ovary.  Show small and large ovarian follicles.

F. Testis slide (slide # 12). The endocrine cells you need to focus on are between the seminiferous tubules. They are called interstitial cells.  What hormone do these cells produce? ________________________________

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CHALLENGE YOURSELF:

1. Following hypophyectomy (removal of the pituitary gland), which of the conditions will NOT occur:a.) sterilityb) hypothyroidismc) diabetes mellitusd) diabetes insipidus

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2. The adrenal cortex secretes: 3. Glycogenesis is governed by:a. glucocorticoids a. glucagonb. mineralocorticoids b. insulinc. androgens c. growth hormoned. all of the above d. cortical steroids

4. Which of the following is NOT essential for life? 5. Cushing Syndrome is due to:a. parathyroids a. excess cortisolb. anterior pituitary b. excess growth hormonec. adrenal cortex c. hypoparathyroidismd. adrenal medulla d. epinephrine oversecretion

6. ADH hyposecretion leads to: 7. Which is primarily exocrine tissue?a. goiter a. pancreasb. diabetes insipidus b. thyroidc. dwarfism c. parathyroidd. adrenogenital syndrome d. adenohypophysis

8. Which mineral is critical to proper thyroid function? 9. Norepinephrine is produced by the:a. iron a. zona glomerulosab. iodine b. zona reticularisc. magnesium c. adrenal medullad. selenium d. neurohypophysis

10. An autoimmune attack of the TSH receptor causes: 11. TSH is produced by the:a. Addison’s disease a. thyroid glandb. Acromegaly b. parathyroid glandc. Hypoparathyroidism c. adenohypophysisd. Grave’s disease d. neurohypophysis

12. Melatonin is produced by the:a. pineal glandb. adenohypophysisc. testesd. placenta

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