LAB 11
ENDOCRINE SYSTEM
Objective: To understand the important role of the endocrine system in regulating the activity of
body cells. To explain the function of the various hormones and the results of their hyposecretion
or hypersecretion.
The endocrine system works with the nervous system in controlling much of what goes on in the body. Review these
basic facts regarding the endocrine system:
1.
It is composed of glands.
2.
Glands produce hormones.
3.
Hormones are chemical messengers that are released directly into the blood (no ducts).
4.
Hormones work at specific locations (targets).
5.
Hormones work by attaching to receptors at the target.
6.
Receptors may be on the target cell membrane or inside the target cell (intracellular).
7.
The pituitary is often called the master gland of the body since it oversees much of the action of other glands.
8.
The pituitary gland is controlled by the hypothalamus.
9.
The pituitary gland is functionally and structurally related to the hypothalamus.
10. Structural relationships include direct axonal connections between the hypothalamus and the posterior pituitary
and a specialized “portal” system (a capillary network).
11. Functional relationships include release of releasing and inhibiting hormones by the hypothalamus which affect the
anterior pituitary and the production of oxytocin and ADH by the hypothalamus which are stored and released as
needed by the posterior pituitary.
A. Gross Anatomy of the Endocrine System
Using models and books, name and locate all of the endocrine glands. Fill in the table below.
GLAND
HORMONES PRODUCED
Anterior pituitary
Posterior pituitary
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B. Histology of Selected Endocrine Glands
Obtain slides of these glands and observe the histological features listed. Be able to identify each tissue.
1.
Thyroid gland
2.
3.
a.
Find follicles. What is produced by the follicles? How?
b.
Find parafollicular cells. What is produced here?
c.
What chemical element is critical in the production of the major thyroid hormones?
d.
What is the target of the hormone produced by the parafollicular cells?
Parathyroid gland
a.
What is the physical relationship between this gland and the thyroid?
b.
Normally, how many parathyroid glands are there?
c.
How can one distinguish the parathyroid gland from the thyroid?
d.
What hormone is produced by the parathyroid gland? What is its target?
Adrenal gland
a.
Differentiate between the cortex and the medulla.
b.
How many zones are present in the cortex? Identify them.
c.
What hormones are produced in each of the cortical zones? (Fill in the following table).
CORTICAL ZONE
HORMONE CLASS
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SPECIFIC HORMONE/S
4.
d.
What is the importance of the medulla?
e.
What histological feature allows the medulla to do its work quickly and efficiently?
f.
Why is the medulla often referred to as a “postganglionic sympathetic neuron.”
Islets of Langerhans (Pancreas)
a.
How many cell types make up the Islets of Langerhans?
b.
What hormones are produced by each of the cell types?
CELL TYPE
c.
5.
HORMONE
What is the major function of the Islets of Langerhans?
Pituitary gland
a.
How can one distinguish between the anterior and posterior pituitary? Why?
b.
What hormones are produced by the posterior pituitary?
c.
What are the chemical “signals” that cause the anterior pituitary to release its hormones?
d.
Where do these “signals” come from?
e.
How do these “signals” get to the anterior pituitary?
C. Endocrine Table- Complete the following table of endocrine glands.
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ENDOCRINE GLANDS: REGULATION AND EFFECTS
GLAND
HORMONE
STIMULATED
INHIBITED
Antidiuretic Hormone (ADH)
[supraoptic nucleus of
hypothalamus]
POSTERIOR
PITUITARY
Oxytocin
[paraventricular nucleus of
hypothalamus]
Growth Hormone (GH)
Prolactin (PRL)
ANTERIOR
PITUITARY
Thyroid Stimulating
Hormone
(TSH)
Adrenocorticotropic
Hormone
(ACTH)
Follicle Stimulating Hormone
(FSH)
Luteinizing Hormone (LH)
THYROID
GLAND
PARATHYROID
GLAND
Thyroxin
(produced by follicular cells)
Calcitonin
(produced by parafollicular
cells)
Parathyroid Hormone (PTH)
(secreted by chief cells)
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TARGET
EFFECTS OF HORMONE
ENDOCRINE GLANDS: REGULATION AND EFFECTS
GLAND
HORMONE
STIMULATED
INHIBITED
Glucocorticoids
(Cortisol)
ADRENAL
GLAND (Cortex)
Mineralocorticoids
(Aldosterone)
Gonadocorticoids
(sex hormones)
ADRENAL
GLAND (Medulla)
Epinephrine &
Norepinephrine
Insulin
(ß cells in islets of
Langerhans)
PANCREAS
TESTES
Glucagon
(alpha cells in islets of
Langerhans)
Testosterone
Estrogen
OVARIES
Progesterone
PINEAL GLAND
Melatonin
THYMUS GLAND
Thymic Hormones
(Thymopoietins &
Thymosins)
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TARGET
EFFECTS OF HORMONE