Chapter 13 - Endocrine Glands lab

Vascular cast of a thyroid gland (SEM). Many of the follicles are cut in cross section. Each follicle is encapsuled by a "basket-like" network of capillaries. The capillary network is often in common with adjacent one.

thyroid

A. Pituitary gland B. Parathyroid gland C. Adrenal glands D. Testis E. Thyroid gland F. Pancreatic islets G. Ovaries

A. Divided into two parts: anterior and posterior; secretes many hormones affecting the physiology of the human body; anterior secretes growth hormones, prolactin, adrenocorticotropic hormone, thyroid stimulating hormone, follicle stimulating hormone, and luteinizing hormone; posterior secretes antidiuretic hormone, and oxytocin B. Secretes parathyroid hormone that increases the amount of Ca2+ in the blood and phosphate levels C. Secretes hormones adrenaline and steroids aldosterone and cortisol; secretes either norepinephrine or epinephrine (adrenalin), which serves as hormones for the body to prepare itself for stressful situations D. Secretes steroid testosterone and regulates development of male characteristics E. Secretes hormones influencing metabolic rate, protein synthesis, and calcium metabolism; secretes thyroxine T3 and T4 which controls metabolic rate and growth F- Secretes hormones that regulate the levels of glucose and lipid metabolism; secretes hormone somatostatin, which is produced by ∂-cells and it inhibits secretion of insulin and glucagon; contains glucogen-secreting ß cells, which increases blood sugar, and insulin-secreting ß cells, which decreases blood sugar G- Secretes steroids estrogen and progesterone which regulates changes in menstrual cycle and during pregnancy

A. Pituitary gland B. Parathyroid gland C. Adrenal glands D. Testis E. Thyroid gland F. Pancreatic islets G. Ovaries

A. Pituitary gland B. Parathyroid gland C. Adrenal glands D. Testis E. Thyroid gland F. Pancreatic islets G. Ovaries

Afferent Blood Vessels - penetrate the capsule and branch into sinusoids that supply the cortex and medulla.

Adrenal Gland

Capsule - enclosed by a thin layer of connective tissue.

Adrenal Gland

Cortex - cells that synthesize and secrete steroid hormones.

Adrenal Gland

Nerves - cross-sections are seen in the capsule.

Adrenal Gland

7. A. What endocrine gland does this specimen belong to? What hormone does this gland produce? What are the hormone(s) primary function(s)? . Thyroid -Calcitonin - Thyroglobulin that gets endocytosed into the active forms of Thyroxine (T3 and T4) - Calcitonin lowers blood calcium levels - Thyroxine (T3 and T4) hormones control metabolic rate and growth, even fetal growth. B. What structure is this? . Thyroid follicles surrounded by simple cuboidal follicular cells and capillaries. Also the gel like mass, colloid, which is made up of thyroglobulin and bound thyroid hormones. The clear spaces around the colloids are the shrinkage artifacts.

C. Give a brief description of the following structures: . Colloid: Is the gel like mass that each lumen of each follicle is filled with. It is made up of mostly thyroglobulin protein and bound thyroid hormones like thyroxin or triiodothyronine. It also has a clear space around it known as the shrinkage artifact. Follicular cells: These are cells ranging from simple cuboidal to columnar epithelium and line the follicles. The type that lines them depends on the functional activity. They are also responsible for secreting thyroid hormones when active.

Gonadotropes are cells in the anterior pituitary that produce gonadotropins, including luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH stimulates the Leydig cells in the testes to secrete testosterone. This increase in the blood levels of testosterone down regulates LH production. When the gonads are removed by castration, the absence of this negative feedback causes hypertrophy of the gonadotropes in the anterior pituitary.

Nucleus (blue) Nucleolus (dark blue) Nuclear Envelope (purple) Mitochondria (red) Rough Endoplasmic Reticulum (cyan) - hypertrophy from large amounts of newly synthesized gondatropins Secretion Granules (black) Cytoplasm (green)

Mammotrophs are cells in the anterior pituitary that produce prolactin (PRL). They release PRL in response to thyrotropin-releasing hormone and are inhibited by dopamine. Other regulators include estrogen and progesterone. PRL stimulates lactation by the mammary gland. Mammotrophs during lactation are characterized by large, round to oval secretory granules.

Nucleus (blue) / Nuclear Envelope (purple) Golgi Apparatus (yellow) - well-developed when actively secreting Mitochondria (red) Rought Endoplasmic Reticulum (cyan) - abundant throughout the cytoplasm Secretion Granules (black) Cytoplasm (green)

Gonadotropes are cells in the anterior pituitary that produce gonadotrophs, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This cell secretes FSH/LH in response to gonadotrophin-releasing hormone (GnRH) and is inhibited by sex steroids (androgens and estrogen). Gonadotropes contain abundant smaller, secretion granules and distended rough endoplasmic reticulum.

Nucleus (blue) Nucleolus (dark blue) Nuclear Envelope (purple) Golgi Apparatus (yellow) - well-developed Mitochondria (red) Rought Endoplasmic Reticulum (cyan) - distended vesicular elements Secretion Granules (dark green) Cytoplasm (green)

Gonadotroph Gonadotropes are cells in the anterior pituitary that produce gonadotropins, including luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH stimulates the Leydig cells in the testes to secrete testosterone. This increase in the blood levels of testosterone down regulates LH production. When the gonads are removed by castration, the absence of this negative feedback causes hypertrophy of the gonadotropes in the anterior pituitary.

Nucleus (blue) Nucleolus (dark blue) Nuclear Envelope (purple) Mitochondria (red) Rough Endoplasmic Reticulum (cyan) - hypertrophy from large amounts of newly synthesized gondatropins Secretion Granules (black) Cytoplasm (green)

Thyrotrophs are cells in the anterior pituitary that produce thyroid stimulating hormone (TSH). They release TSH in response to thyrotropin releasing hormone (TRH) and are inhibited by thyroid hormones triiodothyronine (T3) and thyroxine (T4). Thyrotrophs are characterized by small, round secretory granules.

Nucleus (blue) Nucleolus (dark blue) Nuclear Envelope (purple) Mitochondria (red) Rought Endoplasmic Reticulum (cyan) Secretion Granules (black) - most are found adjacent to the plasma membrane Cytoplasm (green)

Somatotrophs Somatotrophs are cells in the anterior pituitary that produce growth hormone (GH). They release GH in response to growth hormone releasing hormone and are inhibited by somatostatin. GH stimulates body growth, especially growth of the epiphyseal cartilages.

Nucleus (blue) Nucleolus (dark blue) Nuclear Envelope (purple) Mitochondria (red) Rought Endoplasmic Reticulum (cyan) Secretion Granules (black) Cytoplasm (green)

What endocrine gland does this specimen belong to? Why is it often referred to as the "master gland"?

The pituitary gland. It's often referred to as the master gland because it produces hormones that regulate the other endocrine glands in the body, and it also has direct effects on its target tissue/organ.

Zona fasciculata Zona reticularis Sinusoidal capillaries Zona glomerulosa

Zona glomerulosa

The endocrine system is composed of glands that synthesize and secrete products, called hormones, directly into the blood rather than through a duct. Hormones are transported throughout the body where they influence only those cells that have receptors for that hormone.

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