BIO 211 LAB Test 1
Terms in this set (45)
It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) covered by a dural fold (diaphragma sellae). The pituitary is functionally connected to the hypothalamus by the median eminence via a small tube called the infundibular stem (Pituitary Stalk). The pituitary fossa, in which the pituitary gland sits, is situated in the sphenoid bone in the middle cranial fossa at the base of the brain.
Anterior Pituitary Histology
At 40x the pars distalis (A) and the pars intermedia (B) of the adenohypophysis (anterior pituitary) and the pars nervosa (C) of the neurohypophysis (posterior pituitary) can be observed. The pars tuberalis and infundibulum were not a part of this preparation. The pars distalis secretes Growth Hormone (GH), Thyroid-stimulating hormone (TSH), Adrenocorticotrophic hormone (ACTH), Follicle-stimulating hormone (FSH), Lutenizing hormone (LH),and Prolactin. The pars intermedia secretes Melanocyte-stimulating hormone (MSH). The pars nervosa stores ADH (antidiuretic hormone)and Oxytocin which were secreted by the hypothalamus.
Pituitary Gland Histology
Pituitary Gland Histology (overview)
Pituatry Gland Histology
(Anterior on the left and Posterior on the right)
Anterior Pituitary (Adenohypophysis)
Communication between the hypothalamus and the anterior pituitary occurs through chemicals (releasing hormones and inhibiting hormones) that are produced by the hypothalamus and delivered to the anterior pituitary through blood vessels. The releasing and inhibiting hormones are produced by specialized neurons of the hypothalamus called neurosecretory cells. The hormones are released into a capillary network (primary plexus) and transported through veins (hypophyseal portal veins) to a second capillary network (secondary plexus) that supplies the anterior pituitary. The hormones then diffuse from the secondary plexus into the anterior pituitary, where they initiate the production of specific hormones by the anterior pituitary. Many of the hormones produced by the anterior pituitary are tropic hormones (tropins), hormones that stimulate other endocrine glands to secrete their hormones
Posterior Pituitary (Neurohypophysis)
Communication between the hypothalamus and the posterior pituitary occurs through neurosecretory cells that span the short distance between the hypothalamus and the posterior pituitary. Hormones produced by the cell bodies of the neurosecretory cells are packaged in vesicles and transported through the axon and stored in the axon terminals that lie in the posterior pituitary. When the neurosecretory cells are stimulated, the action potential generated triggers the release of the stored hormones from the axon terminals to a capillary network within the posterior pituitary. Two hormones, oxytocin and antidiuretic hormone (ADH), are produced and released in this way.
AP: acidophil cells
The pink acidophils secrete growth hormone (GH) and prolactin (PRL)
AP: basophil cells
The dark purple basophils secrete corticotrophin (ACTH), thyroid stimulating hormone (TSH), and gonadotrophins follicle stimulating hormone-luteinizing hormone (FSH and LH)
The pale staining chromophobes have few cytoplasmic granules, but may have secretory activity.
Post. Pituitary: pituicytes
This region of the pituitary is non secretory. Its cells are neuroglial-like pituicytes
The pineal gland releases melotonin
Pineal Gland Histology
Pineal Gland Histology (close up)
The thyroid gland is found in the neck, inferior to (below) the thyroid cartilage (also known as the Adam's Apple) and at approximately the same level as the cricoid cartilage. The thyroid controls how quickly the body uses energy, makes proteins, and controls how sensitive the body should be to other hormones.
The thyroid gland participates in these processes by producing thyroid hormones, the principal ones being triiodothyronine (T3) and thyroxine (T4). These hormones regulate the rate of metabolism and affect the growth and rate of function of many other systems in the body. T3 and T4 are synthesized utilizing both iodine and tyrosine. The thyroid gland also produces calcitonin, which plays a role in calcium homeostasis
The thyroid gland is composed of many spherical hollow sacs called thyroid follicles. In this tissue section, each follicle appears as an irregular circle of cells. The type of cells, which surround the follicle are simple cuboidal epithelium. These follicles are filled with a colloid, which usually stains pink. The cells use the thyroglobulin and iodide stored in the colloid to produce the primary thyroid hormones - including thyroxine.
TG: Follicle Cells
Thyroid follicles and colloid The simple cuboidal epithelium lining the follicles produces the thyroglobulin which is stored in the colloid follicles. Later it is taken back up by these same cells, cleaved, and released as T3 & T4.
Between these follicles are the parafollicular cells which produce calcitonin.
The parathyroid consists chiefly of chief cells (duh!). The chief cells are small cells arranged into curvilinear cords. Parathyroid chief cells secrete parathyroid hormone (PTH)(again, duh!), which stimulates osteoclast activity and thus raises the blood calcium level. PTH thus works antagonistically with calcitonin (from thyroid C cells) to regulate blood calcium.
The parathyroid also contains oxyphil cells
PTG: Oxyphil Cells
The larger, purp/pink cells in the middle are oxyphil cells; they have a smaller, darker nucleus and relatively larger amount of cytoplasm than the majority of cells, which are called chief cells (pretty much surrounding the oxyphils). The significance of the oxyphil cells is not clear.
PTG: Chief Cells
Parathyroid chief cells secrete parathyroid hormone (PTH), which stimulates osteoclast activity and thus raises the blood calcium level. PTH thus works antagonistically with calcitonin (from thyroid parafollicular cells) to regulate blood calcium.
Each adrenal gland (one on top of each kidney) is separated into two distinct structures (which are encapsulated), the adrenal cortex and medulla, both of which produce hormones. The cortex mainly produces cortisol, aldosterone, and androgens, while the medulla chiefly produces epinephrine and norepinephrine.
Adrenal Gland Histology
ADG: Adrenal Cortex
Adrenal Cortex: Zona Glomerulosa
the most superficial layer of the adrenal cortex, lying directly beneath the adrenal gland's capsule. Its cells are ovoid in shape and are arranged in clusters or arches (glomus is Latin for "ball").
In response to increased potassium levels, renin or decreased blood flow to the kidneys, cells of the zona glomerulosa produce and secrete the mineralocorticoid aldosterone into the blood as part of the renin-angiotensin system. Aldosterone regulates the body's concentration of electrolytes, primarily sodium and potassium, by acting on the distal convoluted tubule of kidney nephrons to:
increase sodium reabsorption
increase potassium excretion
increase water reabsorption through osmosis
Zona Glomerulosa- produces hormone Aldosterone
Adrenal Cortex: Zona Fasciculata
sits directly beneath the zona glomerulosa. Constituent cells are organized into bundles or "fascicles".The zona fasciculata chiefly produces glucocorticoids (mainly cortisol in the human), which regulates the metabolism of glucose, especially in times of stress (e.g., part of the fight-or-flight response), it is stimulated by the hormone Adrenocortictropic Hormone [(ACTH]) which is released from the anterior portion of the pituitary and axised upon this adrenal gland. This tissue also generates a small amount of weak androgens (e.g., dehydroepiandrosterone). The main source of androgen's will come from the Zona Reticularis region
Zona Fasciculata- produces hormone Cortisol
Adrenal Cortex: Zona Reticularis
The innermost layer of the adrenal cortex, the zona reticularis sits beneath the zona fasciculata and atop the adrenal medulla.
Its cells are arranged in a network of cords (a reticulum) and have the same functions as cells of the zona fasciculata.
It is thought that the zona reticularis is the principal source of glucocorticoids and adrenal androgens, with the zona fasciculata activating only after prolonged stimulation.
Zona Reticularis- produces sex hormones Androgen
The adrenal medulla consists of irregularly shaped cells grouped around blood vessels. These cells are intimately connected with the sympathetic division of the autonomic nervous system (ANS). These adrenal medullary cells are modified postganglionic neurons, and preganglionic autonomic nerve fibers lead to them directly from the central nervous system.
Rather than releasing a neurotransmitter, the cells of the adrenal medulla secrete hormones.
Composed mainly of hormone-producing chromaffin cells, the adrenal medulla is the principal site of the conversion of the amino acid tyrosine into the catecholamines adrenaline (epinephrine), noradrenaline (norepinephrine), and dopamine
It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as an exocrine gland, secreting pancreatic juice containing digestive enzymes that pass to the small intestine. These enzymes help to further break down the carbohydrates, proteins, and fats in the chyme.
Pancreatic Islets (Islets of Langerhans)
Pancreatic islets of Langerhans are small nests of cells, arranged into curvilinear cords, scattered throughout the pancreas.
Islets are usually conspicuously paler (less intensely stained) than the Exocrine Acinar Tissue of the exocrine pancreas, but in any case islets differ markedly from exocrine pancreas in the arrangement of cells (cords rather than acini).
Pancreas: Acinar cells
Grey Cells Here
Acinar cells belong to the exocrine pancreas and secrete digestive enzymes into the gut via a system of ducts.
Pancreas: Alpha Cells
Red Cells Here
Alpha cells secrete glucagon
Pancreas: Beta Cells
Blue Cells Here
Beta cells secrete insulin
The organs that makes gametes. The gonads in males are the testicles and the gonads in females are the ovaries. The gonads are controlled hormonally by luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secreted by the anterior pituitary gland. The anterior pituitary gland's excretion of LH and FSH are, in turn, controlled by the hypothalamus' gonadotropin-releasing hormone.
"A" marks the primordial or primary follicles in this image. "B" is a Graafian follicle with its oocyte. Estrogen and progesterone are produced by the follicles under the influence of FSH and LH from the pituitary gland (hypophysis). The germinal epithelium (a single layer of cells surrounding this organ) is not easily seen at this magnification.
The testis is composed of tightly coiled seminiferous tubules (A). Two are seen here in perfect cross section. ( Cut on other plains they may appear very elongated.) Spermatogenesis occurs in the seminiferous tubule resulting in the production of sperm. Between these tubules are interstitial cells (B), the producers of testosterone. The pituitary hormones FSH and LH are essential for proper functioning of this organ.
The thymus gland releases thymopoietins and thymosin to activate T-cells. It is usually considered an gland of the lymphatic system.
Thymus Gland Histology
the thymus can be divided into a central medulla and a peripheral cortex which is surrounded by an outer capsule. The cortex and medulla play different roles in the development of T-cells. Cells in the thymus can be divided into thymic stromal cells and cells of hematopoietic origin (derived from bone marrow resident hematopoietic stem cells). Developing T-cells are referred to as thymocytes and are of hematopoietic origin. Stromal cells include thymic cortical epithelial cells, thymic medullary epithelial cells, and dendritic cells.
Red Blood Cells
the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen (O2) to the body tissues via the blood flow through the circulatory system. They take up oxygen in the lungs and release it while squeezing through the body's capillaries.
These cells' cytoplasm is rich in hemoglobin, an iron-containing biomolecule that can bind oxygen and is responsible for the blood's red color.
cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a hematopoietic stem cell. Leukocytes are found throughout the body, including the blood and lymphatic system.
Neutrophils defend against bacterial or fungal infection and other very small inflammatory processes that are usually first responders to microbial infection; their activity and death in large numbers forms pus.
Eosinophils primarily deal with parasitic infections and an increase in them may indicate such. Eosinophils are also the predominant inflammatory cells in allergic reactions. The most important causes of eosinophilia include allergies such as asthma, hay fever, and hives; and also parasitic infections. Generally their nucleus is bi-lobed. The cytoplasm is full of granules which assume a characteristic pink-orange color with eosin stain.
Basophils are chiefly responsible for allergic and antigen response by releasing the chemical histamine causing inflammation. The nucleus is bi- or tri-lobed, but it is hard to see because of the number of coarse granules which hide it. They are characterized by their large blue granules
Lymphocytes are much more common in the lymphatic system. Lymphocytes are distinguished by having a deeply staining nucleus which may be eccentric in location, and a relatively small amount of cytoplasm. The blood has three types of lymphocytes: B cells, T cells, Natural Killer Cells
Monocytes share the "vacuum cleaner" (phagocytosis) function of neutrophils, but are much longer lived as they have an additional role: they present pieces of pathogens to T cells so that the pathogens may be recognized again and killed, or so that an antibody response may be mounted. Monocytes eventually leave the bloodstream to become tissue macrophages which remove dead cell debris as well as attacking microorganisms. They have the kidney shaped nucleus and are typically agranulated. They also possess abundant cytoplasm.
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