Histology of Endocrine Organs Flashcards
Endocrine Gland Organization
- _ cells (lacking free surface) arranged as _/_ and some as isolated individual cells
- Derived from epithelia
- Well vascularized - vessels often have _ endothelium
Endocrine Gland Organization
- Epithelioid cells (lacking free surface) arranged as Cords/Follicles and some as isolated individual cells
- Derived from epithelia
- Well vascularized - vessels often have Fenestrated endothelium
Anatomy of Pituitary Gland
- Anterior pituitary ( _ ) constitutes 80% of gland - comprised of _ epithelial cells controlled by _ released from hypothalamus
- Posterior pituitary ( _ ) comprised of axons from hypothalamus and support cells
- Axons carry _ and _ for storage and release
Anatomy of Pituitary Gland
- Anterior pituitary (Adenohypophysis) constitutes 80% of gland - comprised of Glandular epithelial cells controlled by Neurohormones released from hypothalamus
- Posterior pituitary (Neurohypophysis) comprised of axons from hypothalamus and support cells
- Axons carry ADH and Oxytocin for storage and release
Microscopic Appearance of Pituitary
Major Cell Types in Anterior Pituitary
- _ cells - secrete GH
- _ cells - secrete TSH regulating thyroid gland secretion
- _ cells - secrete ACTH and MSH
- ACTH stimulates adrenal cortex to secrete stress-related hormones and mediate metabolism
- MSH stimulates melanocytes to produce melanin
- _ cells - secrete FSH and LH that act on gonads
- _ cells - secrete Prolactin that stimulates milk production
Major Cell Types in Anterior Pituitary
- Somatotropic cells - secrete GH
- Thryotropic cells - secrete TSH regulating thyroid gland secretion
-
Corticotropic cells - secrete ACTH and MSH
- ACTH stimulates adrenal cortex to secrete stress-related hormones and mediate metabolism
- MSH stimulates melanocytes to produce melanin
- Gonadotropic cells - secrete FSH and LH that act on gonads
- Mammotropic cells - secrete Prolactin that stimulates milk production
Cells of Pars Distalis (Anterior Pituitary)
- _ (lighter staining)
- Somatotrophs - GH
- Mammotrophs - Prolactin
- _ (darker staining)
- Corticotrophs - ACTH
- Thyrotrophs - TSH
- Gonadotrophs - FSH/LH
- Chromotrophs - unknown function
- Sinusoidal (fenestrated) capillaries
Cells of Pars Distalis (Anterior Pituitary)
-
Acidphils (lighter staining)
- Somatotrophs - GH
- Mammotrophs - Prolactin
-
Basophils (darker staining)
- Corticotrophs - ACTH
- Thyrotrophs - TRH
- Gonadotrophs - FSH/LH
- Chromotrophs - unknown function
- Sinusoidal (fenestrated) capillaries
Pars Intermedia
- Between pars _ and pars _
- Rudimentary in adults and function unknown
- Small _ and colloid-filled follicles lined by cuboidal epithelium
- Frequently has cleft (remnant of lumen of _ pouch)
Pars Intermedia
- Between Pars Distalis and Pars Nervosa
- Rudimentary in adults and function unknown
- Small Basophils and colloid-filled follicles lined by cuboidal epithelium
- Frequently has cleft (remnant of lumen of Rathke’s pouch)
Pars Nervosa
- Continues with median eminence of hypothalamus via _ _
- Does not manufacture hormones, rather stores and releases them from axon terminals
- Consists of:
- Hypothalamic unmyelinated axons
- _ bodies - expanded axonal nerve terminals storing ADH/Oxytocin
- _ (glia-like) supporting the nerver fibers
- _ capillaries
- Hypothalamic unmyelinated axons
Pars Nervosa
- Continues with median eminence of hypothalamus via Infundibular Stalk
- Does not manufacture hormones, rather stores and releases them from axon terminals
- Consists of:
- Hypothalamic unmyelinated axons
- Herring bodies - expanded axonal nerve terminals storing ADH/Oxytocin
- Pituicytes (glia-like) supporting the nerver fibers
- Fenestrated capillaries
- Hypothalamic unmyelinated axons
Infundibulum
- Suspends pituitary gland from hypothalamus
- _ portion (infundibular stalk) - part connecting the pars _ and _ _ of hypothalamus
- Consists of unmyelinated axons (nerve body in hypothalamus, terminals in pars nerovsa)
- _ portion - surrounding pars _ enveloping the infundibular stalk. May form a partial or total collar
- Consists of numerous cuboidal cells arranged in cords
Infundibulum
- Suspends pituitary gland from hypothalamus
-
Neural portion (infundibular stalk) - part of neurohypophysis connecting the Pars Nervosa and Median Eminence of hypothalamus
- Consists of unmyelinated axons (nerve body in hypothalamus, terminals in pars nerovsa)
-
Adenohypophysis portion - surrounding Pars Tuberalis enveloping the infundibular stalk. May form a partial or total collar
- Consists of numerous cuboidal cells arranged in cords
Blood Supply to Hypophysis:
Hypothalamo-Hypophyseal Portal System
Posterior Pituitary Gland: Hypothalamo-Hypophyseal Tract
- _ - targets the kidney; regulates sodium and water retention
- _ - targets uterine smooth muscle and stimulates lactation; induces birth. May be involved in sexual arousal and pair and social bonding.
Posterior Pituitary Gland: Hypothalamo-Hypophyseal Tract
- ADH - targets the kidney; regulates sodium and water retention
- Oxytocin - targets uterine smooth muscle and stimulates lactation; induces birth. May be involved in sexual arousal and pair and social bonding.
Pineal Gland
- Out pocketing of diencephalon’s roof of 3rd ventricle
- Flatten cone-shaped, 3-5 mm diameter
- Role in growth, development and _ rhythms
- Covered with pia mater
- Synthesizes _ and serotonin
- Consists of:
- _
- Neuroglia
- Calcified granular material (brain sand)
- Ca3(PO4)2 crystals located intercellular spaces showing up beginning early childhood; important radiogenic marker (for midline brain; secreted by pinealocytes)
Pineal Gland
- Out pocketing of diencephalon’s roof of 3rd ventricle
- Flatten cone-shaped, 3-5 mm diameter
- Role in growth, development and Circadian rhythms
- Covered with pia mater
- Synthesizes Melatonin and serotonin
- Consists of:
- Pinealocytes
- Neuroglia
- Calcified granular material (brain sand)
- Ca3(PO4)2 crystals located in intercellular spaces showing up beginning early childhood; important radiogenic marker (for midline brain; secreted by pinealocytes)
Thyroid Anatomy and Blood Supply
- Butterfly-shaped, bi-lobed endocrine gland just below larynx and anterior to trachea
- Blood supply is from the _ _ vessels and _ _ vessels
Thyroid Gland and Blood Supply
- Butterfly-shaped, bi-lobed endocrine gland just below larynx and anterior to trachea
- Blood supply is from the superior thyroid vessels and inferior thyroid vessels
Microscopic Anatomy of Thyroid
- Characterized by structures called _ consisting of a layer of _ cells (simple cuboidal to columnar epithelium) surrounding a fluid called _
- Colloid contains _, a storage form of the thyroid hormones, _ and _ (iodine-containing hormones)
- Only gland to store hormone outside the cell. Thyroid hormones control basal metabolism, O2 usage, body temperature, etc.
Microscopic Anatomy of Thyroid
- Characterized by structures called follicles consisting of a layer of follicular cells (simple cuboidal to columnar epithelium) surrounding a fluid called colloid
- Colloid contains thyroglobulin, a storage form of the thyroid hormones, T3 and T4 (iodine-containing hormones)
- Only gland to store hormone outside the cell. Thyroid hormones control basal metabolism, O2usage, body temperature, etc.
Parafollicular C Cells
- Lie just outside the follicles
- Secrete _ when blood levels of calcium are high
- Lowers circulating calcium levels by:
- Stimulating secretion by kidneys
- Decreasing the calcium-releasing activity of osteoclasts
- Increasing osteogenesis by osteoblasts
Parafollicular C Cells
- Lie just outside the follicles
- Secrete Calcitonin when blood levels of calcium are high
- Lowers circulating calcium levels by:
- Stimulating secretion by kidneys
- Decreasing the calcium-releasing activity of osteoclasts
- Increasing osteogenesis by osteoblasts
Parathyroid Glands
- Small ovoid glands lying on the posterior surface of the thyroid gland that release _
- Usually two pairs but can be more.
- Major importance in regulating serum _ and _ levels.
- Blood supply to the parathyroid glands
is similar to the thyroid.
Parathyroid Glands
- Small ovoid glands lying on the posterior surface of the thyroid gland that release PTH
- Usually two pairs but can be more.
- Major importance in regulating serum Calcium and Phosphate levels.
- Blood supply to the parathyroid glands
is similar to the thyroid.
Parathyroid Gland Microscopic Anatomy
- _ cells release parathyroid hormone (PTH)
- Secretion occurs when the blood concentration of calcium falls below the normal range of 9.5-10.5 mg/dL
- Secretion stops when the level of calcium returns to normal
- _ cells - function unknown
Parathyroid Gland Microscopic Anatomy
-
Chief (Principle) Cells release parathyroid hormone (PTH)
- Secretion occurs when the blood concentration of calcium falls below the normal range of 9.5-10.5 mg/dL
- Secretion stops when the level of calcium returns to normal
- Oxyphil Cells - function unknown
Adrenal Gland Microscopic Anatomy
- The gland is divided into an outer _ and an inner central core called the _
Adrenal Gland Microscopic Anatomy
- The gland is divided into an outer Adrenal Cortex and an inner central core called the Adrenal Medulla
Adrenal Gland Cortex
Adrenal Cortex
- Distinctive yellow color due to stored _ in its cells
- More than 25 different steroid hormones ( _ ) are secreted from the cortex; vital for survival
- Structurally and functionally 3 zones:
- Zona _ ( _-corticoids) - influence sodium and potassium levels (salt)
- _ – targets kidney function. Mostly secreted in response to low BP or blood volume; controlled by RAAS
- Zona _ ( _-corticoids) - influence glucose metabolism and immune system; released under the control of _ from the anterior pituitary.
- _ - deals with stress and mediates glucose metabolism and serves as negative feedback mechanism for the immune system (anti-inflammatory action)
- Zona _ ( _ ) - influence secondary sex characteristics
- Zona _ ( _-corticoids) - influence sodium and potassium levels (salt)
Adrenal Cortex
- Distinctive yellow color due to stored Lipids in its cells
- More than 25 different steroid hormones (Corticosteroids) are secreted from the cortex; vital for survival
- Structurally and functionally 3 zones:
-
Zona Glomerulosa (Mineralcorticoids) - influence sodium and potassium levels (salt)
- Aldosterone - targets kidney function. Mostly secreted in response to low BP or blood volume; controlled by RAAS
-
Zona Fasciculata (Glucocorticoids) - influence glucose metabolism and immune system; released under the control of ACTH from the anterior pituitary.
- Cortisol - deals with stress and mediates glucose metabolism and serves as negative feedback mechanism for the immune system (anti-inflammatory action)
- Zona Reticularis (Androgens) - influence secondary sex characteristics
-
Zona Glomerulosa (Mineralcorticoids) - influence sodium and potassium levels (salt)
Adrenal Medulla
- Forms the inner core of each adrenal gland
- Primarily consists of clusters of large, spherical cells called _ cells (target of sympathetic neurons)
- When stimulated by the sympathetic division of the ANS, one population of cells secretes the hormone _ ( _ ) and a second population secretes the hormone _ ( _ )
- These hormones work with the sympathetic nervous system to prepare the body for an emergency or fight-or-flight situation
Adrenal Medulla
- Forms the inner core of each adrenal gland
- Primarily consists of clusters of large, spherical cells called Chromaffin Cells (target of sympathetic neurons)
- When stimulated by the sympathetic division of the ANS, one population of cells secretes the hormone Epinephrine (Adrenaline) and a second population secretes the hormone Norepinephrine (Noradrenaline)
- These hormones work with the sympathetic nervous system to prepare the body for an emergency or fight-or-flight situation
Chromaffin Cells
- _ cells - smaller with granules less electron dense
- _ cells - larger with granules more electron dense
Chromaffin Cells
- Epinephrine Cells - smaller with granules less electron dense
- Norepinephrine Cells - larger with granules more electron dense
Pancreas Histology
- Exocrine portion makes up most of the gland; aids in digestion
- Exocrine cells are organized in structures called _ _
- Endocrine cells organized into clusters called _ _ or _ of _
- Scattered amongst the exocrine cells
Pancreas Histology
- Exocrine portion makes up most of the gland; aids in digestion
- Exocrine cells are organized in structures called Pancreatic Acini
- Endocrine cells organized into clusters called Pancreatic Islets or Islets of Langerhans
- Scattered amongst the exocrine cells
Endocrine Pancreas
- _ cells secrete _ when blood glucose levels drop; stimulates release of glucose from liver glycogen stores
- _ cells secrete _ when blood glucose levels are elevated and promotes glycogen storage in liver and entry into cells
- _ cells secrete _ slowingthe release of insulin and glucagon thereby controlling the rate of nutrient entry into the bloodstream and cells; stimulated by high levels of nutrients in the bloodstream
- _ cells secrete _ _ that inhibit the release of somatostatin
Endocrine Pancreas
- Alpha Cells secrete Glucagon when blood glucose levels drop; stimulates release of glucose from liver glycogen stores
- Beta Cells secrete Insulin when blood glucose levels are elevated and promotes glycogen storage in liver and entry into cells
- Delta cells secrete Somatostatin slowingthe release of insulin and glucagon thereby controlling the rate of nutrient entry into the bloodstream and cells; stimulated by high levels of nutrients in the bloodstream
- F Cells secrete Pancreatic Polypeptide that inhibit the release of somatostatin
Pancreatic Blood Supply