University:
Texas A&M University
Course:
BIOL 319 | Integrated Human Anatomy and Physiology I
Academic year:

2021
Views:

159

Pages:

58
Author:

Lily Callahan

ENDOCRINE SYSTEM Pituitary gland Adrenal gland Part 2 Thyroid gland Objectives Part 1 • Distinguish between the neurohypophysis and the adenohypophysis and identify the cell types present in a slide or photomicrograph of the pituitary. • Identify thyroid follicles, follicular cells, colloid, capillaries and parafollicular cells. • Identify the capsule, chief cells, and oxyphil cells in the parathyroid gland. Part 2 • Identify the capsule, cortex, zona glomerulosa, zona fasciculata, zona reticularis, medulla, and chromaffin cells in the adrenal gland. • Identify the pinealocytes and corpora arenacea in the pineal gland. • Identify the islets of Langerhans in the pancreas Adrenal Adrenal Adrenal Adrenal Adrenal Releases of neurons associated with the adrenals (both direct and indirect) BLOOD SUPPLY SINUSOIDS, MEDULLARY ARTERIES, ADRENAL VEIN BLOOD SUPPLY SINUSOIDS, MEDULLARY ARTERIES, ADRENAL VEIN ZONA GLOMERULOSA ZONA FASCICULATA ZONA RETICULARIS Adrenal Arterial and venous blood flow to the adrenal gland. • Peripheral arteries > cortical arteries > capillaries & sinusoids irrigating cortex > join medullary capillaries and arterioles > medullary fenestrated sinusoids with dual blood supply (arterial medullary blood and venous cortex blood) > medullary veins > suprarenal vein. Human fetal adrenal cortical cell with lots of SER and large spherical mitochondria with tubular cristae Adrenal -cortex and medulla cortex medulla Adrenal - central vein Adrenal - central vein Slide 77: Adrenal gland Cortex Medulla Zona reticularis Zona Zona Capsule fasciculata glomerulosa The zona glomerulosa layer is regulated by pituitary adrenocorticotrophin hormone (ACTH). Slide 77: Adrenal gland Trabeculae of cortex Sinusoidal blood channels Chromaffin cells of medulla Lipid droplets are abundant in these steroid-secreting cells. Cholesterol precursors for steroid hormones are stored in lipid droplets. Also SER would be abundant in these cells to provide the enzymes for steroid production. The zona reticularis has a rich vascularization with wide capillaries. Adrenal function Aldosterone stimulates Na+ resorption in: distal tubule of kidney gastric mucosa salivary glands sweat glands Cortisol - anti-inflammatory effects stabilizes lysomsomal membranes causes atrophy of lymphoid tissues throughout body decreases # of circulating lymphocytes Adrenal function: blood pressure Slow but sustained effect on blood pressure Quick effect on blood pressure is by vasoconstriction of angiotensin II 258 Slide 78: Pineal gland Capsule . Trabeculae Lobule Corpora arenacea (brain sand) Melatonin release highest in the dark period. Neuroglia Pinealocytes Pineal gland: melatonin effect on hamster testis Pineal gland 78 34218 Rat pancreas Alpha cells are generally on the border of islets of Langerhans and Beta cells are located more centrally in the islets. Islet cells 34218 Rat pancreas Alpha cells are generally on the border of islets of Langerhans and Beta cells are located more centrally in the islets. Alpha cells Beta cells Immunocytochemistry with antibodies against hormones of the alpha and beta cells. Islet cells Slide 70: Pancreas (Islets of Langerhans) Endocrine Islets of Langerhans Exocrine pancreatic acini and exocrine duct Clinical Correlation There are numerous diseases that affect the endocrine system. For example, Hashimoto's thyroiditis is an auto-immune disease resulting in hypothyroidism while Grave's disease is the most common form of hyperthyroidism. Marty Feldman in Young Frankenstein (1974) suffered from Grave’s disease. Cushing syndrome results from excessive production of glucocorticoids. However, the most common cause of Cushing syndrome use of oral corticosteroid medication. Left untreated, Cushing syndrome can result in exaggerated facial roundness, weight gain around the midsection and upper back, thinning of your arms and legs, and stretch marks Endocrine System Worksheet Hormone Source Target(s) Action(s) GnRH (Gonadotropinreleasing hormone) Hypothalamus Adenohypophyisis (anterior pituitary) Stimulates the release of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) TRH (Thyrotropinreleasing hormone) Hypothalamus Adenohypophyisis (anterior pituitary) Stimulates the release of thyrotropin (TSH) CRH (Corticotropinreleasing hormone) Hypothalamus Adenohypophyisis (anterior pituitary) • • GH (Growth hormone) Adenohypophyisis (anterior pituitary; acidophils) Muscle, adipose tissue, bone (whole body effects) • • • Stimulates synthesis of proopiomelanocortin (POMC) Stimulates release of both blipotropin (b-LPH) and corticotropin (ACTH) Stimulates cellular metabolism, uptake of AA, and protein synthesis. Stimulates growth in epiphyseal plates of long bones via insulinlike growth factors (IGFs) produced in liver. Increases growth of skeletal muscle and increases release of FA from adipose cells for energy production by body cells Endocrine System Worksheet Hormone Source Target(s) Action(s) PRL (Prolactin) Adenohypophyisis (anterior pituitary; acidophils) Mammary glands Promotes milk secretion ACTH (Adrenal corticotropin) Adenohypophyisis (anterior pituitary; basophils) Adrenal cortex Stimulates secretion of adrenal cortex hormones TSH (Thyrotropin) Adenohypophyisis (anterior pituitary; basophils) Thyroid Stimulates thyroid hormone synthesis, storage, and liberation FSH (Follicle-stimulating hormone) Adenohypophyisis (anterior pituitary; basophils) Testis / Ovaries • MSH (Melanocytestimulating hormone) Intermediate lobe of pituitary (pars intermedia) Melanocytes of skin Promotes production of melanin resulting in darkening of the skin ADH (Vasopressin/ antidiuretic hormone) Neurohypophysis (posterior pituitary) Kidney Increases water permeability of renal collecting ducts • Promotes spermatogenesis in men Promotes ovarian follicle development and estrogen secretion in women Endocrine System Worksheet Hormone Source Target(s) Action(s) Melatonin Pineal gland Hypothalamus, pituitary gland, and other endocrine tissues Maintains circadium rhythm of physological functions and behaviors. Aldosterone Adrenal cortex (zona glomerulosa) Kidney • • Cortisol Adrenal cortex (zona fasciculata) Liver, immune system, lipids, muscle, cells of body • • • • Catecholamines (Norepinephrine. Epinephrine) Adrenal medulla Nervous system and circulatory system • • • • • • Thyroglobulin Thyroid Cells of body • • Stimulates Na+ reabsorption in the distal convoluted tubules. Major regulator of salt balance Involved in stress response Increases circulating blood glucose levels by stimulating gluconeogenesis in many cells and glycogen synthesis in the liver Induces fat mobilization and muscle proteolysis Suppresses many immune functions Released during intense emotional reactions (such as fright) 80% catecholamines released from adrenal is epinephrine Increased blood pressure Vasoconstriction Changes in heart rate Elevated blood glucose levels Precursor for active thyroid hormones (T 4 and T3) Controls basal metabolic rate in cells throughout the body Endocrine System Worksheet Hormone Source Target(s) Action(s) Calcitonin Thyroid (Parafollicular cells) Osteoclasts in bone • • Triggered by elevated blood Ca2+ Inhibits osteoclast activity PTH (Parathyroid hormone) Parathyroid • • • Stimulates osteoblasts to produce osteoclast-stimulating factor that increases the number and activity of osteoclasts Stimulates Ca2+ reabsorption in the distal convoluted tubules of renal cortex Increases Ca2+ absorption in the small intestine by stimulating vitamin D activation • Osteoblasts Distal convoluted tubules of renal cortex Small intestine • • Glucagon Pancreatic islets (alpha cells) Liver, muscle, and adipose cells • • Elevates blood glucose levels Accelerates conversion of glycogen, AA, and FA in the liver cells into glucose, which is then released into bloodstream Insulin Pancreatic islets (beta cells) Liver, muscle, and adipose cells • • Lowers blood glucose levels Accelerates membrane transport of glucose into liver cells, muscle cells, and adipose cells Accelerates conversion of glucose into glycogen in liver cells • pars distalis of Pituitary (Herlant's stain) with chromophobe cells , acidophils, and basophils VARIATIONS IN THE MICROVASCULATURE COMMON ARTERIOLE  CAPILLARY  VENULE VENOUS PORTAL SYSTEM CAPILLARY  PORTAL VEIN  CAPILLARY ARTERIAL PORTAL SYSTEM CAPILLARY  PORTAL ARTERIOLE  CAPILLARY Portal system functions to create a local change in blood composition PORTAL vessel VARIATIONS IN THE MICROVASCULATURE COMMON ARTERIOLE  CAPILLARY  VENULE VENOUS PORTAL SYSTEM CAPILLARY  PORTAL VEIN  CAPILLARY ?) ( ENDOCRINE EXAMPLE ARTERIAL PORTAL SYSTEM CAPILLARY  PORTAL ARTERIOLE  CAPILLARY ?) ( ENDOCRINE EXAMPLE Releasing hormones are distributed in second capillary bed of venous portal system Releasing hormones are distributed in second capillary bed of venous portal system Into the first capillary network Releasing hormones are distributed in second capillary bed of venous portal system Into the first capillary network Second capillary network 490 Human pituitary VENOUS PORTAL SYSTEM 490 Human pituitary Pars distalis VENOUS PORTAL SYSTEM (1 st CAPILLARY in hypothalamus) PORTAL VEIN In stalk 490 Human pituitary Pars distalis VENOUS PORTAL SYSTEM (1 st CAPILLARY in hypothalamus) PORTAL VEIN In stalk 490 Human pituitary 2 nd CAPILLARY Pars distalis Pars distalis VENOUS PORTAL SYSTEM ISLETS Of LANGERHANS First capillary network of the ARTERIAL PORTAL SYSTEM modifies blood composition with insulin / glucagon First capillary network ISLETS Of LANGERHANS First capillary network of the ARTERIAL PORTAL SYSTEM modifies blood composition with insulin / glucagon First capillary network Second capillary network Second capillary network uses the modified blood composition with insulin (+) / glucagon (-) to regulate acinar cell protein enzyme production 34218 Rat pancreas Islet cells ARTERIAL PORTAL SYSTEM 34218 Rat pancreas Islet cells 1 st CAPILLARY 2 nd CAPILLARY ARTERIAL PORTAL SYSTEM venous portal system Into the first capillary network First capillary network of the venous PORTAL SYSTEM modifies blood composition with releasing hormones / venous portal system Into the first capillary network First capillary network of the venous PORTAL SYSTEM modifies blood composition with releasing hormones / Second capillary network uses the modified blood composition with releasing hormones to stimulate production and release of hormones from cells in pars distalis Second capillary network ISLETS Of LANGERHANS First capillary network of the ARTERIAL PORTAL SYSTEM modifies blood composition with insulin / glucagon First capillary network Second capillary network Second capillary network uses the modified blood composition with insulin (+) / glucagon (-) to regulate acinar cell protein enzyme production First capillary network First capillary network Second capillary network First capillary network These ARTERIAL PORTAL SYSTEMs (locally connecting the islets with surrounding acinar cells) are the reason why the islets are distributed throughout the pancreas. First capillary network These ARTERIAL PORTAL SYSTEMs (locally connecting the islets with surrounding acinar cells) are the reason why the islets are distributed throughout the pancreas. Second capillary network Ductless gland - endocrine Gland with ducts - exocrine Blood supply VENOUS PORTAL SYSTEM CAPILLARY  PORTAL VEIN  CAPILLARY Answers to questions in lab manual 1. What hormones do acidophils and basophils produce and what is the action of these hormones? • Acidophils: secrete somatotrophin (GH, growth hormone [stimulates body growth]) and prolactin (PRL [stimulates synthesis of milk]) • Basophils: secrete ACTH [stimulates adrenal cortex], FSH [in females: stimulates release of estrogens; in males: stimulates production of sperm], LH [in females: egg maturation and release; in males: stimulates testes to secrete testosterone], TSH [stimulates thyroid gland to secrete thyroxine] (& hCG only during pregnancy)= 2. Where are the cell bodies for the nerve fibers in the pars nervosa? • Hypothalamus 3. What is their (parafollicular cells, “C cells”) function? • Secrete calcitonin – reduced blood calcium levels 4. What is the effect of thyroid hormones on carbohydrate metabolism? Where are high affinity thyroid hormone receptors located in a cell? • Thyroid hormones increase the number and size of mitochondria and stimulate mitochondrial protein synthesis, helping to enhance metabolic activity 5. Is this layer (zona glomerulosa) regulated by pituitary adrenocorticotrophin hormone (ACTH)? • Yes Answers to questions in lab manual 6. Why would these cells have abundant lipid droplets? What organelle would you expect to also be abundant? • Cholesterol precursors for steroid hormones stored in lipid droplets; SER 7. Is vascularization rich or sparse in this zone? • Rich vascularization by wide capillaries. 8. Describe the arterial and venous blood flow to the adrenal gland. • Peripheral arteries > cortical arteries > capillaries & sinusoids irrigating cortex > join medullary capillaries and arterioles > medullary fenestrated sinusoids with dual blood supply (arterial medullary blood and venous cortex blood) > medullary veins > suprarenal vein. 9. Is melatonin release highest in the light or dark period? • Dark period 10. Where in the islets are alpha cells and beta cells located? • Alpha cells are generally on the border of islets of Langerhans and beta cells are located throughout the islets. Answers to questions in lab manual 11. What is the effect of glucagon on glycogen breakdown and storage of triglycerides in the liver? • Glucagon increases the blood glucose levels by stimulating glycogen breakdown and gluconeogenesis in the liver. 12. Describe the symptoms associated with Grave’s disease. • Weight loss, nervousness, sweating, heat intolerance, and other features. 13. What is the most common cause of Cushing syndrome? • The most common cause of Cushing syndrome is exogenous administration of glucocorticoids prescribed by a health care practitioner to treat other diseases.

Endocrine System Part 2

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