anatomy summary: hormones
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Anatomy Summary: Hormones. Figure 7-2 (1 of 2). Anatomy Summary: Hormones. Figure 7-2 (2 of 2). Pituitary gland ( Hypophysis ). Pituitary gland – two-lobed organ that secretes nine major hormones Neurohypophysis – posterior lobe ( neural tissue ) and the infundibulum - PowerPoint PPT PresentationTRANSCRIPT
Copyright © 2010 Pearson Education, Inc. Figure 7-2 (1 of 2)
Anatomy Summary: Hormones
Copyright © 2010 Pearson Education, Inc. Figure 7-2 (2 of 2)
Anatomy Summary: Hormones
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Pituitary gland (Hypophysis)
• Pituitary gland – two-lobed organ that secretes nine major hormones
• Neurohypophysis – posterior lobe (neural tissue) and the infundibulum
• Receives, stores, and releases hormones from the hypothalamus
• Adenohypophysis – anterior lobe, made up of glandular tissue
• Synthesizes and secretes a number of hormones
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Neurohypophysis hormones
Hormone Target Effect
Antidiuretic hormone (ADH)
Arginine vasopresin (AVP)
Kidneys Reabsorption of water,
elevation of blood volume and pressure (vasoconstriction)
Oxytocin (OT) Uterus, mammary glands (female)
Ductus deferens and prostate gland (male)
Labor contractions, milk ejection
Contractions of ductus deferens and prostate gland
Hormones that are produced in the hypothalamus and stored in the neurohypophysis
Copyright © 2010 Pearson Education, Inc. Figure 7-12, steps 1–4
HYPOTHALAMUS
Vein
POSTERIOR PITUITARY
Vesicles are transported down the cell.
Vesicles containing hormone are stored in posterior pituitary.
Hormones are releasedinto blood.
Hormone is made and packaged in cell body of neuron.
1
2
3
4
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• Portal system - a system of blood vessels that begins and ends in capillaries. The blood, after passing through one capillary bed, is passing through a second capillary network.
• All blood entering the portal system will reach the target cells before returning to the general circulation
Question – why is such a system important in the communication between the hypothalamus and the
hypophysis?
Hypophyseal portal system
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Pituitary-Hypothalamic Relationships: anterior Lobe• The hypophyseal portal system,
consisting of:
• The primary capillary plexus in the infundibulum
• The hypophyseal portal veins
• The secondary capillary plexus
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The anterior lobe• There is no direct neural contact with the hypothalamus• Hormone production is regulated by the hypothalamus
• Regulatory factors from the hypothalamus arrive directly to the
adenohypophysis through the hypophyseal portal system• Releasing hormones stimulate the synthesis and release of
hormones
• Inhibiting hormones shut off the synthesis and release of hormones
• The hormones of the anterior pituitary (7) are called tropic/trophic hormones because they “turn on” other glands or organs
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Tropic Hormones of the Anterior Pituitary
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The Pituitary Gland: Anterior
Figure 7-13
HYPOTHALAMIC HORMONES
ANTERIOR PITUITARYHORMONES
NONENDOCRINETARGETS
ENDOCRINE TARGETSAND THE HORMONESTHEY SECRETE
Somatostatin
GHRH* GnRH
Portal system
Anterior pituitary
FSH LH
Neurons in hypothalamussecreting trophic hormones
To target tissues
GH
Endocrine cellsof the gonads
Endocrinecells
Many tissues
Germ cellsof the gonads
Thyroid gland
Thyroid hormones
Adrenalcortex
Cortisol
Liver
IGFs AndrogensEstrogens,
progesterone
PRFs TRH CRH
TSH ACTHProlactin
Breast
Dopamine*
(Gonadotropins)
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Anterior pituitary hormonesRegion
Hormone Target Effect Hypothalamic regulatory hormone
Follicle-stimulating hormone (FSH)
Follicle cells of the ovaries, sustentacular cells of testes
Secretion of estrogen, follicle development, stimulation of sperm maturation
Gonadotropin-releasing hormone (GnRH)
Luteinizing-Hormone (LH)
Follicle cells of ovary
Interstitial cell of testes
Ovulation, formation of corpus luteum, secretion of progesterone
Secretion of testosterone
Gonadotropin-releasing hormone (GnRH)
Prolactin (PRL)
Mammary glands Production of milk Prolactin-releasing factor (PRF)
Prolactin-Inhibiting hormone (PIH)Growth hormone (GH)
All cells Growth, protein synthesis, lipid mobilization and catabolism
Growth-hormone- releasing hormone (GH-RH)
Growth-hormone-inhibiting hormone (GH-IH)
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Anterior pituitary hormonesRegion
Hormone Target Effect Hypothalamic regulatory hormone
Follicle-stimulating hormone (FSH)
Follicle cells of the ovaries, sustentacular cells of testes
Secretion of estrogen, follicle development, stimulation of sperm maturation
Gonadotropin-releasing hormone (GnRH)
Luteinizing-Hormone (LH)
Follicle cells of ovary
Interstitial cell of testes
Ovulation, formation of corpus luteum, secretion of progesterone
Secretion of testosterone
Gonadotropin-releasing hormone (GnRH)
Prolactin (PRL)
Mammary glands Production of milk Prolactin-releasing factor (PRF)
Prolactin-Inhibiting hormone (PIH)Growth hormone (GH)
All cells Growth, protein synthesis, lipid mobilization and catabolism
Growth-hormone- releasing hormone (GH-RH)
Growth-hormone-inhibiting hormone (GH-IH)
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Anterior pituitary hormones
Region Hormone Target Effect Hypothalamic regulatory hormone
Thyroid-stimulating hormone (TSH/ thyrotropin)
Thyroid gland Secretion of thyroid hormones (T3, T4)
Thyrotropin-releasing hormone (TRH)
Adrenocorticotropic hormone (ACTH)
Adrenal cortex (zona fasciculate)
Secretion of glucocorticoids (cortisole, corticosterone)
Corticotrophin-releasing hormone (CRH)
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Anterior pituitary hormonesRegion
Hormone Target Effect Hypothalamic regulatory hormone
Follicle-stimulating hormone (FSH)
Follicle cells of the ovaries, sustentacular cells of testes
Secretion of estrogen, follicle development, stimulation of sperm maturation
Gonadotropin-releasing hormone (GnRH)
Luteinizing-Hormone (LH)
Follicle cells of ovary
Interstitial cell of testes
Ovulation, formation of corpus luteum, secretion of progesterone
Secretion of testosterone
Gonadotropin-releasing hormone (GnRH)
Prolactin (PRL)
Mammary glands Production of milk Prolactin-releasing factor (PRF)
Prolactin-Inhibiting hormone (PIH)Growth hormone (GH)
All cells Growth, protein synthesis, lipid mobilization and catabolism
Growth-hormone- releasing hormone (GH-RH)
Growth-hormone-inhibiting hormone (GH-IH)
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The thyroid gland on the anterior side of the neck. The thyroid gland has a right lobe and a left lobe connected by a narrow isthmus
http://webanatomy.net/histology/endocrine_histology.htm
Thyroid Gland
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• Thyroid hormone – major metabolic hormone
• Consists of two related iodine-containing compounds
• T4 – thyroxine; has two tyrosine molecules plus four bound iodine atoms
• T3 – triiodothyronine; has two tyrosines with three bound iodine atoms
Thyroid Hormone
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Functions of Thyroid Hormones Elevates rates of oxygen consumption and energy consumption; in
children, may cause a rise in body temperature Increases heart rate and force of contraction; generally results in a
rise in blood pressure Increases sensitivity to sympathetic stimulation Stimulates red blood cell formation and thus enhances oxygen
delivery Activate genes that code for enzymes that are involved in
glycolysis (Glucose oxidation) increase rate of ATP production In the nucleus – activate genes that control the synthesis of
enzymes that involve with energy production and utilization (for example increase of production of sodium-potassim ATPase that uses ATP)
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TSH
T4, T3
T4 T3
Hypothalamus
Anteriorpituitary
Thyroidgland
Systemicmetabolic
effects
Stimulus
Integrating center
Efferent pathway
Effector
Systemic response
TRH
Tonic release
KEY
Negative feedback
Thyroid Hormone Control Pathway
Figure 23-11
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Protein hormones that control calcium
Parathyroid gland – PTH PTH—most important hormone in Ca2+ homeostasis
Thyroid gland – calcitonin Liver and Kidney - Calcitriol – also known as vitamin D3
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• Calcitonin targets the skeleton, where it:• Inhibits osteoclast activity (and thus bone
resorption) and release of calcium from the bone matrix
• Stimulates calcium uptake and incorporation into the bone matrix
• Regulated by a humoral (calcium ion concentration in the blood) negative feedback mechanism
Calcitonin
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• PTH release increases Ca2+ in the blood:• Stimulates osteoclasts to digest bone matrix
• Enhances the reabsorption of Ca2+ and the secretion of phosphate by the kidneys
• Increases absorption of Ca2+ by intestinal mucosal
• Rising Ca2+ in the blood inhibits PTH release
• The antagonist is the Calcitonin secreted by the thyroid gland
Effects of Parathyroid Hormone
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Simple Endocrine Reflex: Parathyroid Hormone
Figure 7-10
Bone and
kidney
Low plasma [Ca2+]
Plasma [Ca2+]
Bone resorption
Kidneyreabsorption of
calcium
Parathyroid cell
Parathyroid hormone
Production of calcitriolleads to intestinalabsorption of Ca2+
Negative feedback
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Pancreas structure
Exocrine pancreas (99% of volume)
Cells (pancreatic acini) forming glands and
ducts that secrete pancreatic fluid and enzymes
with digestive function
Endocrine pancreas (1%)
Small groups of cells scattered in clusters
(pancreatic islets) that secrete hormones
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• Structurally and functionally, they are two glands in one
• Adrenal medulla – neural tissue; part of the sympathetic nervous system
• Adrenal cortex - three layers of glandular tissue that synthesize and secrete corticosteroids
Adrenal (Suprarenal) Glands
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Adrenal Cortex• Synthesizes and releases steroid hormones called
corticosteroids• Different corticosteroids are produced in each of the three
layers• Zona glomerulosa – glomerulus- little ball. Secretes
mineralocorticoids – main one aldosterone• Zona fasciculata – glucocorticoids (chiefly cortisol)• Zona reticularis – gonadocorticoids (chiefly androgens)
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Zona glomerulosa – Mineralocorticoids
• Aldosterone secretion is stimulated by:• Rising blood levels of K+
• Low blood Na+
• Decreasing blood volume or pressure
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Aldosterone and urine concentration• Aldosterone is a steroid secreted by the adrenal cortex
• It is secreted when blood sodium falls or if blood potassium rises or when blood pressure decreased
• Aldosterone increases reabsorption of Na+ in the kidneys in exchange for secretion of K+ ions – water follow
• Net effect is that the body retains NaCl and water and urine volume reduced
• The retention of salt and water help to maintain blood pressure and volume
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Zona fasciculata - Glucocorticoids (Cortisol/hydrocortisone)
• Main hormones secreted are the Cortisol/hydrocortisone and small amounts of corticosterone
• It protects against hypoglycemia by stimulating catabolism of energy stores.
• While adrenaline is responsible for rapid metabolic responses the glucocorticoids are responsible for long-term stress:
• Glucocorticoids accelerate the rates of glucose synthesis and glycogen formation – especially in the liver
• Promotes the utilization of fatty acids as source of energy - glucose-sparing effect
• Clucocorticoids also have anti-inflammatory effect – inhibit the activities of WBC (use?)