Endocrine Glands

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Endocrine Glands
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Endocrine Glands

• Islets of Langerhans
• Gonads
• Ovaries
• Testes
• Pineal gland
• Thymus
• others

• Hypothalamus
• Pituitary
• Anterior lobe
• Posterior lobe
• Thyroid gland
• Parathyroid glands
• Adrenal Glands
• Cortex
• Medulla

Hormonal Communication
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Hypothalamus

• Part of brain
• Regulates ANS, emotions, feeding/satiety, thirst,
  body temperature, etc.
• Hormones related to these functions
• Releasing hormones
• Axonal transport to posterior lobe

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Anterior Pituitary

• Releasing hormones regulate AP aka
• adeno hypo physis glands under
  growth
• All proteins
• TSH (thryoid stimulating hormone/thyrotropin)
• ACTH (adrenocorticotropic hormone)
• FSH (gonadotropin)
• LH (gonadotropin)
• Tropins/tropic hormones
• GH (growth hormone)
• Prolactin-releasing H

Hypothalamic Pituitary Axis Animation IP Web
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Anterior Pituitary
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Anterior P. Homeostatic Imbalances

• Growth hormone (GH or hGH)
• Promotes mitosis, cell division
• Elongation of long bones, etc.
• Healing of wounds Lack of hGH retards growth
• Hypersecretion in youth produces giantism
• Hyposecretion in childhood produces pituitary
  dwarfism
• Hypersecretion in adult produces acromegaly

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Posterior Pituitary

• Axonal transport to Posterior Pituitary aka
• neuro hypo physis
• nerve under growth
• Hypothalamic cell bodies synthesize
• oxytocin
• ADH

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PituitaryPosterior lobe

• Oxytocin
• Stimulates smooth muscle contraction of uterus
  mammary glands.
• Antidiuretic H.
• Stimulates water reabsorption in collecting
  ducts.
• Stimulates vasoconstriction (vasopressin)
• Lack ? diabetes insipidus

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Posterior Pituitary Homeostatic Imbalances

• ADH
• Hyposecretion produces diabetes insipidus
  tasteless
• Excessive thirst and urination
• central or neurogenic DI
• gestagenic or gestational DI
• nephrogenic DI
• dipsogenic DI

Diabetes Insipidus Foundation, Inc.
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Thyroid Gland

• Location in neck
• Inferior to larynx
• Anterior lateral to trachea
• Composed of follicles
• Follicle cells produce thyroglobulin
• Thyroxin (T4)
• Triiodothyronine (T3)
• Both thyroid hormone, bodys major metabolic
  hormone
• Parafollicular/ C cells
• Calcitonin
• Decreases blood Ca2 by depositing it in bones

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Homeostatic imbalances

• Hypothyroidism results
• Myxedema (in adults)
• Goiterlow levels of iodine
• Cretinism (in children)
• Hyperthyroidism results
• Graves disease

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Parathyroid Glands

• Four small glands embedded in posterior of
  thyroid
• Parathyroid hormone (PTH)
• Stimulates osteoclasts to free Ca2 from bone
• Stimulates Ca2 uptake from intestine kindey

Hormonal Regulation of Calcium
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Parathyroid Homeostatic Imbalances

• Severe hyperparathyroidism causes massive bone
  destruction
• If blood Ca2 fall too low, neurons become
  overactive, resulting in tetany

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• Feedback Loop
• Negative feedback in calcium homeostasis. A rise
  in blood Ca2 causes release of calcitonin from
  the thyroid gland, promoting Ca2 deposition in
  bone and reducing reabsorption in kidneys.
• A drop in blood Ca2 causes the parathyroid gland
  to produce parathyroid hormone (PTH), stimulating
  the release of Ca2 from bone.
• PTH also promotes reabsorption of Ca2 in kidneys
  and uptake of Ca2 in intestines.

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Adrenal Glands

• One on top of each kidney
• Cortex
• Corticosteroid
• glandular
• Medulla
• Catecholamines
• neurohormonal
• Epinephrine
• Norepinephrine

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Adrenal Cortex

• Cortex
• Activity stimulated by ACTH
• Controls prolonged responses by secreting
  corticosteroids.
• Mineralcorticoids
• Aldosterone? regulate salt and water balance
• Glucocorticoids
• Cortisol? regulate glucose metabolism and the
  immune system.
• Gonadocorticoids
• Androgens
• Estrogens

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Adrenal Cortex Imbalances

• Hypersecretion leads to Cushings disease
• ACTH-releasing tumors or side effects of
  corticoid drugs.
• Hyposecretion leads to Addisons Disease
• Deficits in glucocorticoids and mineralcorticoids

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Adrenal Medulla

• Medulla
• The adrenal medulla mediates shortterm responses
  by secreting catecholamine hormones.
• Cells are modified neurons (lack axons)
• Epinephrine (adrenaline)
• Norepinephrine (noreadrenaline)
• enable a rapid ( fight-or-flight ) responses to
  stress by increasing blood glucose and blood
  pressure and directing blood to the heart, brain,
  and skeletal muscles.

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Pancreas

• Consists of two major types of secretory tissues
  which reflects its dual function
• Exocrine gland
• secretes digestive juice
• localized in the acinar cells
• Endocrine gland
• releases hormones
• localized in the islet cells (islets of
  Langerhans)

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Pancreatic Islets

• About a million embedded in pancreas
• Control centers for blood glucose
• Insulin from beta cells
• Glucagon from alpha cells

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Insulin Glucagon
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Islets of Langerhans

• Insulin stimulates glucose uptake, glycogenesis
• Glucagon stimulates glycogenolysis, glucose
  release from liver (vs gluconeogenesis)

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• Feedback Loop
• A rise in blood glucose causes release of insulin
  from beta cells the pancreas, promoting glucose
  uptake in cells and storage as glycogen in the
  liver.
• A fall in blood glucose stimulates alpha cells in
  the pancreas to secrete glucagon, which causes
  the liver to break down glycogen and release
  glucose.

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Pancreas Homeostatic ImbalancesDiabetes siphon
mellitus mel honey

• Symptoms
• Polyuria
• Polydipsia
• Polyphagia

Blood Level Regulation in Diabetics
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Gonads

• Ovaries
• Estrogens
• Progesterone
• Testes
• Testosterone
• Reproductive functions when we study reproductive
  system.

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Pineal gland

• Melatonin
• ? Inhibits early puberty
• ? Day/night cycles
• Timing of sleep, body temperature, appetite
• Secretes melatonin during darkness
• Participates in setting the bodys clock
• Melatonin is a potent antioxidant
• Melatonin is high when young and is reduced as we
  age

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Thymus

• Thymus gland
• Thymopoietins, thymic factor, thymosins
• Influence development of T lymphocytes

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Non-Endocrine Gland Hormones

• Stomach (gastrin)
• Small intestine (duodenum?intesetinal gastrin,
  secretin, cholecystokinin)
• Heart (atrial natriuretic peptide)
• Kidneys (erythropoietin, active vitamin D3)
• Adipose tissue (leptid, resistin)
• Skin
• Placenta (human chorionic gonadotropin, human
  placental lactogen, relaxin)

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Functions regulated by the Endocrine System

• Growth
• Healing
• Water balance Blood Pressure
• Calcium Metabolism
• Energy Metabolism
• Stress
• Regulation of other Endocrine Organs

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Growth

• Growth hormone-releasing hormone
• Human growth hormone (hGH)
• Thyrotropin (TSH)
• Thyroxine triiodothyronine
• Calcitonin
• Somatostatin (GHIH)

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Healing

• Growth hormone-releasing hormone
• Human growth hormone (hGH)
• Thyrotropin (TSH)
• Thyroxine triiodothyronine
• Calcitonin
• Glucagon, Insulin
• Erythropoietin

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Water balance Blood pressure

• ADH
• Aldosterone
• Angiotensin II
• Atrial natriuretic H.
• Epinephrine

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Calcium Metabolism

• Calcitonin
• Parathyroid H. (PTH)
• Estrogens/androgens
• Growth hormone

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Energy Metabolism

• Thyroxine triiodothyronine
• Thyroid-stimulating H. (thyrotropin, TSH)
• Epinephrine norepinephrine
• Insulin
• Glucagon
• Adrenocorticotropic H. (ACTH)
• Cortisol

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Stress

• Epinephrine norepinephrine
• T4 T3 ??
• ACTH
• Cortisol