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ENDOCRINE SYSTEM
FUNCTION
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HORMONE TYPES AND FUNCTIONS
 Hormone -
 Types of Hormones
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 Hormone Actions
 Hormone Receptors -
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Hormone/receptor binding may cause:
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 Hormone Mechanisms
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Two mechanisms enable hormone/receptor binding to influence cellular activity:
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Second Messengers -
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Cyclic AMP 
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PIP Mechanism 
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Direct Activation of Genes in the Receptor Cell 
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 Hormone Regulation
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Nervous System -
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Endocrine Gland Stimuli
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Stimulation or inhibition of endocrine glands can be from 3 sources:
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Hormonal Stimuli -
 Example:
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Humoral Stimuli  Example:
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Neural Stimuli  Example:
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Feedback Mechanisms
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Negative Feedback System -
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Positive Feedback System -
Hyposecretion or Hypersecretion 
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Examples:
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MAJOR ENDOCRINE GLANDS
THE PITUITARY GLAND (HYPOPHYSIS) -
 Two major lobes:
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Posterior Lobe (Neurohypophysis)
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Derived from:
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Hypothalamic-hypophyseal tract -
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Two hormones released by neurohypophysis:
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Produced in:
 Supraoptic Nucleus  ADH (Antidiuretic hormone) -
 Paraventricular Nucleus  Oxytocin -
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Both are secreted into:
Anterior Lobe (Adenohypophysis)
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Derived from:
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Hypophyseal Portal System or Hypothalamopituitary Portal System
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Hormones secreted:
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Nontropic hormones – exert their major effects on nonendocrine targets
 Growth hormone (GH or Somatotropin) 
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 Prolactin (PRL) 
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Tropic hormones – regulate hormonal function of other endocrine glands
 Thyroid Stimulating Hormone (TSH) 
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 Adrenocorticotropic Hormone (ACTH or Corticotropin) 
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Follicle Stimulating Hormone (FSH) 
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Luteinizing Hormone (LH) 
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THE THYROID GLAND
 Location and structure
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Follicles 
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Thyroglobulin 
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 Hormones secreted
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T4 (thyroxin) and T3 (triiodothyronine) 
T4 converted to:
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Effects:
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Hyposecretion -
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Hypersecretion -
Calcitonin 
Parafollicular cells (C-cells) -
THE PARATHYROID GLANDS
 Location and structure
 Parathyroid Hormone (PTH) –
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Effects:
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Hypersecretion (hyperparathyroidism) -
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Hyposecretion (hypoparathyroidism) -
THE ADRENAL (SUPRARENAL) GLANDS
 Location and structure
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Adrenal Cortex -
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Three regions of adrenal cortex:
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Zona glomerulosa 7
 Aldosterone -
 Mechanisms regulating aldosterone secretion:
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Stimulated by:
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Inhibited by:
Zona fasciculata -
 Cortisol -
 Hypersecretion -
 Hyposecretion -
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Zona reticularis -
Adrenal Medulla
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Chromaffin cells 8
THE PANCREAS
 Location and structure
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Acinar cells -
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Islets of Langerhans 
Alpha cells –
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Beta cells –
 Pancreatic hormones
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Insulin 
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Glucagon 
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Gluconeogenesis –
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Glycogenolysis –
*Both hormones are affected by blood sugar levels and by each other.*
 Diabetes
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Diabetes insipidus – not related to problems with insulin
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Diabetes mellitus –
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Two types:
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Type 1 or Juvenile Onset Diabetes –
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Type 2 or Adult Onset Diabetes –
Both types involve:
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Ketone bodies result from:
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Ketosis or acidosis –
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Symptoms
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Polyuria –
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Polydipsia –
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Polyphagia –
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THE PINEAL GLAND
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THE THYMUS GLAND
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THE GONADS
 Testosterone –
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 Estrogens and progesterone –
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ENDOCRINE GLANDS: REGULATION AND EFFECTS
GLAND
POSTERIOR
PITUITARY
HORMONE
STIMULATED
INHIBITED
Antidiuretic Hormone (ADH)
[supraoptic nucleus of
hypothalamus]
Oxytocin
[paraventricular nucleus of
hypothalamus]
Growth Hormone (GH)
Prolactin (PRL)
ANTERIOR
PITUITARY
Thyroid Stimulating Hormone
(TSH)
Adrenocorticotropic Hormone
(ACTH)
Follicle Stimulating Hormone
(FSH)
Luteinizing Hormone (LH)
THYROID
GLAND
PARATHYROID
GLAND
Thyroxin
(produced by follicular cells)
Calcitonin
(produced by parafollicular
cells)
Parathyroid Hormone (PTH)
(secreted by chief cells)
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TARGET
EFFECTS OF HORMONE
ENDOCRINE GLANDS: REGULATION AND EFFECTS
GLAND
HORMONE
STIMULATED
INHIBITED
Glucocorticoids
(Cortisol)
ADRENAL GLAND
(Cortex)
Mineralocorticoids
(Aldosterone)
Gonadocorticoids
(sex hormones)
ADRENAL GLAND
(Medulla)
Epinephrine &
Norepinephrine
Insulin
(ß cells in islets of
Langerhans)
PANCREAS
TESTES
Glucagon
(alpha cells in islets of
Langerhans)
Testosterone
Estrogen
OVARIES
Progesterone
PINEAL GLAND
Melatonin
THYMUS GLAND
Thymic Hormones
(Thymopoietins & Thymosins)
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TARGET
EFFECTS OF HORMONE