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Chapter 42
Hormones & the
Endocrine System
Outline
Endocrine Glands
Hormones & the
Endocrine System
Pheromones
Steroid Hormones
Peptide Hormones
Hypothalamus and Pituitary Gland
Other Endocrine Glands and Hormones
Thyroid
Parathyroid
Adrenal
Pancreas
Gonads
2
The Human Endocrine System
3
Chemical Signals
Hormones & the
Endocrine System
4
Pheromones
Chemical signals that work at a distance between
individuals
A woman’s axillary extract can alter another
woman’s menstrual cycle
Hormones
Chemical signals that work
- At a distance between organs, or
- Locally between adjacent cells
Target Cell Concept
5
Action of Hormones
Hormones & the
Endocrine System
Hormones
Chemical signals produced by one cell that
regulate the metabolism of other cells
Steroid Hormones
- Can cross cell membranes
Peptide Hormones
- Most bind to receptor in plasma membrane
 First
Messenger
- Causes internal release of cAMP
 Second
Messenger
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Peptide Hormone
7
Steroid Hormone
8
Human Endocrine System
Hormones & the
Endocrine System
Endocrine glands
Ductless glands that secrete hormones directly
into the bloodstream
- Most endocrine hormones are peptides
- Only gonads and adrenal cortex produce steroid
hormones
Effects of hormones are moderated in two ways
- Negative feedback opposes release
- Antagonistic hormones oppose each other’s
actions
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Hormones & the
Endocrine System
Hypothalamus and Pituitary Gland
Hypothalamus regulates internal environment
Acts through autonomic system
Also controls glandular secretions of pituitary gland
Posterior Pituitary
- Antidiuretic Hormone (ADH)

Controlled by negative feedback
- Oxytocin

Controlled by positive feedback
Anterior Pituitary
- Hypothalamus controls by producing
Hypothalamic-releasing hormones, and
 Hypothalamic-inhibiting hormones

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Hypothalamus and the Pituitary
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Anterior Pituitary Hormones
Hormones & the
Endocrine System
Anterior pituitary hormones that affect other
glands:
Thyroid-Stimulating Hormone (TSH)
Adrenocorticotropic Hormone (ACTH)
Gonadotropic Hormones
Anterior pituitary hormones that do NOT affect
other glands
Prolactin (PRL)
Melanocyte-Stimulating Hormone (MSH)
Growth Hormone (GH)
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Effect of Growth Hormone
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Acromegaly
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Thyroid Glands
Hormones & the
Endocrine System
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Composed of large number of follicles filled with
Triiodothyronine (T3), and
Thyroxine (T4)
Thyroid hormones increase metabolic rate
Thyroid-induced abnormalities
Simple goiter - Poor hormone production
Cretinism - Poor thyroid development
Myxedema - Hypothyroidism
Exophthalmic goiter - Hyperthyroidism
Simple Goiter
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Cretinism
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Calcitonin
Hormones & the
Endocrine System
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Regulates blood calcium level (in part)
Secreted by thyroid gland when blood calcium level rises
Brings about deposit of calcium in the bones
Low calcium level in blood stimulates the release of
parathyroid hormone (PTH)
Parathyroid hormone causes
- Phosphate level in blood to decrease, and
- Calcium level in blood to increase
Insufficient production of parathyroid hormone leads to
tetany
Regulation of Blood Calcium Level
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Hormones & the
Endocrine System
Adrenal Glands
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Paired – One sits atop each kidney (ad-renal)
Each consists of outer cortex and inner medulla
Inner portion, the adrenal medulla
- Produces
 Epinephrine,
and
 Norepinephrine
- Short-term response to stress (fight or flight)
Outer portion, adrenal cortex
- Produces
 Mineralocorticoids,
 Glucocorticoids
and
- Long-term response to stress
Adrenal Glands
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Glucocorticoids
Hormones & the
Endocrine System
22
Cortisol
Raises blood glucose level
Promotes breakdown of muscle proteins to amino
acids
Promotes metabolism of fatty acids
Counteracts inflammatory response
Mineralocorticoids
Hormones & the
Endocrine System
23
Aldosterone
Promotes two renal functions:
- Absorption of sodium, and
- Excretion of potassium
Renin-angiotensin-aldosterone system
- Raises blood pressure
- Angiotensin II constricts arterioles
- Aldosterone causes kidneys to reabsorb sodium
(causing water retention)
Atrial natriuretic hormone (ANH) is antagonistic to
aldosterone
Regulation of
Blood Pressure and Volume
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Addison Disease
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Cushing Syndrome
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Pancreas
Hormones & the
Endocrine System
Made up up exocrine and endocrine tissue
Endocrine Portion of the Pancreas:
- Consists of pancreatic islets
- Produce and secrete
 Insulin
Secreted during high blood glucose level
Stimulates uptake of glucose by cells
 Glucagon
Secreted during low blood glucose level
Stimulates liver to break down glycogen
Exocrine Portion of the Pancreas:
- Secretes enzymes and buffers into intestine
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Regulation of Blood Glucose Level
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Other Endocrine Glands
Hormones & the
Endocrine System
Gonads
Testes
- Produce testosterone
- Secondary sex characteristics
Ovaries
- Produce estrogen and progesterone
- Reproduction
- Secondary sex characteristics
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The Effects of Anabolic Steroid Use
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Other Endocrine Glands
Hormones & the
Endocrine System
Pineal Gland
Produces melatonin
Involved in Circadian rhythms
Thymus Gland
Secrete thymosins
Aid in differentiation of lymphocytes
Prostaglandins
Produced within cells
 Not distributed in blood
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Melatonin Production
32
Review
Endocrine Glands
Hormones & the
Endocrine System
Pheromones
Steroid Hormones
Peptide Hormones
Hypothalamus and Pituitary Gland
Other Endocrine Glands and Hormones
Thyroid
Parathyroid
Adrenal
Pancreas
Gonads
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Ending Slide Chapter 42
Hormones & the
Endocrine System