hormones - Zanichelli

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Sylvia S. Mader
Immagini e
concetti
della biologia
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
C10 Coordination by
hormone
signaling
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
The endocrine system
The nervous and endocrine systems work together to
control and stimulate the activity of the other systems.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
The endocrine system
The endocrine system utilizes chemical signals (hormones).
Hormones act more slowly
but are longer lasting than
neurotransmitters as they
travel in the bloodstream.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hormones
Peptide hormones are water-soluble, transported in blood
but can not cross the membranes.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hormones
Steroids are lipid-soluble and must be bound to carrier
proteins to be transported in blood vessels.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Glands and hormones
The endocrine system consists of endocrine glands that
secrete a great variety of hormones.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Glands and hormones
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Glands and hormones
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Glands and hormones
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hypothalamus and hypophysis
Hypothalamus and hypophysis (pituitary gland)
coordinate the endocrine system.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hypothalamus and hypophysis
The hypothalamus is a part of the nervous and endocrine
system and stimulates the pituitary glands secretion.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hypothalamus and hypophysis
The hypothalamus produces the hormones released by the
posterior pituitary:
•ADH causes the reabsorption of water by the kidneys.
•Oxytocin stimulates the uterus to contract during
childbirth and promotes milk letdown while nursing.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hypothalamus and hypophysis
The hypothalamus produces hypothalamicreleasing and hypothalamic-inhibiting hormones
that control the anterior pituitary.
The anterior pituitary gland produces non-tropic
and tropic hormones.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hypothalamus and hypophysis
Non tropic hormones include prolactin (PRL), growth
hormone (GH) and melanocyte-stimulating hormone
(MSH).
Tropic hormones are thyroid-stimulating hormones
(TSH), adrenocorticotropic hormone (ACTH) and the
gonadotropic hormones (FSH and LH).
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Negative feedback mechanisms
The hypothalamus stimulates the anterior pituitary to
release hormones, which stimulate the target gland to
release a third hormone.
Hormone 3 feeds back to
control the hypothalamus
and anterior pituitary.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hormones, metabolism, homeostasis
Adrenal glands respond to stress.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hormones, metabolism, homeostasis
The adrenal medulla releases epinephrine and
norepinephrine, which have a short-term effect.
The adrenal cortex secretes hormones that provide
long-term responses to stress (sex hormones,
glucocorticoids and mineralocorticoids).
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Thyroid
The thyroid and the parathyroid regulate the blood
calcium levels.
Calcitonin is secreted by the thyroid and causes
blood calcium levels to decrease.
Parathyroid hormone (PHT) reduces the blood
phosphate levels and increases the blood calcium
levels.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Adrenal and thyroid disfunctions
Cushing syndrome is caused by a disfunction of the
adrenal cortex and is characterized by a tendency toward
diabetes mellitus, subcutaneous fat accumulation in the
trunk and a moon-shape face.
The thyroid regulates development and increases the
metabolic rate.
Hypothyroidism is the cause of cretinism and simple
goiter.
Hyperthyroidism can lead to exophthalmic goiter,
characterized by an enlarged thyroid and protruding eyes.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Pancreas
Pancreas regulates the glucose level in the blood.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Epiphysis
Epiphysis (or pineal gland), located in the brain, is
involved in biorhythms. The hormone melatonin is
produced primarily at night and is involved in the daily
sleep-wake cycle.
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Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012