Download Mechanisms and Pituitary

Essentials of human Anatomy
and Physiology
Fifth Edition
Seeley, Stephens and Tate
Chapter 10: The Endocrine
System
The Endocrine System
 Living systems require coordination and
integration
 Endocrine and nervous systems are the
control systems of the body
 Endocrine control:
Slower
Longer acting
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Slide 9.1
The Endocrine System
 Nervous system control (later)
 More rapid
 Short duration
 The two systems are interrelated
 Act to maintain homeostasis
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Slide 9.1
The Endocrine System
 Endocrine glands vs. Exocrine glands
 Endocrine glands make hormones
 Hormones released into blood
 Circulate throughout the body
 Act only at “receptor sites” on
target cells: very specific
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Slide 9.1
The Endocrine System
 Hormones control several major
processes
 Reproduction
 Growth and development
 Mobilization of body defenses
 Maintenance of much of homeostasis
 Regulation of metabolism
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Slide 9.1
Hormone Overview
 Hormones (Gr. “to set in motion”) are produced
by specialized cells
 Blood transfers hormones to target sites
 Hormones alter the physiology of other
cells
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Slide 9.2
The Chemistry of Hormones
 Amino acid-based hormones
 Proteins
 Peptides
 Amines
 Steroids – made from cholesterol
 Prostaglandins – made from highly
active lipids
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Slide 9.3
Mechanisms of Hormone Action
 Hormones affect only certain tissues or
organs (target cells or organs)
 Target cells must have specific protein
receptors
 Hormone binding influences the function
of the cells
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Slide 9.4
Effects Caused by Hormones
 Changes in plasma membrane
permeability or electrical state
 Synthesis of proteins, such as enzymes
 Activation or inactivation of enzymes
 Stimulation of mitosis
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Slide 9.5
Steroid Hormones: Mechanism of
Action (DNA or “Gene Expression”)
 Hormones diffuse through the plasma
membrane of target cells
 Enter the nucleus
 Bind to a specific protein within the
nucleus
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Slide 9.6
Steroid Hormone Action
 Hormone-protein complex binds to a
specific site on the cell’s DNA
 Activates genes that result in synthesis
of new proteins
 New protein influences cell function
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Slide 9.6
Steroid Hormone Action
Figure 9.1a
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Slide 9.7
Nonsteroid Hormone Action:
“Second Messenger System”
 Hormone binds to a membrane receptor
 Hormone does not enter the cell
 Sets off a series of reactions that
activates an enzyme
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Slide 9.8
Nonsteroid Hormone Action:
“Second Messenger System”
 Catalyzes a reaction that produces a
second messenger molecule
Cyclic AMP (cAMP)
 cAMP activates additional intracellular
changes to promote a specific response
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Slide 9.8
Nonsteroid Hormone Action
Figure 9.1b
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Slide 9.9
Control of Hormone Release
 Hormone levels in the blood are
maintained by negative feedback
 A stimulus (like low hormone levels in the blood)
triggers the release of more hormone
 Hormone release stops once an
appropriate level in the blood is reached
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Slide 9.10
Hormonal Stimuli of Endocrine
Glands
 Endocrine glands
are activated by
other hormones
Figure 9.2a
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Slide 9.11
Humoral Stimuli of Endocrine
Glands
 Changing blood
levels of certain
ions stimulate
hormone release
Figure 9.2b
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Slide 9.12
Neural Stimuli of Endocrine Glands
 Nerve impulses
stimulate hormone
release
 Most are under
control of the
sympathetic nervous
system
Figure 9.2c
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Slide 9.13
Location of Major Endocrine Glands
Figure 9.3
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Slide 9.14
Pituitary Gland
 Size of a grape
 Hangs by a stalk from the hypothalamus
 Protected by the sphenoid bone (what
part??)
 Has two functional lobes
 Anterior pituitary – glandular tissue
 Posterior pituitary – nervous tissue
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Slide 9.15
Hormones of the Anterior Pituitary
 Six anterior pituitary hormones
 Two affect non-endocrine targets
 Four stimulate other endocrine glands
(tropic [“tropic” = “feeding”] hormones)
 All six are secreted by the anterior pituitary
(glandular tissue)
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Slide 9.16
Hormones of the Anterior Pituitary
 Characteristics of all anterior pituitary
hormones
 Proteins (or peptides)
 Act through second-messenger systems
 Regulated by hormonal stimuli, mostly
negative feedback
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Slide 9.16
Hormones of the Anterior Pituitary
Figure 9.4
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Slide 9.17
Functions of Anterior Pituitary
Hormones
 Growth Hormone (GH)
Action: growth of skeletal muscles and
long bones; maintains size
Target: bone and muscle
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Slide 9.18
Functions of Anterior Pituitary
Hormones
 Prolactin (PRL)
Action: Stimulates and maintains milk
production following childbirth
 Target: mammary tissue
 Function in males is unknown
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Slide 9.19
Functions of Anterior Pituitary
Hormones
 Adrenocorticotropic hormone (ACTH)
 Action: Regulates endocrine activity of the
adrenal cortex
 Target: Cells of adrenal cortex
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Slide 9.19
Functions of Anterior Pituitary
Hormones
 Thyroid-stimulating hormone (TSH)
 Action: Influences growth and activity of the
thyroid gland
 Target: cells of the thyroid gland
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Slide 9.19
Functions of Anterior Pituitary
Hormones
 Gonadotropic hormones
 Target: male/female gonads
 Action: Follicle-stimulating hormone (FSH)
 Stimulates follicle development in
ovaries
 Stimulates sperm development in
testes
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Slide 9.20a
Functions of Anterior Pituitary
Hormones
 Gonadotropic hormones (continued)
 Luteinizing hormone (LH)
 Action:
 Triggers ovulation in females
 Causes ruptured follicle to become the
corpus luteum in females
 Stimulates testosterone production in
males (ICSH)
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Slide 9.20b
Pituitary - Hypothalamus
Relationship
 Release of hormones is controlled by
the hypothalamus
 Hypothalamus produces two hormones
Made by neurons
transported the posterior pituitary by
neurons
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Slide 9.21
Pituitary - Hypothalamus
Relationship
 The posterior pituitary is NOT an
endocrine gland
 Does NOT make hormones
 Is NOT glandular
 Only releases hormones
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Slide 9.21
Hormones of the Posterior Pituitary
 Oxytocin
 Target: Smooth muscle of uterus, breast
 Action:
 stimulates contractions of the uterus
during labor
 causes milk ejection
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Slide 9.22
Hormones of the Posterior Pituitary
 Antidiuretic hormone (ADH)
 Target: Kidney tubules
 Action:
 Inhibits urine production
 In large amounts, causes increased
blood pressure (vasopressin)
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Slide 9.22
Hormones of the Posterior Pituitary
Figure 9.5
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Slide 9.22b