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1
Endocrine System
Nervous System controls the Endocrine System
• The endocrine system, along with the nervous system,
functions in the regulation of body activities. (________
____________________)
• The nervous system acts through electrical impulses and
neurotransmitters to cause muscle contraction and glandular
secretion.
Nervous VS Endocrine
• The nervous system coordinates rapid and precise responses
to stimuli using action potentials.
• The endocrine system maintains long-term control using
___________________.
– The endocrine system works in parallel with the
nervous system to control _____________________.
Two major categories of glands in the body
• Exocrine
– Exocrine glands have ________________that carry their secretory product to a surface
• Endocrine
– The endocrine glands do ______________________________ to carry their product to a
surface
Endocrine Glands
• The endocrine glands do not have ducts to carry their product to a surface. (ductless glands)
• Only ____________________________________________________________
• The secretory products of endocrine glands (hormone) are secreted ___________
__________________________________________________
• The Hormone is transported throughout the body, by blood, where they influence only those cells
that have receptor sites for that hormone.
Exocrine Glands
• Exocrine glands _________________ that carry their secretory product to a surface.
• These glands include
– ___________________________
– ____________________________
– glands that secrete digestive enzymes
• These type of glands _______________________________________________
Endocrine System
• Second messenger system of the body
• Uses chemical messages (hormones) that are released into the blood
• Hormones control several major processes
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Hormones
• 2 Types of hormones
• ________________________________ – are lipid like carbon rings
– These hormones are able to pass though the cell membrane.
– This type of hormones is produced in the adrenal glands and the Gonads (testis and
ovaries)
• ________________________________ – made up of amino acids
- These hormones cannot pass though the cell membrane because they cannot dissolve in fats. Ex.
Insulin
Mechanisms of Hormone Action
 Hormones can only affect certain tissues or organs (called target cells or target organs)
 Target cells/organs must have specific protein receptors
 Hormone binding to receptor then influences the working of the cells
Effects Caused by Hormones
 Changes in plasma membrane permeability or electrical state
 Synthesis of __________________, such as enzymes
 Activation or inactivation of enzymes
 Stimulation of ________________________________
Steroid Hormone Action
 Diffuse through the plasma membrane of target cells
 Enter the __________________
 Bind to a specific protein within the nucleus
 Bind to specific sites on the cell’s DNA
 Activate genes that result in __________________
Nonsteroid Hormone Action
 Hormone binds to a membrane receptor
 Hormone _________________________________
 Sets off a series of reactions that activates an enzyme
 Catalyzes a reaction that produces a second messenger
molecule
 Oversees additional intracellular changes to promote a specific
response
Control of Hormone Release
 Hormone levels in the blood are maintained by ____________
_______________________
 A stimulus or low hormone levels in the blood triggers the
release of more hormone
 Hormone release stops once an appropriate level in the blood
is reached
Hormonal Stimuli of Endocrine Glands
 Endocrine glands are activated by __________________
Humoral Stimuli of Endocrine Glands
 ____________________________stimulate hormone release
Neural Stimuli of Endocrine Glands
 __________________ stimulate hormone release
 Most are under control of the sympathetic nervous system (ex. fight or flight)
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Location of Major Endocrine Organs
Pituitary Gland
 Size of a grape
 Hangs by a stalk from the ___________________
 Protected by the sphenoid bone
 Has two functional lobes
 ___________________– glandular tissue
 ___________________– nervous tissue
Hormones of the Anterior Pituitary
 Six anterior pituitary hormones
 Two affect non-endocrine targets
 Four stimulate other endocrine glands (referred to
as tropic hormones)
 Characteristics of all anterior pituitary hormones
 ___________________ (or peptides)
 Act through ___________________ (no direct
communication)
 Regulated by hormonal stimuli, mostly negative
feedback
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Growth Hormone (GH)
 General metabolic
hormone
 Major effects are
directed to growth of
____________
 Causes amino acids to
be built into proteins
 Causes fats to be
broken down for a
__________________
Functions of Other Anterior
Pituitary Hormones
 Prolactin (PRL)
 Stimulates and
maintains ____
____________
following childbirth
 Function in males is ___________________
 Adrenocorticotropic hormone (ACTH)
 Regulates endocrine activity of the _________________
 Thyroid-stimulating hormone (TSH)
 Influences growth and activity of the _______________
Functions of Other Anterior Pituitary Hormones
 Gonadotropic hormones
 Regulate hormonal activity of the gonads
 _____________________________(FSH)
 Stimulates follicle development in ovaries
 Stimulates sperm development in testes
 ___________________ (LH)
 Triggers ___________________
 Causes ruptured follicle to become the
corpus luteum
 Stimulates ___________________
production in males
 Referred to as interstitial cellstimulating hormone (ICSH)
Pituitary - Hypothalamus Relationship


Hypothlamus produces two hormones that are transported to neurosecretory cells of the posterior
pituitary
 The posterior pituitary is not strictly an endocrine gland (doesn’t make hormones), but does store
and release hormones
Hormones of the Posterior Pituitary
 Oxytocin
 Stimulates _______________________________________________
 Causes milk ejection
 Antidiuretic hormone (ADH)
 Can inhibit ___________________
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In large amounts, causes vasoconstriction
leading to ___________________
(vasopressin)
Thyroid Gland
 Found ___________________
 Consists of two lobes and a connecting isthmus
 Produces two hormones
 ___________________
 Calcitonin
 Major metabolic hormone
 Composed of two active iodine-containing
hormones
 Thyroxine (T4) – secreted by thyroid follicles
 Triiodothyronine (T3) – conversion of T4 at target tissues
Parathyroid Gland
 Tiny masses on the posterior of the thyroid
 Secrete parathyroid hormone
 Stimulate osterclasts to _________________________
 Stimulate the kidneys and intestine to absorb more calcium
 Raise ___________________in the blood
Adrenal Glands
 Two glands
 ________________ – outer glandular region
in three layers
 ______________ – inner neural tissue region
 Sits on top of the ___________________
Hormones of the Adrenal Cortex
 Mineralocorticoids (mainly aldosterone)
 Produced in outer adrenal cortex
 Regulate ___________________in blood,
water, and electrolyte balance
 Target organ is the ________________
 Production stimulated by renin and aldosterone
 Production inhibited by atrial natriuretic peptide
 Glucocorticoids (including cortisone and cortisol)
 Produced in the middle layer of the adrenal cortex
 Promote normal ___________________
 Help resist ___________________
 Released in response to increased blood levels of ACTH
 Sex hormones
 Produced in the inner layer of the adrenal cortex
 _______________ (male) and some ________________ (female)
Hormones of the Adrenal Medulla
 Produces two similar hormones (catecholamines)
 ___________________
 ___________________
 These hormones prepare the body to deal with ___________________
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Pancreatic Islets
 The pancreas is a mixed gland
 The islets of the pancreas produce hormones
 _______________ – allows glucose to cross plasma membranes into cells from beta cells
 _______________ – allows glucose to enter the blood from alpha cells
 These hormones are antagonists that maintain ___________________homeostasis
Pineal Gland
 Found on the third ventricle of the brain
 Secretes ___________________
 Helps establish the body’s ______________
 May have other as-yet-unsubstantiated functions
Thymus
 Located posterior to the sternum
 Largest in infants and children
 Produces thymosin
 Matures some types of white blood cells
 Important in developing ___________________
Hormones of the Ovaries
 Estrogens
 Produced by Graafian follicles or the placenta
 Stimulates the development of secondary female characteristics
 Matures female ___________________
 Helps prepare the uterus to ___________________
 Helps maintain ___________________
 Prepares the breasts to produce milk
 Progesterone
 Produced by the corpus luteum
 Acts with estrogen to bring about the ___________________
 Helps in the implantation of an ___________________ in the uterus
Hormones of the Testes
 Interstitial cells of testes are hormone-producing
 Produce several androgens
 ___________________ is the most important androgen
 Responsible for adult male secondary sex characteristics
 Promotes growth and maturation of ___________________
 Required for ___________________