Download 05 Endocrine System note

The Endocrine System
 a collection of glands that release hormones into the blood
stream
 hormones are classified according to their activation site.
 Some affect many cells throughout the body (i.e. growth
hormone, insulin, epinephrine (adrenaline)) and others
target specific cells or tissues (i.e. parathyroid, gastrin).
o what do they do?!
 (Hormones are chemical regulators produced by cells in one
part of the body that affect cells in another part of the body.)
Chemical Control Systems
 the endocrine system maintains control over a long duration
(nervous system adjusts to short term  more on this later)
So… How does it work?
 the hypothalamus regulates the pituitary gland through
nerve stimulation, but it is the pituitary gland that
stimulates the glands of the endocrine system to release
hormones
 How did scientists find out about the hormones that are in
very low concentration in the blood?
 A lot of trial and error and “oops!” moments (often removing
an organ and seeing what goes wrong)
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Types of Hormones
There are two types of hormones: steroid and protein
 Steroid hormones: made from cholesterol
soluble in fat
eg. sex hormones
These hormones act by diffusing directly into the target cell
and activating specific genes to illicit response. *see fig.4 pg. 374
for more detail.
 Protein hormones:
made from amino acid chains
water soluble
eg. insulin and GH
Chemical Signals
How do hormones signal cells?
 Hormones can only affect the cells that contain the right
type of receptor capable of recognizing and interacting with
the hormone
 There are two types of hormones that differ in their structure
as well as how they act upon target cells. (see page 374)
1. Steroid hormones
 enter the target cell by passing through the target cell
membrane and binding to a receptor protein in the
cytoplasm of the cell (see figure 4, p. 374)
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 the binding of the hormone to the regulatory sites (site other
than active site) to induce or suppress the expression of
specific genes in that cell
2. Peptide (protein) hormones
 Along with most hormones that are derived from amino
acids, peptide hormones are not able to pass through the
plasma membrane, thus they bind to specific receptors
embedded on the outer side of the target cell’s plasma
membrane.
 Creates a signal transduction pathway that converts the
extracellular signal to intercellular signals that alter the
target cells behaviour. (see figure 5, p. 375)
 In many cases the binding of the hormone to its receptor on
the outside of the target cells activates a G protein which
binds to an enzyme called adenylyl cyclase, activating it.
 Adenylyl cyclase catalyzes the conversion of ATP into
cyclic AMP
 The production of cyclic AMP can be stopped by a second
type of G protein which inhibits the activity of Adenylyl
cyclase
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Major Glands of the Endocrine System
 Pituitary Gland  “master gland”
(See section 8.1)
 pea sized gland located at the base of
the brain that controls other
endocrine glands and regulates body
growth
 produces and stores hormones; hormones stored in the
pituitary gland are secreted when stimulated by the
hypothalamus via nerve impulses
 composed of two lobes: posterior and anterior
 posterior: stores many hormones produced by the
hypothalamus (travel to pituitary gland through blood)
 anterior: produces its own hormones, BUT still under control
of the hypothalamus (both +ve and –ve) …they act as a team!
* See pg. 377 for summary of pituitary hormones
 Thyroid Gland an H-shaped
gland in the front of the neck that
secretes a hormone that controls the
speed at which the body cells work
(Section 8.3)
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 Secretion of thyroid hormones is under negative control
(feedback) from the hypothalamus: via TSH.
 *See fig. 3 pg. 385 for diagram.
 See table 1, pg. 387 for a summary of thyroid hormones
 Parathyroid Glands  4 small glands located behind (in)
the thyroid gland that regulate the Ca2+ (important in muscle
function and much more) content in the blood (Section 8.3)
 See fig. 5 pg. 385 for diagram.
 See table 1, pg. 387 for a summary of parathyroid hormones
 Adrenal Glands  located on kidneys – they regulate the
use of carbohydrates and salts and prepare body for
emergency by producing adrenaline (p. 381-382)
 Two glands; each gland is made of two glands encased in
one shell: the adrenal cortex (outer), and the adrenal
medulla (inner)
 Adrenal medulla: produces epinephrine (adrenaline) and
norepinephrine (noradrenaline)
 Adrenal cortex: three different hormones: glucocorticoids,
mineralocorticoids, sex hormones (androgens) in small
amounts.
 See fig. 5 pg. 382 for diagram.
 See table 1, pg. 382 for a summary of adrenal hormones
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Adjustment to Stress (section 8.4)
 Prostaglandins  involved in stress response (among other
things – there are 16 different types) by increasing blood flow,
and relaxing smooth muscle in paths to lungs.
* more localized response
 See table 1, pg. 388 for a summary
 See table 2, pg. 389 for Problems associated with long-term stress
 See table 3, pg. 391 for a list of banned performance enhancing drugs
 Pancreas  a digestive gland that secretes pancreatic juice
to small intestine and insulin into the blood stream.
(See section 8.2)
 has two cell types:
produces hormones AND
enzymes in islets of
Langerhans: produce
insulin and glucagon
 β cells: produce insulin
(when glucose ↑) : makes
cells more permeable to
glucose, therefore, blood
glucose decreases
* in liver, glucose is turned
into glycogen (store)
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 α cells: produce glucagon (when glucose ↓): causes blood
glucose to increase as glycogen is converted from the liver.
See fig. 1 pg. 378 for diagram of feedback system involved.
*Additional info on diabetes: see pg. 379.
Sex Hormones: (Section 8.5)
 Ovaries  female sex glands – estrogen and progesterone
 Estrogen and progesterone are involved in the complex
female sexual cycle in which one egg matures aprox. every
28 days.
 Changes in these pituitary hormones cause changes in
ovarian hormones: estrogen and progesterone throughout
the cycle and through pregnancy if it occurs.
 Testes  male sex glands – testosterone
 Testosterone stimulates spermatogenesis, devel. of male
secondary sex characteristics, and is also associated w sex
drive
* see pg. 389-90 for more detail on anabolic steroids
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Independent Reading Assignment
Use your textbook, sections 8.1 through to 8.5 to help
you complete the following chart below, for each of the
following hormones:
Pituitary Hormones
Produced elsewhere
Growth hormone (GH)
Thyroid stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH)
Follicle Stimulating hormone (FSH)
Luteinizing hormone (LH)
Prolactin
Oxytocin
Antidiuretic Hormone (ADH)
Insulin
Glucagon
Epinepherine/Norepinephrine
Cortisol
Thyroxin
Parathyroid Hormone
Estrogen
Pregesterone
Testosterone
The chart that you complete should have the following
headings:
Hormone
Site of
Target
production
tissues/organs
Function
Disease/
Ailments
…..
You will be able to use your completed chart on you Unit Test,
so it is important that you read your text carefully and provide
a complete summary of these hormones.
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