Download Ch. 45 Endocrine notes-2012

HORMONES AND THE
ENDOCRINE SYSTEM
CHAPTER 45
OVERVIEW: THE BODY’S LONG-DISTANCE
REGULATORS
Animal hormones are chemical signals that
are secreted into the circulatory system and
communicate regulatory messages within the
body
Hormones reach all parts of the body, but only
target cells have receptors for that hormone
COORDINATION BETWEEN ENDOCRINE
AND NERVOUS SYSTEMS
 The endocrine system secretes hormones that
coordinate slower but longer-acting responses
including reproduction, development, energy
metabolism, growth, and behavior
 The nervous system conveys high-speed electrical
signals along specialized cells called neurons; these
signals regulate other cells
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling.
CONCEPT 45.1: HORMONES AND OTHER SIGNALING
MOLECULES BIND TO TARGET RECEPTORS,
TRIGGERING SPECIFIC RESPONSE PATHWAYS
Intercellular Communication
The ways that signals are transmitted between
animal cells are classified by two criteria
 The type of secreting cell
 The route taken by the signal in reaching its
target
ENDOCRINE SIGNALING
Endocrine cells that release specific signaling
molecules, which can travel long distances
through the blood to reach all parts of the
body.
Maintains homeostasis, mediates responses
to stimuli, regulates growth and development
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
PARACRINE AND AUTOCRINE SIGNALING
 Paracrine signaling —target
cells lie near the secreting
cells
 Autocrine signaling—target
cell is also the secreting cell
 Both use local regulators
that travel short distances,
reaching target cells by
diffusion
 Both play roles in regulating
blood pressure, nervous
system function, and
reproduction
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. b. Cells communicate over short distances by using local regulators that target cells in the vicinity of the emitting
cell.
SYNAPTIC AND NEUROENDOCRINE
SIGNALING
Synaptic signaling--neurons form specialized
junctions with target cells, called synapses
At synapses, neurons secrete molecules called
neurotransmitters that diffuse short distances
and bind to receptors on target cells
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. b. Cells communicate over short distances by using local regulators that target cells in the vicinity of the emitting
cell.
SYNAPTIC AND NEUROENDOCRINE
SIGNALING
 Neuroendocrine signaling--specialized neurosecretory
cells secrete molecules (neurohormones) that travel
to target cells via the bloodstream (e.g. vasopressin —
essential to kidney function and water balance)
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
SIGNALING BY PHEROMONES
 Members of the same
animal species sometimes
communicate with
pheromones, chemicals
that are released into the
environment
 Pheromones serve many
functions, including
marking trails leading to
food, defining territories,
warning of predators, and
attracting potential mates
Essential knowledge 3.E.1: Individuals can act on information and communicate it to others.
a. Organisms exchange information with each other in response to internal changes and external cues, which can change behavior.
LO 3.42 The student is able to describe how organisms exchange information in response to internal changes or environmental cues.
ENDOCRINE TISSUES AND ORGANS
 Endocrine glands –
endocrine cells
grouped together in
ductless organs
 Secrete hormones
directly into surrounding
fluid
 Exocrine glands –
have ducts and
secrete substances
onto body surfaces or
into cavities
MULTIPLE EFFECTS OF HORMONES
The same hormone
may have different
effects on target
cells that have
 Different
receptors for the
hormone
 Different signal
transduction
pathways
FEEDBACK REGULATION
Negative feedback
inhibits a response
by reducing the
initial stimulus, thus
preventing excessive
pathway activity
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external
environmental changes.
a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating physiological processes,
returning the changing condition back to its target set point.
FEEDBACK REGULATION
Positive feedback
reinforces a
stimulus to produce
an even greater
response
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external
environmental changes.
b. Positive feedback mechanisms amplify responses and processes in biological organisms. The variable initiating the response is moved farther
away from the initial set-point. Amplification occurs when the stimulus is further activated which, in turn, initiates an additional response that
produces system change.
INSULIN AND GLUCAGON: CONTROL OF
BLOOD GLUCOSE
 Insulin produced by
alpha cells of
pancreatic islets
 Reduces blood glucose
levels by
 Promoting the cellular
uptake of glucose
 Slowing glycogen
breakdown in the liver
 Promoting fat storage,
not breakdown
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
INSULIN AND GLUCAGON: CONTROL OF
BLOOD GLUCOSE
 Glucagon produced by
beta cells of pancreatic
islets
 increases blood
glucose levels by
 Stimulating conversion
of glycogen to glucose in
the liver
 Stimulating breakdown
of fat and protein into
glucose
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
DIABETES MELLITUS
Caused by a deficiency of insulin or a
decreased response to insulin in target tissues
It is marked by elevated blood glucose levels
 Type 1 diabetes mellitus (insulin-dependent) is
an autoimmune disorder in which the immune
system destroys pancreatic beta cells
 Type 2 diabetes mellitus (non-insulin-dependent)
involves insulin deficiency or reduced response of
target cells due to change in insulin receptors
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external
environmental changes.
c. Alteration in the mechanisms of feedback often results in deleterious consequences.
CONCEPT 45.3: THE HYPOTHALAMUS AND
PITUITARY ARE CENTRAL TO ENDOCRINE
REGULATION
Endocrine pathways are subject to regulation
by the nervous system, including the brain
COORDINATION OF ENDOCRINE AND
NERVOUS SYSTEMS IN VERTEBRATES
 The hypothalamus receives
information from the
nervous system and
initiates responses through
the endocrine system
 Attached to the
hypothalamus is the
pituitary gland
 Posterior pituitary - stores and
secretes hormones that are
made in the hypothalamus
 Anterior pituitary - makes and
releases hormones under
regulation of the hypothalamus
POSTERIOR PITUITARY HORMONES
The two hormones released from the posterior
pituitary act directly on nonendocrine tissues
• Oxytocin regulates milk
secretion by the
mammary glands
• Antidiuretic hormone
(ADH) regulates water
uptake by the kidneys
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
ANTIDIURETIC HORMONE (ADH)
Ch. 44
 Eating a bag of salty pretzels
decreases blood osmolarity
 This triggers the release of ADH by
posterior pituitar y
 ADH makes kidneys retain more
water and excrete more
concentrated urine
 Blood osmolarity increases,
osmoreceptor s in hypothalamus
reduce ADH production
 What do you think happens if you
drink a large volume of water?
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external
environmental changes.
a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating physiological processes,
returning the changing condition back to its target set point.
ANTERIOR PITUITARY HORMONES
 Hormone production here
is controlled by releasing
and inhibiting hormones
from the hypothalamus
 For example, prolactinreleasing hormone from
the hypothalamus
stimulates the anterior
pituitary to secrete
prolactin (PRL), which has
a role in milk production
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
 The release of thyroid
hormone results from
a hormone cascade
pathway involving the
hypothalamus,
anterior pituitary, and
thyroid gland
 Hormone cascade
pathways typically
involve negative
feedback
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external
environmental changes. a. Negative feedback mechanisms…
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical
signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
http://www.answeringchristianity.com/thyroid_gland_1.jpg
THYROID REGULATION: A HORMONE
CASCADE PATHWAY
DISORDERS OF THYROID FUNCTION AND
REGULATION
 Hypothyroidism, too little thyroid function,
can produce symptoms such as
 Weight gain, lethargy, cold intolerance
 Hyperthyroidism, excessive production of
thyroid hormone, can lead to
 High temperature, sweating, weight loss,
irritability, and high blood pressure
 Graves disease, a form of hyperthyroidism caused
by autoimmunity, is typified by protruding eyes
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external
environmental changes.
c. Alteration in the mechanisms of feedback often results in deleterious consequences.
 Thyroid hormone refers
to a pair of hormones
 Triiodothyronin (T 3 ),
with three iodine atoms
 Thyroxine (T 4 ), with four
iodine atoms
 Insufficient dietary
iodine causes pituitary
to secrete TSH
  TSH levels lead to an
enlarged thyroid gland,
called a goiter
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external
environmental changes.
c. Alteration in the mechanisms of feedback often results in deleterious consequences.
Campbell, Reece, and Simon. (2007 ). Essential Biology with Physiology.
MALNUTRITION CAN ALTER THYROID
FUNCTION
CONCEPT 45.4: ENDOCRINE GLANDS RESPOND TO
DIVERSE STIMULI IN REGULATING HOMEOSTASIS,
DEVELOPMENT, AND BEHAVIOR
Endocrine signaling regulates homeostasis,
development, and behavior
PARATHYROID HORMONE AND VITAMIN D:
CONTROL OF BLOOD CALCIUM
 Two antagonistic hormones regulate the homeostasis
of calcium (Ca 2+ ) in the blood of mammals
• Parathyroid hormone (PTH)
is released by the
parathyroid glands
• Calcitonin is released by the
thyroid gland
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c.
Signals released by one cell type can travel long distances to target cells of another cell type.
PTH INCREASES THE LEVEL OF BLOOD
Ca 2+
 PTH releases Ca 2+ from
bone and stimulates
reabsorption of Ca 2+ in the
kidneys
 It also has an indirect
effect, stimulating the
kidneys to activate vitamin
D, which promotes intestinal
uptake of Ca 2+ from food
 Calcitonin decreases the
level of blood Ca 2+
 It stimulates Ca 2+ deposition in
bones and secretion by kidneys
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental
changes.
ADRENAL HORMONES: RESPONSE TO
STRESS
The adrenal glands are adjacent to the
kidneys
Each adrenal gland actually consists of two
glands: the adrenal medulla (inner portion)
and adrenal cortex (outer portion)
http://biology-forums.com/gallery/14755_28_08_12_1_42_24_82281403.jpeg
HORMONES FROM THE
ADRENAL MEDULLA
The adrenal medulla secretes epinephrine
(adrenaline) and norepinephrine
(noradrenaline)
They are secreted in response to stressactivated impulses from the nervous system
They mediate various fight-or-flight responses
SHORT TERM STRESS
 Epinephrine and
norepinephrine
 Trigger the release of glucose
and fatty acids into the blood
 Increase oxygen delivery to
body cells
 Direct blood toward heart,
brain, and skeletal muscles
and away from skin, digestive
system, and kidneys
 The release of epinephrine
and norepinephrine occurs
in response to involuntary
nerve signals
Essential knowledge 3.E.1: Individuals can act on information and communicate it to others.
a. Organisms exchange information with each other in response to internal changes and external cues, which can change behavior.
HORMONES FROM THE ADRENAL CORTEX
The adrenal cortex releases a family of
steroids called corticosteroids in response to
stress
These hormones are triggered by a hormone
cascade pathway via the hypothalamus and
anterior pituitary (ACTH)
Humans produce two types of corticosteroids:
glucocorticoids and mineralocorticoids
 Glucocorticoids, such
as cortisol, influence
glucose metabolism
and the immune system
 Mineralocorticoids,
such as aldosterone,
affect salt and water
balance
 The adrenal cortex also
produces small
amounts of steroid
hormones that function
as sex hormones
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
GONADAL SEX HORMONES
 The gonads, testes and
ovaries, produce most of
the sex hormones:
androgens, estrogens, and
progestins
 All three sex hormones are
found in both genders, but
in significantly different
proportions
 Synthesis of the sex
hormones is controlled by
FSH and LH from the
anterior pituitary
TESTOSTERONE
 The testes primarily synthesize androgens,
mainly testosterone, which stimulate
development and maintenance of the male
reproductive system (sperm production)
 Testosterone causes an increase in muscle
and bone mass and is often taken as a
supplement to cause muscle growth, which
carries health risks
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
ESTROGENS AND PROGESTINS
Estrogens, most importantly estradiol, are
responsible for maintenance of the female
reproductive system and the development of
female secondary sex characteristics
In mammals, progestins, which include
progesterone, are primarily involved in
preparing and maintaining the uterus
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.