Transcript video slide

Chapter 26
Chemical Regulation
PowerPoint Lectures for
Biology: Concepts and Connections, Fifth Edition
– Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Testosterone and Male Aggression: Is There a Link?
•
Testosterone and other androgens develop and
maintain male reproductive anatomy and secondary
sexual characteristics
•
Does testosterone promote aggressive behavior?
– In male cichlid fish, androgen levels increase
during territorial displays
– The connection in humans is problematic
•
Hormones and other chemical signals enable organ
systems to function cooperatively
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
THE NATURE OF CHEMICAL REGULATION
26.1 Chemical signals coordinate body functions
• Hormones are chemical signals that
communicate regulatory messages throughout
the body
– Secreted by endocrine glands that make up
the endocrine system
– Travel in the circulatory system to target
cells
• Local regulators secreted into interstitial fluid
affect nearby target cells
• Pheromones carry messages between
different individuals of a species
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• The endocrine system collaborates with the
nervous system in controlling whole-body
activities
– Neurosecretory cells perform functions of
both systems
– Chemical neurotransmitters carry
information from one nerve cell to another
or to other cells
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 26-1a
Secretory
vesicles
Blood
vessel
Target
cell
Endocrine cell
Hormone
molecules
LE 26-1b
Blood
vessel
Neurosecretory
cell
Target
cell
Hormone
molecules
LE 26-1c
Nerve
cell
Nerve
signals
Neurotransmitter
molecules
Nerve
cell
26.2 Hormones affect target cells by two main
signaling mechanisms
• Hormones are made of proteins, amines, or
steroids
• Hormone signaling involves three key events
– Reception of the signal
– Signal transduction
– Response: change in target cell's behavior
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
•
Water-soluble hormone mechanism
1. Hormone binds to receptor protein on
target cell's plasma membrane
2. Activation of protein initiates signal
transduction pathway
3. Final relay molecule activates protein that
carries out cell's response
–
One hormone may trigger a variety of
responses
Animation: Water-Soluble Hormone
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 26-2a
Water-soluble
hormone
(epinephrine)
Target
cell
Receptor
protein
Plasma
membrane
Signal
transduction
pathway
Relay
molecules
Glycogen
Glucose
Cellular response
(in this example, glycogen breakdown)
•
Steroid hormone mechanism
1. Hormone diffuses through plasma
membrane of target cell
2. Binds to receptor protein in cytoplasm or
nucleus, creating a complex that
transduces the signal
3. Hormone-receptor complex attaches to
specific site on cell's DNA
4. Binding to DNA stimulates transcription of
genes into RNA, which is translated into
proteins
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 26-2b
Lipid-soluble
hormone
(testosterone)
Target
cell
Receptor
protein
Nucleus
Hormonereceptor
complex
DNA
Transcription
mRNA
New
protein
Cellular response:
activation of a gene and synthesis of new protein
Animation: Lipid-Soluble Hormone
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
THE VERTEBRATE ENDOCRINE SYSTEM
26.3 Overview: The vertebrate endocrine system
• The vertebrate endocrine system consists of
more than a dozen glands
– Glands can be endocrine specialists or
have endocrine and nonendocrine function
– Hormones can have a narrow or wide range
of targets and effects
– Only sex organs and cortex of adrenal
gland produce steroid hormones
– Most endocrine glands produce
water-soluble hormones
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• The pineal gland is an outgrowth of the brain
– Secretes melatonin, affecting animal's daily
and seasonal rhythms
– Cues reproductive activity in mammals
• The thymus gland plays an important role in
the immune system
– Stimulates development of T cells
– Shrinks drastically at puberty
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 26-3
Hypothalamus
Pineal gland
Pituitary gland
Thyroid gland
Parathyroid glands
Thymus
Adrenal glands
(atop kidneys)
Pancreas
Ovary
(female)
Testes
(male)
26.4 The hypothalamus, closely tied to the
pituitary, connects the nervous and endocrine
systems
• The hypothalamus exerts master control over
the endocrine system
– Receives information from nerves about
internal and external conditions
– Uses the pituitary gland to relay directives
to other glands
• Releasing and inhibiting hormones from the
hypothalamus control the pituitary
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 26-4a
Brain
Hypothalamus
Posterior pituitary
Anterior pituitary
Bone
• The posterior pituitary is an extension of the
hypothalamus
– Stores and secretes hormones made in the
hypothalamus
– Oxytocin and antidiuretic hormone (ADH)
• The anterior pituitary is composed mostly of
glandular tissue
– Synthesizes and secretes its own hormones
• TSH, ACTH, FSH, LH, growth hormone,
prolactin, and endorphins
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 26-4b
Hypothalamus
Hormone
Neurosecretory
cell
Posterior
pituitary
Anterior
pituitary
Blood
vessel
Oxytocin
ADH
Uterine muscles
Mammary glands
Kidney tubules
LE 26-4c
Neurosecretory
cell
Blood
vessel
Releasing hormones
from hypothalamus
Endocrine cells of
the anterior pituitary
Pituitary hormones
TSH
ACTH
FSH
and
LH
Growth
hormone
(GH)
Prolactin
(PRL)
Endorphins
Thyroid
Adrenal
cortex
Testes or
ovaries
Entire
body
Mammary
glands
(in mammals)
Pain
receptors
in the brain
• The hypothalamus acts through the anterior
pituitary to direct activity of the thyroid gland
– Hypothalamus produces TRH
– TRH stimulates anterior pituitary to produce
TSH
– TSH influences thyroid to release thyroxine
– Controlled by a negative-feedback
mechanism
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 26-4d
Hypothalamus
Inhibition
TRH
Anterior
pituitary
TSH
Thyroid
Thyroxine
Inhibition
• Other critical pituitary hormones
– Growth hormone (GH) promotes protein
synthesis and use of fat for energy
• Too much or too little leads to various
human disorders
– Prolactin (PRL) has many different effects in
different species
– Endorphins are the body's natural
painkillers
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
HORMONES AND HOMEOSTASIS
26.5 The thyroid regulates development and
metabolism
• Thyroid hormones affect virtually all the tissues
of vertebrates
• Thyroid gland produces T4 (thyroxine) and T3
– Play crucial roles in development and
maturation
• In mammals, thyroid hormones maintain
normal blood pressure, heart rate, muscle
tone, and digestive and reproductive functions
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
– Hyperthyroidism
• Excess T4 and T3 in the blood
• Most common result is Graves disease
– Hypothyroidism
• Insufficient amounts of T4 and T3
• Can result from defective thyroid gland or
insufficient iodine in diet
• Can lead to cretinism and goiter
– Negative feedback maintains homeostatic
levels of T4 and T3
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 26-5b
No inhibition
Hypothalamus
TRH
No inhibition
Anterior
pituitary
TSH
No iodine
Thyroid
Thyroid grows
to form goiter
Insufficient
T4 and T3
produced
26.6 Hormones from the thyroid and parathyroids
maintain calcium homeostasis
• Blood calcium levels are regulated by two
antagonistic hormones
– Calcitonin from the thyroid
– Parathyroid hormone (PTH) from the four
parathyroid glands
• Feedback systems keep calcium levels near
the homeostatic set point
– Failure can have drastic effects on the body
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 26-6
Calcitonin
Thyroid
gland
releases
calcitonin
Stimulates
Ca2+ deposition
in bones
Reduces
Ca2+ uptake
in kidneys
Blood Ca2+ falls
Stimulus:
Rising
blood Ca2+
level
(imbalance)
Homeostasis: Normal blood
calcium level (about 10 mg/100mL)
Stimulus:
Falling
blood Ca2+
level
(imbalance)
Blood Ca2+ rises
Active
vitamin D
Stimulates
Ca2+ release
from bones
Increases
Ca2+ uptake
in kidneys
Parathyroid
glands
release parathyroid
hormone (PTH)
Increases
Ca2+ uptake
in intestines
PTH
Parathyroid
gland
26.7 Pancreatic hormones regulate blood
glucose levels
• The pancreas secretes two antagonistic
hormones critical in regulating the body's
energy supply
– Insulin signals cells to use and store
glucose
– Glucagon causes cells to release stored
glucose into the blood
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Negative feedback manages the amount of
glucose circulating in blood versus amount
stored as glycogen
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 26-7
Body
cells
take up more
glucose
Insulin
Beta cells
of pancreas stimulated
to release insulin into
the blood
Liver takes
up glucose
and stores it as
glycogen
High blood
glucose level
Stimulus:
Rising blood glucose
level (e.g, after eating
a carbohydrate-rich
meal)
Homeostasis: Normal blood glucose level
(about 90 mg/100 mL)
Blood glucose level
rises to set point;
stimulus for glucagon
release diminishes
Liver
breaks down
glycogen and
releases glucose
to the blood
Blood glucose level
declines to a set point;
stimulus for insulin
release diminishes
Stimulus:
Declining blood
glucose level
(e.g., after
skipping a meal)
Alpha
cells of
pancreas stimulated
to release glucagon
into the blood
Glucagon
CONNECTION
26.8 Diabetes is a common endocrine disorder
• In diabetes mellitus, body cells are unable to
absorb glucose from the blood
– Results from a lack of insulin or a failure of
cells to respond to it
– Cells burn fats or protein as fuel
– Glucose remains in the blood, is excreted in
urine
– Can be a life-threatening disease
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Type 1 (insulin-dependent) diabetes is an
autoimmune disease
– Usually develops in childhood
– Pancreas does not produce enough insulin
– Treated by injections of insulin
• Type 2 (non-insulin-dependent) diabetes is
usually associated with being overweight
– Characterized by deficiency of insulin or
reduced responsiveness of target cells
– Treated by diet and lifestyle changes
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Diabetes can be detected by a glucose
tolerance test
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 26-8
Blood glucose (mg/100mL)
400
350
300
Diabetic
250
200
150
Normal
100
50
0
0
1
2
1
2
3
Hours after glucose ingestion
4
5
26.9 The adrenal glands mobilize responses to
stress
• Adrenal glands atop the kidneys are actually
two glands fused together
• The adrenal medulla ensures rapid, short-term
response to stress
– Responds to nerve signals from the
hypothalamus
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
– Produces fight-or-flight hormones
epinephrine and norepinephrine
• Mobilize glucose
• Increase blood pressure, breathing, and
metabolic rates
• Change blood-flow patterns
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• The adrenal cortex provides a slower, longer
lasting response to stress
– Responds to endocrine signals: ACTH from
the pituitary
– Secretes corticosteroids
• Glucocorticoids act mainly on salt and water
balance
• Mineralocorticoids mobilize cellular fuel
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
CONNECTION
26.10 Glucocorticoids offer relief from pain, but
not without serious risks
• Glucocorticoids relieve inflammation and pain
– Often prescribed for athletic injuries
– Can mask injury and suppress immunity
– Increase risk of diabetes, eye problems,
bone fractures
• Former basketball player Bill Walton has
drawn attention to the dangers
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Major human endocrine glands and some of their
hormones
Table 45.1
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Table 45.1
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
26.11 The gonads secrete sex hormones
• Estrogens, progestins, and androgens are
steroid sex hormones
– Produced by the gonads in response to
signals from the hypothalamus and pituitary
– Both males and females have all three
hormones in different proportions
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
•
Females have a high ratio of estrogens to androgens
– Estrogens stimulate development of female
characteristics and maintenance of reproductive
system
– Progestins prepare and maintain uterus to support
an embryo
•
Males have a high ratio of androgens to estrogen
– Androgens stimulate development of male
characteristics and maintenance of reproductive
system
– Testosterone is the main androgen
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings