2. Endocrine vs. Nervous System
• Major communication systems in the body
• Integrate stimuli and responses to changes
in external and internal environment
• Both are crucial to coordinated functions of
highly differentiated cells, tissues and
organs
• Unlike the nervous system, the endocrine
system is anatomically discontinuous.
3. Introduction
• The endocrine system includes the organs of the body
that secrete hormones directly into body fluids such
as blood
– Regulates chemical reaction in cells and therefore control
functions of the organs, tissues, and other cells
bloodstream
to
Glands
into
secrete
hormones
34-3
target tissues
4. Hormones
• Endocrine glands
– Ductless
– Release hormones
• Directly into target tissues
• Into bloodstream to be carried to target tissues
• Hormones – chemicals secreted by a cell
that affect the functions of other cells
34-4
5. Hormones (cont.)
• Many are derived from steroids that easily
cross the cell membrane
• Examples of steroid hormones
–
–
–
–
Estrogen
Progesterone
Testosterone
Cortisol
hormones
34-5
6. Hormones (cont.)
• Nonsteroidal hormones
• Prostaglandins
– Made of amino acids or
proteins and cannot cross the
cell membrane easily
– Local, or tissue, hormones
– Derived from lipid molecules
– Do not travel in the
bloodstream
– Target tissues are located close
by
– Produced by organs such as
– Bind to receptors on the
surface of the cells
– G-protein – activated by the
hormone-receptor complex
•
•
•
•
•
• Activates enzymes inside cell
34-6
Kidneys
Heart
Stomach
Uterus
Brain
7. Negative and Positive
Feedback Loops
• Control hormone levels
• Negative feedback loop
– Hormone release stops in response to decrease
in stimulus
• Stimulus (eating) raises blood glucose levels
• Pancreas releases insulin in response to elevated
blood glucose
• Blood glucose decreases as it is used by the body or
stored in the liver
• Insulin release stops as blood glucose levels
normalize
34-7
8. Negative and Positive
Feedback Loops (cont.)
• Positive feedback loop
– As long as stimulus is present, action of
hormone continues
• Infant nursing at mother’s breast stimulates
hypothalamus stimulates posterior pituitary
• Oxytocin released stimulates milk production and
ejection from mammary glands
• Milk release continues as long as infant continues to
nurse
34-8
9. Apply Your Knowledge
Match the following:
ANSWER:
___ Chemicals that effect cell function A. Nonsteroidal hormone
E
B
___ Easily cross cell membranes
B. Steroidal hormone
A
___ Made of amino acids
C. G-protein
D
___ Target nearby cells
D. Prostaglandins
___ Activated by hormone-receptor
C
complex
E. Hormones
___ Cannot cross cell membranes easily
A
B
___ Estrogen and cortisol
34-9
10. Hypothalamus
• Hormones
– Oxytocin
– Antidiuretic hormone (ADH)
• Hormones transported to the posterior
pituitary for storage
• Directs posterior pituitary to release
hormones
34-10
Glands
11. Pituitary Gland
• Controlled by the hypothalamus
• Located at the base of the brain
– Protected by a bony structure called the sella turcica
– The optic chiasm is located just above the pituitary gland
• Carries visual information to the brain for interpretation
• Two lobes
– Anterior lobe
– Posterior lobe
Glands
34-11
12. Pituitary Gland (cont.)
Growth hormone
Stimulates increase in size
of muscles and bones
Luteinizing
Prolactin Stimulates milk
production
Anterior
Lobe
Females: stimulates ovulation
and estrogen production
Males: stimulates testosterone production
Adrenocorticotropic
Stimulates the adrenal cortex
to release its hormones
Thyroid-stimulating
Stimulates the thyroid
gland to release its
hormones
Follicle-stimulating
Females: stimulates estrogen
production and maturation of the ova
Males: stimulates sperm production
34-12
13. Pituitary Gland (cont.)
Oxytocin
Posterior
Lobe
Antidiuretic hormone (ADH)
Stimulates the kidneys to
conserve water
34-13
Females: causes
contraction of the
uterus and ejection of
breast milk
Males: stimulates
contraction of the
prostate and vas
deferens during
sexual arousal
14. Apply Your Knowledge
Match the following:
ANSWER:
D, E Stored in posterior pituitary
___
A. Follicle-stimulating hormone
___ Milk production
B
B. Prolactin
D, E Produced by hypothalmus
___
C. Luteinizing hormone
___ Stimulates sperm production
A
D. ADH
___ Maturation of ova
A
E. Oxytocin
___ Stimulates ovulation
C
Super!
___ Conservation of water
D
___ Production of testosterone
C
___ Contraction of uterus
E
34-14
15. Thyroid Gland and
Parathyroid Glands
Thyroid Gland
Located below the larynx
Divided into follicles that store some of the hormones
Major hormones
T3 T4
Stimulate protein synthesis and
increase cellular energy
production
Lowers blood calcium levels
by activating osteoblasts that
Glands
build new bone tissue
34-15
16. Thyroid Gland and
Parathyroid Glands (cont.)
• Parathyroid glands
– Four located on the posterior surface of the thyroid
gland
– Secrete parathyroid hormone (PTH)
• Agonist to calcitonin by raising blood calcium levels
through activation of osetoclasts (dissolve bone)
– As bone dissolves, calcium levels in blood increase
Glands
34-16
17. 34-17
Apply Your Knowledge
True or False:
ANSWER:
__ Thyroid hormones stimulate protein synthesis.
T
Thyroid follicles store
__ The thyroid gland does not store hormones. some hormones.
F
__ PTH activates osteoblasts.
F
PTH activates osteoclasts.
__ Calcitonin increases cellular energy production.
F
Thyroid hormone
increases cellular
energy production.
T
__ The four parathyroid glands are located on the thyroid gland.
__ Calcitonin lowers blood calcium levels.
T
18. Adrenal Glands
• Located on top of each kidney
• Divided into the adrenal medulla and adrenal cortex
• Adrenal medulla
– Central portion
– Hormones
• Epinephrine
• Norepinephrine
• Same effects as sympathetic nervous system
Glands
34-18
19. Adrenal Glands (cont.)
• Adrenal cortex
– Outermost portion
– Secretes many hormones, but main ones are
• Aldosterone
– Stimulates body to retain sodium and water
– Important in maintaining BP
• Cortisol
– Released when stressed
– Decreases protein synthesis, resulting in slowed tissue
repair
– Decreases inflammation
34-19
20. Apply Your Knowledge
Match the following:
ANSWER:
____ Adrenal medulla
B, D
A. Cortisol
C
____ Sodium retention
B. Epinephrine
A
____ Decreases inflammation
C. Aldosterone
B, D
____ Sympathetic effects
D. Norepinephrine
____ Maintains blood pressure
C
Excellent!
____ Released during stress
A
A, C
____ Adrenal cortex
34-20
21. 34-21
Pancreas
• Located behind the
stomach
• Both exocrine gland and
endocrine gland
– Exocrine – secretes
digestive enzymes into a
duct leading to the small
intestine
– Endocrine – secretes
hormones into bloodstream
Glands
22. Pancreas (cont.)
• Islets of Langerhans secrete hormones into
bloodstream
– Alpha cells secrete glucagon
– Beta cells secrete insulin
Blood glucose
concentrations
Blood glucose
concentrations
Protein synthesis
Protein synthesis
34-22
23. Apply Your Knowledge
What are the effects of insulin and glucagon?
ANSWER: Insulin decreases blood glucose concentration and
increases protein synthesis.
Glucagon does just the opposite. It increases blood glucose
and decreases protein synthesis.
Yippee
!
34-23
24. Other Hormone-Producing
Organs
• Pineal body
• Thymus gland
– Small gland
– Located between
cerebral hemispheres
– Melatonin
– Located between
lungs
– Thymosin
• Promotes
production of
T lymphocytes
• Regulates circadian
rhythms
• May play a role in
onset of puberty
Glands
34-24
25. Other Hormone-Producing
Organs (cont.)
• The gonads
• Small intestine
– Ovaries
– Secretin
– Cholecystokinin
• Estrogen
• Progesterone
– Testes
• Heart
– Atrial natriuretic
peptide – regulates BP
• Testosterone
• Stomach
– Gastrin
• Kidneys
– Erythropoietin –
stimulates blood cell
production
34-25
Glands
27. Apply Your Knowledge
Match the following:
ANSWER:
D
___ Between lungs
A. Pineal body
A
___ Melatonin
B. Heart
G
___ Estrogen/testosterone
C. Kidneys
F
___ Gastrin
D. Thymus gland
E
___ Secretin
E. Small intestine
C
___ Erythropoietin
F. Stomach
B
___ Atrial natriuetic peptide
G. Gonads
D
___ Thymosin
E
___ Cholecystokinin
34-27
28. 34-28
The Stress Response
• Stressor
– Any stimulus that
produces stress
– Types
• Physical factors
• Psychological factors
• Positive stimuli
29. The Stress Response (cont.)
• Physiologic response to stress caused by
hormone release
– General stress syndrome
• Increased heart rate, respiratory rate, and BP
• Increase in glucose and fatty acids in blood, which
leads to weight loss
• Increase in cortisol if stress prolonged
– Decreased body repair
– Susceptibility to illness
34-29
30. Apply Your Knowledge
Match the following:
ANSWER:
___ Extreme heat
A
A. Physical stress
___ Death of friend
B
B. Psychological stress
___ Fractured leg
A
C. Positive stimulus
___ Wedding
C
___ Exam
B
___ Hearing an explosion nearby
B
___ “A” on an exam
C
___ Flu
A
___ Car stolen
B
34-30
31. 34-31
Common Diseases and Disorders
Disease/Disorder
Acromegaly
Description
Too much growth hormone produced in adults;
enlargement of bones and thickened skin
Addison’s disease Adrenal gland fails to produce enough
corticosteroids
Cretinism
Extreme form of hypothyroidism present prior
to or soon after birth
Cushing’s disease Hypercortisolism; over-production of cortisol
Diabetes insipidus Kidneys fail to reabsorb water, resulting in
excessive urination; hyposecretion of ADH
32. 34-32
Common Diseases and Disorders
(cont.)
Disease/Disorder
Diabetes mellitus
Description
Chronic disease characterized by elevated
blood glucose levels
Type I
Insulin-dependent diabetes mellitus; usually develops
in childhood
Noninsulin-dependent diabetes mellitus; primarily in
adults but increased incidence in teens
Occurs during pregnancy; usually temporary
Type II
Gestational
Dwarfism
Too little growth hormone (somatotropin)
produced during childhood
33. 34-33
Common Diseases and Disorders
(cont.)
Disease/Disorder Description
Gigantism
Too much growth hormone produced during
childhood
Goiter
Enlargement of thyroid gland, causing
swelling in neck; deficiency of iodine in diet
Grave’s disease
Hyperthyroidism; antibodies attach to thyroid
gland, causing it to produce too much thyroid
hormone
Thyroid gland produces inadequate amounts of
thyroid hormone; common in females over 50
Myxedema
34. Apply Your KnowledgeCorrect!
True or False:
ANSWER:
in an adult
___ Acromegaly develops as a result of too much growth hormone in a child.
F
T
___ In diabetes insipidus, the kidneys fail to reabsorb water.
___ Too little growth hormone in childhood results in dwarfism.
T
___ Myxedema is the result of hyperthyroidism.
F
hypothyroidism
___ Addison’s disease is the result of too little corticosteroid.
T
___ Cushing’s disease is the result of too little ACTH.
F
too much ACTH
___ Cretinism is an extreme form of hyperthyroidism present at birth.
F
hypothyroidism
34-34
35. In Summary
• The organs of the
endocrine system
secrete hormones
directly into blood and
other body fluids.
• Hormones secreted by
the endocrine system
control the functions
of other cells.
• Endocrine organs
–
–
–
–
–
–
–
–
–
34-35
Hypothalamus
Pituitary gland
Thyroid gland
Parathyroid glands
Adrenal glands
Pancreas
Pineal body
Thymus gland
Gonads, stomach small
intestine, heart,
kidneys