chapter 50 endocrine system
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Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
CHAPTER 50
Endocrine Systems
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All the endocrine glands and other organs with hormone-
secreting cells
Heart
Adrenal glands (medulla and cortex)
Thyroid
Pineal
Parathyroids
Pancreas
Stomach and small intestine
Adipose tissue
Liver and kidneys
Ovaries (in females)
Anterior pituitary gland
Posterior pituitary gland
Hypothalamus
Cortex
Medulla (not visible)
Testes (in males)
Endocrine system
Figure 50.1
Different organs and glands secrete
different types of hormones
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Hormones - chemical signals produced by endocrine cells
-travel through the blood stream and act on their target cells
Endocrine system
Endocrine cells
Target cells
hormone
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Endocrine system
Amines
Proteins/peptides
: water soluble (except thyroid hormone)
=> unable to cross plasma membrane
=> signal through cell surface receptor
Hormones - chemical signals produced by endocrine cells
-travel through the blood stream and act on their target cells
Amines or
proteins/peptide
3 types of hormones
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Endocrine system
Steroids
: lipid soluble => cross plasma membrane => bind to either cytosolic or
nuclear receptor
Hormones - chemical signals produced by endocrine cells
-travel through the blood stream and act on their target cells
3 types of hormones
Amines
Proteins/peptides
: water soluble (except thyroid hormone)
=> unable to cross plasma membrane
=> signal through cell surface receptor
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Endocrine system
Steroids
: lipid soluble => cross plasma membrane => bind to either cytosolic or
nuclear receptor
Hormones - chemical signals produced by endocrine cells
-travel through the blood stream and act on their target cells
3 types of hormones
Amines
Proteins/peptides
: water soluble (except thyroid hormone)
=> unable to cross plasma membrane
=> signal through cell surface receptor
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Endocrine system
Function in
- Metabolism
- Mineral Balance
- Growth and Differentiation
- Reproduction
- Response to stress
Hormones - chemical signals produced by endocrine cells
-travel through the blood stream and act on their target cells
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! Only cells having the proper receptors can respond to a hormone
! Hormones activate only specific cells
! Hormone interacts noncovalently and reversibly with the receptor
" Prevents cell from being permanently stimulated
8
Endocrine system
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Endocrine system
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Link between Endocrine system and Nerve system
To venous
circulation
Pituitary
Posterior pituitary gland
Portal veins
Capillaries
Hypothalamus ()
Hypothalamus
Hypothalamic nuclei
1) make neurohormones
Infundibular
stalk
Arterial blood
supply
Anterior
pituitarygland
()
3) Travel through portal vein
to anterior pituitary gland
2) Neurohormones are released from axo
of hypothalamic neurons into capillaries
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Link between Endocrine system and Nerve system
To venous
circulation
Pituitary
Posterior pituitary gland
Portal veins
Capillaries
Hypothalamus ()
Hypothalamus
Hypothalamic nuclei
1) make neurohormones
2) Neurones secrete neurohormo into capillaries
Infundibular
stalk
Arterial blood
supply
Anterior
pituitarygland
()
3) Travel through portal vein
to anterior pituitary gland
4) Anterior pituitary gland synthesize several hormones
5) Secrete into the circulation hormones
neurohormones
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Link between Endocrine system and Nerve system
To venous
circulation
Pituitary
Posterior pituitary gland
Portal veins
Capillaries
Hypothalamus ()
Hypothalamus
Hypothalamic nuclei
1) make neurohormones
2) Neurones secrete neurohormo into capillaries
Infundibular
stalk
Arterial blood
supply
Anterior
pituitarygland
()
3) Travel through portal vein
to anterior pituitary gland
4) Anterior pituitary gland synthesize several hormones
5) Secrete into the circulation hormones
neurohormones
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Hormonal Control of Metabolism and Energy Balance
e.g., Thyroid hormone ()
!Increase Glucose metabolism
!Increase in heat production
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Hormonal Control of Metabolism and Energy Balance
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Hypothalamus
TRH
TSH
Thyroid
Anterior
pituitarygland
Normal levels
of T4and T3
T4 and T3
inhibit TRH secretion
as well as expression
of TRH precursor
negative
feedback
1) TRH (thyrotropin -releasing hormone)
Is released from hypothalamus
2) TSH (thyroid-stimulating hormone)
Is released from anterior pituitary gland
3) T4 and T3 (thyroid hormones)
is released from thyroid
Keeping balance
e.g., Thyroid hormone () Fig 50.6
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Diseases caused by too little or too much Thyroid Hormone
15
Hypothyroidism
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Hypothalamus
TRH
TSH
Thyroid
Anterior
pituitarygland
Normal levels
of T4and T3
T4 and T3
inhibit TRH secretion
as well as expression
of TRH precursor
negative
feedback
1) Decrease in TSH (thyroid-stimulating hormone)
2) Decrease in T4 and T3 (thyroid hormones)
-most common cause of hypothyroidism
=> Weight gain, sensation of coldness
Keeping balance
Hypothyroidism :Low T3, T4
Diseases caused by too little or too much Thyroid Hormone
Fig 50.6
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Hypothalamus
TRH
TSH
Thyroid
Anterior
pituitary
gland
Normal levels
of T4and T3
T4 and T3
inhibit TRH secretion
as well as expressionof TRH precursor
negative
feedback
Increase in TSH (thyroid-stimulating hormone)
Thyroid cells are destroyed by immune cells
=> Decrease in T4 and T3 (thyroid hormones)
Hypothyroidism
e.g., Hashimotos thyroiditis :autoimmune disease
Promote the abnormal growth of thyroid : Goit
Diseases caused by too little or too much Thyroid Hormone
Fig 50.6
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Hyperthyroidism(overactive thyroid gland)
Graves disease: - autoimmune disease
-caused by hyperthyroidism
Causes: Production of antibodies against TSH receptor present on Thyroid
follicular cells
=> constitutively active
receptor (TSH receptor is always active)
=> Excessive production of T3 T4
=> weight loss, heat intolerance
Protruding eyeballs
Diseases caused by too little or too much Thyroid Hormone
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Hypothalamus
Thyroid
Anterior
pituitarygland
4)Excess TRH
5)Excess TSH & overstimulation
of thyroid
1) Reduced iodine intake
2) Low T4and T3due to lack of
iodine
3) Reduced
negativefeedback
6)Enlarged
thyroid
Diet can affect production of thyroid hormone :
Iodine is required for T4, T3 production
Diseases caused by too little or too much Thyroid Hormone
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Glucose Homeostasis
PancreasSmall intestine
Pancreatic
islets of Langerhans
:spherical clusters of
endocrine cells
Beta cells
produce
insulin
Alpha cells
produce
glucagon
glucagon
Insulin
=>Produced in pancreas
Two hormones involved in Glc Homeostasis
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Glucose Homeostasis
PancreasSmall intestine
Pancreatic
islets of Langerhans
:spherical clusters of
endocrine cells
Beta cells
produce
insulin
Alpha cells
produce
glucagon
glucagon
Insulin
=>Produced in pancreas
Two hormones involved in Glc Homeostasis
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Glucose Homeostasis
Homeostasis : bodys tendency to maintain relatively constant internal condition
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Glucose Homeostasis
3) insulin stimulate
glucose uptake
into cells
(mainly in adipose orskeletal muscle
Cells)
1) Glucose level
Increases above normal
(eating)
Normal blood
glucose level
2) Stimulate secretion of
insulin from Pancreas
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Glucose
molecule
Insulin
receptor
Without insulin
GLUT (glucose transporter)
Glucose Homeostasis
3) insulin stimulate
glucose uptakeinto cells
(mainly in adipose or
skeletal muscle
Cells- express glucose
transporter GLUT)
1) Glucose level
Increases above normal
(eating)
2) Stimulate secretion of
insulin from Pancreas
Most of GLUTs are
located membrane bound
vesicles inside the cells
And only a few are
present in plasms
membrane.
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Glucose Homeostasis
3) insulin stimulate
glucose uptake
into cells
(mainly in adipose orskeletal muscle
Cells)
1) Glucose level
Increases above normal
(eating)
2) Stimulate secretion of
insulin from Pancreas
Insulin
receptor
With insulin
Insulin
Insulin stimulate movement
Of these GLUT to the plasma
Membrane
=> Increased glc uptake
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Glucose Homeostasis
3) insulin stimulate
glucose uptake
into cells
(mainly in adipose orskeletal muscle
Cells)
4)Blood glucose
level decreases.
1) Glucose level
Increases above normal
(eating)
Normal blood
glucose level
2) Stimulate secretion of
insulin from Pancreas
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Glucose Homeostasis
Liver
4)Blood glucose
level increases.
1) Glucose level
decreases above normal
(fasting)
Normal blood
glucose level
2) glucose-monitoring
regions in the hypothalamus
stimulate production of
glucagon from Pancreas
3) High Glucagon
Glycogen Noncarbo
hydrates
Glucose
Glucose
glycogenolysis
Gluconeogenesis
(generation of
Glc)
3)Glucagon stimulates
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Glucose Homeostasis
When blood glucose
level increases.
Normal bloodglucose level
When blood glucose
level decreases.
Insulin from pancreas
Glucagon from pancreas
Blood glucoselevel increases.
Blood glucose
level decreases.
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Glucose Homeostasis
When blood glucose
level increases.
Normal bloodglucose level
When blood glucose
level decreases.
Insulin from pancreas
Glucagon from pancreas
Blood glucoselevel increases.
Blood glucose
level decreases.
What happens if this system doesnt work?
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Diabetes
! Type 1 Diabetes mellitus (T1DM)
! Type 2 Diabetes mellitus (T2DM)
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Diabetes
! Type 1 Diabetes mellitus (T1DM)
" Autoimmune disease where immune system destroyes beta cells =>can not produce insulin
when blood glc increases => no insulin production => accumulation of
Glc in blood
" Also calledjuvenile diabetes(usually diagnosed in children and
Young adults)
" Treated by administration of insulin
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Diabetes
! Type 1 Diabetes mellitus (T1DM)
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Diabetes
! Type 2 Diabetes mellitus (T2DM)
Most common form of diabetes
2) Diminished Glc uptake
1) Insulin cant signal
to Glucose transporter
1) Pancreas do not produce enough insulin (but not by the attack of immune cells)
2) cells of the body lose much of their ability to respond to insulin
Insulin resistance
Constant high blood Glc level
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Diabetes
! Type 2 Diabetes mellitus (T2DM)
Many life style factors are important in development of Type 2diabetes
: High level of Physical activity
Healthy diet
Keeping normal weight
no smoking
=> 89% lower chance to get
type II diabetes
Obesity is cause for over than 1/2 of type II diabetes
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Diabetes
Type 2 Diabetes mellitus (T2DM)
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Control of growth and differentiation
anterior
pituitary
Produces Growth hormone (GH)
Produces IGF1 (insulin like growth factor-1)
Liver
Elongation of bonesduring puberty
Gonadal hormone
: seal growth plate( )
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2
When a person develop a tumor
causing the production of
excessive GH during childhood
-> becomes very tall -> Pituitary giant
Control of growth and differentiation
If a person develop a tumor
causing the production of
excessive GH after puberty,
-> develops a condition called
Acromegaly (enlargement and thickening of feet and hands)
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3
low amount of GH produced => Short stature
Can be treated by injection of GH
e.g, Lionel (Leo) Messi
Control of growth and differentiation
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4
Stress Hormone
1. Increase heart rate to maximize blood pumping
2. Maximize oxygen intake3. Increase production of glucose to provide
energy to muscle cells
4. Increase alertness
Stress
Cortisol
(a member of glucocorticoids)
Adrenal
cortex
Anterior
pitutiary
Hypothalamus
ACTH
released into
blood
Secete Releasing
factor
Acute stress (Table 50.3)
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5
Stress Hormone
1. Lower immune systems
2. Slow down thinking
3. Create blood sugar imbalances4. Raise your blood pressure
5. Weaken muscle tissue
6. Decrease bone density
7. Craving for sweets and carbohydrate
8. Increase fat to stomach areas
Stress
Cortisol
(a member of glucocorticoids)
Adrenal
cortex
Anterior
pitutiary
Hypothalamus
ACTH
released into
dlood
Secete Releasing
factor
Exposure to Chronic stress
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