ENDOCRINE SYSTEM Flashcards
a molecule that is released in one part of the
body but regulates the activity and growth of cells in other parts of the body.
Hormone
- Help regulate.
a. Chemical composition and volume of internal
environment (extracellular fluid).
b. Metabolism and energy balance.
c. Contraction of smooth and cardiac muscle fibes.
d. Glandular secretions.
e. Some immune system activities - Control growth and development.
- Regulate operation of reproductive systems.
- Help establish circadian rhythms.
Functions of Hormone
• Neurons release neurotransmitters at
synapses, neuromuscular or
neuroglandular
junctions.
• Effectors include
other neurons,
muscles, glands.
• Rapid responses from
effectors.
NERVOUS SYSTEM
• Releases hormones
into interstitial fluid
→ blood → general
circulation.
• Effectors: virtually
any type of body cell,
so can have
widespread effects
on diverse aspects of
metabolism.
• Slower, long-lasting
responses as
hormones linger in
blood.
ENDOCRINE SYSTEM
Neurons release
neurotransmitters at
synapses,
neuromuscular or
neuroglandular
junctions.
NERVOUS SYSTEM
Effectors include
other neurons,
muscles, glands.
NERVOUS SYSTEM
Effectors include
other neurons,
muscles, glands.
NERVOUS SYSTEM
Rapid responses from
effectors.
NERVOUS SYSTEM
Releases hormones
into interstitial fluid
→ blood → general
circulation.
ENDOCRINE SYSTEM
Effectors: virtually
any type of body cell,
so can have
widespread effects
on diverse aspects of
metabolism.
ENDOCRINE SYSTEM
Slower, long-lasting
responses as
hormones linger in
blood.
ENDOCRINE SYSTEM
• Secretion enters
interstitial fluid and
then → bloodstream.
• Stay in the body:
endo-
• Examples: all
hormones such as
growth hormone,
insulin, adrenalin,
estrogen,
testosterone.
ENDOCRINE GLANDS
Secretion enters
interstitial fluid and
then → bloodstream.
ENDOCRINE GLANDS
• Stay in the body:
endo-
• Examples: all
hormones such as
growth hormone,
insulin, adrenalin,
estrogen,
testosterone.
ENDOCRINE GLANDS
Secrete substances
that enter ducts.
EXOCRINE GLANDS
• Ultimately exit the
body (exo-)
• Examples: mucus,
saliva, and other
digestive secretions,
sweat, tears.
EXOCRINE GLANDS
• In endocrine glands
- Pituitary, thyroid, parathyroid, adrenal, pineal.
• In cells within organs that do produce hormones but also have other functions.
- Hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue, and placenta.
ENDOCRINE CELLS THAT MAKE HORMONES
In endocrine glands
Pituitary, thyroid, parathyroid, adrenal, pineal.
In cells within organs that do produce hormones but
also have other functions.
Hypothalamus, thymus, pancreas, ovaries, testes,
kidneys, stomach, liver, small intestine, skin, heart,
adipose tissue, and placenta.
• Hormones are carried in blood stream.
• But only certain cells can be affected by hormones.
- These target cells have 1000’s of receptors specific
for a particular hormone.
- Response determined by responding cell: different
cells may respond differently to the same hormone.
- Cell may have > 1 type of receptor, so can respond
to more than one hormone.
HORMONE ACTION
• Lipid-soluble
- Steroids, such as testosterone, estrogens.
- Thyroid hormones: T3 (triiodothyronine) and T4
(thyroxine) – synthesized by attaching iodine to amino
acid tyrosine.
- Nitric oxide (NO) – both a hormone & NT.
• Water-soluble
- Amino acid derivatives, serotonin, histamine, and
catecholamines (collective term): Epi, NE, and dopamine.
- Peptides: antidiuretic hormone (ADH) or vasopressin,
oxytocin.
- Proteins: insulin and growth hormone.
- Eicosanoid hormones: prostaglandins and leukotrienes.
• General action depends on chemistry.
HORMONE CHEMISTRY
- Steroids, such as testosterone, estrogens.
- Thyroid hormones: T3 (triiodothyronine) and T4
(thyroxine) – synthesized by attaching iodine to amino acid tyrosine. - Nitric oxide (NO) – both a hormone & NT.
Lipid-soluble
such as testosterone, estrogens.
Steroids
T3 (triiodothyronine) and T4 (thyroxine) – synthesized by attaching iodine to amino acid tyrosine.
Thyroid hormones
both a hormone & NT.
Nitric oxide (NO)
- Amino acid derivatives, serotonin, histamine, and
catecholamines (collective term): Epi, NE, and dopamine. - Peptides: antidiuretic hormone (ADH) or vasopressin,
oxytocin. - Proteins: insulin and growth hormone.
- Eicosanoid hormones: prostaglandins and leukotrienes.
Water-soluble
Amino acid derivatives, serotonin, histamine, and
catecholamines (collective term):
Epi, NE, and dopamine.
— antidiuretic hormone (ADH) or vasopressin,
oxytocin.
Peptides
insulin and growth hormone.
Proteins
prostaglandins and leukotrienes.
Eicosanoid hormones
• Release occurs in short bursts.
• Regulated by:
- Signals from nervous system
a. Example: adrenal medulla release of epinephrine.
- Chemical changes in blood
a. Example: blood Ca2+ affects parathyroid hormone.
- Other hormones
a. Example: ACTH (adrenocorticotropic hormone) from pituitary stimulates release of cortisol from adrenal cortex.
CONTROL OF HORMONE SECRETIONS
Release occurs in short bursts.
CONTROL OF HORMONE SECRETIONS
a. Example: adrenal medulla release of epinephrine.
Signals from nervous system
a. Example: blood Ca2+ affects parathyroid hormone.
Chemical changes in blood
a. Example: ACTH (adrenocorticotropic hormone) from pituitary stimulates release of cortisol from adrenal cortex.
Other hormones
ACTH
adrenocorticotropic hormone
• Serve as major link between nervous and endocrine
systems.
• Hypothalamic cells synthesize:
- Many releasing and inhibiting hormones.
- Two hormones (oxytocin and ADH – antidiuretic
hormone) that are then stored and released from the
posterior pituitary.
• Anterior pituitary synthesizes 7 hormones.
• Regulate growth, development, metabolism, and
homeostasis.
HYPOTHALAMUS AND PITUITARY
Serve as major link between nervous and endocrine
systems.
HYPOTHALAMUS AND PITUITARY
ADH
antidiuretic hormone
• Located in depression in sphenoid bone just inferior
to the brain.
• Pituitary is attached to hypothalamus by stalk
(infundibulum).
• Pituitary has 2 lobes: anterior and posterior.
PITUITARY
Pituitary is attached to hypothalamus by stalk
infundibulum
SEVEN ANTERIOR PITUITARY HORMONES
- Human growth hormone (hGH)
- Thyroid-stimulating hormone (TSH)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin
- Adrenocorticotropic hormone (ACTH)
- Melanocyte-stimulating hormone (MSH)
• Released by somatotrophs - most numerous cell in the anterior pituitary.
• hGH (most abundant) promotes synthesis of insulin-
like growth factors (IGFs) = somatomedins.
- Secreted by liver, muscle, cartilage, bone cells.
- Actions of IGFs much lie those of insulin.
• Regulation
- By hypothalamic hormones.
a. Growth hormone-releasing hormone (GHRH).
b. Growth hormone-inhibiting hormone (GHIH)
- By blood glucose levels.
a. Low blood glucose levels → release of GHRH.
• Actions of hGH
- Stimulates protein synthesis.
a. Maintains muscle and bone mass.
b. Promotes healing of injuries, tissue repair.
- Makes “fuel” (ATP) available for growth.
a. Causes fat breakdown (“baby fat”) and release of fatty
acids into blood.
b. Breaks down liver glycogen → releases glucose into
blood.
HUMAN GROWTH HORMONE (hGH)
- most numerous cell in the anterior pituitary.
Released by somatotrophs
hGH (most abundant) promotes synthesis of insulin-
like growth factors (IGFs)
somatomedins.
IGFs
insulin- like growth factors
Regulation
- By hypothalamic hormones
a. Somatocrinin or Growth hormone-releasing hormone (GHRH)
b. Somatostatin or Growth hormone-inhibiting hormone (GHIH)
Regulation
- By blood glucose levels.
a. Low blood glucose levels → release of GHRH.
Growth hormone-releasing hormone (GHRH).
Somatocrinin
Growth hormone-inhibiting hormone (GHIH)
Somatostatin
a. Maintains muscle and bone mass.
b. Promotes healing of injuries, tissue repair.
Stimulates protein synthesis.
a. Causes fat breakdown (“baby fat”) and release of fatty acids into blood.
b. Breaks down liver glycogen → releases glucose into
blood.
Makes “fuel” (ATP) available for growth.
• Stimulates the formation and secretion of thyroid
hormones (T3, T4) by thyroid gland.
• Regulations of TSH (negative feedback).
- Low blood levels of T3, T4 →
- Hypothalamus → Thyrotropin-releasing hormone (TRH)
→
- TRH stimulates release of TSH (thyroid-stimulating
hormone).
- TSH stimulates thyroid production of T3, T4.
THYROID-STIMULATING HORMONE (TSH)
TRH
Thyrotropin-releasing hormone
T4
Thyroxine
T3
triiodothyronine
• In females
- FSH starts follicle development →
a. Starts egg production.
b. Starts estrogen production from follicle cells.
- LH stimulates formation of corpus luteum.
a. Completion of egg and its ovulation.
b. Secretion of progesterone + estrogen
• In males
- FSH → sperm production in testes.
- LH → release of testosterone from testes.
• Regulation (feedback mechanism).
- Gonadotrophin-releasing hormone (GnRH) from
hypothalamus → release of FSH or LH from anterior
pituitary.
- FSH → increases estrogen in females.
- LH → increases estrogen (E) and progesterone (P) in
females and testosterone (T) in males.
- High levels of these ovarian or testicular hormones (E, P, and T) suppress production of GnRH.
FOLLICLE STIMULATING HORMONE (FSH) AND
LUTEINIZING HORMONE (LH)
a. Starts egg production.
b. Starts estrogen production from follicle cells.
FSH starts follicle development
a. Completion of egg and its ovulation.
b. Secretion of progesterone + estrogen
LH stimulates formation of corpus luteum.
- FSH → sperm production in testes.
- LH → release of testosterone from testes.
In males
- Gonadotrophin-releasing hormone (GnRH) from
hypothalamus → release of FSH or LH from anterior
pituitary. - FSH → increases estrogen in females.
- LH → increases estrogen (E) and progesterone (P) in
females and testosterone (T) in males. - High levels of these ovarian or testicular hormones (E, P, and T) suppress production of GnRH.
Regulation (feedback mechanism)
• Initiates and maintains milk production by mammary glands.
- Ejection of milk depends on oxytocin.
• Regulation
- Prolactin inhibiting hormone (PIH) suppresses prolactin release.
- High levels of estrogen → PRH (prolactin releasing
hormone → prolactin release.
• Unknown function in males
- Hypersecretion → erectile dysfunction
PROLACTIN (PRL)
Ejection of milk depends on
oxytocin
Hypersecretion → erectile dysfunction
Unknown function in males
Initiates and maintains milk production by mammary
glands.
PROLACTIN (PRL)
• Controls the production and secretion of
glucocorticoids from adrenal cortex.
• Regulation of ACTH
- Corticotrophin releasing hormone (CRH) from
hypothalamus stimulates secretion of ACTH.
- Stress-related stimuli can also stimulate ACTH release.
- Glucocorticoids inhibit CRH and ACTH release.
- Glucocorticoids – controlling effect on salt and water
balance and helps control blood pressure.
- ACTH also used to regulate the level of steroid hormone
cortisol, which is released from the adrenal gland.
a. Cortisol – controls blood sugar level, regulates
metabolism, reduce inflammation, and assist with
memory formulation.
ADRENOCORTICOTROPIC HORMONE (ACTH)
Controls the production and secretion of
glucocorticoids from adrenal cortex.
ADRENOCORTICOTROPIC HORMONE (ACTH)
CRH
Corticotrophin releasing hormone
from hypothalamus stimulates secretion of ACTH.
Corticotrophin releasing hormone (CRH)
Stress-related stimuli can also
stimulate ACTH release.
Glucocorticoids inhibit
CRH and ACTH release
- Corticotrophin releasing hormone (CRH) from
hypothalamus stimulates secretion of ACTH. - Stress-related stimuli can also stimulate ACTH release.
- Glucocorticoids inhibit CRH and ACTH release.
Regulation of ACTH
controlling effect on salt and water balance and helps control blood pressure.
Glucocorticoids
ACTH also used to regulate the level of steroid hormone cortisol, which is ___________
released from the adrenal gland.
controls blood sugar level, regulates
metabolism, reduce inflammation, and assist with
memory formulation.
Cortisol