Chemical Classification of
Hormones
(continued)
• Glycoproteins:
– Long polypeptides (>100) bound to 1 or more
carbohydrate (CHO) groups.
• __________________.
Hormone receptors
Cells of target organ have specific receptors for hormones.
Hormone binds to receptor and stimulates a specific
cellular response
- protein & peptide hormones - receptor is in
____________________
- steroid hormones - receptor is in ________
- prostaglandin hormones - receptor is in
_______________________
1.___________of receptors on or in cell regulate degree of cell
stimulation and cellular response to the hormone
2. ______________ can regulate whether there is a increase or
decrease in the number of receptors
Lack of _____________ receptor in male - Testicular
Feminization
Hormone Transport
• Transport mechanism depends on
hormone ____________
– Protein hormones – __________ – carried in
dissolved form
– Steroid & Thyroid hormones –
_____________– have limited solubility in
aqueous solution (plasma)
• These hormones – ______– specific and
nonspecific carriers
– Hormones must penetrate cell or bind to
specific receptors ____________) to initiate
action
• Are only about 1% of hormones are unbound
What is a 2nd messenger???
• Some hormones __________ enter the
cell
• Bind to receptors on cell membrane
• Hormone = messenger
• _______________ = relays info from
the hormone to the inside of the cell
Hormones That Use 2nd
Messengers
• Hormones that cannot pass through
plasma membrane use 2nd messengers.
– ____________, __________, and
glycoprotein hormones bind to receptor
proteins on the target plasma membrane.
• Actions are mediated by 2nd messengers
(signal-transduction mechanisms).
– Extracellular hormones are transduced into
intracellular 2nd messengers.
Hormones That Bind to Nuclear
Receptor Proteins
• Lipophilic steroid and
thyroid hormones are
attached to __________
carrier proteins.
– dissociate from
___________ and diffuse
across membrane
– Receptors on nucleus for
the lipophilic hormones
are known as nuclear
______________.
– Complex binds with
_____
– Activates genes – mRNA
–Ribosome – new or
more protein (enzymes
etc)
Steroid Hormones
Receptors are
mainly in the
nucleus
Steroid Hormones
Capillary
Steroid
Release from blood
circulation
Progesterone
Glucocorticoids
receptors are
mainly in the
cytoplasm
Uterine
Diffuses in cytoplasm
Glandular
Epithelial
DNA
Rough
Cell
Endoplasmic
Steroid
Reticulum
Nucleus
Chromatin
mRNA
Receptor
Protein
Synthesis
Bilaminar Cell Membrane
Secretion
What is a 2nd messenger???
• 1. Adenylate –Cyclase- cyclic AMP
• 2. Phospholipase C-Ca
• 3. Tyrosine kinase
Adenylate Cyclase-cAMP: Table
11.4
• Polypeptide or glycoprotein hormone binds to
receptor protein causing dissociation of a subunit
of _______________.
• G-protein subunit binds to and activates
adenylate cyclase.
• ATP
cAMP + PPi
• cAMP attaches to inhibitory subunit of protein
kinase.
• Inhibitory subunit dissociates and activates
protein kinase.
Adenylate Cyclase-cAMP
• ______________
enzymes within the
cell to produce
hormone’s effects.
• Modulates activity
of enzymes present
in the cell.
• Alters metabolism
of the cell.
• cAMP inactivated
by
phosphodiesterase.
– Hydrolyzes
cAMP to inactive
fragments.
(continued)
Ca2+ 2nd messenger system
1
6
Ca + Calmodulin
2
3
4
See Table 11.5
7 = Calmodulin activates protein kinase
8 = response to hormone
Epi Can Act Through Two 2nd
Messenger Systems
Tyrosine Kinase
• Insulin receptor consists of 2 units that
_________ when they bind with insulin.
– Insulin binds to ligand–binding site on plasma
membrane, activating enzymatic site in the
cytoplasm.
• Autophosphorylation occurs, increasing
tyrosine kinase activity.
• Activates signaling molecules.
– Stimulate_______, _______ and ___________
synthesis.
Tyrosine Kinase
(continued)
Hypothalamus & Pituitary
Glands
• Hypothalamus – control center
– Numerous autonomic nervous system control
functions
– Hypothalamic – releasing hormones
• – travel to anterior pituitary
– Causes release of other hormones
• http://www.ansi.okstate.edu/resourceroom/reprod/all/animations/ see HP Clip
Pituitary Gland
• Hypophysis or
hypophysial gland
– Location___________
sella turcia (bone pocket)
• Structurally and
functionally divided into:
– Neurohypophysis – pars
nervosa or posterior lobe
– Adenohypohyysis – pars
distalis – anterior lobe
• Communicates with
hypothalamus
Pituitary Gland
(continued)
• Posterior pituitary (neurohypophysis):
– Formed by down growth of the ______ during fetal
development.
– Composed of axons with neural origin – primarily from
supraoptic and paraventricular nuclei of
hypothalamus
• Mainly an extension of hypothalamus
– ______________ in hypothalamus
– Axons form stalk to the posterior pit
– Nerve endings in the actual lobe
– Nerve cell bodies in hypothalamus = hormone
source.
– Hormones carried down axoplasm into post pit
– stored until release
Pituitary Hormones
(continued)
• Posterior pituitary:
– Stores and releases 2 hormones that are produced in the
hypothalamus: ADH & Oxytocin
• Antidiuretic hormone (ADH/vasopressin):
– Promotes the retention of H20 by the kidneys.
– Alcohol inhibits release of ADH = increased urination
– Works to maintain blood pressure by regulation of water in blood
» Increases blood pressure – via contraction of SM
» Stimulates glycogenolysis
» Increases water readsorption – kidney nephrons
– Diabetes insipidus – lack of ____________ = dilute urine + excess
amounts of urine (polyuria) and large amount of fluid intake (polydispsia)
– Diabetes Mellitus – lack of ____________________
» Also large amounts of urine – but urine contains large amounts of
glucose
Pituitary Hormones
(continued)
• Posterior pituitary:
• Antidiuretic hormone (ADH/vasopressin):
• Receptors for ADH response:
– _____________ – in hypothalamus,
esophagus, and stomach
– _____________receptors – sense blood
volume in atria of heart
– _______________ – carotid sinus and aortic
arch
• Sense pressure
Pituitary Hormones
(continued)
• Posterior pituitary:
Antidiuretic hormone
(ADH/vasopressin):
• Stimuli for ___________ release:
–
–
–
–
Osmotic pressure
Decrease in blood volume (hemorrhage)
Morphine, nicotine, barbituates
Pain, emotion, stress, exercise
• Stimuli that inhibit ADH release:
– _________________ (both ADH & Oxytocin)
– _________________
Pituitary Hormones
(continued)
Oxytocin:
• Functions: promote ____________
– Stimulates contractions of the uterus (myometrium)
during parturition.
– Stimulates contractions of the mammary gland alveoli
(myoepithelial cells) .
» _______________________ reflex.
– Prior to parturition – ________________ of oxytocin
receptors via other hormones
» If not, would be running around lactating and having
uterine contractions all the time.
Neural Pathway
to Hypothalamus
Posterior Pituitary: Oxytocin
Hypothalamus
Spinal
Cord
Nerve Cells
Neuroendocrine Cells
Synthesis Oxytocin
Oxytocin
• stored in nerve terminal
Posterior Pituitary
stimulation of nerve
(Neurohypophysis)
releases oxytocin in
capillary
• contraction of
Capillaries
myoepithelial cells for milk
Oxytocin
letdown
Release - causes milk from
in BloodAveoli to release into
glands
•Also causes:
- Stimulation of cervix at
parturition
- Clitoral and ejaculation
response
Calf Stimulation
of Mammary Gland
Pituitary Gland
(continued)
Anterior pituitary:
• Master gland (adenohypophysis).
• Derived from a pouch of epithelial tissue
that migrates upward from the mouth.
– Consists of 2 parts:
• Pars distalis: ________________.
• Pars tuberalis: thin extension in contact with the
infundibulum.
• No neural connection between hypothalamus and
ant pit.
• Under control of hypothalamic releasing hormones
• Primarily produce peptides (AA) except for
_______________(catecholamine)
Pituitary Gland
(continued)
Anterior pituitary:
• Releasing hormones – synthesized by
hypothalamic neurons
– Neurons terminate at the _________________ (around
portal vessles)
• AP down neurons – release hormones into capillaries – carried
via portal blood vessels to ant pit.
• Hormones can be stimulatory or inhibitory
Pituitary Hormones
Anterior Pituitary:
– ____________effects:
• High blood hormone
causes target organ to
hypertrophy.
• Low blood hormone
causes target organ to
atrophy.
• 6 different hormones
released but all have
similar affects
Pituitary Gland
(continued)
Anterior Pituitary:
• 1. Growth Hormone (Somatotropin)
– 1. ____________– stimulates growth of body cells –
esp bone and muscle
– 2. Anabolism – increases _________ transport into
the cells
• Insulin like affect because insulin also causes not only glucose
uptake but AA as well
• _________________: opposite of anabolism – breaks cells down
– 3. Increases fat metabolism – lipolysis (anti-insulin)
• Increases FFA levels in blood to provide energy
– Fasting & stress
– When should you “work out”?
– 4. Increases blood glucose
– 5. _________________ – increases milk production
Pituitary Gland
(continued)
• Anterior Pituitary: GH
– 1.Young Animal: Excess GH = _________
• Increase in long bones
• Epiphyseal cartilage –
– Continue to grow until puberty (how we know if a sheep is a
lamb or mutton)
– Then no additional linear growth
– 2. After puberty = ________ – continual growth in
areas which have responsive cartilage
• Jawbone, hands, face, feet – thick coarse skin &
muscle hypertrophy
– Lower GH = ___________– decreased development
& no puberty or adult sexual development.
Pituitary Gland
(continued)
• Anterior Pituitary: ____________
– Increases mammogenesis – pregnancy &
lactation following birth
– Decrease prolactin = no lactation
– Fescue toxicosis = cows, horse, sheep
• Decrease in prolactin, especially problematic in
horses
Prolactin
•Secreted from anterior pituitary
Dopamine
Stimulatory factors
(-)
•In Mammals, mammary gland
development and milk production
• Receptors are everywhere
(+)
Estrogen
(+)
Prolactin
* Target Tissues
• Induces __________ growth in
rabbit, rodent, humans. Maintains
in dos, rodents an skunks
• Chickens- depresses LH, FSH,
causes broodiness
• Blocks GnRH, stopping ovulation
cycles
Pituitary Gland
(continued)
• Anterior Pituitary: Thyroid Stimulating
Hormone
– Regulates size & secretory activity of gland
– Cold stress = ____________in TSH activity
– Decrease TSH activity = __________
– Excess TSH activity = hyperthyroidism
Pituitary Gland
(continued)
• Anterior Pituitary: Adrenocorticotropic
hormone (ACTH)
– Stimulates outer portion of adrenal glands
(__________)
– Adrenal cortex has 3 principal classes of
hormones
• 1. _______________ – cortisol and corticosterone
• 2. mineralocorticoids –
______________________
• 3. androgens – sex steroids
• Stress and hypoglycemia (low blood sugar) =
increase in ACTH
Pituitary Gland
(continued)
• Anterior Pituitary: Leutenizing hormone
– Stimulates _________________ – ovary –
• corpus luteum – progesterone
• Follicle – estrogen
– Maturation of____________
– Ovulation
– Formation of CL
– Both LH & FSA – maturation of graafian
follicle
– Stimulates __________ secretion in males
(interstitial cells of testes)
Pituitary Gland
(continued)
• Anterior Pituitary: Follicle stimulating
hormone (FSH)
– _________ – trigger, promote development
– Stimulates follicle cells – __________
– In males – development seminiferous tubules
& maintenance of spermatogenesis
• Deficiency = delayed _______ or amenorrhea
• Excess = precocious puberty (less than 8 yrs old in
humans; less than 10 in males)
Hypothalamus-Anterior Pituitary interrelationship
• ________________ portal system
caries hypothalamic hormones
specifically to the anterior pituitary
without dilution in the systemic
blood.
1. Allows rapid response
2. Little dilution of peptide
hormones
3. Peptide hormones have
short 1/2 life
• Specific hypothalamic nuclei
secrete releasing or release
• inhibiting factors that control
release of pituitary hormones.
Hypothalamic Control of
Posterior Pituitary
• Hypothalamus
neuron cell bodies
produce:
– ADH: supraoptic
nuclei.
– Oxytocin:
paraventricular
nuclei.
• Transported along the
hypothalamohypophyseal tract.
• Stored in posterior
pituitary.
• Release controlled by
neuroendocrine
reflexes.
Hypothalamic Control of the
Anterior Pituitary
• Hormonal control rather
than neural.
• Hypothalamus neurons
synthesize releasing
and inhibiting
hormones.
• Hormones are
transported to axon
endings of median
eminence.
• Hormones secreted into
the hypothalamohypophyseal portal
system regulate the
secretions of the
anterior pituitary
Question:
• Does the posterior pituitary produce
any hormones?
• NO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Mechanism of Thyroid Hormone
Action
•
•
•
•
•
Thyroxine (tetraiodothyronine) T4
Travels attached to ____________ (thyroxine-binding globulin)
Small amount of __________
Carrier proteins have a ___________affinity for T4
Free T3 is what is physiologically active
– So, why do we have T4???
– T4 passes into cytoplasm and is converted to T3.
– Receptor proteins located in nucleus.