Download Endo Part 3 - Missouri State University

Endo Part 3
Can Males Lactate?
• Yes,
– In humans, some men can breastfeed
– In rats, some males breastfeed their young.
– Receptors for both are similar
– Hormones are similar in size and chemical
makeup
– Have similar functions
– ___________ can induce both to be secreted
Feedback Control of the Anterior
Pituitary
• Anterior pituitary and hypothalamic
secretions are controlled by the
______________organs they regulate.
– Secretions are controlled by ___________
feedback inhibition by target gland hormones.
• ______________ feedback at 2 levels:
– The target gland hormone can act on the
hypothalamus and inhibit secretion of
____________ hormones.
– The target gland hormone can act on the
anterior pituitary and inhibit __________ to the
releasing hormone.
Feedback Control of the Anterior
Pituitary
(continued)
• Short feedback loop:
– Retrograde transport
of blood from anterior
pituitary to the
hypothalamus.
• Hormone released by
anterior pituitary
___________secretion
of releasing hormone.
• _______________
feedback effect:
– During estrus,
______________
stimulates
“___________
surge.”
Higher Brain Function and
Pituitary Secretion
• Axis:
– Relationship between _________ pituitary
and a particular target gland.
• Pituitary-gonad axis.
• Hypothalamus receives input from
higher brain centers.
– Psychological stress affects:
• _______________ rhythms.
• ________________ cycle.
ADRENAL GLANDS
______ adrenal glands:
Location:
Immediately anterior to the kidneys,
encased in a _________tissue capsule
The exact location relative to the kidney
and the shape of the adrenal gland vary
among species.
Adrenal Glands
• History –
– Brown-Sequard (1856) adrenalectomy – fatal to dog
– Cannon (1929) – fight or flight – adrenomedulla
• Paired organs that cap the kidneys.
• Each gland consists of an outer _____________
and inner ________________.
• In ____________ – no distinct cortex or medulla
Adrenal Glands
• Adrenal cortex:
– Does not receive
________
innervation.
– Must be stimulated
______________
(ACTH).
• Consists of 3 zones:
– Zona __________
– Zona fasciculata.
– Zona reticularis.
• Secretes
________________
(continued)
Immune
system:
suppressed
Stress
Circadian
rhythm
Hypothalamus
CRH
Anterior
Pituitary Gland
(-)
Posterior
Pituitary Gland
ACTH
Glucocorticoids,
Adrenals Catecholamines,
etc..
Kidney
Muscle:
Net loss of amino
Acids (glucose)
Liver:
Deamination of
proteins into amino
acids,
gluconeogenesis
(glucose)
Fat Cells:
Free fatty
acid
mobilization
Heart rate:
Increased
Hypothalamopituitary
adrenal axis
The adrenal gland has
two distinct regions:
• An inner medulla:
- _______________epinephrine (E)
- norepinephrine (NE).
- richly innervated by preganglionic sympathetic fibers
and is, in essence, an extension of the sympathetic
nervous system (involved in the “fight or flight” reaction).
• An outer cortex:
- Secretes several classes of _________hormone
- three concentric zones of cells that differ in the major
steroid hormones they secrete.
Adrenal
CORTEX
Zona Glomerulosa
Mineralocorticoids (Aldosterone)
Na+, K+ and water homeostasis
Zona Fasciculata
Glucocorticoids (Cortisol)
Glucose homeostasis and many
others
Zona Reticularis
sex steroids (androgens)
Medulla: Catecholamines
•
Functions of the Adrenal
Cortex
Zona glomerulosa: Mineralcorticoids
– __________________
• Stimulate kidneys to reabsorb Na+ and secrete K+.
– Deoxycorticosterone
• Zona fasciculata: Glucocorticoids
– __________________
• Inhibit glucose utilization and stimulate
gluconeogenesis.
• Zona reticularis (DHEA): _______ steroids:
• Androgens – significant amounts
• Estrogens – insignificant amounts
Functions of the Adrenal
Cortex
(continued)
Functions of the Adrenal
Cortex
(continued)
• Carried by plasma specific – binding
globulins
• Mechanism of action
– Enters cell, ___________receptor, enters
nucleus, increases mRNA, increases
__________ formation
Adrenal Glands
• Adrenal medulla:
– Derived from _______________ neural crest
ectoderm (same tissue that produces the
sympathetic ganglia).
• Synthesizes and secretes:
– ____________________ (mainly Epi but some NE).
Functions of the Adrenal
Medulla
• Actions
– _____________ respiratory rate.
– Increase HR and cardiac output.
– __________________ blood vessels, thus
increasing venous return.
– Stimulate glycogenolysis.
– Stimulate ____________________
– Increases BMR
– Stimulates spleen contraction – increased
RBC’s in blood
Functions of the Adrenal
Medulla
• Stimuli
– Hypoglycemia
– Emergency situation
Stress and the Adrenal Gland
• Non-specific response
to stress produces the
general adaptation
syndrome (GAS).
• Alarm phase:
– Adrenal glands
activated.
• Stage of resistance:
– Stage of
readjustment.
• Stage of exhaustion:
– Sickness and/or
death if readjustment
is not complete.
Thyroid Hormones
• Thyroid gland is
located just below
the larynx.
• Thyroid is the
_____________ of
the pure endocrine
glands.
• Follicular cells
secrete
___________.
• Parafollicular cells
secrete
___________.
Thyroid Hormones
• Different activity in different animals
– Fish – no specific organs, follicles scattered
– Birds – 2 lobes – widely separated, no
isthmus
– Snakes – 1 gland, anterior to heart
Production of Thyroid
Hormones
• ___________ (I-) actively transported into
the follicle and secreted into the colloid.
• Oxidized to iodine (Io).
• Iodine attached to tyrosine within
thyroglobulin chain.
– Attachment of 1 iodine produces
monoiodotyrosine (MIT).
– Attachment of 2 iodines produces
diiodotyrosine (DIT).
Production of Thyroid
Hormones
(continued)
• _______ and ________ produced.
• TSH stimulates pinocytosis into the
follicular cell.
– Enzymes hydrolyze T3 and T4 from
thyroglobulin.
• Attached to TBG and released into blood.
Production of Thyroid
Hormones
(continued)
Actions of T3
• Stimulates ________synthesis.
• Promotes maturation of nervous system.
• Stimulates rate of cellular respiration by:
– Production of uncoupling proteins.
– ____________ active transport by Na+/K+ pumps.
– Lower cellular [ATP].
• Increases ____________ heat.
• Increases ______________ rate.
– Stimulates increased consumption of glucose, fatty
acids and other molecules.
Mechanism of Thyroid Hormone
Action
• Thyroxine (tetraiodothyronine) T4
• Travels attached to _______________ (thyroxine-binding
globulin)
• Small amount of T3
• 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.
Diseases of the Thyroid
• Iodine-deficiency
(endemic) goiter:
– Abnormal growth
of the thyroid
gland.
• In the absence of
sufficient iodine,
cannot produce
adequate amounts
of T4 and T3.
Diseases of the Thyroid
(continued)
– Adult myxedema:
– Symptoms:
•
•
•
•
Decreased metabolic rate.
Weight gain.
Decreased ability to adapt to cold.
Lethargy.
• Grave’s disease:
– Autoimmune disorder:
• Cretinism:
– Hypothyroid from end of 1st trimester to 6 months postnatally.
• Severe mental retardation.
Parathyroid Glands
• Embedded in the lateral
lobes of the thyroid gland.
• Parathyroid hormone (PTH):
– Only hormone secreted
by the parathyroid glands.
• Single most important
hormone in the control of
blood [___________].
• Stimulated by
___________blood [Ca2+].
• Promotes ________ in blood
[Ca2+] by acting on bones,
kidney and intestines.
Actions of Calcitonin
• Secreted by __________ cells
• Works with parathyroid cells to regulate
Ca levels
• Stimulates secretion of ________ in urine
• Actions work to lower blood Ca levels
Pancreatic Islets (Islets of
Langerhans)
• Alpha cells secrete ________.
– Stimulus is decrease in blood
[glucose].
– Stimulates glycogenolysis and
lipolysis.
– Stimulates conversion of fatty
acids to ketones.
• Beta cells secrete ________.
– Stimulus is increase in blood
[glucose].
– Promotes entry of glucose into
cells.
– Converts glucose to glycogen and
fat.
– Aids entry of amino acids into
cells.
Pineal Gland
• Secretes __________________:
– Production stimulated by the suprachiasmatic
nucleus (SCN) in hypothalamus.
• SCN is primary center for circadian rhythms.
• Light/dark changes required to synchronize.
• Melatonin secretion increases with darkness and peaks
in middle of night.
– May inhibit _________________.
– May function in the __________ of puberty
(controversial).
– Controls estrus in sheep, goats, and horses
Pineal Gland
(continued)
Thymus
• Site of production of ____ cells (thymusdependent cells), which are lymphocytes.
– Lymphocytes are involved in cell-mediated immunity.
• Secretes hormones that are believed to
stimulate T cells after leave thymus.
– Thymus gland size is large in newborns and children.
• _____________ after puberty and becomes
infiltrated with strands of fibrous tissue.
Gonads and Placenta
• Gonads (testes and ovaries):
– Secrete sex hormones.
• Testosterone.
• Estradiol 17-b.
• Progesterone.
• Placenta:
– Secretes large amounts of _____________,
progesterone
Autocrine and Paracrine
Regulation
• Autocrine:
– Produced and act within the same tissue of an
organ.
• All autocrine regulators control gene expression in target
cells.
• Paracrine:
– Produced within one tissue and regulate a different
tissue of the same organ.
• Cytokines (lymphokines):
– Regulate different cells (interleukins) .
• Growth factors:
– Promote growth and cell division in any organ.
• Neutrophins:
– Guide regenerating peripheral neurons.
Prostaglandins
•
•
•
•
Most diverse group of ________ regulators.
Produced in almost every organ.
Wide variety of functions.
Different prostaglandins may exert
antagonistic effects in some tissues.
– Immune system:
• ___________________________________.
– Reproductive system:
• ________________________________.
– Digestive system:
• ______________________________
Lipid Hormones - Prostaglandins
Fatty Acids
Prostaglandins
Phospholipids
1. Produced by all tissues
- Rate limiting (Phospholipase A2)
of body
2. Can have a local effect
on tissues (same tissue
Arachidonic Acid - Precursor to Prostaglandins
which produced it)
Aspirin inhibits
Cyclo-oxygenase
3. Rapidly degraded in lungs
PGE2
Causes vasodilatation of
blood vessels
PGF2a
Causes vasoconstriction of
Blood vessels
Prostaglandins
(continued)
Prostaglandins
(continued)
– Respiratory system:
• May _____________________________.
– Circulatory system:
• _____________________________.
– Urinary system:
• Vasodilation.
• See pg 318
• Inhibitors of prostaglandin synthesis:
– Non-steroidal anti-inflammatory drugs (NSAIDS).
• Aspirin, indomethacin, ibuprofen: inhibit COX1.
– Celecoxib and rofecoxib: inhibit COX2.