Endo Part 3

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Endo Part 3
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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

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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.

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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.

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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.

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______ adrenal glandsLocationImmediately
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
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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

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Adrenal Glands (continued)

• Adrenal cortex
• Does not receive ________ innervation.
• Must be stimulated ______________ (ACTH).
• Consists of 3 zones
• Zona __________
• Zona fasciculata.
• Zona reticularis.
• Secretes ________________

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Hypothalamopituitary adrenal axis
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• 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.

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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
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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

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Functions of the Adrenal Cortex (continued)
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Functions of the Adrenal Cortex (continued)

• Carried by plasma specific binding globulins
• Mechanism of action
• Enters cell, ___________receptor, enters nucleus,
  increases mRNA, increases __________ formation

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Adrenal Glands

• Adrenal medulla
• Derived from _______________ neural crest
  ectoderm (same tissue that produces the
  sympathetic ganglia).
• Synthesizes and secretes
• ____________________ (mainly Epi but some NE).

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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 RBCs
  in blood

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Functions of the Adrenal Medulla

• Stimuli
• Hypoglycemia
• Emergency situation

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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.

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Thyroid Hormones

• Thyroid gland is located just below the larynx.
• Thyroid is the _____________ of the pure
  endocrine glands.
• Follicular cells secrete ___________.
• Parafollicular cells secrete ___________.

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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

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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).

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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.

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Production of Thyroid Hormones (continued)
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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.

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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.

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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.

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Diseases of the Thyroid (continued)

• Adult myxedema
• Symptoms
• Decreased metabolic rate.
• Weight gain.
• Decreased ability to adapt to cold.
• Lethargy.
• Graves disease
• Autoimmune disorder
• Cretinism
• Hypothyroid from end of 1st trimester to 6 months
  postnatally.
• Severe mental retardation.

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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.

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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

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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.

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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

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Pineal Gland (continued)
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Thymus

• Site of production of ____ cells
  (thymus-dependent 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.

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Gonads and Placenta

• Gonads (testes and ovaries)
• Secrete sex hormones.
• Testosterone.
• Estradiol 17-b.
• Progesterone.
• Placenta
• Secretes large amounts of _____________,
  progesterone

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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.

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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
• ______________________________

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Lipid Hormones - Prostaglandins
Fatty Acids
Prostaglandins 1. Produced by all tissues of
body 2. Can have a local effect on tissues
(same tissue which produced it) 3. Rapidly
degraded in lungs
Phospholipids
- Rate limiting (Phospholipase A2)
- Precursor to Prostaglandins
Arachidonic Acid
Aspirin inhibits
Cyclo-oxygenase
PGF2a
PGE2
Causes vasoconstriction of Blood vessels
Causes vasodilatation of blood vessels
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Prostaglandins (continued)
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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.