ENDOCRINE SYSTEMReview

PETER REONISTO, MDMOORPARK COLLEGE

Nervous System vs. Endocrine System

3) Hormones travel more slowly than nerve impulses, the endocrine system tends to regulate slow processes such as growth and metabolism.

Endocrine cells of the body contained in:

1. “Pure” endocrine organs

Pituitary gland

Pineal gland

Thyroid gland

Parathyroid gland

Adrenal gland

Major Endocrine Organs

Major Endocrine Organs

Endocrine cells of the body contained in:

2. “Partly” endocrine organs

Pancreas

Thymus

Gonads

Hypothalamus

CLASSES OF HORMONES

AMINO ACID-BASED Most hormones Proteins Modified amino acid

peptides

STEROIDS Lipid molecules derived

from cholesterol Sex hormones Adrenal cortex

hormones

CONTROL OF HORMONE SECRETION1. Humoral2. Neural3. Hormonal

CONTROL OF HORMONE SECRETION1. Humoral- influenced by plasma concentration of the substance.Parathyroid

gland

Low Ca2+ blood concentration

Parathyroid gland

Parathormone secretion

Nephron, intestinal cells

Action

CONTROL OF HORMONE SECRETION2. Neural- SNS stimulationAdrenal medulla

Preganglionic SNSfibers

Medulla of adrenal gland

Body

Actions: “Fight, flight, or fright” response

Adrenaline secretion

CONTROL OF HORMONE SECRETION3. Hormonal-influenced by the amount of hormones in the plasma

Releasinghormones Hypothalamus

Adenohypohysis

Thyroidgland

Body

Releasing hormones

Stimulating Hormones

Adrenalcortex

Gonads(Testis)

Cortisol Androgens

Thyroxine Cortisol Androgens

IncreaseMetabolic

rate

Anti-stress Sperm formation

MAJOR ENDOCRINE ORGAN

PITUITARY GLAND

PITUITARY GLAND• Or, hypohysis• Secretes at least 9

major hormones• Location:

> Hypophyseal fossa

Depression in theSella turcica of the

Spenoid bone

ANATOMY: PITUITARY GLAND

infundibulum

Anterior Pituitary Gland

Adenohypophysis

1. Pars distalis2. Pars intermedia3. Pars tuberalis

Adenohypophysis

1. Pars distalis

Largest division

Contains 5 different endocrine cells that make and secrete 7 different hormones

Pars distalis 5 CELL CLASSES:1. Somatotrophic cell

(most abundant)

2. Mammotrophic cells

3. Thyrotrophic cells

4. Corticotrophic cells

5. Gonadotrophic cells

Growth Hormone (Somatotrophic Hormone / Somatotropin / GH)Growth of the entire body

Prolactin (PRL)Breast milk production

Thyroid Stimulating Hormone (TSH)Thyroid gland stimulation to release thyroid hormone

Adrenocorticotropic Hormone (ACTH)Adrenal Cortex stimulation to release glucocorticoids

Melanocyte Stimulating Hormone (MSH)Stimulates melanocytes to produce melanin pigment

Follicle Stimulating Hormone (FSH)Gonads: maturation of sex cells; secretes sex hormones

Leutenizing Hormone (LH)Gonads: maturation of sex cells; secretes sex hormones

Gonadotropins

Pars distalis 5 CELL CLASSES:Growth Hormone (Somatotrophic Hormone / Somatotropin / GH)Growth of the entire body

Prolactin (PRL)Breast milk production

Thyroid Stimulating Hormone (TSH)Thyroid gland stimulation to release thyroid hormone

Adrenocorticotropic Hormone (ACTH)Adrenal Cortex stimulation to release glucocorticoids

Melanocyte Stimulating Hormone (MSH)Stimulates melanocytes to produce melanin pigment

Follicle Stimulating Hormone (FSH)Gonads: maturation of sex cells; secretes sex hormones

Leutenizing Hormone (LH)Gonads: maturation of sex cells; secretes sex hormones

F L A T

Tropic Hormones -Regulate the secretionof hormones by other Endocrine glands

M P G

Act directly on non-endocrinetarget tissues

HYPOTHALAMIC CONTROL OF THE ADENOHYPOPHYSIS

Controlled by RELEASING HORMONES and INHIBITING HORMONES

Target cell Target cell PeripheralEndocrine

gland

PeripheralEndocrine

gland

PeripheralEndocrine

gland

-

HYPOPHYSEAL PORTAL SYSTEM

Releasing hormones are made inHypothalamic neurons

Hypothalamic neurons

Releasing hormones are secreted atthe neuron synapse

To the primary capillary complex

Primary capillary complex

Releasing hormones goes to the Hypophyseal portal vein

To the secondary capillary complex

SecondaryCapillarycomplex

Releasing hormones leaves the plexus &attach to the adenohypophyseal cells

SomatotropicMammotropicThyrotropicCorticotropicGonatotropic

Posterior Pituitary Gland

Neurohypophysis1. Median eminence2. Infundibular stalk3. Pars nervosa

Medianeminence

Infundibularstalk

Parsnervosa

NEUROHYPOPHYSIS HORMONE PRODUCTIONHormone produced at neuron cell bodies located at the SUPRAOPTICand PARAVENTRICULAR nuclei ofthe Hypothalamus

Hormones are transportedalong the axons(Hypothalamic-hypophysealTract)

Hormones are stored indilated axon terminalscalled HERRING BODIES

Upon stimulation, stored hormones are released in thecapillary bed for distributionthroughout the body

ADHOxytocin

NEUROHYPOPHYSIS: Hormones

CELL TYPE HORMONE TARGET/EFFECTS

Neurons from supraoptic nucleus of hypothalamus

Antidiuretic hormone (ADH, vasopressin)

Stimulates kidneys (distal tubules and collecting tubules) to reclaim water from urine. Raises blood pressure by constricting peripheral arterioles when blood volume is low.

Neurons from paraventricular nucleus of hypothalamus

Oxytocin Initiates labor through uterine contraction Facilitates milk ejection from breast

MAJOR ENDOCRINE ORGAN

THYROID GLAND

THYROID GLAND located in theanterior neck; on the trachea justinferior to the larynx

PARATHYROID GLANDLocated at the posteriorsurface of the thyroid gland

PARATHORMONE

FUNCTION:Increase bloodCalcium level

ADRENAL GLANDADRENAL CORTEXADRENAL MEDULLA

Mineralocorticoid (Aldosterone)

Glucocorticoid (Cortisol)

Balance electrolyte Concentration (Na+/K+)--Inc Na+ Reabsorption--Inc K+ excretion--Inc water reabsorption

Glucocorticoid (Cortisol)

Produce sex hormone precursor (DHEA) ----Dehydroepiandrosterone---

Stress control

ADRENAL MEDULLA: HormonesSimulate a “fight, fright, flight response”

PANCREAS

Other Endocrine GlandsPineal Gland

• secretes melatonin• regulates circadian rhythms

Thymus Gland• secretes thymosins• promotes development of certain lymphocytes• important in role of immunity

Reproductive• ovaries produce estrogens and progesterone• testes produce testosterone• placenta produces estrogens, progesterone, and gonadotropins

END