Chapter 18 The Endocrine System - PowerPoint PPT Presentation


PPT – Chapter 18 The Endocrine System PowerPoint presentation | free to download - id: 3bd38c-M2NkN


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation

Chapter 18 The Endocrine System


Chapter 18 The Endocrine System Endocrine and nervous systems work together Endocrine system hormones released into the bloodstream travel throughout the body – PowerPoint PPT presentation

Number of Views:420
Avg rating:3.0/5.0
Slides: 47
Provided by: homepageS68
Learn more at:


Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Chapter 18 The Endocrine System

Chapter 18The Endocrine System
  • Endocrine and nervous systems work together
  • Endocrine system
  • hormones released into the bloodstream travel
    throughout the body
  • results may take hours, but last longer
  • Nervous system
  • certain parts release hormones into blood
  • rest releases neurotransmitters excite or inhibit
    nerve, muscle gland cells
  • results in milliseconds, brief duration of

General Functions of Hormones
  • Help regulate
  • extracellular fluid
  • metabolism
  • biological clock
  • contraction of cardiac smooth muscle
  • glandular secretion
  • some immune functions
  • Growth development
  • Reproduction

Endocrine Glands Defined
  • Exocrine glands
  • secrete products into ducts which empty into body
    cavities or body surface
  • sweat, oil, mucous, digestive glands
  • Endocrine glands
  • secrete products (hormones) into bloodstream
  • pituitary, thyroid, parathyroid, adrenal, pineal
  • other organs secrete hormones as a 2nd function
  • hypothalamus, thymus, pancreas,ovaries,testes,
    kidneys, stomach, liver, small intestine, skin,
    heart placenta

Hormone Receptors
  • Hormones only affect target cells with specific
    membrane proteins called receptors

Circulating Local Hormones
  • Circulating hormones
  • act on distant targets
  • travel in blood
  • Local hormones
  • paracrines act on neighboring cells
  • autocrines act on same cell that secreted them

Lipid-soluble Hormones
  • Steroids
  • lipids derived from cholesterol on SER
  • different functional groups attached to core of
    structure provide uniqueness
  • Thyroid hormones
  • tyrosine ring plus attached iodines are
  • Nitric oxide is gas

Water-soluble Hormones
  • Amine, peptide and protein hormones
  • modified amino acids or amino acids put together
  • serotonin, melatonin, histamine, epinephrine
  • some glycoproteins
  • Eicosanoids
  • derived from arachidonic acid (fatty acid)
  • prostaglandins or leukotrienes

Action of Lipid-Soluble Hormones
  • Hormone diffuses through phospholipid bilayer
    into cell
  • Binds to receptor turning on/off specific genes
  • New mRNA is formed directs synthesis of new
  • New protein alters cells activity

Action of Water-Soluble Hormones
  • Can not diffuse through plasma membrane
  • Hormone receptors are integral membrane proteins
  • act as first messenger
  • Receptor protein activates G-protein in
  • G-protein activates adenylate cyclase to convert
    ATP to cAMP in the cytosol
  • Cyclic AMP is the 2nd messenger
  • Activates kinases in the cytosol to speed up/slow
    down physiological responses
  • Phosphodiesterase inactivates cAMP quickly
  • Cell response is turned off unless new hormone
    molecules arrive

Hormonal Interactions
  • Synergistic effect
  • a second hormone, strengthens the effects of the
  • two hormones acting together for greater effect
  • thyroid strengthens epinephrines effect upon
  • Permissive effect
  • you need two hormone present for one hormone to
    work properly
  • estrogen LH are both needed for oocyte
  • Antagonistic effects
  • two hormones with opposite effects
  • insulin promotes glycogen formation glucagon
    stimulates glycogen breakdown

Control of Hormone Secretion
  • Regulated by signals from nervous system,
    chemical changes in the blood or by other
  • Negative feedback control (most common)
  • decrease/increase in blood level is reversed
  • Positive feedback control
  • the change produced by the hormone causes more
    hormone to be released
  • Disorders involve either hyposecretion or
    hypersecretion of a hormone

Hypothalamus and Pituitary Gland
  • Both are master endocrine glands since their
    hormones control other endocrine glands
  • Hypothalamus is a section of brain above where
    pituitary gland is suspended from stalk
  • Hypothalamus receives input from cortex,
    thalamus, limbic system internal organs
  • Hypothalamus controls pituitary gland with 9
    different releasing inhibiting hormones

Pituitary Gland
Hormones human growth hormone- hGH thyroid
stimulating - TSH follicle stimulating-
FSH leutinizing hormone - LH prolactin adrenocorti
cotropin - ACTH melanocyte stimulating - MSH
  • 5 types of cells
  • somatotrophs secrete hGH/somatotropin
  • thyrotrophs secrete TSH/thyrotropin
  • gonadotrophs secrete FSH, LH
  • lactotrophs secrete prolactin
  • corticotrophs secrete ACTH/corticotropin MSH
  • Pea-shaped, 1/2 inch gland found in sella turcica
    of sphenoid
  • Infundibulum attaches it to brain
  • Anterior lobe 75 develops from roof of mouth
  • Posterior lobe 25
  • ends of axons of 10,000 neurons found in
  • neuroglial cells called pituicytes

Human Growth Hormone
  • Produced by somatotrophs
  • induces target cells to make insulin-like growth
    factors (IGFs) that act locally or enter
  • common target cells of IGFs are liver, skeletal
    muscle, cartilage and bone
  • GH IGFs increase cell growth cell division by
    increasing their uptake of amino acids
    synthesis of proteins
  • stimulate lipolysis in adipose so fatty acids
    used for ATP
  • retard use of glucose for ATP production by cells
  • reduces uptake of glucose by the liver and
    promote breakdown of liver glycogen so blood
    glucose levels stay high enough to supply brain
  • Excess of growth hormone
  • raises blood glucose concentration
  • pancreas releases insulin continually
  • Leads to beta-cell burnout
  • Diabetogenic effect
  • causes diabetes mellitis if no insulin activity
    can occur eventually

Regulation of hGH
  • Low blood sugar stimulates release of GNRH from
  • anterior pituitary releases more hGH, more
    glycogen broken down into glucose by liver cells
  • High blood sugar stimulates release of GHIH from
  • less hGH from anterior pituitary, glycogen does
    not breakdown into glucose

Thyroid Stimulating Hormone (TSH)
  • Hypothalamus regulates thyrotroph cells
  • Thyrotroph cells produce TSH
  • TSH stimulates the synthesis secretion of T3
    and T4
  • Metabolic rate stimulated

Thyroid Gland
  • comprised of microscopic sacs called follicles
    follicular cells making up the walls, surrounds a
  • synthesize T3 T4 (thyroxin)
  • In between follicular cells cells are
    parafollicular cells
  • produce calcitonin
  • On each side of trachea is lobe of thyroid
  • connected by an isthmus
  • Weighs 1 oz has rich blood supply

Formation of Thyroid Hormone
  • Iodide trapping follicular cells actively take
    up iodine from blood
  • Synthesis of thyroglobulin (TGB) follicular
    cells make TGB - secreted into the follicle lumen
    as the material colloid
  • Iodination of colloid iodine ions are oxidated
    (I2- -gt I2) by peroxidase within the cell
  • oxidized iodine then binds onto tyrosine residues
    on the TGB within colloid
  • Coupling of T1 and T2 forms T3 T4
  • Uptake of colloid by follicular cells digestion
    cleaves off T3 and T4
  • Secretion of T3 T4 into blood T3 T4 are
    transported in blood bound to thryoxine-binding

Actions of Thyroid Hormones
  • T3 T4 increases metabolic rate
  • stimulates synthesis of protein
  • stimulates breakdown of fats
  • stimulates cholesterol excretion
  • increases use of glucose oxygen
  • (ATP production)
  • increases body temperature (calorigenic effect)

Control of T3 T4 Secretion
  • Low blood levels of hormones stimulate
    hypothalamus -gt TRH
  • It stimulates pituitary to release TSH
  • TSH stimulates gland to raise blood levels
  • T3 and T4 regulate themselves through a negative
    feedback loop

Parathyroid Glands
  • Principal cells produce parathyroid hormone (PTH)
  • Oxyphil cell function is unknown
  • 4 pea-sized glands found on back of thyroid gland

Parathyroid Hormone
  • Raises blood calcium levels
  • increases activity of osteoclasts (bone degrading
  • increases reabsorption of Ca2 by kidney
  • promote formation of calcitriol (vitamin D3) by
    kidney which increases absorption of Ca2 and
    Mg2 by intestinal tract
  • Opposite function of calcitonin (thyroid)
  • High or low blood levels of Ca2 stimulate the
    release of different hormones --- PTH or CT
  • high level of calcium in blood - release of
    calcitonin by parafollicular cells, promotes
    uptake of calcium into bone matrix, lowers blood
  • low level of calcium in blood - release of PTH by
    parathyroid glands, promotes release of calcium
    from bone, raises blood calcium

Follicle Stimulating Hormone (FSH)
  • Releasing hormone from
    hypothalamus controls
  • Gonadotrophs release
    follicle stimulating hormone
  • FSH functions
  • initiates the formation of follicles within the
  • stimulates follicle cells to secrete estrogen
  • stimulates sperm production in testes

Luteinizing Hormone (LH)
  • Releasing hormones from hypothalamus stimulate
  • Gonadotrophs produce LH
  • In females, LH stimulates
  • secretion of estrogen
  • ovulation of 2nd oocyte from ovary
  • formation of corpus luteum
  • secretion of progesterone
  • In males, stimulates interstitial cells
    to secrete testosterone

Ovaries and Testes
  • Ovaries
  • estrogen, progesterone, relaxin inhibin
  • regulate reproductive cycle, maintain pregnancy
    prepare mammary glands for lactation
  • Testes
  • produce testosterone
  • regulate sperm production 2nd sexual

Prolactin (PRL)
  • Hypothalamus regulates lactotroph
  • Lactotrophs produce prolactin
  • Under right conditions, prolactin causes
    milk production
  • Suckling reduces levels of hypothalamic
    inhibition and prolactin levels rise along with
    milk production
  • Nursing ceases milk production slows

Melanocyte-Stimulating Hormone
  • Secreted by corticotroph cells
  • Releasing hormone from hypothalamus increases its
    release from the anterior pituitary
  • Function not certain in humans (increase skin
  • May have a role in promoting sexual performance

Adrenocorticotrophic Hormone
  • Hypothalamus releasing hormones stimulate
  • Corticotrophs secrete ACTH ( MSH also)
  • ACTH stimulates cells of the adrenal cortex

Adrenal Glands
  • Cortex derived from mesoderm
  • Medulla derived from ectoderm
  • One on top of each kidney
  • 3 x 3 x 1 cm in size and weighs 5 grams
  • Cortex produces 3 different types of hormones
    from 3 zones of cortex mineralcorticoids
    (aldosterone), glucocorticoids (cortisol)
  • Medulla produces epinephrine norepinephrine

  • Cortex
  • 3 zones
  • Medulla

  • 95 of these hormones - aldosterone
  • Functions
  • increase reabsorption of Na with Cl- ,
    bicarbonate and water following it
  • promotes excretion of K and H
  • dehydration, hemorrhage (decrease in blood
    volume) - decreases blood pressure - secretion of
    renin from kidneys which stimulates angiotensin
    II release from lungs - stimulates aldosterone
    release from adrenal cortex - increases water
    uptake from kidneys and increased excretion of K
    into urine

  • 95 of hormonal activity is due to cortisol
  • neurosecretory cells secrete corticotropin-releasi
    ng hormone (CRH)
  • CRH promotes the release of ACTH where it
    stimulates the adrenal cortex to secrete corticol
  • Functions helps regulate metabolism
  • increases rate of protein synthesis
  • increases conversion of amino acids to glucose
    energy for protein synthesis
  • stimulates lipolysis for glucose synthesis (for
  • increases glucose synthesis ATP production
    provides resistance to stress by making nutrients
    available for ATP
  • raises BP by vasoconstriction (decreases blood
  • anti-inflammatory effects reduced (skin cream)
  • reduces release of histamine from mast cells
  • decreases capillary permeability
  • depresses phagocytosis

  • Small amount of male hormone produced by the zona
  • insignificant in males
  • may contribute to sex drive in females
  • is converted to estrogen in postmenopausal females

Adrenal Medulla
  • hormone producing cells Chromaffin cells
    receive direct innervation from sympathetic
    nervous system
  • Produce epinephrine norepinephrine
  • Hormones are sympathomimetic
  • effects mimic those produced by sympathetic NS
  • cause fight-flight behavior
  • sympathetic preganglionic neurons secrete
    acetylcholine - which stimulates secretion by
    the AM

Posterior Pituitary Gland (Neurohypophysis)
  • Does not synthesize hormones
  • Consists of axon terminals of hypothalamic
  • Neurons release two neurotransmitters that enter
  • antidiuretic hormone
  • oxytocin

  • Two target tissues both involved in
    neuroendocrine reflexes
  • During delivery
  • babys head stretches cervix
  • hormone release enhances uterine muscle
  • baby placenta are delivered
  • After delivery
  • suckling hearing babys cry stimulates milk
  • hormone causes muscle contraction milk ejection

Antidiuretic Hormone (ADH)
  • Known as vasopressin
  • Functions
  • decrease urine production
  • decrease sweating
  • increase BP
  • Dehydration
  • ADH released
  • Overhydration
  • ADH inhibited

  • Organ (5 inches) consists of head, body tail
  • Cells (99) in acini produce digestive enzymes
  • Endocrine cells in pancreatic islets produce
  • Exocrine acinar cells surround a small duct
    digestive enzymes

  • Endocrine cells secrete near a capillary
  • 1 to 2 million pancreatic islets
  • Contains 4 types of endocrine cells
  • Alpha cells (20) produce glucagon
  • Beta cells (70) produce insulin
  • Delta cells (5) produce somatostatin
  • F cells produce pancreatic polypeptide

Regulation of Glucagon Insulin Secretion
  • Low blood glucose stimulates release of glucagon
  • High blood glucose stimulates secretion of insulin

Pineal Gland
  • Melatonin secretion produces sleepiness - occurs
    during darkness due to lack of stimulation from
    sympathetic ganglion
  • Small gland attached to 3rd ventricle of brain
  • Consists of pinealocytes neuroglia
  • Melatonin responsible for setting of biological
  • Jet lag SAD treatment is bright light
  • light strikes retina and stimulates
  • suprachiasmatic region of
  • hypothalamus
  • stimulates sympathetic ganglion
  • which then stimulates the
  • pineal gland
  • light -gt NE -gt no melatonin
  • dark -gt lack of NE -gt melatonin

Thymus Gland
  • Important role in maturation of T cells
  • Hormones produced by gland promote the
    proliferation maturation of T cells
  • thymosin
  • thymic humoral factor
  • thymic factor
  • thymopoietin

  • Local hormones released by all body cells
    normally and upon trauma
  • synthesized from arachidonic acid (fatty acid)
  • Leukotrienes influence WBCs inflammation
    allergic response
  • Prostaglandins alter
  • smooth muscle contraction, glandular secretion,
    blood flow, platelet function, nerve
    transmission, metabolism etc.
  • Ibuprofen other nonsteroidal anti-inflammatory
    drugs treat pain, fever inflammation by
    inhibiting prostaglandin synthesis
  • PGs are synthesized by an enzyme complex
    containing the enzymes COX1 and COX2
  • Aspirin and ibuprofen can inhibit activity of
    COX1 isoform short term anti-inflammatory
  • Vioxx, Bextra and Celebrex inhibit activity of
    COX2 isoform long term anti-inflammatory

Pituitary Gland Disorders
  • Hyposecretion during childhood pituitary
    dwarfism (proportional, childlike body)
  • Hypersecretion during childhood giantism
  • very tall, normal proportions
  • Hypersecretion as adult acromegaly
  • growth of hands, feet, facial features
    thickening of skin

Thyroid Gland Disorders
  • Hyposecretion of TSH during infancy results in
    dwarfism retardation called cretinism
  • Hypothyroidism - undersecretion of T3 and T4
  • Caused by low production of TSH
  • in adults produces sensitivity to cold, low body
    temp. weight gain mental dullness
  • Hyperthyroidism oversecretion of T3 and T4
    (Graves disease)
  • caused by the inability of the thyroid to respond
    to TSH levels
  • weight loss, cardiac complications, increased
    fluid behind the eyes goiter enlarged thyroid

Cushings Syndrome
  • Hypersecretion of glucocorticoids
  • Redistribution of fat, spindly arms legs due to
    muscle loss
  • Wound healing is poor, bruise easily

Addisons disease
  • Hyposecretion of glucocorticoids
  • hypoglycemia, muscle weakness, low BP,
    dehydration due to decreased Na in blood
  • mimics skin darkening effects of MSH
  • potential cardiac arrest

Diabetes Mellitus Hyperinsulinism
  • Diabetes mellitus marked by hyperglycemia
  • excessive urine production (polyuria)
  • excessive thirst (polydipsia)
  • excessive eating (polyphagia)
  • Type I----deficiency of insulin (under 20)
  • Type II---adult onset
  • drug stimulates secretion of insulin by beta
  • cells may be less sensitive to hormone