The Endocrine System

1
The Endocrine System

• Endocrine and nervous systems work together
• Endocrine system
• hormones released into the bloodstream travel
  throughout the body
• target is usually far from site of synthesis
• binds to receptors on or in target
• targets cells throughout the body
• results may take hours, but last longer
• Nervous system
• certain parts release hormones into blood
• rest releases neurotransmitters that excite or
  inhibit nerve, muscle gland cells
• results in milliseconds, brief duration of
  effects

2
General Functions of Hormones

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

3
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

4
Extracellular Signaling Mechanisms

• most signals produced by cells within the body
  bind to receptors that are specific for that
  signal
• most receptors are found on the cell surface
• although some can be found within the cell!
• binding of the signal (ligand) to the receptor
  results in a series of events (signal
  transduction) within the cell that changes the
  cells function
• e.g. may change the transcription rate of a gene
  effects protein production

5
Hormones Mechanisms of Signaling

• hormone producing cell endocrine cell
• e.g. thyroid, pituitary
• Autocrine signaling
• cell responds to the hormone it produces
• Paracrine signaling
• local action
• local hormone (paracrine hormones)
• act on neighboring cells
• autocrines act on same cell that secreted them
• Endocrine signaling
• circulating hormones (endocrine hormones)
• act on distant targets
• travel in blood

6
Types of Hormones

• water-soluble
• lipid -soluble

7
Lipid-soluble Hormones

• Steroids
• lipids derived from cholesterol
• made in SER
• different functional groups attached to core of
  structure provide uniqueness
• e.g. cortisol, progesterone, estrogen,
  testosterone, aldosterone
• Thyroid hormones
• tyrosine ring plus attached iodines
• are lipid-soluble
• Retinoic acid
• lipids derived from retinol (vitamin A)
• regulate proliferation, differentiation and death
  of many cell types
• some vitamins can acts a lipid-soluble hormones
• e.g. vitamin D
• Nitric oxide (NO)
• - gas

testosterone
aldosterone
cortisol
8
Lipid-soluble Hormones

• Eicosanoids
• prostaglandins or leukotrienes
• derived from arachidonic acid (fatty acid)
• AA is converted either into prostaglandin H or
  into the leukotrienes
• conversion of AA into prostaglandins is regulated
  by the COX enzymes
• both act in the inflammatory reaction
• e.g. stimulate smooth muscle cells to contract
• e.g. stimulate nerve cells pain

9
Water-soluble Hormones

• Amine, peptide and protein hormones
• modified amino acids to protein chains
• serotonin, melatonin, histamine, epinephrine,
  insulin, dopamine
• protein hormones comprised of one or many
  polypeptide chains
• insulin, glucagon
• peptide hormones comprised of chains of amino
  acids
• e.g. growth hormone, oxytocin
• amine hormones derived from the amino acids
  tyrosine or tryptophan
• epinephrine (tyrosine and phenylalanine),
  serotonin (tryptophan), dopamine (tyrosine)
• can also act as neurotransmitters

insulin
10
Action of Lipid-Soluble Hormones Endogenous
signaling

• Hormone must be carried by a transport protein
  that allows it to dissolve within the aqueous
  (watery) environment of the blood plasma
• Hormone diffuses through phospholipid bilayer
  into cell
• the receptor is located within the cell
  (cytoplasm or the nucleus)
• binding of H to R results in its translocation
  into the nucleus
• the H then binds directly to specific sequences
  within the DNA response elements
• this binding turns on/off specific genes
  activates or inhibits gene transcription
• if turned on - new mRNA is formed directs
  synthesis of new proteins
• new protein alters cells activity
• if turned off no new protein results and the
  cells activity is altered

11
Action of Lipid-Soluble Hormones

• some lipid-soluble hormone dont cross the plasma
  membrane too large
• therefore they bind with receptors on the cell
  surface and trigger signaling events within the
  cells
• signal similar to water-soluble hormones
• e.g. prostaglandins

12
Action of Water-Soluble Hormones

• easily travels through the blood - hydrophilic
• but cannot diffuse through plasma membrane!
• therefore absolutely requires the expression of
  receptors on the cell surface integral membrane
  proteins that act as first messenger
• the receptor protein activates a series of
  signaling events within the cells
• e.g. epinephrine binds to receptor and activates
  an adjacent G-protein in membrane
• G-protein activates adenylate cyclase to convert
  ATP to cyclic AMP (cAMP) in the cytosol
• cAMP is the 2nd messenger
• cAMP activates a series of proteins in the
  cytosol called kinases
• kinases act to phosphorylate their targets
  either activating them or inhibiting them
• this speeds up/slows down physiological responses
  within the cell
• phosphodiesterase inactivates cAMP quickly
• many second messengers are made in cells in
  response to specific hormones
• e.g. calcium, IP3, DAG
• Cell response is turned off unless new hormone
  molecules arrive
• this mechanism allows for amplification one H-R
  combination can activate two G proteins which
  activates 4 kinases which activate 16 more
  kinases etc.

13
Hormonal Interactions

• Permissive effect
• Second hormone permits the action of the first
• estrogen LH are both needed for oocyte
  production
• Synergistic effect
• two hormones act together for greater effect (vs.
  individually)
• thyroid strengthens epinephrines effect upon
  lipolysis
• Antagonistic effects
• two hormones with opposite effects
• insulin promotes glycogen formation glucagon
  stimulates glycogen breakdown

14
Control of Hormone Secretion

• Regulated by signals from nervous system,
  chemical changes in the blood or by other
  hormones
• 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

15
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 7
  different releasing inhibiting hormones PLUS
  two additional hormones (ADH oxytocin)

16

• hypothalamus
• -Emotions, autonomic functions, hormone
  production
• -mamillary bodies serve as relay stations for
  reflexes related to smell
• -supraoptic and preoptic regions that function in
  vision
• -major functions
• 1. control of the ANS integrates signals from
  the ANS (regulated smooth and cardiac muscle
  contraction)
• major regulator of visceral activities (heart
  rate, food movements, contraction of bladder)
• 2. produces hormones connects with pituitary to
  regulate its activity

3. regulates emotional and behavioral patterns
rage, aggression, pain and pleasure sexual
arousal 4. regulates eating drinking
hypothalamus contains a thirst center which
responds to a rise in osmotic pressure in the
ECF (dehydration) 5. controls body temperature
monitors temp of blood flowing through the
hypothalamus
17
Pituitary Gland

• cells secrete 9 different hormones
• regulates the activity of the pituitary through
  its secretion of 7 specific releasing and
  inhibiting hormones
• e.g. pituitary hormone somatotropin
• hypothalmic hormones somatotropin releasing
  hormone (SRH) and somatotropin inhibiting hormone
  (SIH)
• also secretes two specific hormones that are
  stored in the pituitary oxytocin and
  anti-diuretic hormone (ADH)
• portion that marks the connection with the
  pituitary median eminence
• near the ME is a group of cells neurosecretory
  cells
• secrete the hypothalmic releasing and inhibiting
  hormones that regulate the pituitary
• stored in synaptic vesicles
• released upon production of an action potential
  via exocytosis into the blood stream
• Diffusion down to the anterior pituitary

18
Pituitary Gland
-hypothalamic hormones (releasing hormones) reach
the pituitary via a portal system of capillaries
hypophyseal portal system (HPS) -flow of blood
from the hypothal. into portal veins that carry
blood to the capillaries of the ant
pituitary -superior hypophyseal arteries
are branches off of the internal carotid- -bring
blood into the hypothal. -where the hypothal. and
infundibulum meet they divide into the
primary plexus of the HPS -from this plexus blood
drains into hypophyseal portal veins -at the
anterior pituitary these portal veins divide into
the secondary plexus of the HPS -release of the
hypothalmic releasing inhibiting hormones into
the primary plexus of the HPS and travel to the
secondary plexus

• 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
  hypothalamus
• neuroglial cells called pituicytes

19
Anterior 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

20
Anterior Pituitary Gland Control of Secretion

• first level of regulation releasing and
  inhibiting hormones of the hypothalamus
• second level is negative feedback by hormones
  release by the target gland
• e.g. corticotropin (ACTH) release stimulated by
  CRH/corticotropin releasing hormone
• travels to anterior pituitary and stimulates
  release of ACTH
• ACTH travels to the adrenal gland stimulates
  production and secretion of cortisol
• increase of cortisol beyond the normal range
  triggers release of CIH/corticotropin inhibiting
  hormone
• CIH shuts down the secretion of ACTh by the
  anterior pituitary

21
Human Growth Hormone

• Produced by somatotrophs
• release is stimulated by GHRH from the
  hypothalamus
• promotes synthesis of insulin-like growth factors
• IGFs are made primarily by the liver
• common target cells for IGFs skeletal muscle,
  cartilage and bone cells
• increases cell growth cell division by
  increasing their uptake of amino acids
  synthesis of proteins
• hGH also
• stimulates lipolysis in adipose - so fatty acids
  can be used for ATP
• stimulates synthesis and release of glucose into
  the blood by the liver gluconeogenesis
• retards use of glucose for ATP production so
  blood glucose levels remain high enough to supply
  brain
• hGH secretion is promoted by decreased fatty
  acids and amino acids in the blood, decreased
  blood sugar, deep sleep, increased activity by
  the sympathetic NS, hormones (glucagon, estrogen,
  cortisol and insulin)

• Excess of growth hormone
• raises blood glucose concentration
• pancreas releases insulin continually
• beta-cell burnout
• Diabetogenic effect eventually causes diabetes
  mellitis if no insulin activity occurs

22
Regulation of hGH

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

23
Medical application

• 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

24
Thyroid Stimulating Hormone (TSH)

• Hypothalamus regulates thyrotroph cells
• Thyrotroph cells produce TSH
• TSH stimulates the synthesis secretion of T3
  and T4
• Metabolic rate stimulated

25
Follicle Stimulating Hormone (FSH)

• Releasing hormone from
  hypothalamus controls
  gonadotrophs
• Gonadotrophs release
  follicle stimulating hormone
• FSH functions
• initiates the formation of follicles within the
  ovary
• stimulates follicle cells to secrete estrogen
• stimulates sperm production in testes

26
Luteinizing Hormone (LH)

• Releasing hormones from hypothalamus stimulate
  gonadotrophs
• 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

27
Prolactin (PRL)

• Hypothalamus regulates lactotroph cells
• Lactotrophs produce prolactin (also produced by
  breast tissue)
• during pregnancy high levels of estrogen
  contribute
• Under right conditions, prolactin increases
  mammary gland size and causes milk production
• during pregnancy high levels of progesterone
  prevent milk let-down
• also contributes to female orgasm, proliferation
  of oligodendrocytes (!)
• hypothalamus normally inhibits prolactin
  production when not pregnant
• arcuate nucleus produces dopamine which inhibits
  lactotroph activity
• Suckling reduces levels of hypothalamic
  inhibition and prolactin levels rise along with
  milk production
• milk let-down also requires action of oxytocin
  (promoted also by suckling)
• also provides feelings of sexual gratification
  after intercourse
• counteracts dopamine (sexual arousal) produces
  a sexual refractory period

28
Adrenocorticotrophic Hormone

• Hypothalamus releasing hormones stimulate
  corticotrophs
• Corticotrophs secrete ACTH MSH
• ACTH stimulates cells of the adrenal cortex that
  produce glucocorticoids

29
Melanocyte-Stimulating Hormone

• Secreted by corticotroph cells under the control
  of MRH (MSH-releasing hormone)
• Releasing hormone from hypothalamus increases its
  release from the anterior pituitary
• Function not certain in humans (increase skin
  pigmentation in frogs )

30
Posterior Pituitary Gland (Neurohypophysis)

• Does not synthesize hormones
• Consists of axon terminals of hypothalamic
  neurons
• Neurons release two neurotransmitters that enter
  capillaries
• antidiuretic hormone
• oxytocin

31
Oxytocin

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

32
Antidiuretic Hormone (ADH)

• Known as vasopressin
• Functions
• decrease urine production
• decrease sweating
• increase BP

• Dehydration
• ADH released
• Overhydration
• ADH inhibited

33
The peripheral endocrine glands

• thyroid and parathyroid
• adrenal glands
• ovaries and testes
• pancreas

34
Thyroid Gland

• comprised of microscopic sacs called follicles
  follicular cells making up the walls, surrounds a
  lumen
• 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

35
Formation of Thyroid Hormone

• Iodide trapping follicular cells actively take
  up iodide ions from blood
• Synthesis of thyroglobulin (TGB) RER of
  follicular cells make TGB - secreted into the
  follicle lumen
• Iodination of colloid iodide ions are oxidated
  (i.e reform I2) by peroxidase, iodine molecule
  then binds onto tyrosine residues on the TGB
  known as colloid
• this oxidation is required because negatively
  charges ions cant bind onto the tyrosine amino
  acids
• Coupling of T1 and T2 one iodine molecule T1
  two iodine molecules T2
• Inside the lumen - form T3 T4
• T2 T2 T4 T1 T2 T3
• Uptake of colloid by follicular cells colloid
  reenters the follicular cells by pinocytosis,
  merge with lysozymes
• digestion of TGB cleaves off T3 and T4 hormones
• Secretion of T3 T4 into blood T3 T4 are
  transported in blood bound to thryoxine-binding
  globulin (TBG)

36
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)

37
Control of T3 T4 Secretion

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

38
Medical application Thyroid disorders

• -hyperthyroidism
• -most common form Graves disease
• 7 to 10 times more common in females
• autoimmune disorder
• antibodies that mimic the action of TSH
• enlargened thyroid and exophthalmos (edema behind
  the eyes)
• hypothyroidism reduced production of TSH and
  thryoid hormones
• -common treatment oral L-thyroxin
• - can produce myxedema in the adult
• more common in females
• edema within the facial tissues, slow heart rate,
  low body temperature
• congenital hypothyroidism
• causes severe mental retardation and stunted bone
  growth
• babies appear normal due to maternal thyroid
  hormones so testing is required

39
Parathyroid Glands

• Principal cells (chief cells) produce parathyroid
  hormone (PTH)
• Oxyphil cell function is unknown

• 4 pea-sized glands found on back of thyroid gland

40
Parathyroid Hormone

• Raises blood calcium levels (also regulates Mg
  and phosphate levels
• increases activity of osteoclasts, increases of
  OCs
• releases calcium and HPO4 into the blood
• acts on the kidneys to increase reabsorption of
  Ca2 back into the blood (also same for Mg)
• increases loss of HPO4 into the urine decreases
  the overall level of HPO4 in the blood
• promotes formation of calcitriol (vitamin D3) by
  kidney which increases absorption of Ca2 and
  Mg2 by intestinal tract
• Opposite function of calcitonin (CT 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
  calcium
• low level of calcium in blood - release of PTH by
  parathyroid glands, promotes release of calcium
  from bone, raises blood calcium

41
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)
  androgens
• Medulla produces epinephrine norepinephrine

42
AdrenalGland

• Cortex
• 3 zones
• Medulla

43
Mineralocorticoids

• from the zona glomerulosa of the adrenal cortex
• 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 and
  Na uptake from kidneys and increased excretion of
  K and H into urine
• the increase water reabsorption back into the
  blood increases blood volume and pressure
• angiotensin II also stimulates contraction of
  smooth muscle within arterioles

44
Glucocorticoids

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

45
Androgens

• Small amount of male hormone produced by the zona
  reticularis
• insignificant in males
• may contribute to sex drive in females
• secreted as dehydroepiandrosterone (DHEA)
• is converted to estrogen in postmenopausal
  females
• also used by body builders since it is a
  precursor to functional testosterone
• high dose administration to be useful side
  effects?
• http//skepdic.com/dhea.html
• http//en.wikipedia.org/wiki/Dehydroepiandrosteron
  e

46
Adrenal Medulla

• modified sympathetic ganglion part of the ANS!
• the cells lack axons are cluster around blood
  vessels
• these 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 adrenal medulla

47
Cushings Syndrome
Medical application Adrenal Gland disorders

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

Addisons disease

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

48
Pancreas

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

49

• 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 or GHIH
• F cells produce pancreatic polypeptide

50
Regulation of Glucagon Insulin Secretion

• Low blood glucose stimulates release of glucagon
• High blood glucose stimulates secretion of insulin

51
Medical application Diabetes Mellitus

• 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
• cells may be less sensitive to hormone

52
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
  characteristics

53
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
  clock
• 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

54
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

55
The stress response

• helpful stress eustress
• stressor any disturbance in the homeostatic
  balance of the human body
• when homeostasis can counteract these stressors
  the body remains within normal physiologic
  parameters
• if not a series of reactions occurs stress
  response
• three stages
• 1. initial fight or flight response
• 2. slower resistance reaction
• 3. exhaustion

56

• fight or flight
• initiated by nerve impulses of the hypothalamus
  to the adrenal medulla (ANS)
• release of epinephrine and norepinephrine
• prepares the body for immediate physical response
• short lived response
• resistance
• initiated by hypothalmic releasing hormones
• CRH, GHRH and TRH
• helps the body continue fighting the stressor
• if the body fails to combat the stressor, our
  body
• enters the last stage
• exhaustion
• resources become depleted so they can no longer
  continue the resistance stage
• prolonged exposure to cortisol can cause wasting
  of skeletal muscle, suppression of the immune
  system, ulceration of the GI tract and failure of
  the beta cells of the pancreas to make insulin
  (diabetes)

-increased blood sugar from breakdown or
neogenesis
-increased glucose used to make ATP and drive
metabolism
57
Stress and Disease

• can lead to specific diseases by temporarily
  inhibiting the immune system
• includes gastritis, ulcerative colitis, irritable
  bowel syndrome, migraines, anxiety, hypertension,
  asthma, rheumatoid arthritis
• role for interleukin-1 (IL-1) which is secreted
  by macrophages in the immune system
• IL-1 can stimulate secretion of ACTH by the
  anterior pituitary
• causes production of cortisol
• increased resistance to stress good
• BUT if not controlled exhaustion bad!

58
Eicosanoids

• Local hormones released by all body cells
• synthesized from arachidonic acid
• Leukotrienes influence WBCs inflammation
• 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

59
Nonsteroidal Anti-inflammatory Drugs

• Answer to how aspirin or ibuprofen works was
  discovered in 1971
• inhibit a key enzyme in prostaglandin synthesis
  (COX) without affecting the synthesis of
  leukotrienes
• Treat a variety of inflammatory disorders
• rheumatoid arthritis

60
Aging and the Endocrine System

• Production of human growth hormone decreases
• muscle atrophy
• Production of TSH increase with age to try and
  stimulate thyroid
• decrease in metabolic rate, increase in body fat
  hypothyroidism
• Thymus after puberty is replaced with adipose
• Adrenal glands produce less cortisol
  aldosterone
• Receptor sensitivity to glucose declines
• Ovaries no longer respond to gonadotropins
• decreased output of estrogen (osteoporosis
  atherosclerosis)