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Endocrine System

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Marieb s Human Anatomy and Physiology Ninth Edition Marieb w Hoehn Chapter 16 Endocrine System Lecture 14 – PowerPoint PPT presentation

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Title: Endocrine System


1
Mariebs Human Anatomy and Physiology Marieb w
Hoehn
  • Chapter 16
  • Endocrine System
  • Lecture 14

2
Lecture Overview
  • The Adrenal Glands
  • The Pancreas
  • Other Endocrine Tissues
  • Stress and its effects
  • Life-span changes

3
Location/Blood Supply of the Adrenal
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
4
Adrenal Glands
Figure from Holes Human AP, 12th edition, 2010
Adrenal cortex and medulla are functionally
distinct
5
Hormones of the Adrenal Medulla
  • Epinephrine (80) and Norepinephrine (20)
  • derived from amino acid tyrosine
  • hormones of fight or flight are called
    catecholamines
  • release controlled by sympathetic nervous system
    (neural control of hormone release)
  • hormone releasing cells are considered
    equivalent to postganglionic sympathetic neurons
  • increases heart rate and blood pressure
  • dilates respiratory airways
  • promotes glycogenolysis and gluconeogenesis
  • activates reticular formation
  • increases metabolic rates

6
Adrenal Cortex and its Hormones
  • Yellowish appearance of cortex is due to stored
    lipids, especially cholesterol and various fatty
    acids
  • Produces more than 25 steroid hormones
  • Hormones of the Adrenal Cortex are
  • Called adrenocortical steroids, or
    corticosteroids
  • Carried in blood by transcortins
  • Essential to life
  • Affect cellular metabolism by determining the
    nature and concentration of cellular enzymes
  • Not stored in cell

7
Adrenocortical Steroids - Aldosterone
  • increases blood volume and pressure by promoting
    conservation of sodium ions and water (distal
    tubules of kidney)
  • Activated by 1) the renin-angiotensin system and
    by 2) changing concentrations of of Na and K
  • Zona glomerulosa

Figure from Holes Human AP, 12th edition, 2010
Aldosterone is a mineralocorticoid
8
Adrenocortical Steroids - Glucocorticoids
  • Cortisol (hydrocortisone) a glucocorticoid
  • ? protein synthesis, ? protein catabolism
  • increases fatty acid release (glucose-sparing
    effect)
  • stimulates gluconeogenesis
  • controlled by CRH from hypothalamus and ACTH
    from anterior pituitary

Produced in the Zona Fasciculata Blood levels
peak shortly after arising in morning Glucocortico
ids have anti-inflammatory and anti-immune effects
Figure from Holes Human AP, 12th edition, 2010
9
Anti-Inflammatory Effects of Steroids
Figure from Holes Human AP, 12th edition, 2010
  • Eicosanoids are important paracrine factors that
    mediate many processes in the body, including
  • Inflammation- blood vessel constriction -
    blood clotting- smooth muscle contraction and
    relaxation

10
Adrenocortical Steroids - Androgens
  • Adrenal androgens (gonadocorticoids)
  • supplement sex hormones from the gonads (release
    stimulated slightly by ACTH inhibitory stimulus
    unknown). Mostly dehydroepiandrosterone (DHEA)
  • may be converted to estrogen in the blood (?)
  • When secreted in normal amounts, neither adrenal
    androgens or estrogens affect sexual
    characteristics (may affect sex drive in ?)
  • Produced in the Zona Reticularis
  • Tumors of this region can lead to androgenital
    syndrome (masculinization)

11
Endocrine Pancreas
Figures from Holes Human AP, 12th edition, 2010
12
Cells of the Pancreatic Islets
  • Alpha cells - Glucagon
  • Beta cells Insulin, amylin
  • Delta cells
  • Somatostatin (growth hormone-inhibiting hormone,
    GH-IH)
  • Suppresses release of insulin and glucagon
  • Slows rates of food absorption
  • F cells
  • Pancreatic polypeptide (inhibits GB contractions
    exact physiological role is uncertain)

13
Insulin
Insulin decreases blood glucose levels by
allowing cells to take up glucose from the
blood Binding enhances glucose uptake Brain,
kidneys, liver, RBCs are insulin
independent Insulin release is also affected by
the ANS
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
14
Glucagon
Raises blood glucose levels by - stimulating
breakdown of stored molecules- increasing
release and formation of glucose
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
15
Insulin and Glucagon
Figure from Holes Human AP, 12th edition, 2010
Example of a humoral stimulus (glucose) for
hormone secretion
16
Pineal Gland
Pinealocytes synthesize melatonin from serotonin
17
Melatonin
  • regulates circadian rhythms - daily changes in
    physiological processes that follow a regular
    pattern
  • Light (eyes) ? retina ? hypothalamus ? reticular
    formation ?
  • ? melatonin ? pineal ? sympathetic fibers ?
    spinal cord
  • may control onset of puberty (melatonin levels
    decline at puberty)
  • helps regulate female reproductive cycle
  • may protect CNS against free radicals
    (antioxidant)

18
Other Endocrine Glands
  • Reproductive Glands
  • ovaries secrete estrogen and progesterone
  • testes secrete testosterone
  • placenta secretes estrogen, progesterone, and
    gonadotropins, e.g., hCG
  • Thymus Gland
  • secretes thymosins
  • promotes development of T-lymphocytes
  • Heart
  • secretes natriuretic peptides (ANP, BNP)
  • - Natri sodium uretic in the urine
  • promote loss of water and Na at the kidney
  • secreted when atria/ventricles are stretched
  • - inhibit renin release
  • - inhibit secretion of ADH and aldosterone

19
Other Endocrine Glands
  • Adipose Tissue
  • Leptin
  • After eating, adipose tissue absorbs glucose and
    lipids
  • Peptide hormone, leptin, is released
  • Binds to receptors in hypothalamus (esp. arcuate
    and paraventricular nuclei)
  • Alters levels of other substances in brain
  • Increased sympathetic activity
  • Decreased insulin secretion
  • Permissive effect on GnRH (effects on
    reproductive function)
  • Sense of satiety and suppression of appetite
  • Levels are normal in most obese individuals
    receptors or cellular pathways may be defective
  • Resistin
  • Reduces insulin sensitivity throughout body
    (insulin antagonist)
  • May be one of the missing links between obesity
    and diabetes
  • TNF? - in obese people, inhibits glut4 protein
    activates stress hormones

20
Patterns of Hormonal Interaction
  • Cells in the body are normally responding to
    multiple hormones simultaneously
  • Four outcomes of multiple stimulation
  • Antagonistic effects opposing effects, e.g.,
    PTH-calcitonin, insulin-glucagon
  • Synergistic effects additive, effect is greater
    than either alone, e.g., GH and glucocorticoids
  • Permissive effects first hormone is needed for
    second to produce its effect, e.g., estrogen
    up-regulation of progesterone receptors,
    leptin/GnRH
  • Integrative effects produce different, but
    complementary effects, e.g., PTH and calcitriol

21
Stress
  • Types of Stress
  • physical stress
  • psychological (emotional) stress
  • (Stress is any condition, physical or emotional,
    that threatens homeostasis)
  • Stress Response (General Adaptation Syndrome
    GAS)
  • hypothalamus triggers sympathetic impulses to
    various organs
  • epinephrine is released
  • cortisol is released to promote longer-term
    responses
  • Three general phases of the GAS in response to
    stress A R E
  • Alarm phase
  • Resistance phase
  • Exhaustion phase

22
Responses to Stress
Exhaustion - ? lipid reserves - ? production of
glucocorticoids - electrolyte imbalance -
damage to vital organs
Figure from Holes Human AP, 12th edition, 2010
23
GH Abnormalities
Figure from Holes Human AP, 12th edition, 2010
Growth Hormone Ups and Downs
  • Gigantism - hypersecretion of GH in children
  • Acromegaly hypersecretion of GH in adults
  • Dwarfism hyposecretion of GH in children

Age 9
Age 16
Age 33
Age 52
24
Diabetes ( Overflow)
  • Diabetes Mellitus (DM)
  • Hyposecretion or hypoactivity of insulin
  • Three Ps of Diabetes Mellitus (mellitum honey)
  • Polyuria (increased urination)
  • Polydipsia (increased thirst)
  • Polyphagia (increased hunger)
  • Hyperglycemia, ketonuria, glycosuria
  • Renal Glycosuria
  • excretion of glucose in the urine in detectable
    amounts
  • normal blood glucose concentrations or absence of
    hyperglycemia
  • Diabetes Insipidus (insipidus tasteless)
  • Hyposecretion or hypoactivity of ADH
  • Polyuria
  • Polydipsia

25
Life-Span Changes
  • endocrine glands shrink
  • GH levels even out, muscular strength decreases
  • ADH levels increase due to slower break down
  • calcitonin levels decrease
  • PTH increases, osteoporosis risk increases
  • insulin resistance may develop
  • changes in melatonin secretion affect the body
    clock
  • thymosin production declines increasing risk of
    infections

26
Hormone Summary Table I Pituitary Hormones
Tissue Tissue
Name Origin Destination Action on Target Tissue Control of Release1
FOLLICLE STIMULATING HORMONE (FSH) anterior pituitary males seminiferous tubules of testes females ovarian follicle males sperm production females follicle/ovum maturation Gonadotropin Releasing Hormone (GnRH)
LUETINIZING HORMONE (LH) anterior pituitary In males interstitial cells in testes in females mature ovarian follicle males testosterone secretion females ovulation Gonadotropin Releasing Hormone (GnRH)
THYROID STIMULATING HORMONE (TSH) anterior pituitary thyroid secrete hormones Thyrotropin Releasing Hormone (TRH)
GROWTH HORMONE (GH) anterior pituitary bone, muscle, fat growth of tissues Growth Hormone Rleasing Hormone (GHRH)
ADRENOCORTICO-TROPIC HORMONE (ACTH) anterior pituitary adrenal cortex secrete adrenal hormones Corticotropin Releasing Hormone (CRH)
PROLACTIN (PRL) anterior pituitary mammary glands produce milk Prolactin Releasing Hormone (PRH)
ANTI-DIURETIC HORMONE (ADH) (VASOPRESSIN) posterior pituitary Collecting ducts of kidneys reabsorption of water increases blood pressure increase in osmolarity of plasma or a decrease in blood volume
OXYTOCIN (OT) posterior pituitary uterine smooth muscle breast contraction during labor milk letdown Stretching of uterus infant suckling
Se(x)
T
G
A
P
27
Hormone Summary Table II
Tissue Tissue
Name Origin Destination Action on Target Tissue Control of Release
TRIIODOTHYRONINE (T3) THYROXINE (T4) Thyroid (follicular cells) all cells increases rate of metabolism (BMR) Thyroid Stimulating Hormone (TSH)
CALCITONIN Thyroid (C cells) Intestine, bone, kidney Decreases plasma Ca2 (? intestinal absorp of Ca ? action of osteoclasts ? excretion of Ca by kidney ? plasma Ca2
PARATHYROID HORMONE (PTH) Parathyroids Intestine, bone, kidney Increases plasma Ca2 (? intestinal absorp of Ca ? action of osteoclasts ? excretion of Ca by kidney ? plasma Ca2
EPINEPHRINE/ NOREPINEPHRINE(Catecholamines) Adrenal Medulla cardiac muscle, arteriole and bronchiole smooth muscle, diaphragm, etc increases heart rate and blood pressure... (fight or flight) Sympathetic Nervous System
ALDOSTERONE (Mineralocorticoids) Adrenal Cortex Kidneys sweat glands salivary glands pancreas reabsorption of water and Na (increases blood pressure) and excretion of K (mineralocorticoid) Angiotensin II ? plasma Na ? plasma K
CORTISOL(Glucocorticoids) Adrenal Cortex all cells Diabetogenic anti-inflammatory(glucocorticoid) ACTH
INSULIN ß-cells of Pancreatic Islets all cells, liver and skeletal muscle pushes glucose into cells from blood, glycogen formation (decreases blood glucose) ? plasma glucose SNS
GLUCAGON a-cells of pancreatic Islets liver and skeletal muscle breakdown of glycogen (increase in blood glucose) ? plasma glucose
TESTOSTERONE Testes secondary sex organs development and maintenance LH
ESTROGEN Ovaries secondary sex organs development at puberty and maintenance throughout life LH
NATRIURETIC PEPTIDES atria and ventricles of heart adrenal cortex, kidneys increased excretion of sodium and water from kidneys, ? blood volume, ? blood pressure Stretching of atria and ventricles
28
Review
  • Reaction to stress occurs in three stages
  • Short term
  • Alarm or fight or flight
  • Reactions similar to sympathetic stimulation
  • Mediated by hormones of the adrenal medulla
  • Long term
  • Resistance
  • Long-term raising of blood glucose
  • Mediated by hormones of the adrenal cortex
  • Exhaustion
  • Failure of compensatory mechanisms

29
Mid-term Checkup
Based on the three (3) grades you have received
so far, you should do a mid-term checkup. To find
your average so far, total the three grades
youve received and divide by 300 (the total
amount of points possible so far for the course).
Example (83 67 90) ? 300 0.80
(80) Dropping the low grade (8390) ? 200
0.87 (87) To figure out what you need to
AVERAGE for the next lecture or lab exam and the
final COMBINED to get a particular grade
( (Grade you want) ? 100 x 600 ) - Total pts.
so far
Average grade needed

300 (if no grade dropped) or 400 (if low grade
dropped)
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