Title: Endocrine System
1Mariebs Human Anatomy and Physiology Marieb w
Hoehn
- Chapter 16
- Endocrine System
- Lecture 14
2Lecture Overview
- The Adrenal Glands
- The Pancreas
- Other Endocrine Tissues
- Stress and its effects
- Life-span changes
3Location/Blood Supply of the Adrenal
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
4Adrenal Glands
Figure from Holes Human AP, 12th edition, 2010
Adrenal cortex and medulla are functionally
distinct
5Hormones 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
6Adrenal 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
7Adrenocortical 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
8Adrenocortical 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
9Anti-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
10Adrenocortical 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)
11Endocrine Pancreas
Figures from Holes Human AP, 12th edition, 2010
12Cells 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)
13Insulin
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
14Glucagon
Raises blood glucose levels by - stimulating
breakdown of stored molecules- increasing
release and formation of glucose
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
15Insulin and Glucagon
Figure from Holes Human AP, 12th edition, 2010
Example of a humoral stimulus (glucose) for
hormone secretion
16Pineal Gland
Pinealocytes synthesize melatonin from serotonin
17Melatonin
- 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)
18Other 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
19Other 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
20Patterns 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
21Stress
- 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
22Responses to Stress
Exhaustion - ? lipid reserves - ? production of
glucocorticoids - electrolyte imbalance -
damage to vital organs
Figure from Holes Human AP, 12th edition, 2010
23GH 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
24Diabetes ( 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
25Life-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
26Hormone 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
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A
P
27Hormone 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
28Review
- 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
29Mid-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)