Transcript THE ENDOCRINE SYSTEM

THE ENDOCRINE SYSTEM
ALL ABOUT YOUR HORMONES!!
He Pingping (he only reaches 2.4 feet), meets Bao Xishun (towering at 7.9 feet) tall!
THE IMPORTANCE OF THE ENDOCRINE
SYSTEM
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Body systems interact through the use of chemicals:
hormones
Chemicals produced in glands and secreted directly
into the blood are endocrine hormones; carried by the
circulatory system
Hormones are classified according to their activation
site
Hormones: (Greek: hormon – to excite, set into motion)
 Are produced by glands and sent to the
bloodstream
 Exert effect somewhere else in the body
 Are required in small amounts only
 Act in the metabolic pathway
MINKOWSKI & MERING
1889
 Removed dog
pancreases
 What happened?
 Fatigued and lost wt.
 Ants were found in
the kennels! Why?
 Increased glucose in
urine
 Hormones are hard to
study...no hormonal
response works
independently!
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CHEMICAL CONTROL SYSTEMS
Provide integration and control of organs and
tissues along with the nervous system
 Nervous system enables quick changes to
environment
 Endocrine system designed to maintain control
over longer durations
 The hypothalamus regulates the pituitary- the
master gland- through nerve signals, but the
pituitary, through other glands, affect the nerve
activity of the hypothalamus
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IMPORTANT ENDOCRINE ORGAN
TWO TYPES OF HORMONES
Steroid hormones (made from cholesterol
(testosterone, estrogen) and Protein hormones
 Steroids diffuse from capillaries into interstitial
fluid, then into target cells
 Combine with receptor molecules in the
cytoplasm
 Hormone-receptor complex then moves into
nucleus and attaches to segment of
chromatin with complementary shape
 Activates a gene to produce a specific protein
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STEROID HORMONES – SEX HORMONES
PROTEIN HORMONES – INSULIN, GH
Made up of chains of AA (insulin, GH)
 Combine with specific receptors on the cell
membrane
 Some activate the enzyme adenylyl cyclase
which causes cell to convert ATP into cyclic AMP
(cyclic adenosine monophosphate)
 Cyclic AMP functions as a messenger,
activating other enzymes in the cytoplasm to
carry our normal functions
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PROTEIN HORMONES
THE PITUITARY: THE MASTER GLAND
Exercises control over
other endocrine
glands
 Two lobes: Anterior
and Posterior
 Anterior – produces
and stores hormones
 Posterior – stores
hormones produced by
hypothalamus
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HOMEWORK!
Copy the chart on P 377 into your notes!
 Familiarize your self with the pituitary
hormones!
 http://www.youtube.com/watch?v=8fh2HmdxQjQ
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HORMONES THAT AFFECT BLOOD
SUGAR
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The Pancreas contains
two types of cells
 Produces digestive
enzymes
 Produces hormones –
located in structures
called the islets of
Langerhans
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Over 2000 islets (each
containing thousands of
cells) are scattered
throughout pancreas
Islets contain alpha and
beta cells which are
responsible for the
production of insulin and
glucagon
STORING AND RELEASING GLUCOSE!
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Insulin released when blood sugar levels increase
 insulin causes cells of muscles, liver, and other
organs to become permeable to glucose.
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Liver converts glucose to glycogen
Insulin causes decreases in blood sugar level
 Glucagon causes increase in blood sugar level
(released when blood sugar levels are low,
promotes conversion of glycogen to glucose.
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http://www.youtube.com/watch?v=NazZCu1lwOE&feature=related
GREAT CANADIANS!
Dr. Charles Best and
Dr. Frederick Banting
 1923 Nobel Prize for
the discovery of
Insulin (Best was
excluded!!)
 Did not profit from the
discovery...unheard of
today!
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ADRENAL GLANDS
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Located above each kidney
 Inner gland – adrenal medulla
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medulla surrounded by outer casing (adrenal cortex),
regulated by the nervous system
 hormones regulate the adrenal cortex
Adrenal medulla produces two hormones
(produced when cells within adrenal medulla are
stimulated by sympathetic nerves in times of
stress
 epinephrine
 norepinephrine
FIGHT OR FLIGHT!!
These two hormones initiate fight-or-flight
biological responses
 blood sugar level rises
 glycogen converted to glucose
 ensures greater energy reserve available
 increase heart and breathing rates as well as cell
metabolism
 blood vessels dilate = allowing more oxygen and
nutrients to reach tissues
 irises dilate
 http://www.youtube.com/watch?v=RyP8L3qTW9
Q
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ADRENAL CORTEX
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Produces three different types of hormones
 Glucocorticoids
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Mineralocortiocoids
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one of the most important - Cortisol, increases level of
amino acids in blood and helps in recovery of stress by being
converted to glucose in liver, supplying more energy needed
for repair or recovery by cells or participating in protein
synthesis
Salt and water balance – ALDOSTERONE!
Sex hormones
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Small amounts!
LONG TERM STRESS RESPONSE
hypothalamus sends hormone to anterior lobe of
pituitary
 stimulates pituitary to secrete corticotrophin
(adrenocorticotropic hormone; ACTH)
 blood carries ACTH to target cells in adrenal
cortex
 cells of adrenal cortex secrete mineralocorticoids
and glucocorticoids (one of which is cortisol)
 these are carried to target cells in liver and
muscles
 as cortisol levels rise, hypothalamus and
pituitary production of regulatory hormones
decreases
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SHORT TERM STRESS RESPONSE
regulated by adrenal medulla
 epinephrine & norepinephrine
 aldosterone is one of most important
mineralocorticoids
 increases sodium retention and water
reabsorption by kidneys
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HOMEWORK!
Copy Chart on p 382 into your notebook
 Do Q 1-7, Page 383
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THYROID GLAND
located at base of neck
 two important thyroid hormones (which regulate
body metabolism, growth, and differentiation of
tissues)
 thyroxine (T4)
 triiodothyronine (T3)
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HORMONES THAT AFFECT METABOLISM
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Three different glands affect metabolism
thyroid gland
 helps regulate body metabolism (glucose oxidation
rate)
 produces three hormones
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triiodothyronine, thyroxine, calcitonin
parathyroid gland
 produces parathyroid hormone
 helps regulate calcium levels in blood and lower
phosphate levels
anterior pituitary gland
 produces growth hormones and regulatory
hormones
THYROID GLAND
individuals who secrete higher levels of thyroxine
oxidize sugars and other nutrients at a faster
rate
 When glycogen stores are filled, excess sugar is
converted to fat
 control of thyroid hormones is accomplished by
negative feedback
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FEEDBACK LOOP...
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receptors in hypothalamus are activated if the
metabolic rate decreases
nerve cells secrete TRH (thyroid releasing hormone)
this stimulates pituitary to release TSH (thyroid
stimulating hormone)
 carried by blood to thyroid gland which then
releases thyroxine which raises metabolism by
stimulating sugar utilization by cells
 high levels of thyroxine cause pathway to be
turned off, inhibiting release of TRH
thyroxine contains calcitonin
 hormone acting on bone cells to lower level of
calcium found in blood
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when inadequate amounts of iodine
OH NO!
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when inadequate
amounts of iodine are
obtained from the
diet, thyroid enlarges,
producing a goiter.
PARATHYROID GLANDS
Four parathyroid glands hidden within larger
thyroid gland
 Usually nerves or other hormones regulate the
endocrine glands with the parathyroid glands
being the exception
 These maintain homeostasis by responding
directly to chemical changes in their
immediate surroundings
 Raises calcium levels in the blood
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PTH (parathyroid hormone) also help activate
vitamin D. (Low levels of vit D cause rickets!)
RICKETS AND GOITERS...
HUMAN GROWTH HORMONE (AKA
SOMATOTROPIN)
Too little = dwarfism
 Too much = gigantism
 Released by Ant. Pit.
 GH increases cell size
in muscle cell and
connective tissue by
promoting Pro
Synthesis (increasing
Amino Acid uptake)
 Promotes fat burning
 Dec. Levels of GH
with age
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HGH
AND
CONTROVERSY...
Should you take it?
Did Roger Clemens?
HOMEWORK!
Copy Chart on P. 387
 Read 384-387, Do Nelson Biology 387 # 1-8
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ADJUSTMENTS TO STRESS
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When initiator of
stress is identified,
endocrine and nervous
systems make
adjustments enabling
body to cope with
problem
NERVOUS SYSTEM
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increases heart rate
diverts blood to needed muscles
activates reninangiotensin-aldosterone
pathway in response to reduced blood flow to
kidneys by increasing Na+ reabsorption,
kidneys help maintain increased fluid volume
thus helping to sustain adequate blood
pressure during stress.
Activation of hypothalamus causes increased
release of antidiurectic hormone ADH which
further increases water reabsorption from
nephron to help maintain body fluids.
ENDOCRINE SYSTEM
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hormones provide more sustained response to
stimulus
hormones provide more blood glucose to cope with elevated
energy requirements
 insulin release inhibited
 regulation of blood pressure and volume
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WE HAVE A PROBLEM...
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Operating with elevated blood sugar, blood
pressure, and heart rate creates problems for the
body in terms of long-term stress
PROSTAGLANDINS
local responses to changes in immediate
environment of cells detected by mediator cells
 these produce low concentrations of
prostaglandins (hormones having pronounced
effects in small localized areas) that tend to be
absorbed by surrounding tissues (some absorbed
by capillaries and carried in blood)
 Released during stress and allergic reactions
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STEROIDS...
CHEMICALLY ENHANCED SPORTS
PERFORMANCE
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Anabolic steroids – designed to mimic many of the
muscle-building traits of the sex hormone
testosterone
In 1988 Olympic, Canadian sprinter Ben Johnson was
disqualified for using Stanozolol
There are a number of health risks linked to extended
use of anabolic steroids:
 prematurely fuse growth plates in long bones of
teens, thereby reducing height potential
 mood swings (e.g. rage)
There are a myriad of drugs that affect the body
 sharpshooters use beta blockers that slow the
heartbeat (helps to steady ain and calm jangled
nerves)
EPO and HGH are hard to detect b/c they are
naturally occuring in the body
HOMEWORK
Read Chart P.391
 Read Pages 388-392, Do Page 392 # 1-9
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REPRODUCTIVE HORMONES
MALE ANATOMY - REVIEW
MALE REPRODUCTIVE SYSTEM
male sex hormones androsterone and
testosterone
 produced in interstitial cells (found between
seminiferous cells) of testes
 testosterone
 stimulates spermatogenesis
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influences development of secondary male
sexual characteristics at pituitary
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spermatogonia divide and differentiate into mature sperm
cells
stimulating maturation of testes and penis
promotes development of facial and body
hair, growth of larynx
increases production of body oils
FEEDBACK!
Hypothalamus and
pituitary gland control
production of sperm
and male sex
hormones in testes
 Negative feedback
systems ensure
adequate numbers of
sperm cells and
constant levels of
testosterone are
maintained
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FEMALE ANATOMY - REVIEW
FEMALE REPRODUCTIVE SYSTEM
females follow complicated sexual cycle
 one egg matures ~ every month
 hormone levels fluctuate through reproductive
years ending at menopause
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OOGENESIS AND OVULATION
ovaries contain fibrous connective tissue and
small groups of cells called follicles (two types of
cells)
 primary oocyte
 granulosa cells
 primary oocyte contains 46 chromosomes,
undergoes meiosis, transformed to mature oocyte
(ovum)
 granulosa cells provide nutrients for oocyte
 each ovary contains ~ 400000 follicles at puberty,
many follicles develop during each reproductive
cycle, usually only one becomes dominant and
reaches maturity
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OVULATION
Hormone produced in pituitary controls follicle
development
 Eventually a dominant follicle pushes outward,
ballooning outer wall of ovary
 Secondary oocyte releases – ovulation
 Surrounding follicle cells remain within ovary
and are transformed into corpus luteum,
secreting hormones necessary for pregnancy.
 Secondary oocyte enters oviduct and begins
Meiosis II
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MENSTRUAL CYCLE
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Takes about 28 days
Divided into four distinct phases
 flow phase – shedding of endometrium (menstruation)(Day
1-5)
 follicular phase – development of follicles within ovary
- hormone estrogen secreted (day 6-13)
 ovulatory phase – egg bursts from ovary and follicular
cells differentiate into
corpus luteum
 luteal phase – development of corpus luteum, secretion of
estrogen and progesterone, prepares uterus for embryo and
inhibits further ovulation (Day 15-28)
HORMONAL CONTROL OF FEMALE
REPRODUCTIVE SYSTEM
Hypothalamus-pituitary complex regulates
production of estrogen and progesterone
 Gonadotropins
 Female follicle-stimulating hormone (FSH)
 Luteinizing hormone (LH)
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Gonadotropins regulate control of hormones
produced by ovaries
 Ovarian hormones regulate gonadotropins via
negative feedback mechanisms
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GREAT VISUALS OF THE HORMONE
CYCLES…
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http://www.youtube.com/watch?v=8_rfZ_qj1z4&fe
ature=related
HOW THE PILL WORKS…
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http://www.pbs.org/wgbh/amex/pill/sfeature/sf_cy
cle.html