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Hormones and the endocrine system

A presentation of the human endocrine system. Text: Mader Biology 8e, Ch 42
by

Audrey E

on 7 January 2015

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Transcript of Hormones and the endocrine system

Hormones &
the endocrine system

What's a
hormone
?

signalling molecule
transported via
blood
(
exocrine
glands release products via ducts )
Peptide
autocrine
paracrine
endocrine
intracellular pathways
local communication
pheromone
social communication
peptides
proteins
glyco-
amino acid mods
cannot directly enter a cell
first messenger
second messenger
peptide hormone
signal molecule
G protein-coupled
receptor (GPCR)
epinephrine
cyclic adenosine monophosphate (cAMP)
cell action
glycogen → glucose
Steroid
hormone-receptor
complex
can
cross membrane
enzyme cascade activated
transcription
translation
slower-acting
longer-lasting
Hypothalamus
Anterior
pituitary
Posterior
pituitary
Releasing hormones
Inhibiting hormones
T
hyrotropin
RH
(
TRH
)
C
orticotropin
RH
(
CRH
)
G
o
n
adotropin
RH
(
GnRH
)
G
rowth
h
ormone
RH
(
GHRH
)
Dopamine
Somatostatin
Adrenal glands
(suprarenal)
TSH
+
PRL
ACTH
FSH
+
LH
GH
GH release-inhibiting hormone
A
dreno
c
ortico
t
ropic
hormone
(
ACTH
)
F
ollicle
s
timulating
hormone
(
FSH
)
T
hyroid
s
timulating
hormone
(
TSH
)
Pr
o
l
actin
(
PRL
)
M
elanocyte
s
timulating
hormone
(
MSH
)
G
rowth
hormone
(
GH
)
Pancreas
Thyroid &
parathyroid glands
A
nti
d
iuretic
hormone
(ADH)
Oxytocin
Vasopressin
T cell maturation
Hyperthyroidism
Hypothyroidism
Graves disease:
enlarged or overactive thyroid
underactive thyroid
Triiodothyronine
T
Thyroxine
T
4
3
20% of thyroid hormone in blood
4x as potent as T4
short half-life
increase
basal metabolic rate
synergize w/ GH
control metabolism
produces melatonin
circadian rhythm (night-day cycle)
antioxidant, anti-inflammatory roles
some influence on FSH / LH, puberty
causes pigmentation in fishes, amphibs, reptiles w/ melanophores
involved in human tanning, not base skin color variation
lactation
sexual gratification, refractory period
diurnal, ovulatory, seasonal changes
increases during pregnancy
(even for father)
stims
adrenal glands
to produce
cortisol
glucocorticoids
mineralocorticoids
cys – tyr – ile – gln – asn – cys – pro – leu – gly – NH2
cys – tyr – phe – gln – asn – cys – pro – arg – gly – NH2
Gonads
internal temp
water balance
heartbeat
autonomic controls
neurosecretory cells → portal veins → pituitary → body
tiredness
low cold tolerance
weight gain
congenital: cretinism
iodine deficiency
Hashimoto's thyroiditis
damage/lack of thyroid, ant. pituitary, hypothalamus
autoimmune disorder - immunoglobulins bind to TSH receptor
insomnia
low heat tolerance
weight loss
85% of T3 made
w/ deiodinase
exophthalmic goiter
Adipose tissue
leptin
surpresses appetite
increases energy expenditure
ghrelin
increase appetite and fat mass
secreted by empty stomach
stops when stomach stretches
helps regulate reward perception
hypothalamus
Stomach
most active during childhood, shrinks & becomes fatty w/ age
(+) selection: MHC interaction?
if none, destroy
(-) selection: self-MHC reaction?
destroy
secretes
thymosins
that
promote T lymphocyte differentiation, stim immune system
weak-binding and autoreactive cells undergo apoptosis
myxedema coma
(back view)
retain
water
by increased absorption in
kidney
nephron collecting ducts
constricts blood vessels
very short half-life between 16–24 minutes
involved in homeostasis but also social/sexual behavior
the “bonding hormone”
orgasm, social recognition, pair bonding, anxiety, maternal behaviors
stimulates
uterine wall contraction
and
mammary gland function
positive feedback
L
uteinizing
hormone
(
LH
)
gonadotropic hormones
act on
gonads
to stim
sex hormone production
"activated" at puberty
facilitates sexual behavior; incr. testosterone capacity
M release at regular freq,
F vary w/ cycle
GnRH surge at ovulation
prolactin
↓-regs GnRH
unknown roles in placenta, gonads, cancers of breast/ovary/prostate/endometrium
increased production assoc. w/ Alzheimer’s, major depression
expressed in placenta - controls gestation length?
may trigger parturition (childbirth)
involved in metabolism (thyroid sys)
possible anti-depression/suicide use?
excess amt
↓-regs dopamine
,
↑-regs prolactin
,
↓-regs GnRH
aka somatoliberin
(stims somatotropin)
releases GH, which is needed for normal
postnatal growth
,
bone growth
, regulatory effects on protein, carbohydrate, and lipid
metabolism
promotes slow-wave sleep
skeletal, muscular growth
incr.
ribosome activity
,
amino acid uptake
promotes fat metabolism
promotes diabetes mellitus
after epiphyseal plate closure at end of puberty, causes
acromegaly
feet, hands, face grow
Pituitary dwarfism
Gigantism
too little GH
too much GH
normal proportions and mental development
digestive slowdown
induced by low pH (stomach acidity)
↓-regs insulin
,
glucagon
,
gastrin
,
secretin
, etc release
↓-regs GH
, opposes
GHRH
↓-regs TSH
↓-regs prolactin
↓-regs adenylate cyclase
(cAMP creation catalyzer) in parietal cells
Prolactin-inhibiting hormone
complex, many neural pathways like
reward
addiction
emotion
Calcitonin
lowers
blood calcium levels
, countering PTH
inhibits Ca2+ uptake in
intestines
and reabsorption in
kidneys
inhibits
phosphate reabsorption
prevents hypercalcemia
necessary for clotting
stims
osteoblasts
, decr.
osteoclast
action
preserves skeleton, esp. during pregnancy/lactation
P
ara
t
hyroid
hormone
(
PTH
)
stims
thyroid
hormone

production
negative feedback loop w/ T4 and T3
raises
blood calcium levels
, countering calcitonin
increases
phosphate excretion
demineralizes bones
indirectly stims
osteoclasts
by inhibiting
osteoblasts
activates vitamin D in
kidneys
Hyperparathyroidism
Hypoparathyroidism
too much PTH
semen propulsion?
Islets of Langerhans
glucagon
insulin
alpha cells
beta cells
lowers blood glucose by increasing uptake
increases blood glucose by stimming
liver
to convert stored glycogen into glucose
Diabetes mellitus
Type I
Type II
Gestational
muscle/fat
: take up glucose
liver/muscle
: convert to glycogen
promotes fat/protein buildup
note: not anatomically correct
lack of insulin
insulin insensitivity
liver fails to convert glucose into glycogen
cells don't take up glucose
Thymus
ovaries + testicles
estrogens
androgens
development/maintenance of "female" secondary sex characteristics
layer of fat beneath the skin
breast development
larger pelvic girdle, etc
necessary for oocyte development
stimulate uterine lining
estriol
estradiol
estrone
peri-pubertal development
adult-type body odor, acne
pubarche (pubic hair)
growth spurt, etc
development/maintenance of "male" secondary sex characteristics
large vocal cords
facial hair
sweat glands, baldness, etc
sperm development
aggression
muscle trophism
testosterone
anabolic steroids
progesterone
menstrual cycle, pregnancy, and embryogenesis
promote uterine lining growth
produced by
ovaries
and
placenta
progestogens
Calcitriol
stimulated by PTH, prolactin
hormonally active metabolite of vitamin D
stims Ca2+ uptake in
intestines
and reabsorption in
kidneys
cholecalciferol (D3)
calcitriol
Prostaglandins
uterine contraction
pyrogen mediation (triggering fever)
↓ gastric acid
secretion,
↑ gastric mucus
secretion
blood pressure
pain sensitization, etc
hypercalcemia
soft bones
kidney stones
may occur in response to low vitamin D levels
too little PTH
hypocalcemia
bone pain
twitching or tetany (involuntary contraction)
Chvostek sign
Trousseau sign
Erythropoietin
stimulates RBC production and accelerates maturation
fetal / perinatal period:
liver
adulthood:
kidneys
Cortisol
Glucocorticoids
reduce
inflammation
stimulate
gluconeogenesis
and
amino acid uptake
in
liver
inhibit
sugar uptake
in
muscles
and
adipose tissue
stimulate
fat breakdown
in
adipose tissue
increases
vigilance
/
arousal
response to stress / low blood sugar
Mineralocorticoids
salt / water balance
Aldosterone

reabsorption of Na+
/
excretion of K+
atrial natriuretic
hormone (ANH)
prostaglandin
angiotensin I→II
Epinephrine / Norepinephrine
fight-or-flight (sympathetic) response
80%
20%
↑ heart
rate
↑ respiratory
rate / bronchodilation
↑ liver
glycogenolysis
↑ lipolysis
↑ muscle
contraction / blood flow
↑ blood pressure
pupil
dilation
bladder
relaxation
vigilant concentration > tunnel vision

brain
oxygen supply
Cushing's disease
Addison's disease
Cushing's syndrome
hypersecretion of adrenal hormones
hypercalcemia
hyperkalemia
hyponatremia
metabolic acidosis
non-pituitary cause, like excess cortisol (medication) or adrenal tumor
tendency towards diabetes mellitus
rapid weight gain, central obesity
hyposecretion of adrenal hormones
hypotension
hypoglycemia
hyperpigmentation
1) TRH
2) TSH
3) T3 + T4
1) CRH
2) ACTH
3)
glucocorticoids
mineralocorticoids
nor/epinephrine
1) GnRH
2) FSH + LH
3)
androgens
estrogens
progestogens
Low BP
1) PG
2) Renin
3) Renin act.
4) ADH
4) Aldosterone
High BP
1) ANP
1) GRH
2) GH
Low blood sugar
1) Glucagon
High blood sugar
1) Insulin
paracrine factors
Full transcript