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Chapter 18
The Endocrine System
communication between cells
mechanisms
direct cell-to-cell
cell-to-cell(short distance)
cell-cell
cell-to-cell(long distance)
gap junctions
paracrinelocal chemicals
neurotransmitters
endocrinechemicals via
bloodstream
Table 18-1
Endocrine system
cells (tissues, organs) that produce chemical messengers (hormones) that travel via the bloodstream to have distant effects
Endocrine system
classes of hormones:
peptide:
lipid:
•amino acid derivatives•polypeptides
•eicosaniods(from arachidonic acid)
•steroids(from cholesterol)
fig. 18-2
Endocrine system
receptors and mechanism of action
peptide hormones
receptors on cell surfaceactivate G proteinsuse second messengers
(cAMP)activates enzymesalter cellular activity
Endocrine system
receptors and mechanism of action
steroid hormones
diffuse across membranereceptors in cytoplasmactivate specific genes
alter cellular activity
100 keys (pg. 599)
“Hormones coordinate cell, tissue, and organ activities on a sustained basis. They circulate in the extracellular fluid and bind to specific receptors on or in target cells. They then modify cellular activities by altering membrane permeability, activating or inactivating key enzymes, or changing genetic activity.”
Endocrine reflexes
triggered by:
humoral stimulibody fluid changes
hormonal stimuli
neural stimuli
Endocrine reflexes
many are controlled by negative feedback
simple - a single hormone
complex - two or moreseveral steps
many are controlled by the hypothalamus
the “master gland” of the endocrine system:
pituitary gland
an
teri
or
post
eri
or
fig 18-6
pituitary gland
produces 9 “peptide” hormones
anterior *posterior
TSHACTHFSHLHprolactinGHMSH
ocytocinADH
pituitary gland
controlledby
hypothalamus
produces
RH releasing hormonesIH inhibiting hormones
pituitary gland
controlledby
hypothalamus
fig 18-7
produces
RHIH
pituitary gland
anterior
TSHACTHFSHLHprolactinGHMSH
thyroid glandadrenal glandgamete developmentreproductionmilk productiongrowthpigment cells
pituitary gland
an example
TSH
thyroid gland
1 2
3
4
5
pituitary gland
controlledby
hypothalamus
fig 18-7
produces
RHIH
OT
ADH
OTADH
pituitary gland
fig 18-9
the “master gland”
100 keys (pg. 604)
“The hypothalamus produces regulatory factors that adjust the activities of the anterior lobe of the pituitary gland, which produces 7 hormones. Most of the hormones control other endocrine organs, including the thyroid gland, adrenal gland, and gonads. The anterior lobe also produces growth hormone, which stimulates cell growth and protein synthesis.”
100 keys (pg. 604)
“The posterior lobe of the pituitary gland releases two hormones produced in the hypothalamus; ADH restricts water loss and promotes thirst, and oxytocin stimulates smooth muscle contractions in the mammary lands and uterus (in females) and the prostate gland (in males).”
other endocrine organs
thyroid glandsC-cells of thyroid gland
parathyroid glandsadrenal glands
cortexmedulla
pineal glandpancreasintestines, gonads, kidneys, adipose
other endocrine organs
thyroid glands
produce thyroxine (T3, T4)
affect all cells
O2 use ATP production HR, bp erythropoiesis
other endocrine organs
thyroid glandsC-cells of thyroid gland
parathyroid glands
calcitonin blood [Ca2+ ]
PTH blood [Ca2+ ]
100 keys (pg. 612)
“The thyroid gland produces (1) hormones that adjust tissue
metabolic rates and
(2) a hormone that usually plays a minor
role in calcium ion homeostasis byopposing the action of parathyroid
hormone.”
to here 4/18lec #39
other endocrine organs
adrenal glandscortex
medulla
mineralocorticoidsaldosterone retain Na+
lose K+
glucocorticoidshydrocortisone
anti-inflammatory
NE, E (Sympathetic ANS)
100 keys (pg. 616)
“The adrenal glands produce hormones that adjust metabolic activities at specific sites, affecting either the pattern of nutrient utilization, mineral ion balance, or the rate of energy consumption by active tissues.”
other endocrine organs
pineal gland
produce melatonin
timing of sexual maturation
protect from free radicals
set circadian rhythms
other endocrine organs
pancreas
produces digestive enzymes
contains isletsproduce (4) hormones
insulinglucagon
pancreas
insulin
released when blood [glucose]is greater than ~110 mg/dl
most cells in the body have insulin receptor
insulin dependent
insulin
most cells in the body have insulin receptor
insulin dependent
insulin causes these cells to
glucose absorption glucose utilization
blood [glucose]
pancreas
glucagon
released when blood [glucose]is less than ~70 mg/dl
stimulates:breakdown of glycogenbreakdown of triglyceridesproduction of glucose
blood [glucose]
pancreas
100 keys (pg. 620)
“The pancreatic islets release insulin and glucagon. Insulin is released when blood glucose levels rise, and it stimulates glucose transport into, and utilization by, peripheral tissues.
Glucagon is released when blood glucose levels decline, and it stimulates glycogen breakdown, glucose synthesis and fatty acid release.”
the “other” diabetes
diabetes insipidus
diabetes mellitusflow-through sweet
What would make the urine sweet?
Why would glucose be in the urine?
diabetes mellituscauses
•genetic
•pathological conditions•injury•immune disorder•hormonal abnormality
mutations leading tolow insulin productionabnormal insulindefective receptors
diabetes mellitustypes
•type 1insulin dependent (juvenile onset)
controlled by insulin injections
•type 2insulin independent (adult onset)
controlled by diet/lifestyle
diabetes mellitus
abnormally high blood [glucose](hyperglycemia)
so much glucose in the glomerular filtrate, that PCT can’t reabsorb it all…
(transport proteins are saturated)
… so some ends up in the urineglycosuriapolyuria
diabetes mellitus
health problems
much of the body thinks it is “starving”
diabetic retinopathydiabetic neuropathy risk of MI (3x-5x)
other vascular problems
other endocrine organs
intestinesgonadskidneys
adipose, thymus, heart
digestive hormonesreproductive hormonesEPO, renin
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