Transcript REGULATION cont. THE ENDOCRINE SYSTEM

REGULATION
THE ENDOCRINE SYSTEM
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Body System which
regulates:
overall metabolism
homeostasis
growth
reproduction
ENDOCRINE GLANDS
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Ductless organs that
secrete hormones
directly into the
bloodstream to be
transported to other
parts of the body
HORMONES
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Chemical messengers
that cause a change
in target tissues
activity
Examples:
Insulin (protein-type)
Testosterone (steroid)
Hormones
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Hyposecretion- a
deficiency of a
hormone
Hypersecretion- an
excess of a hormone
Target Tissues
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Tissue that is affected
by a particular
hormone
Different than the
secreting gland
DYNAMIC EQUILIBRIUM
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Steady State
Constant small
corrections that
normally occur to
keep an organism’s
internal environment
within limits needed
for survival (stable)
HOMEOSTASIS
Feedback Mechanism
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Cycle in which output of a system “feeds
back”
Either modifies or reinforces the action of
the system
Feedback responses can be simple or
complex
Positive Feedback
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Change in
environment prompts
a response
Response leads to
greater change and
greater response
Reinforces
Labor and childbirth is
an example
Negative Feedback
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Change prompts
signal which leads to
a decrease or stop of
original responseopposes
Most common
Keeps levels constant
Maintains
Homeostasis
FEEDBACK
Negative Feedback
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Examples:
Regulating human body temperature
Negative Feedback
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Regulates blood glucose levels
Sugar level high
neg feedback
low blood sugar
insulin product
decreases
Pancreas
Secretes
insulin
Blood sugar drops
Pituitary Gland
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Is sometimes called “The Master Gland”
because it controls the other endocrine
glands
It is located at the base of the brain
Pituitary Hormones
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Thyroid Stimulating Hormone (TSH)
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Causes the thyroid gland to release it’s
hormone (thyroxine)
Pituitary Hormones
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Follicle Stimulating
Hormone (FSH)
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Causes human egg
cells to develop in the
ovaries and influences
other reproductive
hormones
Pituitary Hormones
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Growth Hormone (GH)
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Causes bones to grow normally during
childhood
Pituitary Hormones
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Adrenocorticotropic Hormone (ACTH)
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Stimulates the production and release of
hormones from the adrenal glands
Thyroid Gland
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The thyroid gland is H shaped and is
located in the neck around the trachea
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It produces thyroxine that regulates the rate
of body metabolism and is necessary for
normal mental and physical development
Contains Iodine
Parathyroid glands
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The parathyroid glands are located within
the thyroid gland
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They produce the hormone parathormone
which controls the levels of calcium and
phosphorus
Adrenal glands
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The adrenal glands are
located at the top of the
kidneys and produce the
hormones adrenaline and
cortisol
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Cortisol regulates sugar
metabolism, water balance
and helps to maintain
blood pressure
Adrenaline increases sugar
levels in the blood,
increases heart and
breathing rates to get body
ready for “fight or flight”
Pancreas
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The pancreas has cells called the islets of langerhans
 These cells produce the hormones insulin and
glucagon
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Insulin lowers blood glucose levels by increasing the
movement of glucose into the body cells
Within the cells of the liver insulin promotes the
change of glucose to glycogen (a polysaccharide)
Pancreas
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Glucagon raises blood glucose levels by
promoting the change of glycogen in the
liver back to glucose
Gonads – Sex Glands
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The testes are located
in the male scrotum
and produce the
hormone testosterone
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Testosterone promotes
the development of
secondary sex
characteristics in
males (deep voice,
facial and body hair,
and the male body
form)
Gonads – Sex Glands
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The ovaries are located in
the lower abdomen of
females and produce the
hormones estrogen and
progesterone
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Estrogen stimulates the development of the
female reproductive system and the female
secondary sex characteristics (development of
breasts, broadening of hips and with
progesterone, regulation of the menstrual
cycle)
Malfunctions of the Endocrine
System
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Thyroid- Hyperthyroidism
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Hypersecretion of thyroxine = increased
metabolism, nervousness, irritability,
sleeplessness and weight loss
May produce a goiter, an enlargement of the
thyroid gland (which may be caused by lack
of iodine in the diet)
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ThyroidHypothyroidism
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Hyposecretion of
thyroxine in infancy
may cause cretinism
(child will be mentally
retarded and a dwarf)
In adults sluggishness
and weight gain due to
decrease in
metabolism
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Pituitary
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Hypersecretion of
GH in children
leads to gigantism
where the
individual is
abnormally tall
but in proportion
In adults
acromegaly –
large hands, feet
and facial features
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Pituitary
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Hyposecretion of GH leads to dwarfism where
the individual is small but normally
proportioned
Pancreas
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Hypersecretion of insulin can lead to diabetic
shock because blood glucose levels fall
dangerously low
Convulsions, unconsciousness and death may
result
Pancreas
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Hyposecretion of insulin causes diabetes
The glucose does not move into the cells and
the blood glucose level rises
High blood glucose levels can damage organs
and tissues
Insulin injections are given to control the blood
glucose levels