Transcript The Endocrine System

The Endocrine System
--the OTHER sensing and
response system
The Endocrine System
Controls:
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The Endocrine System
Controls:
• Reproduction
• Growth & development
• Homeostasis
• Metabolism
• Immune response
Definitions
• Gland
• Endocrine
• Hormone
Definitions
• Gland—an organ designed to secrete
• Endocrine—secreting inside the body
• Hormone—the secretion of an endocrine
gland
Endocrine vs Exocrine
Endocrine vs Exocrine
Exocrine glands have a duct
Endocrine glands do not
Endocrine glands secrete their
products into the bloodstream
For example:
• Exocrine glands include…
Gland
Duct leads to:
• Sweat glands
• Sebaceous glands
• Pancreas
• Mammary glands
For example:
• Exocrine glands include…
Gland
Duct leads to:
• Sweat glands
surface of skin
• Sebaceous glands
base of follicle
• Pancreas
small intestine
• Mammary glands
nipple
For example:
• Endocrine glands include…
Gland
Duct leads to:
• Anterior pituitary
• Parathyroids
• Adrenal Cortex
For example:
• Endocrine glands include…
Gland
Duct leads to:
• Anterior pituitary
--No duct-• Parathyroids
--No duct-• Adrenal Cortex
--No duct--
These glands secrete hormones
directly to the bloodstream
Negative feedback
• Homeostasis is maintained in the body by
negative feedback—
When anything changes, the response is
to undo that change
• The elements of the system are: stimulus,
sensor, effector and response.
In general:
Effector
Response
lowers it
If the stimulus
is too high
Sensor
Response
raises it
Effector
If the stimulus
is too low
Review
• Body temperature is maintained by a
negative feedback system.
--The sensor is in the hypothalamus.
--The effectors are blood vessels and sweat
glands in the skin.
For body temperature:
Blood vessels
dilate, sweat is
produced
Blood vessels
constrict,
sweat is not
produced
Skin
Hypothalamus
Skin
If the
temperature is
too high
If the
temperature is
too low
For blood sugar:
Insulin causes
body cells to
take in glucose
Pancreas
If the blood
glucose level is
too high
Pancreas
Glucagon
causes the
liver to release
glucose
If the blood
glucose level is
too low
Pancreas
For blood sugar:
• The sensor and effector cells are in the
pancreas
• The pancreas releases insulin into the
bloodstream to lower blood sugar
or
• The pancreas releases glucagon into the
bloodstream to raise blood sugar
Types of hormones
Types of hormones
• Peptide hormones
• Steroid hormones
Types of hormones
• Peptide hormones —proteins and related
molecules
• Steroid hormones —lipid molecules
Types of hormones
• Peptide hormones —proteins and related
molecules
Receptors are on target cell surfaces
• Steroid hormones —lipid molecules
Receptors are in target cell nuclei
Nonsteroid
hormone (first
messenger)
Nonsteroid
hormone (first
messenger)
Cytoplasm
Enzyme
ATP
cAMP
Receptor
protein
Plasma
membrane
of target cell
Second
messenger
Effect on cellular function,
such as glycogen
breakdown
Figure 9.1b
Second-Messenger System
(Non-steroid Hormone Action)
A non-steroid hormone will:
• Bind to a membrane receptor (without
entering cell)
• (Series of reactions)  activates an enzyme
• Enzyme catalyzes a reaction to form the
second-messenger (us. cAMP)
• Second-messenger molecule a specific
response
Steroid
hormone
Steroid
hormone
Nucleus
Receptor
protein
Cytoplasm
Hormone-receptor
complex
DNA
mRNA
New
protein
Plasma
membrane
of target
cell
Figure 9.1a
Direct Gene Activation
(Steroid Hormone Action)
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A steroid hormone will:
Diffuse through membrane of target cells
Enter the nucleus
Bind to a specific protein in the nucleus
Bind to specific sites on the cell’s DNA
Activate genes  synthesis of new
proteins
Endocrine Glands
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Hypothalamus
Anterior pituitary
Posterior pituitary
Thyroid
Parathyroids
Adrenal Medulla
Adrenal Cortex
Pancreas
Location of Endocrine Glands
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Hypothalamus
Anterior pituitary
Posterior pituitary
Thyroid
Parathyroids
Adrenal Medulla
Adrenal Cortex
Pancreas
in the brain
base of the brain
base of the brain
front of the neck
sides of the neck
above the kidney
above the kidney
behind stomach
Location
of Major
Endrocrine
Organs
Figure 9.3
Hormones of each Endocrine
Gland
• Hypothalamus
• Anterior pituitary
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Posterior pituitary
Thyroid
Parathyroids
Adrenal Medulla
Adrenal Cortex
Pancreas
RF’s
ACTH, FSH, GH ,LH,
PRL,TSH
ADH, OT
Cal,T3-4
PTH
EPI, NE
Cor, Ald
Ins, Glu, SS
For example: Blood sugar
Insulin causes
body cells to
take in glucose
Pancreas
If the blood
glucose level is
too high
Pancreas
Glucagon
causes the
liver to release
glucose
If the blood
glucose level is
too low
Pancreas
For example: Metabolism
T3-4Less
RfLess
TSHless T3-4
Ant. Pit. &
Thyroid
If the
metabolism level
is too high
Hypothalamus
RFanterior
pituitary. TSH
causes the
thyroid to
make T3-4 to
increase
metabolism
If the metabolism
level is too low
Ant. Pit. &
Thyroid
Hypothalamus
• --Part of the brain
• --Closely associated with pituitary (blood
vessel and nerve connection)
• --Makes releasing factors (RF’s) to affect
pituitary
Hormones of the Anterior
Pituitary
Figure 9.4
Pituitary
• --Part of the brain, sits in the sella turcica
• --Controlled by hypothalamus, controls
other glands
• --Has two (very different) parts- anterior
and posterior
Anterior Pituitary
• --Controls other glands
--ACTHadrenal cortex
--PRLmammary glands
--FSHovaries
--LHovaries
• --GH is the only hormone with wider
effects—causes growth of bone and
muscle
For the reproductive system
Ant. Pit
Progesterone
and estrogen
stimulate the
hypothalamus
to make RFs
FSH and LH
stimulate the
ovary
Ovaries
Posterior pituitary
• --Direct nervous control from
hypothalamus
• (Hormones are made in hypothalamus,
stored for release)
--OT-causes smooth muscle contraction in
childbirth, nursing, erections, etc.
--ADH—(next slide)
For water
Shuts off
ADH—kidneys
reabsorb less
water
ADH causes
kidneys to reabsorb more
water
Hyp/Post.Pit
Too much
water in the
blood
Hypothalamus
Too little water
in the blood
Post. Pit
Thyroid
• --Controlled by TSH (from ant. pit.)
• Makes
--T3-4— triiodothyronine and thyroxine,
--stimulates most cells to use energy
and make proteins (higher metabolism).
--Contain iodine atoms.
--Calcitonin (not quite the next slide)
Thyroid Gland
Figure 9.7a
For metabolism:
T3-4Less Rf
Less TSH
less T3-4
Ant. Pit. &
Thyroid
If the
metabolism level
is too high
Hypothalamus
RFanterior
pituitary. TSH
causes the
thyroid to
make T3-4 to
increase
metabolism
If the metabolism
level is too low
Ant. Pit. &
Thyroid
For calcium
Calcitonin causes
bones to store
calcium
Parathyroid
hormone causes
bones to release
calcium, kidneys
and intestines to
absorb Ca++
Thyroid
Thyroid/
Parathyroid
Parathyroid
If the blood
calcium level is
too high
If the blood
calcium level is
too low
Parathyroids
• --Four of them! Near the thyroid
• --Makes PTH only (previous slide)—
(antagonistic to calcitonin)
• —affects bones, kidneys and intestines to
increase Ca++ levels
Pancreas
• --Endocrine (islets of Langerhans) and
exocrine (in digestive system)
• Makes—
--glucagon in a (alpha) cells (next slide)
--insulin in b (beta) cells (next slide)
--somatostatin in d (delta) cells
--antagonist to GH
For Blood Sugar:
Insulin causes
body cells to
take in glucose
Pancreas
If the blood
glucose level is
too high
Pancreas
Glucagon
causes the
liver to release
glucose
If the blood
glucose level is
too low
Pancreas
Adrenal glands
• Has two parts– the adrenal cortex
(outside) and adrenal medulla (inside)
--Cortex and gonads make the only steroid
hormones
--Medulla makes neurotransmitters as
hormones
Adrenal cortex
• Outside layer
• Stimulated by ACTH from ant. pit.
• Makes steroids
--aldosterone—causes kidneys to
reabsorb sodium and water
--cortisol—causes tissues to increase
blood nutrients, allows damaged tissues to
heal.
Hormones of the Adrenal Cortex
Figure 9.11
Adrenal Medulla
• Center of the gland
• Derived from nerve tissue, directly
controlled by sympathetic NS
• Hormones are used in NS as
neurotransmitters
--norepinephrine-(aka. adrenalin)
fight-or-flight
--epinephrine (similar to norepinephrine)
For emergency use only
Norepinephrine
(adrenalin)
stimulates
fight-or-flight
responses
Hypothalamus
Adrenal medulla
Direct
sympathetic
nerve
impulses!
Which hormones and glands are
stimulated by:
1) Other hormones and glands?
2) Blood chemistry?
3) Neurons?
Hormonal Stimuli of Endocrine
Glands
Most common
Endocrine glands
are activated by
other hormones
Ex:
Anterior
pituitary
hormones
Figure 9.2a
Humoral Stimuli of Endocrine
Glands
Changing blood
levels of certain
ions stimulate
hormone release
Ex:
Humoral indicates
various body
fluids such as
blood and bile
Calcitonin
Insulin
Parathyroid
hormone
Figure 9.2b
Neural Stimuli of Endocrine
Glands
Nerve impulses
stimulate hormone
release
Most are under the
control of the
sympathetic
nervous system
Ex:
norepinephrine
epinephrine by
adrenal medulla
Figure 9.2c
Major Endocrine Organs
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Pituitary gland
Thyroid gland
Parathyroid glands
Adrenal glands
Pineal gland
Thymus gland
Pancreas
Gonads (Ovaries and Testes)
Hypothalamus