Endocrine System
By:Sarah
Shelby&
Sierra
HELP
FUL P
REFIX
ES
AN
D
SU
FFIXES
-crin (to secrete)dieuret-(to pass urine)endo-(within)exo-(outside)Hyper-(above)Hypo-(below)Para-(beside)Toc-(birth)
Sarah
Function of the System
Endocrine Function
Helps regulate conditions within the body to maintain homeostasis
Secretes hormones in the body’s internal environment
Works with the nervous system so that different parts of the body can communicate with each other and adjust to changing incoming signals
Exocrine Function Secrete substances
outside the body through tubes or ducts; leading to the surface
En
docrin
e v
s. E
xocrin
e
endocrin
eexo
crine
Secrete within the body EX: pituitary gland
Secrete to the outside of the body EX: sweat gland
HORMONES
Hormones are substance(s) that are secreted by endocrine glands and transported into the blood
Hormones influence their target cells during stimulation
A hormone alters the metabolism of the target cells
*Paracrine: secretions affect only neighboring cells
*Autocrine: secretions affect only secreting cell
1
Control of Hormone Secretion
Hypothalamus regulates anterior pituitary gland’s release of hormones that stimulate other endocrine glands to secrete hormones.
Hypothalamus receives information about the internal environment from neural connections and cerebrospinal fluid
Nervous system stimulates glands directly
A group of glands responds directly to changes in the composition of the internal environment
2
Gen
era
l ch
ara
cte
ristic
s
Only target cells can respond to a hormone, they have a specific receptor that other
cells lack such as proteins or glycoprotein (these can bind with a hormone)
Endocrine glands and hormones
Endocrine and nervous system “oversee” the cell- to-cell communication through chemical signals that bind receptors to molecules
Help maintain metabolic processes
Control rate of reactions Help transport substances
across membranes Helps with water balance Helps with electrolyte balance
Steroids and Nonsteroids
Sierra
MOST HORMONES ARE STEROIDS OR
STEROID-LIKE SUBSTANCES WHICH
ARE SYNTHESIZED FROM
CHOLESTEROLAMINES
PEPTIDESPROTEINS
OR GLYCOPROTEIN WHICH IS
SYNTHESIZED FROM AMINO ACIDS.
Hormones can produce change in the target cell, even at low concentrations.
Steroids are carried through the bloodstream and are weakly bound to plasma proteins, so they can be efficiently released to their target cells.
3
Steroid hormones are insoluble in water but soluble in lipids
When a steroid hormone enters a target cell:1. The steroid hormone diffuses through the cell
membrane2. Then binds to a specific protein molecule-the
receptor for the hormone3. The resulting hormone-receptor complex binds in
the nucleus to particular regions of the target cell’s DNA and copies genes into the mRNA molecules
4. mRNA molecules leave the nucleus and enter cytoplasm
5. mRNA molecules and the ribosome direct the synthesis of specific proteins
NONSTEROID HORMONES
INCLUDEAMINES
PEPTIDESAND PROTEINS
WHICH USUALLY BIND RECEPTORS TO TARGET CELL
MEMBRANES
The receptors are protein molecules that have a binding and activity siteMessages are sent to the target cell by joining the binding site of it’s receptor (hormones sending the message)This stimulates the receptor’s activity site to interact with other membrane proteins
Receptor binding can alter functions of enzymes or
membrane transport mechanisms, which changes
concentration of other cellular components
Nonsteroid hormones
The hormone
triggerin
g this
is
First messenger
Nonsteroid hormones
Biochemicals in cells that
produce changes in response to
hormone building
Is called Second messenger
The process of chemical
communication from the outside to the inside of the cell
Is calledSignal
transduction
The second messenger associated with one group
of hormones is cyclic adenosine monophosphate
(cyclic AMP)
It works like this
Hormone binds to
its receptor
Resulting hormone-receptor activates
a G protein
G protein activates a membrane protein called adenylate cyclase
Adenylate cyclase catalyses the
circulation of ATP in cytoplasm into
cAMP
cAMP activates protein kinases enzymes that
transfer phosphate groups from ATP to
their substrate molecules(specific
proteins)
4
prostaglandins
Group of biochemicals that regulate cells
Lipids from a fatty acid in cell membranes called arachidonic acid
Usually only affect the organs where they are produced
Influence movements of sodium ions and water molecules in the kidneys
Helps regulate blood pressure
Produced in many cells
5
NEG
ATIV
E FE
ED
BA
CK
SYS
TEM
Hormone level rises in the blood, the hormone does its effect.
The negative feedback inhibits the system and the hormone secretion decreases.
As the hormone level decreases, the effects of the hormone stop.
When inhibition of the system is lifted, secretion of the hormone takes place once again.
Negative feedback systems keeps hormone levels in the bloodstream relatively stable.6
Major endocrine glands!!!!
Shelby
PIT
UITA
RY G
LAN
D
Attached to the base of the brain and has an anterior and posterior lobe.
Releases hormones from the hypothalamus, which controls the secretions of the anterior lobe.
Posterior lobe releases hormones into the bloodstream in response to nerve impulses from hypothalamus.
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Anterior Pituitary hormones
Growth hormone(GH): stimulates body cells to grow and reproduce, and speeds up rate at which cells use carbohydrates and fats
Prolactin(PRL): promotes milk production following the birth of an infant
Thyroid-stimulating hormone(TSH): controls secretion of hormones from thyroid gland
Thyrotropin-releasing hormone(TRH): from the hypothalamus regulates release of TSH
Adrenocorticotropic hormone (ACTH): controls secretion of hormones from adrenal cortex
Corticotropin-releasing hormone (CRH): regulates ACTH from the hypothalamus, stress can also increase it’s release
Follicle-stimulating hormone (FSH): gonadotropins affecting male and female gonads
Luteinizing hormone (LH): gonadotropins affecting male and female gonads
8
Posterior Pituitary Hormones
Neurons in the hypothalamus produce antidiuretic hormone and oxytocin
ADH causes kidneys to conserve water Hypothalamus regulates ADH secretion
based on the amount of water in body fluids Oxytocin plays a role in childbirth by
contracting muscles from uterine wall, and forcing milk into ducts from milk glands
Stretching of the uterus in later stages of pregnancy stimulates the release of oxytocin
9
Thyroid Gland
Located below the larynx and consists of
2 lobes
Thyroxin tetraiodothyronin
e
Thyroxin triiodothyronin
e
Cells release energy from carbohydrates,
enhance protein synthesis, and
stimulate breakdown of lipids
These 2 increase the rate at whichThese hormones are
essential for growth
and development
Hypothalamus and pituitary gland control
release of these
10
Thyroid continued…
Extrafollicular cells of thyroid secrete calcitonin
This lowers blood levels of calcium and phosphate ions when they
are too high
Calcitonin increases the rate at
which calcium is stored in
bones and excreted by urine
Calcitonin secretion is regulated by
negative feedback involving blood
concentrations of calcium
Parathyroid GlandLocated on
posterior end of thyroid
Parathyroid hormone(PTH) increases blood
calcium ion concentration and
decreases phosphate ion concentrationPTH stimulates
bone reabsorption by
osteoclasts, releasing
calcium into blood
PTH influences kidneys to conserve calcium
A negative feedback mechanism involving blood
calcium levels regulates release of PTH
*Calcitonin and PTH exert opposite
effects in regulating calcium ion levels in
blood
11
Adrenal glands
Adrenal medulla: secretes epinephrine and norepinephrine into the bloodstream(used in times of “fight or flight”) Adrenal cortex: produces over 30 steroidso Aldosterone: (mineralocorticoid) causes kidneys to
conserve sodium ions and thus water, and excrete potassium ions
o Cortisol: (glucocorticoid) influences metabolism of glucose, protein, and fat in response to conditions that stress the body
o Adrenal sex hormones: released by the gonads and may stimulate early development of reproductive organs
12
PANCREAS: SECRETES
HORMONES AS AN
ENDOCRINE GLAND, AND
DIGESTIVE JUICES TO
DIGESTIVE TRACT AS AN
EXOCRINE GLAND
Posterior to stomach
Has 2 cell types:Alpha cells: secrete glucagon-glucagon increases the blood levels of glucose by stimulating the breakdown of glycogen and conversion of noncarbohydrates into glucose
Beta cells: secrete insulin-insulin decreases the blood levels of glucose by stimulating the liver to form glycogen, increasing protein synthesis, and stimulating adipose cells to store fat
*insulin and glucagon coordinate to maintain a relatively stable blood glucose concentration
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Other Endocrine GlandsPineal gland: lies near the
upper portion of the thalamus, and secretes
melatonin which is involved in regulation of circadian
rhythms-also linked to the onset of
puberty
Thymus gland: lies between lungs and sternum, secretes
thymosins that affect production of T lymphocytes
ovaries produce estrogen Placenta produces estrogen, progesterone,
and gonadotropin Testes produce testosteroneProduces
atrial natriuretic peptide
Kidney produces
erythropoietin
All pictures from BingAll info from the anatomy book