What is the Endocrine System? A system of glands, each of which
secretes a type of hormone directly into the bloodstream to
regulate the body. Hormones released directly into the blood are
referred to as endocrine hormones.
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Homeostasis NS & ES These two systems actually work
together to maintain homeostasis! Like the Nervous System, the
Endocrine System communicates with parts of the body. Instead of
transmitting messages along neurons, hormones are released to bring
about change/ body responses.
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NS & ES Homeostasis Both are important chemical control
systems that enable the body to communicate to various body parts.
The nervous system enables the body to adjust quickly to changes in
the environment. The endocrine system is designed to maintain
control over a longer duration.
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Glands A gland is an organ. There are many glands found in the
human body. Each synthesize (make) and release substances. Glands
can synthesis chemicals called hormones or substances such as
breast milk and sweat. Endocrine Glands secrete hormones into the
bloodstream. Some glands produce a number of different
hormones.such as the Pituitary Gland!
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What are Hormones? Hormones are chemical substances that carry
a message and activate change in another part of the body. Target
Hormones Hormones that can only be used by specific body organs.
The organs they go to are known as target organs. Follicle
Stimulating Hormone (FSH), Parathyroid Hormone Nontarget Hormones
Hormones that affect many cells throughout the body Examples:
Growth Hormone, Insulin, Epinephrine
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hypothalamus pituitary gland
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Endocrine Glands - Pituitary Often referred to as the master
gland because it controls when other glands release their hormones.
Small sac-like structure composed of two lobes: a posterior lobe
and anterior lobe. Connected to the hypothalamus by a stalk of
nerve fibers. Produces and stores hormones In particular, stores
hormones made by the hypothalamus
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Endocrine Gland - Hypothalamus The area of the brain associated
with homeostasis Found above the pituitary gland, and connected by
nerves Together with the pituitary, functions as a control centre,
coordinating the actions of the endocrine and nervous systems
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Hypothalamus Hormones Secrete two hormones: oxytocin and
antidiuretic hormone Hormones produced in the hypothalamus move to
the pituitary gland via nerves and bloodstream where they are
used/stored.
Endocrine Gland - Thyroid Is located in the neck just below the
larynx and in front of the trachea. One of the largest endocrine
glands. The thyroid gland makes various thyroid hormones, each with
their own roles. Thyroxine regulates the rate of metabolism in the
body The pituitary gland tells the thyroid when to release its
hormones.
Endocrine Gland- Adrenal There is one adrenal gland sitting on
top of each kidney. Mainly responsible for releasing hormones in
response to stress. Adrenaline Epinephrine
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Initiation of Fight or Flight Response Initiation of Physiologi
c Cascade Heart Rate Alertness O 2 to muscles, not digestion
Sensory Perception (Ears, Eyes, Nose, Touch, Taste) Internal
Signals (Thoughts, Emotions, Physical) DANGER! Brain Registers
DANGER! Prepared to Fight or Flee for Safety & Protectio n
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Anxiety Initiation of Physiologi c Cascade Heart Rate Alertness
O 2 to muscles, not digestion Sensory Perception (Ears, Eyes, Nose,
Touch, Taste) Internal Signals (Thoughts, Emotions, Physical) Brain
Registers DANGER! No Danger Anxiety
Endocrine Glands: Pancreas The hormones secreted by the
pancreas mainly control the sugar levels in the body. Glucagon help
to raise blood sugar levels Insulin help to lower blood sugar
levels
Endocrine Glands: Gonads Ovaries Produce egg cells and release
female sex hormones (sex steroids). Estrogen and Progesterone, also
produces small amounts of testosterone Testes Produce sperm cells
and release male sex hormones (sex steroids) Testosterone
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Negative Feedback & Hormones Is a type of control system
that regulates hormone production Works similar to a thermostat on
your furnace When the desired change is detected, the original
action is inhibited
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Examples: Steroid & Protein Hormones Both are target
Hormones Steroid Hormones Made from cholesterol Male and female sex
hormones are steroid hormones There are other steroid hormones too!
Protein Hormones Contain chains of amino acids Include Insulin and
Growth Hormone
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Action of Steroid Hormones Hormone diffuses through cell
membrane of target cell Hormone combines with receptor molecule
They move into the nucleus and attach to DNA DNA activates a gene
to produce a specific protein
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Action of Steroid Hormones
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Action of Protein Hormones Hormone attaches to receptor on cell
membrane of target cell This causes cyclic AMP to be formed which
acts as a messenger within the cell Cyclic AMP activates enzymes in
the cytoplasm which creates the desired hormonal effect