What is the endocrine system?
Chapter 10
Regulating Body Function
 Working closely with
your nervous system is
the endocrine system,
a chemical
communication system
that regulate many body
functions.
Exocrine vs Endocrine
Exocrine Glands
Endocrine
 secrete their products into
 Ductless glands.
ducts that empty onto a
surface or into a cavity.
 Ex: Sweat glands and salivary
glands
 They secrete chemicals
(hormones) into
intracellular spaces.
Regulating Body Function
 A gland is a group of cells, or an organ, that secretes a
chemical substance.
 The endocrine glands secrete chemicals called
hormones directly into the bloodstream.
 The blood carries the hormones directly to the tissue
they are targeted to affect.
 Some hormones are produced continuously, while
others are produced only at certain times.
Regulation of
Hormone Secretion
Negative Feedback
Positive Feedback
 Homeostatic control
 Amplifies changes rather
mechanism that reverses
what is happening in the
body
 More common than positive
feedback.
 Ex: Insulin, Body
Temperature, Blood Pressure
than reverses them.
 Ex: Labor – amplified
contractions.
Mechanisms of Hormone
Action
Nonsteroid Hormones
Steroid Hormones
 Protein
 Lipid-soluble
 Second messenger
 Can pass through cell
mechanism:
 nonsteroid hormones serve
as 1st messenger between
gland and cells;
 Another molecule will then
act as a 2nd messenger
providing communication
within the target cell
membrane of target cell
 Bind with receptors on the
nucleus and act on DNA
Endocrine System
But first….
Pituitary
 The pituitary gland at the base of the brain is a gland
that signals other endocrine glands to produce
hormones when needed.
 It is also known as the “Master Gland” and is located at
the base of the brain.
 It secretes several hormones.
 These regulate the thyroid gland, adrenal glands, and
kidneys- plus your growth and development. It
produces growth hormones.
Pituitary
Anterior
Posterior
 TSH
 ADH
 Anti-duretic
 Oxytocin
 Thyroid stimulating
 ACTH
 Adrenocorticotropic
 FSH
 Follicle-stimulating
 LH
 luteinizing
 GH
 growth
 Prolactin
Hypothalamus
 The hypothalamus is
a vital neuroendocrine
and autonomic control
center beneath the
thalamus.
 Secretes:
 Releasing hormones
 Anterior pituitary
 Inhibiting hormones
 Posterior pituitary
Parathyroid
 The parathyroid glands
direct the distribution of
certain minerals in your
body.
 Increase Ca+ in blood
 Secretes
 Parathyroid hormone or
PTH
Calcium Reabsorption
Pancreas
 The pancreas is part of two body systems- the
digestive system and the endocrine system.
 It is located behind the stomach and supplies the small
intestine with digestive juice.
 It produces insulin and contains small clusters of cells
called the islets of Langerhans, which control blood
sugar levels.
 It produces insulin.
Pancreas
How Insulin Works
Thymus
 The thymus gland is
located in the
mediastinum.
 It is a vital part of the
body’s immune system.
 Produces thymosin
Pineal Gland
 The pineal gland is located in the third ventricle of
the brain.
 It produces melantonin.
Thyroid
 The thyroid gland is
located where the larynx
and trachea meet.
 It regulates the chemical
reactions of nutrients in
the cells.
 It produces thyroxine.
Adrenal
 The adrenal glands are located on your kidneys.
 They secrete hormones that help the body maintain its
levels of sodium and water, aid the digestive process,
and control your body’s response to emergencies.
 It produces adrenaline.
Adrenal
The Body’s Response to Stress
 When your brain
recognizes a stressful
situation, your adrenal
glands responds by
releasing the hormone
adrenaline. This
hormone prepares your
body to respond to
stress.
Reproductive
 During adolescence, the endocrine system plays an
important role in growth and development.
Ovaries
 The ovaries are the
female reproductive
glands.
 They control the
development of
secondary sex
characteristics during
adolescence.
 It produces estrogen.
Placenta
 The placenta anchors the developing fetus to the
uterus and provides a “bridge” for the the exchange of
nutrients and waste products between the mother and
the developing baby.
Testes
 The testes are the male
reproductive glands.
 They control the
development of
secondary sex
characteristics during
adolescence.
 It produces
testosterone.
Endocrine System
Secretions of Hormones
Hyposecretion
Hypersecretion
 Production of too little
 Production of too much
hormone by a diseased gland
hormone by a diseased gland
Diabetes
 Diabetes mellitus is a disease that may be caused by
inadequate insulin production by the pancreas.
 Symptoms include:
 lack of energy
 weight loss
 extreme thirst
 frequent urination
THYROID
HYPOTHRYOIDISM
HYPERTHYROIDISM
 Underactive thyroid gland
 Overactive thyroid gland
can cause a dull facial
expression, hoarse voice,
facial puffiness, coarse, dry
skin and hair, and weight
gain.
 Goiter- caused by low dietary
iodine intake
 Cretinsim- when
hyposecretion occurs in
infants/toddlers
produces symptoms that may
include protrusion of
eyeballs, warm, moist skin,
trembling hands,
nervousness, increased
sweating, disturbed sleep,
and weight loss.
Growth Hormone
hyposecretion
 Dwarfisim
hypersecretion
 Gigantism
 Acromegaly results when GH
is secreted too much after
adolescents.
Parathyroid
 Parathyroid hormone (PTH) and vitamin D help
manage calcium balance in the body
 Calcium is important to many body functions,
including:
 Bone formation
 Hormone release
 Muscle contraction
 Nerve and brain function
Parathyroid and Nerve Cells
Parathyroid
hypersecretion
hyposecretion
 Results in hypercalcemia
 Results in hypocalcemia
 Causes several abdominal,
 Symptoms include:
 Petechiae (red spots on skin)
 Strong muscle contractions
of the hand (cramping)
 Life threatening
 ECG changes
muscle, kidney and
psychological symptoms