• Overview of the Endocrine System
• Endocrine Organs
• Pituitary Gland
• Pineal Gland
• Thyroid gland
• Parathyroid glands
Endocrine glands are glands of
the endocrine system that secrete their
products, hormones, directly into the blood
rather than through a duct.
• The foundations of the endocrine system are
the hormones and glands.
Overview of the Endocrine System
• System of ductless glands that secrete
–Hormones are “messenger molecules”
–Circulate in the blood
–Act on distant target cells
–Target cells respond to the hormones for
which they have receptors
–The effects are dependent on the
programmed response of the target cells
–Hormones are just molecular triggers
• Pituitary Gland
– A marble-sized gland at the base of the brain
– Controlled by the hypothalamus or other neural
mechanisms and therefore the middle man.
– Exercise appears to be a strong stimulant to the
hypothalamus for the release of all anterior
• Posterior Lobe:
Antidiuretic hormone(ADH): Stimulates
reabsorption of water from kidney tubules
Oxytocin: Stimulates utrine contraction and
Brest contraction for milk release.
Production of breast milk .
Human Growth hormone (HGH)
Thyroid stimulating hormones (TSH)
Stimulates the thyroid to release thyroxin.
Stimulates the adrenal cortex to produce:
mineral corticoids,cortisol ,glucocorticoids,androgens.
Luteinizing hormone (LH)
Brings about ovulation and maintains the
Follicle-stimulating hormone (FSH)
Stimulates follicle growth and ovarian
estrogen production; stimulates sperm
production and androgen-binding protein.
Secondary sexual characteristics
Interstitial Cell Stimulating hormones(ICSH)
Works on the somniferous tubules in the testes –
to produce sperm – which take 21 days to
• Pineal Gland
A pea-sized mass of nerve tissue attached by a
stalk to the posterior wall of the third ventricle
of the brain, deep between the cerebral
hemispheres at the back of the skull.
A hormone produced by the pineal gland in
darkness but not in bright light.
o Informing the brain about night and day,
o Also regulate the sleep cycle.
• Thyroid Gland
The thyroid gland is a very vascular organ
that is located in the neck. It consists of two
lobes, one on each side of the trachea, just
below the larynx or voice box.
– Secretes two hormones
• Regulates metabolism
• increases protein synthesis
• promotes glycolysis, gluconeogenesis, glucose
• Parathyroid Gland
Four small masses of epithelial tissue are
embedded in the connective tissue capsule on
the posterior surface of the thyroid glands.
Secrete Parathyroid hormone
Associated with the growth of muscle and
Distribution of calcium and phosphate in the
• Adrenal Gland
The adrenal gland is paired that located near
the upper portion of each kidney. Each gland
is divided into an outer cortex and an inner
Situated directly at the top of each kidney and
stimulated by the sympathetic nervous system,
Epinephrine (fight or flight response)
Increase H.R. and B.P.
Increase metabolic rate
Located slightly behind the stomach
Insulin: reduces blood glucose
– Facilitates glucose transport into the cells
– Inhibits gluconeogenesis
increases blood glucose
The thymus gland is located across the trachea &
bronchi in the upper thorax in the root of the neck,
above and in front of the heart. The thymus is
enclosed in a capsule and divided internally by cross-
walls into many lobules.
Activates the immune system by activating the
• The Gonads
– Interstitial cells secrete androgens
– Primary androgen is testosterone
• Maintains secondary sex characteristics
• Helps promote sperm formation
– Androgens secreted by thecal follicle
• Directly converted to estrogens by follicular granulose cells
– Granulose cells also produce progesterone
– Corpus luteum also secretes estrogen and progesterone
The hypothalamus is a collection of specialized
cells that is located in the lower central part of the
brain, is the main link between the endocrine and
nervous systems. Nerve cells in the hypothalamus
control the pituitary gland by producing chemicals
that either stimulate or suppress hormone secretions
from the pituitary.