THE ENDOCRINE SYSTEM
The endocrine is a body control system. It affects bodily activities by releasing chemical
messages, hormones, into the blood stream. It contains 2 types of glands, the endocrine
and exocrine glands. The endocrine glands form what is generally referred to as a
system, yet the fact that they are not directly inter-connected seems to contradict this
classification. These glands occur through the body at various sites secreting special
products called hormones directly into the surrounding tissues. Hormones are like
chemical agents, which help to organize and control the function of various other glands
and activities such as growth, metabolism, menstruation and immune function.
Exocrine glands secrete their products into ducts. The ducts then carry the secretions
into body cavities or to the body's surface. They include sweat, sebaceous, mucous and
digestive glands.
Endocrine glands are ductless glands and secret their products directly into the blood.
They include the pituitary, thyroid, parathyroids, adrenal, and pineal glands as well as the
pancreas, ovaries, and testes.
Hormones are chemical substances that function to maintain the homeostasis (balance)
of the body by stimulating changes in the cells in body organs.
Pituitary gland regulates many body activities and is nicknamed the 'master gland'. It is
located at the base of the brain, in an area called the hypothalamus. It produces many
hormones the main one being the Human Growth Hormone (HGH), which causes growth
of cells and the body.
Thyroid gland is situated just below the larynx and has two lobes on either side of the
trachea. It is a shield shaped gland. The principal hormone it produces is called thyroxine.
Thyroxine controls metabolism by increasing the rate at which carbohydrates are burned
and proteins and fats are broken down. It also helps regulate growth.
Parathyroid glands are four small glands attached to the outer surface of the thyroid
gland. They release the parathyroid hormones (PTH). PTH control the homeostasis of
the blood, especially calcium and phosphate.
The adrenal glands are small, triangular shaped glands located just above each kidney.
They are divided into the outer adrenal cortex and the inner adrenal medulla. The
adrenal cortex secretes hormones called corticosteroids, which have many functions
including anti-inflammatory functions. The adrenal medulla secretes i) adrenalin and ii)
noradrenaline both of which affect the central nervous system.
The pineal gland is located in the brain. It secretes at least one hormone, melatonin,
which appears to affect the secretion of hormones by the ovaries. Its other functions are
somewhat obscure but has an effect on the sleeping cycle.
The pancreas is both an exocrine and endocrine gland. The endocrine portion consists
of clusters of cells called the Islets of Langerhans. It secrets insulin, a hormone which
controls the blood sugar level.
Endocrine System
Page 1 of 4
The gonads are the ovaries and the testes. The ovaries secrete oestrogens and
progesterone, and the testes secrete testosterone.
HYPO AND HYPER SECRETION - Hypersecretion is oversecretion while hyposecretion
is undersecretion of hormones. Each condition can cause many disorders.
Glands:
Pituitary gland
The root word is
pituita and the
combining form
is -pituitar-
Thyroid
The root word is
thyr and the
combining form
is thyr/o,
-thyroid-
Parathyroid
The root word is
parathyr and
the combining
form is
parathyr/o,
-parathyroidAdrenal
The root word is
adren and the
combining form
is adren/o
Pineal
Endocrine System
FSH,(follicle stimulating hormone) LH, (leutinising hormone)
HGH, (human growth hormone) ACTH (adrenocorticotrophic hormone),
TSH (thyroid stimulating hormone), ADH (anti-diuretic hormone)
Master Gland. Regulates growth, metabolism, kidneys and sex
Hypersecretion: (1) Gigantism and (2) Acromegaly (where the bones of
the face, hands and feet are enlarged)
Hyposecretion: Dwarfism and Acromicria
Hyposecretion of ADH leads to diabetes insipidus
Thyroxin Regulated by the pituitary gland - metabolic rate.
Hyperthyroidism or Grave’s disease characterised by an increased basal
metabolic rate and increased pulse, also exophthalmos which is the
distension of the eyeballs.
Thyrotoxicosis - syndrome due to excessive amounts of thyroid
hormones in the blood
Hypothyroidism or Goitre - enlargement of the thyroid gland which can
lead to the need for a thyroidectomy.
Myxoedema causes swelling of the face, limbs, and hands, slow
metabolism and mental dullness. Congenital myxoedema is called
cretinism
Parathyroid hormone - Calcium metabolism, regulates calcium for use in
bone growth, muscle tone, & nervous activity.
Hyperparathyroidism causes softening of the bone
Hypoparathyroidism leads to spasmodic twitching and contractions of
muscles which is called tetany.
Adrenaline, Cortisol, Regulated by the pituitary. Secretes steroid and
helps the body cope with stress. Regulates balance between salt and
water
Hypersecretion: Cushing’s syndrome (hypercortisolism) characterised by
protein loss, fatigue, osteoporosis, diabetes insipidus and oedema.
Hyposecretion: Addison’s disease (hypocortisolism) characterised by
weight loss, low blood sugar, low blood pressure, depression and salt
cravings.
Produces melatonin, a hormone which modulates wake/sleep patterns
and the gonads. It regulates both sleeping cycles and the hormonal
changes that usher in sexual maturity during adolescence.
Page 2 of 4
Pancreas
The root word is
pancreat and
the combining
form is
pancreat/o
Gonads
Hypothalamus
Thymus
Endocrine – insulin controls level of sugar in the blood
Exocrine – Pancreatic enzymes to aid in digestion
High insulin levels - hyperglycaemia. Diabetes Mellitus results in excess
sugar in the blood - Causes damage to blood vessels and organs kidneys and eyes.
Low insulin levels – hypoglycaemia - characterised by fainting and coma
Regulated by the pituitary. Sex glands, Ovaries - oestrogen and
progesterone. Testes - Testosterone
Regulates the autonomic nervous system - integration of endocrine and
nervous systems
Doubles in size at puberty, shrinks in an adult. Immunological role,
initiates antibody formation in the blood
Terms and word parts:
aden/o
adren/o
adrenocortic/o
andr/o
-crine
end/o
-globulin
glyc/o
-gyne
hormone
hyperhypoinsulin/o
kal/i
ket/o
-micria
natr/i
oestr/o
parathyroid/o
pituitar-plasia
progest/o
-ptosis
thyroid/o
-trophic
-tropic
Endocrine System
gland
adrenal gland
adrenal cortex
male
to secrete
within
protein
sugar
woman
a specific chemical that regulates other cells or organs
above, excessive
below, insufficient
insulin
potassium
ketones
condition of small size
sodium
oestrogen
parathyroid gland
pituitary
condition of growth/formation of (cells)
progesterone
falling / displacement / prolapse
thyroid gland
pertaining to nourishment
pertaining to affinity for / stimulating
Page 3 of 4
Abbreviations:
BSL
BSS
FBS
GTT
HRT
blood sugar level
blood sugar series
fasting blood sugar
glucose tolerance test
hormone replacement therapy
Diabetes:
Diabetes Type I
IDDM
Insulin Dependent - pancreas doesn't make enough insulin.
Formerly called Juvenile Onset Diabetes. Due to beta cell
destruction.
Diabetes Type II
NIDDM
Non-insulin dependent - pancreas makes enough insulin, but
the patient's cells do not use insulin properly. Formerly called
Mature Onset Diabetes
Activity:
Build a word which means:
1.
process of secreting above normal levels of thyroid hormone ______________
2.
enlarged adrenal gland
3.
condition of too little sodium in the blood ______________________________
4.
process of producing too much insulin ________________________________
5.
incision into the thyroid cartilage ____________________________________
_________________________________________
Find the meaning of the following words:
1.
thyroparathyroidectomy
_________________________________________
2.
pituicyte
_________________________________________
3.
hypernatraemia
_________________________________________
4.
androblastoma
_________________________________________
5.
adrenocorticohyperplasia _________________________________________
Endocrine System
Page 4 of 4