the pineal gland
THE ENDOCRINE SYSTEM the hypophysis (or pituitary)
the thyroid gland
HUMAN BODY
a collection of glands: exocrine glands
and endocrine glands.
ENDOCRINE GLAND
a gland whose secretions (called hormones)
are collected by the blood and reach the
tissues through the circulation.
Endocrine glands release hormones directly
into the bloodstream.
They are ductless
They use the bloodstream
the parathyroid
They secrete hormones
the endocrine part of the pancreas
the adrenal gland
HORMONES
the gonads (testicles or ovaries).
released by the thyroid, parathyroid, and
other glands, under the general direction of
the “Master” Pituitary gland.
Chemically, hormones are either:
Steroid or steroid-like hormones such as:
Sex hormones
Adrenal cortex hormones
Non-steroid hormones such as:
Amines
Proteins
Peptides
Glycoproteins
EXOCRINE GLAND
a gland whose secretions are released
PITUITARY GLAND
Lies at the base of the brain in the
sella turcica
Consists of two distinct portions:
Anterior pituitary (adenohypophysis)
Posterior pituitary (neurohypophysis)
The Master Gland”
Primary function is to control
other glands.
Produces many hormones.
Secretion is controlled by the
hypothalamus in the base of
the brain.
externally through ducts (into the skin,
intestinal lumen, mouth, etc.).
Exocrine glands release their secretions into
a duct that carries them out the body.
They have ducts
They deliver their products directly to a
specific site
THE MAIN ENDOCRINE GLANDS
OF THE HUMAN BODY
T4 (thyroxine)
T3 (triiodothyronine)
Calcitonin
lies in the anterior neck just below the
larynyx.
Two lobes, located on either side of the
trachea, connected by a narrow band of
The Pituitary Gland is divided into 2 areas, which
differ
structurally and functionally
each area has separate types of
hormone production
The two segments are:
tissue called the isthmus.
Posterior Pituitary: Sacs inside the gland contain colloid
produces oxytocin and antidiuretic Within the colloid are the thyroid hormones:
hormone (ADH) thyroxine (T4)
Anterior Pituitary: triiodothyronine (T3)
produces thyroid-stimulating When stimulated (by TSH or by cold),
hormone (TSH) these are released into the circulatory
growth hormone (GH) system and the metabolic rate.
adrenocorticotropin (ACTH) “C” cells within the thyroid produce the
follicle-stimulating hormone (FSH) hormone calcitonin.
luteinizing hormone (LH)
prolactin Calcitonin
when released, lowers the amount of
Posterior Pituitary calcium in the blood.
Oxytocin (the natural form of pitocin) hypothyroidism, or Myxedema.
stimulates gravid uterus Inadequate levels of thyroid hormones
causes “let down” of milk from the Increased thyroid hormone release
breast. causes hyperthyroidism, commonly
ADH (vasopressin) causes the kidney to called Graves’ disease.
retain water. Signs and symptoms:
insomnia, fatigue
tachycardia
THYROID GLAND
hypertension
The thyroid gland has two lateral lobes and
heat intolerance
lies just below the larynx
weight loss
It produces three hormones: Long term hyperthyroidism:
Exopthalmos
bulging of the eyeballs
Myxedema symptoms:
Facial bloating
weakness
cold intolerance
lethargy
altered mental status
oily skin and hair
PARATHYROID GLAND
The parathyroid glands are on the posterior
surface of the thyroid gland; Located on the
dorsal surface of the thyroid gland.
There are typically four parathyroid glands
It secretes one hormone:
PTH (parathyroid hormone or
parathormone)
small, pea-shaped glands, located in the
neck near the thyroid
regulate the level of calcium in the body
Hypocalcemia can result if parathyroid are
removed or destroyed.
ADRENAL GLAND This is why it is a dual functioning organ
2 small glands that sit atop both kidneys. as both an exocrine gland and endocrine
The adrenal glands are a pair of glands gland
composed of two sections. Three hormones are secreted from the islet
The cortex cells/ Islets of Langerhans
The medulla Alpha cells secrete glucagon
Each has 2 divisions, each with different o Alpha () cells release
functions. glucagon, essential for
Adrenal Medulla controlling blood glucose
secretes the catecholamine hormones levels.
norepinephrine and epinephrine o When blood glucose
(closely related to the sympathetic levels fall, cells the
component of the autonomic nervous amount of glucagon in the
system). blood .
o The surge of glucagon
Adrenal Cortex stimulates the liver to
secretes 3 classes of hormones, all steroid
hormones:
glucocorticoids
o accounts for 95% of adrenal cortex
hormone production
o the level of glucose in the blood
o Released in response to stress,
injury, or serious infection - like
the hormones from the adrenal
medulla.
Mineralocorticoids
o work to regulate the concentration
of potassium and sodium in the
body.
o Prolonged in adrenal cortex release glucose stores
hormone results in Cushing’s (from glycogen and
Disease. additional storage sites).
Signs & Symptoms of Cushing’s o Also, glucagon stimulates
Disease: the liver to manufacture
o in blood sugar levels glucose -
o unusual body fat distribution o gluconeogenesis.
o rapid mood swings Beta cells insulin
And - if there is an in o release insulin
mineralocorticoids as well (antagonistic to glucagon).
A serious electolyte imbalance will o Insulin the rate at which
occur due to the potassium excretion various body cells take up
by the kidney, which results in glucose. Thus, insulin
hypokalemia. lowers the blood glucose
Sodium can also be retained by the level.
kidney, resulting in hyponatremia. o Insulin is rapidly broken
Causes: down by the liver and
o dysrhythmias must be secreted
constantly.
Delta cells secrete somatostatin
o Produce somatostatin,
which inhibits both
glucagon and insulin.
Other Endocrine Glands
PINEAL GLAND
Secretes melatonin
o coma
o Death
o Removal of tumor.
androgenic hormones
PANCREAS
The pancreas has two major types of
secretory tissue
The pineal glands produce the hormone ADH levels increase due to slower break
melatonin down in liver and kidneys
Calcitonin levels decrease; increase risk of
THYMUS GLAND osteoporosis
Secretes thymosins PTH level changes contribute to risk of
Promotes development of certain osteoporosis
lymphocytes Insulin resistance may develop
Important in role of immunity Changes in melatonin secretion affect the
body clock
Thymosin production declines increasing
REPRODUCTIVE ORGANS
risk of infections
Ovaries produce estrogens and progesterone
Testes produce testosterone
Placenta produces estrogens, progesterone,
and gonadotropin
GONADS
The gonads are the organs responsible for
producing sex cells
The Ovaries in women
The testes in men
o The endocrine glands associated with human
reproduction.
o Female ovaries produce eggs
o Male gonads produce sperm
o Both have endocrine functions.
OVARIES
Located in the abdominal cavity adjacent to
the uterus.
Under the control of LH and FSH from the
anterior pituitary they manufacture
o estrogen
o progesterone
Estrogen and Progesterone
have several functions, including sexual
development and preparation of the uterus
for implantation of the egg.
Testes:
located in the scrotum
produce sperm for reproduction
manufacture testosterone -
promotes male growth and
masculinization
Controlled by anterior pituitary hormones
FSH and LH.
Stress and Its Effects
Survival depends on maintaining
homeostasis
Factors that change the internal
environment are potentially life threatening
Sensing such dangers directs nerve impulses
to the hypothalamus
This can trigger a loss of homeostasis
13.12: Lifespan Changes
Endocrine glands decrease in size
Muscular strength decreases as GH levels
decrease
