1. The Endocrine System
Glands and Hormones
By: Ashley Moran

2. Overview

Second messenger system of the body

Uses chemical messages (hormones)
that are released into the blood

Hormones control several major
processes
- Reproduction
- Growth and development
- Mobilization of body defenses
- Maintenance of much of homeostasis
- Regulation of metabolism

3. Overview

Secretion of most hormones is regulated
by a negative feedback system

The number of receptors for a specific
hormone can be altered to meet the body’s
demand

4. Hormone Overview

Hormones are produced by specialized
cells

Cells secrete hormones into extracellular
fluids

Blood transfers hormones to target sites

These hormones regulate the activity of
other cells

5. Chemical Classification
of Hormones
Steroid Hormones:

Lipid soluble

Diffuse through cell membranes

Enter the nucleus

Bind to a specific protein within the nucleus

Bind to specific sites on the cell’s DNA

Activate genes that result in synthesis of new
proteins

6. Chemical Classification
of Hormones
Nonsteroid Hormones:

Hormone binds to a membrane receptor

Hormone does not enter the cell

Sets off a series of reactions that activates
an enzyme

Catalyzes a reaction that produces a second
messenger molecule

Oversees additional intracellular changes to
promote a specific response

7. Negative Feedback System

Negative feedback is the primary
mechanism through which your endocrine
system maintains homeostasis

Secretion of a specific hormone s turned on
or off by specific physiological changes
(similar to a thermostat)

EXAMPLE: plasma glucose levels and
insulin response

8. Location of Endocrine Organs

9. Pineal Gland

Small pine cone shaped gland that
is part of the thalamus region of the
brain.

Glands secrete melatonin, a
hormone that plays a role in
regulating the body's circadian
rhythm.

10. Hypothalamus

In brain just superior to pituitary

Made of modified nervous tissue

Secretes hormones that are stored
in posterior pituitary

Stimulates pituitary

11. Pituitary gland

“Master gland” of body

Located in the depression of sphenoid bone

Produces many hormones that affect other glands:
− Thyroid stimulating hormone
− Somatotropin- growth hormone
− Lutenizing (LH)- causes ovulation
− ICSH- causes testes to secrete testosterone
− Melanocyte stimulating- distribution of melanin in skin
− ADH- antidiuretic hormone

Secretion is controlled by the hypothalamus in the base
of the brain

12. Thyroid

Found at the base of the throat

Consists of two lobes and a connecting
isthmus

Produces two hormones
− Thyroid hormone
− Calcitonin

13. Thyroid Hormone

Within the colloid are the thyroid
hormones
− Thyroxine (T4) – secreted by thyroid
follicles
− Triiodothyronine (T3) – conversion of
T4 at target tissues
* When stimulated (by TSH or by cold),
these are released into the circulatory
system and ↑ the metabolic rate.

“C” cells within the thyroid produce the
hormone calcitonin.

14. Parathyroid Glands

Tiny masses on the posterior of the
thyroid

Secrete parathyroid hormone:
− Stimulates osterclasts to remove
calcium from bone
− Stimulates the kidneys and intestine to
absorb more calcium
− Raise calcium levels in the blood

15. Thymus

Located on superior surface of the
heart

Thymosin – controls production and
maturation of lymphocytes

Reaches maximum size during
puberty, then shrinks making elderly
people more susceptible to disease

16. Adrenal Glands

Located just above the kidneys

Secretes many hormones

Epinephrine

Norepinephrine

Many steroid hormones, inc estrogen
and androgens.

The Adrenal Medulla secretes the
catecholamine hormones
norepinephrine and epinephrine

17. Pancreas

Located slightly behind the stomach

Secretes insulin, a type of hormone that transports
glucose into cells. It:
− Promotes glycogenesis
− Inhibits gluconeogensis

Also secretes glucagon which increases glucose in
bloodstream

18. Reproductive Glands
Gonads and Ovaries:

the endocrine glands associated with human
reproduction, both have endocrine functions.

Female ovaries produce eggs

Male gonads produce sperm

19. Reproductive Glands
Ovaries:

Located in the abdominal cavity adjacent to the uterus.

Under the control of LH and FSH from the anterior pituitary they
manufacture estrogen and protesterone

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.

20. Disorders and Illnesses
of the Endocrine System

Endocrine illnesses can mostly be divided
into 3 groups:
− Gland hyposecretion
− Gland hypersecretion
− Abnormal growth

Some examples of these include
− Hypothyroidism (hyposecretion)
− Polycystic ovary syndrome (hypersecretion)
− Goiter (growth)

21. Hypothyroidism

The most common cause of hypothyroidism is inflammation of the thyroid gland,
which damages the gland's cells.

Signs and symptoms:
− A physical examination may reveal a smaller than normal thyroid
gland, although sometimes the gland is normal size or even enlarged
(goiter). The examination may also reveal:
− Brittle nails/ hair, pale or dry skin, swelling of the arms and legs
− A chest x-ray may show an enlarged heart.

Laboratory tests to determine thyroid function include:
− TSH test and T4 test

Lab tests may also reveal:
− Anemia on a complete blood count (CBC)
− Increased cholesterol levels
− Increased liver enzymes
− Increased prolactin
− Low sodium

22. Hypothyroidism

Treatment
− The purpose of treatment is to replace the thyroid
hormone that is lacking. Levothyroxine is the most
commonly used medication. Doctors will prescribe the
lowest dose possible that effectively relieves symptoms
and brings your TSH level to a normal range. If the patient
has heart disease or you are older, his/her doctor may
start with a very small dose.
− Lifelong therapy is required unless the patient has a
condition called transient viral thyroiditis.
− The patient must continue taking his/her medication even
when the symptoms go away. When starting medication,
his/her doctor may check hormone levels every 2 - 3
months. After that, thyroid hormone levels should be
monitored at least every year.

23. Polycystic ovary syndrome

One of the most common female endocrine disorders affecting
5% to 10% of women of reproductive age (12-45 years old)

It is a complex, heterogeneous disorder of uncertain etiology,
but there is strong evidence that it can to a large degree be
classified as a genetic disease

The principal features are:
− Anovulation- resulting in irregular menstruation,
− Amenorrhea- ovulation-related infertility
− Polycystic Ovaries- excessive amounts or effects of
androgenic (masculinizing) hormones, resulting in
acne, hirsutism and insulin resistance, often
associated with obesity, Type 2 diabetes, and high
cholesterol levels.

The symptoms and severity of the syndrome vary greatly
among affected women

24. Polycystic ovary syndrome

Diagnosing PCOS
− History taking, specifically for menstrual pattern,
obesity, hirsutism, and the absence of breast
development
− Gynecologic ultrasonography
− Laparoscopic examination may reveal a thickened,
smooth, pearl-white outer surface of the ovary
− Various lab tests such as lipid profile, fasting glucose
tolerance test, and serum levels of androgens

Treatment
− Diet and exorcise is the best treatment because it
helps to stabilize and regulate the body's hormones
− Medications such as Metformin can help with insulin
resistance, birth control pills can regulate menstrual
cycles, Clomid for infertility, etc.

25. Non-toxic Goiter

Enlargement of the thyroid that is not associated with overproduction of
thyroid hormone or malignancy. The thyroid can become very large so
that it can easily be seen as a mass in the neck.

There are a number of factors that may cause the thyroid gland to
become enlarged:
− A diet deficient in iodine can cause a goiter, but this is rarely
the cause because of the readily available iodine in our
diets.
− A more common cause of goiter in America is an increase in
thyroid stimulating hormone (TSH) in response to a defect in
normal hormone synthesis within the thyroid gland.

Diagnosis of goiter:
− Thyroidal radioactive iodine uptake
− Thyroid scan
− Laboratory tests such as measurement of serum free
thyroxine (free T4) or free T4 index and total triiodothyronine

26. Non-toxic Goiter

Treatment (depending on cause)
− In iodine-deficient areas, iodine supplementation of salt;
oral or IM administration of iodized oil yearly; and
iodination of water, crops, or animal fodder eliminates
iodine-deficiency goiter. Goitrogens being ingested
should be stopped.
− In other instances, suppression of the hypothalamic-
pituitary axis with thyroid hormone blocks TSH production
(and hence stimulation of the thyroid). Full TSH-
suppressive doses of l-thyroxine are useful in younger
patients. l-Thyroxine is contraindicated in older patients
with nontoxic nodular goiter, because these goiters rarely
shrink and may harbor areas of autonomy so that l-
thyroxine therapy can result in hyperthyroidism.
− Large goiters occasionally require surgery or 131I to
shrink the gland enough to prevent interference with
respiration or swallowing or to correct cosmetic
problems.