Endocrine system

1. The Endocrine System
This presentation is to supplement the reading of the
‘Endocrine System’ in your anatomy book

2. •Regulates many bodily functions
•Maintains homeostasis by regulating the production of
chemicals that affect most functions of the body
•Secretes substances that aid the nervous system
•Important regulator of growth and development
•Endocrine glands are ductless glands, unlike *exocrine glands
that secrete substances into ducts.
*Exocrine glands are glands that secrete their products (excluding
hormones and other chemical messengers) into ducts
(duct glands) which lead directly into the external environment.
The Endocrine glands produce chemicals call Hormones

3. Negative Feedback Loop
Hormones are released in response to a change in a body condition
If body is high or low from normal level, a signal tells body to make changes that
will bring body back to normal level.
Once body is back to normal level, signal is turned off
HIGH
Lowers
Body Condition
A Gland Releases
a Hormone
Hormone Is Activated
Specific Body Condition

4. Why are hormones needed?
Communication needed to coordinate whole body and many of
its functions.
Chemical messages (Hormones) from one body part are sent to
to cells in other parts of body mainly via the blood stream.
Hormones help the body in maintaining homeostasis.
Homeostasis is the state of steady internal, physical, and
chemical conditions maintained in the body at the correct level.
Homeostasis exists when there is a balance of substances. Endocrine
conditions are due to either hypo (too little) or hyper (too much)
secretions of substances (hormones).

5. Endocrine System Releases
Hormones
Glands which secrete (release)
chemical signals into blood
Chemicals cause changes in other parts of body
Growth hormones
Sex hormones
Response hormones
Metabolism hormones
and more….

6. Hormones coordinate slower but longer acting responses to stimuli
such as stress, dehydration, and low blood glucose (sugar) levels.
Hormones also regulate long term developmental processes by
informing different parts of the body how fast to grow or when to
develop the characteristics that distinguish male from female or
juvenile from adult.
Hormone secreting organs, called endocrine glands, are referred to as
ductless glands because they secrete their chemical messengers directly
into extracellular fluid. From there, the chemicals diffuse into the
circulation.

7. RespondingTo Hormones
Hormones work by a Lock and Key system
Hormone fits receptor on “target” cell. Non target cells do not have a
receptor that can read the hormone signal.
Target Cell
Non-target
cells
Secreting
cell
Can’t
read
signal
Can’t
read
signal

8. Major Glands of the Endocrine System

9. Hypothalamus Gland
 Part of the nervous system and located in the
brain.
 It releases hormones that regulate pituitary
hormones
 Hormones released here have either a
releasing or an inhibiting factor

10. Pineal Gland
•Also located in the brain.
•Releases melatonin, a hormone that
affects sleep cycles (ie. Jet lag)

11. Pituitary Gland
Anterior Pituitary
Connected to the hypothalamus
Most of the hormones are released from the
anterior pituitary
Posterior Pituitary
Hormones released from the posterior
pituitary are made in the hypothalamus.

12. Growth Hormone
(Also called Somatotropin)
Growth hormone acts to promote growth of bones and organs and
is made in the Anterior Pituitary gland
During childhood GH is at maximum
Too little and we have a lack of growth
Too much and we have gigantism, often accompanied by
acromegaly*
*continued growth of extremities of bones and organs

13. Adrenal Gland
Adrenal cortex (outer) produces about 50 different
chemicals including…
Mineralocorticoids (outer layer)
influence salt and water balances ie electrolyte balance
and fluid balance
Glucocorticoids, cortisol (middle layer)
regulation of glucose metabolism
Sex hormones (Inner Most Layer,)
Adrenal medulla (Inner Layer) (catecholamines)
Adrenaline / Noradrenaline
Epinepherine / Norepinepherine

14. Thyroid Gland
Thyroxin: Acts to regulate the body’s metabolic rate
Too little thyroxin = hypothyroidism
May cause depression , attention & memory problems
Too much thyroxin = hyperthyroidism
May cause agitation, irritability, & weight loss
*Goiters = Growths on thyroid gland

15. •Helps maintain proper blood glucose levels
•Is both an endocrine and exocrine gland.
•The islets of Langerhans serve its endocrine(hormone) unit of the
pancreas
•Two types of cells, alpha and beta are produced by the islets of
Langerhans
Insulin is released by
the beta cells which
stimulate the glucose to
be sent to the body’s
cells and convert
unused glucose to
glycogen.
Lowers Blood Sugar
Glucagon is released by
the alpha cells which
stimulate stored
glycogen(stored
sugar)to be
transformed into
glucose again.
Raises Blood Sugar
Pancreas

16. Ovaries
Located in the female pelvic region one attached to
the top of each fallopian tube
Produce the female hormones:
Estrogen:
Affects female sexual characteristics and important
in the maintenance of pregnancy
Progesterone:
A major contributor to the body’s support of
pregnancy

17. •Located in the scrotum, a sac outside the body
•Produce spermatozoa which fertilizes the female egg
•Produce male sex hormones:
Testosterone:
Promotes the development of male sexual characteristics.
Testis