1. The Endocrine System 16

2. Endocrine System: Overview
Endocrine system – the body’s second controlling system which influences metabolic activities of cells by means of hormones secreted from glands
Major organs are the Endocrine glands –
pituitary, thyroid, parathyroid, adrenal, pineal, thymus, pancreas and gonads
Continued on the next slide

3. Endocrine System: Overview (cont)
The hypothalamus has both nervous functions and releases hormones
Other tissues and organs that produce hormones include adipose cells, cells in the walls of the small intestine, stomach, kidneys, and heart

4. Hormones – chemical substances secreted by cells of endocrine glands
Regulate the metabolic function of other cells
Carried by the bloodstream

5. Major Endocrine Organs: Pituitary (Hypophysis)
Pituitary gland
Releases 11 hormones made by either the hypothalamus or the pituitary itself
Regulates major metabolic processes on the body
Growth, stress, reproductive cycles, water balance to name a few.

6. Secretes thyroid hormone (TH) in two forms
Deals with metabolism, temperature, nerve and muscle development
Secretes calcitonin
lowers calcium levels

7. Secretes parathyroid hormone (PTH) Increases blood calcium levels

8. Adrenal hormones
Increases sodium and lowers potassium blood levels through the kidney
Raises blood volume and pressure
constricts blood vessels, and raises heart rate
Help body deal with stress
Epinephrine (adrenalin) and norepinephrine
Cause fight or flight response (short term)

9. Controls blood sugar levels Insulin
pancreas
Controls blood sugar levels
Insulin
Lowers blood sugar
Glucagon
Raises blood sugar

10. ovary Female primary sex organ; produces female sex hormones
Produces estrogen
Produces progesterone
Run the menstrual cycle
Development of the female body sexually

11. Produces male sex hormones
testis
Produces male sex hormones
Mainly secretes testosterone
Produces secondary sex characteristics and sex drive

12. Pineal gland
Produces melatonin
Involved with sleep patterns

13. thymus
secretes thymosin
Help developed white blood cells

14. Hormones and functions
TH- controls metabolism
Calcitonin- lowers blood calcium levels
PTH- raises blood calcium levels
Epinephrine- causes fight or flight response
Insulin- lowers blood sugar levels
Glucagon- raises blood sugar levels
Melatonin- regulates sleep cycles
Thymosin- develops white blood cells

15. Part of the brain that controls the endocrine system
hypothalamus
Part of the brain that controls the endocrine system
Secretes several hormones that act on the pituitary or are only stored in the pituitary

16. Target Cell Specificity
Hormones circulate to all tissues but only activate with very specific target cells
Target cells must have specific receptors to which the hormone binds
These receptors may be intracellular or located on the plasma membrane

17. Amino acid based (proteins)
Types of Hormones
Amino acid based (proteins)
– most hormones belong to this class
Steroids
– gonadal and adrenocortical hormones
- lipid (cholesterol) based
PLAY
InterActive Physiology®: Endocrine System: Orientation

18. Steroid Action (simplified)
Steroids cross the cell membrane
They travel through the cytoplasm and enter the nucleus
They then turn on genes (DNA) which then creates a cellular protein (protein synthesis)

19. Amino acid/Protein hormone action (simplified)
Hormone binds to a cell membrane receptor
This complex binds to another protein in the membrane
This binding process activates a second messenger and in some cases a third messenger
The second or third messengers then trigger a response in the cytoplasm of the cell

20. Control of Hormone Release
Blood levels of hormones:
Are controlled by negative feedback systems
A negative feedback is a system that stops the production of a molecule
PLAY
InterActive Physiology®: Endocrine System: Biochemistry, Secretion, and Transport of Hormones

21. Gigantism- Acromegaly- Dwarfism Diabetes insipidus Endocrine disorders
high GH, normal body proportion
Acromegaly-
high GH but with enlarged extremities
Dwarfism
Low GH
Diabetes insipidus
Low ADH, huge urine output

22. Hyperthyroidism (over secretion)
Endocrine disorders
Hyperthyroidism (over secretion)
high metabolic rate, increased appetite
Graves Disease
Autoimmune disease?
Sweating, increased metabolism, protruding eyes
Hypothyroidism (under secretion)
Low metabolic rate, weight gain, Intolerance to heat (called cretinism in babies when severe)
May be due to lack of iodine, which forms a goiter

23. Diabetes mellitus Hypoglycemia Endocrine disorders
Insulin is either absent or deficient
Genetic and viral infections
Hypoglycemia
Anxiety, nervousness