1. The Endocrine System
Miss Richardson
SBI4U

2. The Endocrine System
The nervous system uses specific molecules (hormones) as signals to control the vertebrate body
Advantages of chemical messengers:
Chemical messengers can spread to all the tissues via the blood
Hormones have a specific shape that will only work on organs, tissues that are a match.

3. Hormones Released from endocrine glands as steroid or protein
Can be transported or stored to the target cell
Induce long-lasting effects

4. Endocrine Glands
Over 200 hormones have been identified and are secreted from tissues and organs known as endocrine glands
Endocrine glands are ductless regions that produce hormones
Endocrine glands (exclusive):
Pituitary
Pineal
Thyroid
Parathyroid
Adrenal
Other tissues and organs contribute:
Hypothalamus
Thymus
Pancreas
Testes
Ovaries

5. Endocrine Glands

6. Sending Molecular Signals
CNS controls hypothalamus, which regulates release of hormones from pituitary
Hormones can act on nearby cells or be transported through blood until they reach a cell with matching receptor (target cell)
Target cell carries the receptor protein which will bind to hormone, changing its shape
Cellular activity is triggered

7. Steroid Hormones Located in cytoplasm of target cell
Lipid soluble and can pass through cell membrane
Once inside cell, binds to receptor protein forming receptor-hormone complex
Complex binds to DNA and changes gene activity by inhibiting or promoting transcription

8. Protein/Peptide hormones
Water soluble
Don’t enter target cell
Hormone receptors located within cell membrane
Protein hormone binds to receptor which triggers events within cytoplasm through secondary messengers
Secondary messengers amplify original signal

9. Pituitary Gland Located in the brain, linked to hypothalamus
2 regions:
Anterior – controlled by hypothalamus
Growth hormone, THS, adrenocorticotropic hormone, gonadotropic hormone, prolactin
Posterior – controlled by nerves
Antidiuretic hormone, oxytocin

10. Hypothalamus
Region of the middle of the base of the brain, responsible for regulation of many functions
Body temperature
Hunger
Moods
Sleep
Sex drive
Thirst

11. Thyroid Gland Consists of two lobes, located in neck below larynx
Produces thyroxine (T4) which increases metabolic rate
Also produces triiodothyronine (T3) and calcitronin
Responsible for regulation of metabolism

12. Thyroid Gland - calcitronin
Calcitronin regulates calcium levels in blood
Essential for healthy teeth and bone development

13. Parathyroid Gland On surface of thyroid gland
Release parathyroid hormone in response to low calcium levels