1. The Endocrine System
H1: Hormonal Control

2. Endocrine System: a system of glands that secrete hormones to regulate body function
HORMONES: chemical messengers or regulators
- they are released by cells in one part of the body and affect cells in other parts of the body to speed up or slow down processes.
Endocrine Hormones – are produced in endocrine glands and secreted directly in the blood and distributed by the circulatory system.

3. Makes hormones and regulates the pituitary gland
Pineal gland (makes serotonin which regulates sleep patterns)

4. Endocrine Gland

5. How do Hormones Signal Cells?
Note: Hormones do not affect ALL cells
Depends on whether or not that cell has a receptor for the particular hormone.
(TARGET CELLS are the cells hormones act on)
There are 2 types of hormones:
1. Steroid Hormones
2. Protein Hormones

6. Steroid Hormones
made from cholesterol (lipid); Complex ring of C, H, and O
Soluble in fat but NOT water – so can dissolve through cell membrane
Inside the cell they bind to receptor in the cytoplasm or nucleus to form the hormone- receptor complex

7. Steroid Hormones
The receptor-hormone complex can then switch certain genes on or off by promoting or inhibiting the transcription of genes
ex: sex hormones
ex: cortisol (stimulates the conversion of amino acids to glucose by the liver and decreases expression of insulin)

8. Steroid Hormones

9. Steroid Hormones
SECRETORY
CELL
HORMONE
TARGET CELL
RECEPTOR

10. Protein Hormones Made of chains of amino acids or modified amino acids
Soluble in water but insoluble in fats (can’t dissolve through cell membrane)
Ex: insulin, growth hormone

11. Protein Hormones
The protein hormones attach to receptor sites on the cell membrane
The hormone-receptor complex leads to the release of a secondary messenger in the cell that can spread throughout the cell and relay messages
Ex of secondary messengers: Ca2+ and cyclic adenosine monophosphate (cyclic AMP)
Secondary messengers then activate enzymes in the cell.

12. Protein
Hormones

13. Animations
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14. Control Systems
The body relies on the nervous system and the endocrine system for control of organs and tissues
The nervous system allows the body to adjust quickly to environmental changes
The endocrine system is designed to maintain control over longer durations

15. Hypothalamus
The hypothalamus in the brain is part of both the nervous system and the endocrine system
As an endocrine gland it creates hormones that either
a) are stored in the (posterior) pituitary gland
b) control the release of hormones from the (anterior) pituitary gland

16. Pituitary Gland (The Master Gland)
“master gland” because it controls the other endocrine glands
(However, it is controlled by the hypothalamus)
Located at the base of the brain; connected to the hypothalamus by a stalk
The pituitary produces and stores hormones
The hypothalamus stimulates their release when necessary

18. Posterior Lobe
Stores and releases hormones that are actually made by the neurosecretory cells of the hypothalamus
The hormones travel from the hypothalamus to the pituitary via specialized nerve cells
They are stored in the pituitary and released into the blood when necessary
(The hypothalamus will send a nerve response to have the hormones released)
Ex: ADH (antidiuretic hormone), oxytocin

19. Posterior Lobe Ex: ADH release
Hypothalamus creates ADH and stores it in pituitary gland
Osmoreceptors in hypothalamus recognize osmotic pressure (solute concentration of blood)
Impulses are sent to pituitary to increase or inhibit the release of ADH into blood stream accordingly

21. Anterior Lobe Produces its own hormones
However, the hypothalamus regulate their release with inhibiting or releasing hormones made by the hypothalamus
The inhibiting and releasing hormones are transported to the anterior lobe of the pituitary via specialized nerve cells
This stimulates the release of pituitary hormones which will travel through the blood to target cells

22. Anterior Lobe Ex: TSH and TRH
The anterior lobe produces and stores TSH (thyroid stimulating hormone)
TSH is released by the anterior lobe when the hypothalamus releases TRH (thyroid releasing hormone)

25. Ie cortisol

26. Thyroid Stimulating Hormone (TSH) Thyroid Gland
Target Organ
Primary Function
Thyroid Stimulating Hormone (TSH)
Thyroid Gland
Releases hormones made in the thyroid (such as thyroxine)
Adrenocorticotropic Hormone (ACTH)
Adrenal Cortex
Stimulates the release of hormones involved in the stress response (such as cortisol)
Somatotropin (STH) also known as Growth Hormone (GH)
Most body cells
Promotes growth
Follicle Stimulating Hormone (FSH)
Gonads (ovaries and testes)
Females: stimulates follicle development in the ovaries
Males: Promotes the development of sperm cells in the testes
Luteinizing Hormone (LH)
Females: stimulates ovulation and the formation of the corpus luteum
Males: stimulates the production of testosterone
Prolactin
Mammary Glands
Maintains milk production in lactating females

27. Posterior Pituitary Hormones
Target Organ
Primary Function
Antidiuretic Hormone (ADH)
kidneys
Increases water reabsorption in the kidney
Oxytocin
Uterus, mammary glands
Initiates strong uterine contractions
Triggers milk release in lactating females