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The Endocrine System

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Title: Chapter 8: Chemical Signals Maintain Homeostasis Author: De Souza, Monica (Michael Power/St Joseph) Last modified by: TCDSB Created Date: 8/16/2006 12:00:00 AM – PowerPoint PPT presentation

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Title: The Endocrine System


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 (cant
    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
  • http//highered.mheducation.com/sites/0072437316/s
    tudent_view0/chapter47/animations.html

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

17
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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

20
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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)

23
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25
Ie cortisol
26
Hormone 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) Gonads (ovaries and testes) 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
Hormone 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
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