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HORMONES: AN OVERVIEW
• Hormones are produced by most plants and
animals.
• Animal hormones
– are made and secreted mainly by endocrine glands,
– are usually carried by the circulatory system, and
– communicate regulatory messages to specific sites in the body.
© 2013 Pearson Education, Inc.
2
• The endocrine system
– consists of all hormone-secreting cells and
– is the body’s main system for internal chemical regulation.
HORMONES: AN OVERVIEW
© 2013 Pearson Education, Inc.
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• Endocrine cells secrete into the bloodstream
hormones that
– can affect many cells in many different body organs but
– only affect target cells, cells that have receptors for that specific hormone.
HORMONES: AN OVERVIEW
© 2013 Pearson Education, Inc.
4
© 2013 Pearson Education, Inc.
Blast Animation: Signaling: EndocrineRight click slide / select “Play”
5
Figure 25.1
Endocrine
cell
Blood
vessel
Membrane-enclosedsacs
Hormone
molecules
Receptor
protein
Target cell
Adrenal glands(type of endocrine
gland), which sitatop the kidneys
6 Figure 25.1a
Endocrinecell
Bloodvessel
Membrane-enclosedsacs
Hormonemolecules
Receptorprotein
Target cell
7
• There are two general mechanisms by which
hormones trigger changes in target cells:
1. Water-soluble hormones trigger responses without ever entering their target cells.
HORMONES: AN OVERVIEW
© 2013 Pearson Education, Inc.
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© 2013 Pearson Education, Inc.
Animation: Water-Soluble HormoneRight click slide / select “Play”
9
Figure 25.2-1
Water-solublehormone Receptor
protein
Target
cell Plasma
membrane
Nucleus
1
10 Figure 25.2-2
Water-solublehormone Receptor
protein
Target
cell Plasma
membrane
Relay
molecules
Signaltransduction
pathway
Nucleus
1
2
11
Figure 25.2-3
Water-solublehormone Receptor
protein
Target
cell Plasma
membrane
Relay
molecules
Signaltransduction
pathway
Cytoplasmic
responseor
Gene regulationNucleus
1
2
3
12
2. Lipid-soluble hormones trigger responses after entering the target cell.
HORMONES: AN OVERVIEW
© 2013 Pearson Education, Inc.
13
© 2013 Pearson Education, Inc.
Blast Animation: Signaling via Steroid HormonesRight click slide / select “Play”
14
© 2013 Pearson Education, Inc.
Animation: Lipid-Soluble HormoneRight click slide / select “Play”
15
Figure 25.3-1
Lipid-solublehormone
Target
cellPlasma
membrane
1
Nucleus
16 Figure 25.3-2
Lipid-solublehormone
Receptorprotein
Target
cellPlasma
membrane
2
1
Nucleus
17
Figure 25.3-3
Lipid-solublehormone
Receptorprotein
Target
cellPlasma
membrane
Hormone-receptorcomplex
Nucleus
2
1
3
18 Figure 25.3-4
Lipid-solublehormone
Receptorprotein
Target
cellPlasma
membrane
Hormone-receptorcomplex
Gene regulation
Nucleus
2
1
3
4
19