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Chapter 45
Hormones and the
Endocrine System
Overview
Metamorphosis – controlled by
hormones
 Hormones – secreted into extracellular
fluid/circulates in blood or
hemolymph/communicates regulatory
*messages
 *only target cells have receptors

Overview(con’t)

Hormones regulate – reproduction,
growth, metabolism, behavior
45.1 Hormones and other signaling molecules bind
to target receptors, triggering specific response
pathways
Types of Secreted Signaling Molecules
1. Hormones – endocrine vs exocrine
2. Local Regulators – paracrine vs
autocrine signaling
3. Neurotransmitters and
Neurohormones - synapse
4. Pheromones

Intercellular Signaling
Synaptic Signaling
Neurohormones
Pheromones
Chemical Classes of Hormones
1. polypeptides
 2. amines
 3. steroid hormones
 Water soluble or lipid soluble

http://bcs.whfreeman.com/thelifewire/cont
ent/chp42/4202s.swf
 Center for BioMolecular Modeling
 Action of Epinephrine on a Liver Cell
 Thyroid Hormone Animation

Scientific Inquiry
Location of receptors and their
interaction with hormones???
 Rats and estradiol(radioactive form)
 Frogs and melanocyte-stimulating
hormone(MSH)
 Fig. 45.4 – What if?

Multiple Effects of Hormones
Water-soluble hormone – tissues vary
in response due to different receptors or
signal transduction pathways
 Fig. 45.8 p. 980
 Lipid-soluble hormone – different
effect on different target cells Ex)
estrogen
- different effect in different species Ex)
thyroxine

Signaling by Local Regulators
Cytokines
 Growth factors
 Nitric oxide
 Prostaglandins

Nitric Oxide
Aspirin and prostaglandins
45.2 Negative feedback and
antagonistic hormone pairs
A) Simple Hormone Pathways – low pH
in duodenum  secretin  pancreas
bicarbonate reduction in stimulus
 B) Insulin and Glucagon – an antagonistic
pair – see Fig. 45.12 p. 983
- alpha and beta cells of pancreas

Control of Blood Glucose
Diabetes Mellitus
Deficiency in insulin or a decreased
response to insulin
 Type I – autoimmune/insulin
dependent/destroys beta cells
 Type II – heredity and excess body
weight/target cells are non-responsive
 http://professional.diabetes.org/admin/Use
rFiles/0%20%20Sean/FastFacts%20March%202013.pdf
