1. Chapter 32

2. I. Types of Signaling A. intracellular – within a cell 1. CDKs 2. cAMP
B. Intercellular –
between cells
1. growth factors (PDGF)
2. neurotransmitters
3. hormones
C. Between organisms

3. II. Types of Signaling Molecules:
A. Local signaling Molecules
1. Secreted into extracellular fluid
2. Travel by diffusion
3. Short lived
4. Very local effects
5. Histamine, neurotransmitters
B. Pheromones
1. Signal other individuals
2. Molecules travel by air
3. Sensed by vomeronasal organ
C. Hormones
1. transported around body by blood

4. III. Hormones A. Produced by endocrine system
Endocrine glands/cells
Some neurons
B. Delivered by blood & interstitial fluid
C. Received by target cells
1. Cells with receptors for that specific hormone
2. Peptide/protein hormone bind membrane receptors
3. Lipid hormones diffuse through cell membrane (they are non-polar) to Intracellular receptors

5. IV. Intracellular receptors
Bind lipid Hormones like steroids
Testosterone & thyroid hormones
Often affect promoters regulating transcription
Why do they need carrier proteins in blood?

6. Intracellular Receptor

7. Neg. Feedback: Anterior Pituitary hormones
Anterior Pituitary regulated by Hypothalamus
Hypothalamus monitors hormone blood levels
Low levels cause hypothalamus to signal Anterior Pituitary via secretory neurons
Neurons make releasing hormones (_RH) that signal the anterior pituitary to begin secreting stimulating hormones (_SH)
Stimulating hormones also called Tropins are hormones that travel to an organ

9. Thyroid function Negative Feed back example
Hypothalamus monitors blood levels of thyroid hormones (T3/T4)
Low levels of T3/T4 cause hypothalamus to make releasing hormones (TRH) that signal the anterior pituitary to begin secreting (TSH ) thyroid stimulating Hormone
TSH binds to receptors in thyroid gland causing it to produce T3 & T4
T3/T4 feed back to shut down hypothal. & pit .

11. Membrane Receptors
Bind peptide/protein hormones
Binding produces 2nd messenger mols. Like cAMP
cAMP initiates chain reaction
resulting series of chem. rxns is called a cascade
Example: Glucagon

12. Glucagon induced cascade

13. Pancreatic Hormones Hormones produced in Pancreatic Islets
2 types of cells in islets
1) alpha cells = glucagon
2) beta cells = insulin

14. Glucagon = peptide hormone
Low blood glucose triggers alpha cells
Glucagon produced, binds to liver cells
Cascade causes breakdown of glycogen into glucose
High blood glucose levels = neg. feedback

15. Insulin High blood glucose levels trigger beta cells Produce insulin
Insulin  cascade resulting in uptake of glucose
(only hormone to do this)
Targets skeletal muscle, fat & liver cells
Promotes:
protein, fat & glycogen synthesis
Low glucose levels = Neg. feedback

17. Diabetes mellitus Cells do not take up glucose properly
Type I = autoimmune attack on
Beta cells (juvenile onset diabetes)
Type II = target cells ignore insulin
Beta cells constant production of insulin  fail
Insulin shots required
Caused by genetics & obesity

19. Hormone Regulation 1)Antagonistic pairs (opposing functions)
2) Negative Feedback – increasing end-product shuts down system
3) Positive Feedback – increasing end-product encourages more production

20. Positive Feedback example posterior pituitary
Oxytocin triggers uterine contractions
And uterine contractions signal hypothalamus to make MORE oxytocin
Oxytocin produced in neuron cell bodies within the hypothalamus
It is then sent down axon to posterior pituitary where it is released and diffuses into blood
Blood carries oxytocin to uterus