Cell signals and control pathways• List and describe the components in specific

2nd messenger signal transduction pathways

• Define each of the following and predict their effect on signal transduction:– agonist and antagonist for one receptor

– receptor isoforms (one ligand, >1 receptor)

– one ligand on one receptor (tonic control)

– two antagonistic ligands on one tissue

http://www.blackwellpublishing.com/

matthews/neurotrans.html

Class problem set: 1. Norepinephrine (NE) is a large protein. Where will receptors for

NE be?

inside the target cell or on the target cell membrane

2. When NE binds an 1 receptor on a cell’s membrane, there is an increase in IP3 and DAG in the cell. What membrane bound amplifier enzyme is activated to cause the IP3 and DAG increase?

3. What ion will be increased in the ICF due to IP3 ?

4. What ICF enzyme will be activated by DAG?

NorepinephrineorEpinephrine

Example of two ligands and two receptor isoforms

Tonic control through one signal molecule

Predict the effect of the following on blood vessel smooth muscle controlled by catecholamines on adrenergic receptors: muscle cell receptor type

1 2 1. increased NE release2. decreased NE release3. addition of 1 agonist4. addition of 2 agonist 5. addition of 1 antagonist6. addition of 2 antagonist7. addition of 1 antagonist

1. Constrict Dilate

2.

3.

4.

5.

6.

7.

Control pathways

- List the components of a control pathway and identify those components in specific neural and endocrine reflex pathways.

Ex/ control of lactation

Negative feedback - maintains homeostasis

Positive feedback - increases response

Example control pathways• You stand up. (A decision in the brain is

transmitted by a motor neuron that releases neurotransmitter to cause coordinated leg muscle contraction.)

• Decreasing plasma Ca2+ is detected by the parathyroid gland cells. The glands release PTH in response. PTH will remove some Ca2+ from bone and increase plasma Ca2+.

• You breath in carbon monoxide. You have no receptors for this gas.