Question

1. Briefly compare endocrine signaling with synaptic transmission.

2. Compare parasympathetic vs. sympathetic control of vascular smooth muscle. Note similarities and differences including the organization of pathways, pre- and post-ganglionic neurotransmitters, etc.

3. Compare blood flow (perfusion) and air/water flow (ventilation) in fish gills, frog lungs, bird lungs and mammalian lungs. Consider how terms of the Fick Diffusion Equation (write out) are manifest in the design of the exchange surfaces.

4. What forces contribute to movement of solutes from a capillary lumen into tissue spaces and return from tissue spaces to the capillary lumen?

Answer 1

Ans 1:

• Endocrine cells and nerve cells work together to coordinate the diverse activities of many cells in a higher animal.
• Endocrine cells secrete many different hormones into the blood to signal specific target cells, which have receptors for binding specific hormones.
• In synaptic signaling transmission, the specificity arises from the contacts between nerve processes and the specific target cells they signal. Only a target cell that is in synaptic contact with a nerve cell is exposed to the neurotransmitter released from the nerve terminal.
• Different endocrine cells must use different hormones in order to communicate specifically with their target cells while many nerve cells can use the same neurotransmitter and still communicate in a highly specific manner.

Figure 1 & 2 showing Endocrine and Synaptic Signaling as follows: