Lecture 9-1

Question 1

Example of receptor, integrator, effector in digestion and absorption

Answer 1

Receptor (signal): Presence of food in digestive tract

Integrator: Causes production/secretion of hormones into bloodstream; specifically gastrin

Effector (response): In the small intestine: increase in the amount of digestive enzymes and relevant transporters: H+ and Cl- are pumped into stomach to digest proteins

Question 2

What are the steps of the mechanism of parietal cells secreting gastrin in the stomach?

Answer 2

1. Gastrin binds to parietal cell-surface receptor
2. Triggers a cellular response
3. Pre-existing active H+ pumps are inserted into the membrane
4. H+ are pumped into the stomach

Cl- flow into the lumen after they’ve moved in on the other side to maintain charge balance

Parietal cells use carbonic anhydrase to produce HCl for stomach acid

Question 3

Overall outcome: Negative feedback to achieve homeostasis.

An _____________ in your body, with systems that ___________, to keep your __________ and _________ happy!

Answer 3

An ADAPTATION in your body, with systems that RESPOND, to keep your ENZYMES and SYSTEMS happy!

Question 4

Where is trypsin found?

Answer 4

The lumen of the small intestine

Question 5

What is required for a hormone to take effect on a cell?

Answer 5

The right receptor

Hormones affect distant cells but the target cell must have the right receptor to receive the signal

Question 6

How are differential gene expression and hormones related?

Answer 6

1) Hormones are released and picked up by a target receptor

2) Hormone enters the cell and can activate or repress certain genes

This leads to different expression of those genes,
leading to different structures and different functions