Which area of the brain may be affected when a client with anxiety disorder shows symptoms related to respiratory activation and increased heart rate?

Medulla and pons.

Explanation: Brain is the part of the body that controls all body activities. Medulla and pins are part of the brain.

Medulla controls respiration. It receives signals from chemoreceptors and send to muscles that allow respiration. It also regulate heart rate and blood pressure to ensure adequate blood supply circulate the body system.

Medulla also help in adjusting respiration when there is need and also generates normal breathing movements by stimulating the nerve that supplies the diaphragm. This pons are located under the medulla and it controls speed of involuntary respiration( respiration

Not under conscious control).

When a patience shows a disorder in respiration, invountary respiration, increase in heart rate its a disorder of Medulla and pons also called Brainstems