How are other body systems affected or involved?

In addition to the nervous system, It has been hypothesized that ADHD affects the endocrine and immune systems. The main interaction with the endocrine systems has to do with disruption of hypothalamus-pituitary-adrenal (HPA) axis activity. The HPA axis deals with many essential functions in the endocrine system, including mood and emotion. This particular function is affected by ADHD, as higher stress levels in those with ADHD cause weaker activation of the HPA axis.

Also, due to certain relations between ADHD and allergic diseases, some researches believe that there is a link between ADHD and the immune system. Similarly, people diagnosed with ADHD were more likely to develop streptococcus-mediated neuropsychiatric disorders. This also points to the relation between ADHD and the immune system. 

Sources

 http://goo.gl/JQQ6EK ; http://goo.gl/IrTt7I

Interview with Charles Pun

Q. What medications do you take for ADHD?
     A. Concerta
Q. What does it do?
     A. It is a stimulant and it helps increase my focus.
Q. How often do you take the medication?
     A. Every morning on weekdays, but not on weekends.
Q. What side effects do you notice?
     A. At first, I wouldn't eat much and couldn't sleep as easily
Q. How effective is it for you?
     A. I think it helps me concentrate more but I don't notice a significant change in focus.
Q. How much do you notice ADHD?
     A. I don't notice it because I never experienced not having ADHD.
Q. Do you feel like you would be different without ADHD?
     A. Yes, I think I would be able to study better.
Q. Do any of your relatives have ADHD?
     A. My mother feels some of the symptoms but was never officially diagnosed.
Q. At what age were you diagnosed?
     A. In 4th grade; 9 years

Sources
Charles Pun ; http://goo.gl/JSdEs9 ; http://goo.gl/RLFMz9

How do the structures work together? What are the processes / mechanisms involved? (physiology)

ADHD = Attention Deficit Hyperactivity Disorder

Genes affect ADHD when a child is born. If they had an ancestor who had ADHD it could be passed through genes. Bad behavior in pregnancy, such as smoking/drinking could lead to the fetus acquiring ADHD when it is born. Although some may believe that somebody that received a head injury has ADHD, it most likely is that they display fits similar to the disorder. Both sugar and sugar substitute, in large amounts, can lead to both diabetes and ADHD. Food preservatives, in large consumption, end up leading to ADHD.

The dopaminergic areas of the brain are smaller in the brain of a child who has ADHD. The dopaminergic area contains the caudate nucleus, globus pallidus, and the frontal lobes. Activation in the front of the brain is lowered in the mind of a child with the disorder.

Beginnings of ADHD fits usually start from age seven. ADHD affects 4.1% of all adults (above age 18) in the US, and 9% of American children. Males are also four times as likely to develop the disorder than females.

Sources:

Abnormal Psychology by Kring, Johnson, Davison, Neale (Book)

http://www.nimh.nih.gov/health/topics/attention-deficit-hyperactivity-disorder-adhd/index.shtml

What are the structures of the nervous system involved?

ADHD = Attention Deficit Hyperactivity Disorder

The particular area that is affected by ADHD is the are of the brain linked to the neurotransmitter dopamine. In studies from adolescence with and without ADHD found that kid's brain structure who had ADHD found that dopaminergic areas of the brain such as the caudate nucleus, globus pallidus, and frontal lobes are smaller. In addition to those findings, the study state that the brain performed different cognitive task while using less of the frontal area. When taking test that required the frontal lobe, they did poorly.