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Oh!!! I see! White hair is primarily due to air bubbles b/c the melanin is replaced, but gray hair is mostly b/c of decreased melanin (air bubbles haven't replaced it yet)

Sorry, another question, are booster shots considered active or passive immunity? I thought it was active since it introduces the antigen and you make your own antibodies, but the training handout says it's passive.

Does anybody know what the systems for next year will be?

fanjiatian wrote:Oh!!! I see! White hair is primarily due to air bubbles b/c the melanin is replaced, but gray hair is mostly b/c of decreased melanin (air bubbles haven't replaced it yet)

Sorry, another question, are booster shots considered active or passive immunity? I thought it was active since it introduces the antigen and you make your own antibodies, but the training handout says it's passive.

Well in white hair, there is pretty much no melanin being produced opposed to grey hair where there may still be a few cells producing melanin. So white hair would have more bubbles since there is less melanin. Yeah, it seems like booster shots would be active immunity. The handout could be wrong, I found one other mistake on it.

The handout is wrong. Receiving a vaccine is a form of artificially (as opposed to naturally) acquired active immunity. The antigens are immunogenic, but not pathogenic (that is, they will trigger the cell-mediated & antibody-mediated immune responses, but will not cause disease), and lead to the formation of memory cells.

Passive immunity involves receiving antibodies. They can come from your mother - either IgG, which cross the placenta, or IgA, which are present in breast milk - or you can receive antibodies intravenously

thedeppmachine15 wrote:Does anybody know what the systems for next year will be?

I've heard if they don't add any new systems, it will go back to circulatory integumentary will be there for sure

In the official training handout from soinc, under the section "Effects of Drugs on the Nervous System", caffeine is listed as suppressing melatonin, the neurotransmitter for sleep. Other sources on the internet and this textbook I have say that caffeine suppresses adenosine, the neurotransmitter for drowsiness. Which is correct?

arooj1a2b3c wrote:In the official training handout from soinc, under the section "Effects of Drugs on the Nervous System", caffeine is listed as suppressing melatonin, the neurotransmitter for sleep. Other sources on the internet and this textbook I have say that caffeine suppresses adenosine, the neurotransmitter for drowsiness. Which is correct?

Adenosine binds to specific receptors on neural membranes, and causes a person to feel sleepy. But when you have caffeine, it binds to the adenosine receptors but doesn't cause drowsiness. Therefore you have fewer receptors for the adenosine to bind to, preventing you from feeling sleepy. I don't think caffeine has a direct affect on melatonin production, but I'm not completely sure. I think the effects of caffeine are most directly caused by how it interacts with adenosine. The training handout has incorrect information about a couple of other things so it might be wrong.

Do you guys know what the difference is between Meissner's corpuscles and Merkel discs? On the soinc notes it says they are both receptors to light touch.

Brett wrote:Do you guys know what the difference is between Meissner's corpuscles and Merkel discs? On the soinc notes it says they are both receptors to light touch.

One difference is, Meissner's corpuscles are located in the dermis and Merkel's discs are located in the epidermis. They also look a lot different because Meissner's corpuscles are much bigger.

Where can i study for anatomy that is on a national level? All the stuff online and in books are too easy and medical text books are too hard.
Do any of you guys have recommendations for books that are hard enough for nationals?