When you say "lower digestive system" I'm assuming you mean your intestines. If that is what you're referring to, it starts at the bottom of your stomach. The bottom of your stomach is connected to your small intestine, which then goes to your large intestine, then to your rectum, and then your anus.
The digestive system starts at the mouth.
The ring shaped muscle in the digestive system is the lower esophageal sphincter (LES).
At their mouths.
yes
mouth
Immediately.
yucky yummy
the Spleen, attached near the lower stomach.
A blockage that prevents food passing though the (lower) digestive system.
Yes.
The body system that the colon belongs to is the digestive system. The colon is also known as the large intestine.
Yes, teeth are part of the digestive system as they help in breaking down food into smaller pieces through chewing. Saliva is also part of the digestive system as it contains enzymes that start breaking down carbohydrates in the mouth.