21.  The myenteric plexus is found in the _____ of the digestive tract wall.  
A.  mucosa
B.  serosa
C.  submucosa
D.  muscularis
E.  adventitia

22.  The enteric plexus  
A.  is found in the mucosa
B.  consists of the myenteric plexus and the ciliac plexus
C.  helps control movement and secretions of the digestive tract
D.  contains parasympathetic neurons
E.  helps control movement and secretions of the digestive tract and contains parasympathetic neurons

23.  Beginning at the lumen, the sequence of layers of the digestive tract wall is  
A.  submucosa, mucosa, serous membrane, muscularis.
B.  muscularis, lamina propria, submucosa, mucosa.
C.  mucosa, submucosa, muscularis, serosa.
D.  peritoneum, submucosa, mucosa, lamina propria.
E.  submucosa, mucosa, adventitia, muscularis.

24.  What is the function of interstitial cells of the myenteric plexus?  
A.  chemoreceptors that detect the chemical composition of food
B.  production of mucus for lubrication and protection
C.  pacemaker cells that promote rhythmic contractions of the smooth muscle
D.  release of enzymes for chemical digestion

25.  Secretions that are added as food moves through the GI tract assist in  
A.  liquefying and digesting the food.
B.  vitamin A and D production and storage.
C.  distribution of nutrients throughout the body.
D.  insulin production.
E.  bile production.

26.  What is the function of enteric sensory neurons?  
A.  detect changes in chemical composition of digestive tract contents
B.  stimulate or inhibit smooth muscle contraction in the digestive tract
C.  stimulate or inhibit glandular secretion in the digestive tract
D.  detect stretch of the digestive tract wall
E.  detect changes in chemical composition of digestive tract contents and detect stretch of the digestive tract wall

27.  Parasympathetic nerves extend to the digestive tract through the ____________ nerve.  
A.  gastric
B.  cardiac
C.  vagus
D.  accessory

28.  The enteric nervous system acts independently of the CNS to control local reflexes in the digestive tract.  
TRUE

29.  What disease is caused by the absence of enteric neurons in the distal large intestine?  
A.  Hirschprung disease
B.  multiple endocrine neoplasia type 2
C.  spastic colon
D.  gastroenteritis

30.  What are the two major neurotransmitters of the ENS in the digestive tract?  
A.  epinephrine and serotonin
B.  epinephrine and norepinephrine
C.  acetylcholine and epinephrine
D.  norepinephrine and acetylcholine