Question

1)

a) What kind of cells control peristalsis in the digestive smooth muscle?___________________________________

b) Tell me about the small intestine – the different sections, their specific names, and at least 2 functions of each.

Section	Specific name	Functions
1 – by stomach
2
3

c) Beginning at the mouth, fill out the chart with the appropriate and SPECIFC names of either the enzyme, macromolecule, or location that the enzyme works.   

Enzyme	What does it digest?	Where along the GI tract does it work?
	Carbohydrates	Mouth & Stomach
	Lipids	Mouth & Stomach
	Proteins	Stomach
Nucleases	Nucleic acids
	Carbohydrates	Small intestine
Pancreatic Lipase

d) What is the average pH of the mouth?________________   What is the average pH of the stomach?_________

What is the average pH of the small intestine?_______________________________

What would be a good thing about the pH changes along the digestive tract?

What are some complications to having wide pH changes along the digestive tract?

Answer 1

1)

a) What kind of cells control peristalsis in the digestive smooth muscle?

Peristalsis defined as motor pattern of the gut organ. Musculature that can propel content into the anal or oral direction. Peristalsis consists of a wave of circular muscle contraction the propagates caudally. Both circular and longitudinal muscle layers participate. Caudad to the peristaltic wave the circular muscle relaxes and the longitudinal muscle contracts. Contraction of the longitudinal layer shortens the distance the chime must move and helps increase the caliber of the intestine. At the wave front the circular layer contracts and the longitudinal muscle relaxes.

b) Tell me about small intestine- the different sections, their specific names, and at least 2 functions of each.

section	Specific name	functions
Upper section	duodenum	1. receives gastric chyme 2. preparation for absorption through small finger-like protrusions called villi
midsection	jejinum	1. specialized for the absorption through its lining by enterocytes 2. villi that increase its surface area
final section	ilium	1. absorb vitamin B12 2. absorb bile acids

c) Beginning at the mouth, fill out the appropriate and SPECIFIC names of either the enzyme, macromolecule, or location that the enzyme works.

enzyme	What does it digest	Where along the GI tract does it works
amylase	carbohydrates	Mouth & stomach
lipase	lipids	Stomach
pepsin	proteins	stomach
nucleases	Nucleic acids	pancreas
Pancreatic lipase	carbohydrates	Small intestine

d) What is the average pH of the mouth?

Answer: 6.5-7.5

What is the average pH of the stomach? ........................

Answer: 1.2-2.4

What is the average pH of the small intestine? ........................

Answer: 7.2-8.6

What would be a good thing about the pH changes along the digestive tract?

Answer: The pH is a way of measuring how acidic or alkaline the body is. The pH in the human digestive tract varies greatly (see Human Digestive Tract pH Range Chart on the left side). The pH of saliva is usually between 6.5 – 7.5. After we chew and swallow food it then enters the fundic or upper portion of the stomach which has a pH between 4.0 – 6.5.This is where “predigestion” occurs while the lower portion of the stomach is secreting hydrochloric acid (HCI) and pepsin until it reaches a pH between 1.5 – 4.0. After the food mixes with these juices it then enters the duodenum (small intestine) where the pH changes to 7.0 – 8.5. This is where 90% of the absorption of nutrients is taken in by the body while the waste products are passed out through the colon (pH 4.0 – 7.0).

What are some complications o having wide Ph changes along the digestive tract?

Answer: Disruption of normal gastrointestinal function as a result of infection, hereditary or acquired diseases, or complications of surgical procedures uncovers its important role in acid-base homeostasis. Metabolic acidosis or alkalosis may occur, depending on the nature and volume of the unregulated losses that occur.