Digestive System HW

Which of the following statements is true regarding the anatomy of the colon and/or small intestine?

-the colon and small intestine both have intestinal crypts -both utilize peristalsis to propel contents -both have circular and longitudinal muscles in the muscularis

Which of the following is/are true regarding mechanical and/or chemical digestion?

-the muscular contractions of the stomach's muscularis layers contribute to mechanical digestion -the action of pepsin on proteins in the stomach is an example of chemical digestion

Which of the following statements is true regarding the swallowing reflex?

-the oral phase is voluntary and the pharyngoesophageal phase is involuntary -four different cranial nerves carry the motor impulses of the reflex

Which of the following statements is/are true about gastric motility?

-the stomach uses the contraction of three layers of muscle to mix, churn, and propel its contents to the duodenum -when the pyloric sphincter is relaxed, chyme moves from the stomach to the duodenum -the receptive-relaxation response of the stomach allows it to accommodate more food

pepsin is _____

autocatalytic

Na+-K+ pumps in the _____ work to actively transport Na+ out of the cell towards the interstitium while cotransporting K+ to the ICF

basal membrane

Ion exchange molecules in the plasma membrane of the parietal cells exchange ___ ions going out for ____ ions coming in.

bicarbonate; chloride

Fats entering the duodenum are coated with lecithin and ____ to keep them emulsified and enhance the efficiency of their digestion.

bile acids

List in order the passage of bile from its point of secretion in the liver to the duodenum.

bile canaliculus bile ductule hepatic duct common hepatic duct bile duct

which are found in bile?

bile pigments, bile acids, cholesterol, phospholipids, water, minerals, micelles, and neutral fats

In order for digestion to occur, chyme is required to contact the microvilli of the intestinal wall because the __________.

brush border enzymes are not secreted into the lumen

How does sucrose change the configuration of sucrase?

by binding to the active site

The catabolic products of which of the following are absorbed into the blood?

carbohydrates and proteins

Enzymes that break down fats and proteins are secreted by ____.

chief

which of the following cells secrete digestive enzymes?

chief cells

Lacteals absorb ____

chylomicrons

trypsin then words on converting both chymotripsinogen and procarboxypeptidase into ______ and carboxypeptidase, respectively

chymotrypsin

The pancreas produces a number of zymogens that are released in the GI tract at the duodenum including procarboxypeptidase, ______, and trypsinogen

chymotrypsinogen

What is the large intestine that excludes the cecum, rectum and anal canal called?

colon

With a ___________ intracellular concentration of sodium, sodium now diffuses from the ___________ to the ICF of the epithelium.

declining; intestinal lumen

functions of stomach acid:

denatures proteins; destroys pathogens; activates pepsin and lingual lipase

the brush border enzyme that finishes the job of protein digestion, splitting the last two amino acids apart is called _____

dipeptidase

which of the following inhibits secretion of the gastric glands?

duodenal pH of less than 2

the submucosal and myenteric plexuses collectively constitute the _____ nervous system

enteric

the network of nerves that regulate digestive motility, secretion, and blood flow is called the _____ system

enteric nervous

The ____ cells are associated with chemical regulation of digestion.

enteroendocrine

Which of the following enzymes does not digest any nutrients?

enteropeptidase

Which protect the stomach lining from the acidic contents?

epithelial cell replacement, tight junctions, and mucous coat

Which phases of swallowing are involuntary?

esophageal and pharyngeal

Which describes segmentation?

non-migrating constrictions and relaxations along the intestines

cusps are a feature of the ____ surfaces of the molars and premolars

occlusal

Where is sucrase found in the human body?

on. the microvilli of the small intestine

how is water absorbed from digestive tract?

osmosis

Defecation is stimulated by ____ and ____ reflexes

parasympathetic; local

The ____ cells secrete the substance that converts pepsinogen to pepsin as well as a hormone that regulates appetite.

parietal

the ____ salivary gland is named for its proximity to the ear

parotid

The chief cells of the stomach secrete ____ into the stomach lumen; which is the presence of HCl becomes ____, the active form of the enzyme.

pepsinogen; pepsin

Role of liver in digestion:

produces bile for fat emulsion

a _____ is any enzyme that digests protein

protease

Replacing both surface cells as well as glandular cells, the ____________ cells divide rapidly

regenerative

The absorption of carbohydrates from the intestinal lumen occurs directly through _____ transport

secondary active

Which of the following is not an enzyme?

secretin

Which hormones inhibit gastric gland secretions?

secretin, gastric inhibitory peptide, and cholecystokinin

Hepatic macrophages occur in blood-filled spaces of the liver called _____.

sinusoids

Which of the following statements is true regarding sucrase?

sucrase breaks sucrose into glucose and fructose

T or F: Distention of the stomach activates a direct stimulatory effect on the gastric glands.

true

T or F: when two different people consume the same food, it is possible that one receives a different number of calories from that food because of differing bacterial populations in the large intestine

true

The ___ cells are found mostly in the proximal and distal regions of the stomach.

mucous

How is HCl made?

-CO2 diffuses into parietal cell; carbonic anhydrase catalyzes reaction b/w CO2 and H2O to form carbonic acid (H2CO3) -carbonic acid dissociates into bicarbonate ion (HCO3-) and H+ -bicarbonate ion transported back into blood stream; exchange bicarbonate (going out) for Cl- (coming in) -H+ ions actively transported into duct of gastric gland; Cl- ions electrically attracted; K+ ions counter-transported into parietal cell in exchange for H+

Functions of Hydrochloric Acid

-activates enzymes pepsin and lingual lipase -breaks up connective tissues and cell walls of plants -destroys most ingested pathogens -converts iron to an absorbable form

Which of the following is a function of the bacterial flora?

-bacteria digest cellulose -synthesize vitamin K

Which of the following statements is true regarding the absorption of nutrients?

-carbohydrates are absorbed as monosaccharides -micelles are required for lipid absorption

Mass movements in the colon are stimulated by the presence of ____ in the _____.

-food; stomach -chyme; duodenum

Which of the following occurs during the gastric phase of gastric secretion?

-gastric secretion begins -secretion of HCl and pepsin is stimulated -gastric activity is stimulated in response to food increasing the pH of the stomach's contents

Which the following statements is true regarding the neural control of defecation?

-intrinsic defecation reflex results in feces moving from the sigmoid colon to the rectum -external anal sphincter is under voluntary control -parasympathetic defecation reflex helps relax the internal anal sphincter

Which of the following is achieved with small intestinal muscle contractions?

-mixing of chyme with secretions -increased contact of chyme with intestinal lining -propelling of contents along the intestines

Purpose of intestinal motility:

-move residue along digestive tract -mixes chyme with secretions -brings chyme into contact with intestinal lining

Which of the following statements is/are true regarding the regulation of digestive secretions?

-pancreatic enzymes are under both neural and hormonal control -via the vagus nerve, acetylcholine stimulates the pancreatic acini

functions of the pancreas include:

-secrete zymogens -secrete enzymes that digest fat and deoxyribonuclease -secretes an enzyme that digests carbohydrates

Functions of secretin:

-secreted in response to chyme's low pH -results in sodium bicarbonate release by the liver and pancreas -ultimately protects the intestinal wall from HCl -helps flush pancreatic enzymes into the duodenum

functions of cholecystokinin

-secreted in response to fats in the small intestine -strong stimulatory effect on gallbladder -stimulates secretion of pancreatic amylase and pancreatic lipase -relaxed the sphincter of the hepatopancreatic ampulla -eventually leads to the emulsification of lipid globules -stimulates bile release into the duodenum

Which of the following is a method of motility in the small intestine?

-segmentation -peristalsis -migrating motor complex

The functions of the gallbladder include:

-stores the substance that breaks globules of fat into droplets -contraction is induced by cholecystokinin

Functions of the liver include:

-synthesizes bile and bile acids -releases its secretions into the bile canaliculi

What is a goblet cell?

A mucus-secreting epithelial cell that distends with mucin before secretion and collapses to a goblet shape after secretion.

What are the microscopic structural subunits of the liver?

Hepatic lobules

the luminal diffusion of Na+ to the ____ is coupled with glucose and galactose _____ into the cell

ICF; cotransport

The acidity of the stomach halts the action of _____ but promotes the action of _____, both of which are salivary enzymes.

amylase; lipase

T or F: chemical digestion is a series of chemical reactions that break large chunks of food into proteins, carbohydrates, and fats.

false: Chemical digestion is a series of hydrolysis reactions that break dietary macromolecules into their monomers: polysaccharides into monosaccharides, proteins into amino acids, fats into monogylcerides and fatty acids, and nucleic acids into nucleotides

T or F: the term contact digestion refers to the fact that segmentation must occur in order to propel intestinal contents distally within the digestive tract.

false; Each absorptive cell of a villus has a fuzzy brush border of microvilli about 1 μm high. The brush border increases the absorptive surface area of the small intestine and contains brush border enzymes in the plasma membrane. They carry out some of the final stages of enzymatic digestion. They are not released into the lumen; instead, the chyme must contact the brush border for digestion to occur. This process is called contact digestion.

T or F: the medulla oblongata controls gastric secretion by utilizing the parasympathetic branch of the nervous and endocrine system.

false; the medulla oblongata is a nervous system structure only and doesn't have endocrine function

anatomically, the ____ of the stomach most closely resemble the ____ of the small intestine

gastric pits; intestinal crypts

Food in the stomach causes G cells to secrete _____, which in turn stimulates the secretion of HCl and pepsinogen.

gastrin

which of the following is a periodontal tissue?

gingiva

Which of the following is a feature that the stomach and the small intestine have in common?

goblet cells

all of the following contribute to the absorptive surface area of the small intestine except: -its length -the brush border -haustra -circular folds -villi

haustra

which blood vessels carry blood to the liver?

hepatic portal vein and hepatic artery

secretin is an example of a _____

hormone

HCl is formed when ____

hydrogen ions and chloride ions join in the duct of the gastric gland

The selective intake of food is known as ____.

ingestion

What phase of gastric regulation includes the inhibition by the enterogastric reflex?

intestinal phase

dysfunction in _____ could cause pernicious anemia

intrinsic factor -essential to absorption of vitamin B12

Within the absorptive cells of the small intestine, ferritin binds the nutrient _____.

iron

The primary function of the ____ intestine is to absorb water and electrolytes, but not other nutrients

large

Which of the following enzymes acts in the stomach?

lingual lipase

How often can a sucrase molecule be used to hydrolyze sucrose?

many times

The peristaltic movement of colonic contents triggered by the gastrocolic reflex approximately 1-3 times per day is called ____.

mass movement

T or F: Mass movements of the colon propel its contents toward the rectum.

true: Strong contractions of the colon called mass movements occur one to three times a day, last about 15 minutes, and move residue several centimeters at a time. They are often triggered by the gastrocolic and duodenocolic reflexes, in which filling of the stomach and duodenum stimulates motility of the colon. Mass movements occur especially in the transverse to sigmoid colon, propelling colonic contents toward the rectum

After contacting the intestinal enzyme enteropeptidase, ____ is converted into ______

trypsinogen; trypsin

what are the typical end products of triglyceride digestion?

two free fatty acids + monoglyceride

nervous stimulation of gastrointestinal activity is mediated mainly through the parasympathetic fibers of the ____ nerves

vagus

Process of forcefully ejecting stomach or intestinal contents via the esophagus or mouth

vomiting

Which of the following are found in intestinal juice?

water and mucus; very little enzymes

3 components of gastric juice

water, pepsin, HCl