A&P 2 - Chapter 22: The Digestive System
Why is the small intestine so long?
Both digestion and absorption are dependent on diffusion - a slow process. Digestion is also dependent on a wide range of enzymatic processes to reduce food to absorbable fragments. The long SI gives the GI tract the time it needs to carry these processes out. Herbivores (plant eaters) need an even longer SI tract to allow the breakdown of plant material by microbes.
Place the following events related to lipid digestion in order.
CCK stimulates gallbladder Emulsification of fats Pancreatic lipases begin to digest triglycerides Micelles form Diffusion across luminal membrane Free fatty acids enter endoplasmic reticulum Chylomicron forms Movement across basolateral membrane Chylomicron enters lacteal
Which of the following are most rapidly cleared from the stomach after eating?
Carbohydrates
Which of the following nutrients are commonly found in human food?
Carbohydrates Proteins Fats
Digestion refers to the process by which:
Complex molecules are broken down into simple ones.
Stomach acid secretion is the result of:
Conversion of H2O to H+ and OH-.
Which of the following might be a consequence of bariatric surgery, where a "band" is placed around the stomach in order to reduce its volume?
Digestion would be decreased and fewer nutrients would be absorbed.
Arrange the following in the order they would be encountered by an ingested food molecule:
Duodenal mucosa Hepatic portal vein Sinusoid Hepatocytes Central vein Hepatic vein Vena cava Right atrium of heart Systemic artery
Match the following with their function.
Enterocolic reflex - Activates large intestine motility in response to stomach stretching Duodenocolic reflex - Activates large intestine motility in response to small intestine stretching Segmentation contraction - Occur infrequently in the large intestine Peristaltic contractions - Carry chyme over large distances in the large intestine
During which phase of swallowing does food enter the stomach?
Esophageal phase
The products of protein digestion are resynthesized into protein within intestinal epithelial cells, and packaged for transport in the lymph.
False
Match each cell type with the molecule it releases.
G cell - Gastrin Parietal cell -Hydrochloric acid Enterochomaffin cell (ECL) - Histamine D cell - Somatostain Vagal neuron - Acetylcholine
In response to stretch/distension of the duodenum:
Gastric contractions decrease.
Which of the following cranial nerves stimulates saliva production?
Glossopharyngeal
Amino acids are absorbed from the small intestine into _________ , which delivers them to the ____________ .
Hepatic portal vein; liver
Which of the following is an example of the gastric phase of gastric digestion?
Increased HCl secretion in response to Gastrin.
Why does the large intestine not contain villi and microvilli?
It is not specialized for absorption. Most nutrient absorption occurs in the small intestine.
Bile is produced by the ______________ and stored in the ______________.
Liver, gallbladder
Rank the following structures in order from smallest to largest.
Microvilli Villi Plicae
The innermost layer within the digestive tract is the ___________.
Mucosa
Which of the following are produced in the gastric pit?
Mucus
Which of the following are secreted into the large intestine?
Mucus
Place the following structures in the correct sequence, starting from the LUMEN of the small intestine.
Muscularis mucosa Submucosa Muscularis externa Serosa
Which of the following is not an accessory tissue or organ that aids in the digestion of food?
Olfactory epithelium
A 43-year-old man presented to the emergency room one clear Tuesday morning complaining of severe pain in his epigastric and umbilical regions. He described the pain as a burning sensation that occurred as he was sitting in rush hour traffic. He was concerned that he may be having a heart attack, so he got to the hospital as fast as he could. Upon further investigation, his physician found that this was not the first time he had experienced this pain. He had frequent nausea and occasional vomiting, but noticed that the pain is worse between meals. He had a high-stress job and took antacids regularly for heartburn. He noted that during the last month, he had been very tired and had dark colored stools. What is a possible diagnosis?
Peptic ulcer
What type of contraction pushes food through the digestive tract?
Peristalsis
Peristalsis differs from segmentation in that:
Peristalsis pushes food through the digestive system, segmentation does not.
Match each intestinal feature with its major function.
Peyer's patch- Supports the immune system Villi - increase surface area for digestion and absorption Goblet cell - Protects the small intestine from stomach acid and abrasion Endocrine cell - Produce the hormone secretin Intestinal crypts - contains stem cells
Which of the following is not a normal function of the stomach?
Absorption of amino acids.
Which of the following is not a normal function of the large intestine?
Absorption of nutrients
Normal gut flora:
Aid in the production of some vitamins. Have more cells that all of the human cells in the body. Affect the development of the immune system. Digest complex carbohydrates.
Which of the following statements about protein utilization in humans is false?
Amino acids can be stored in the liver.
Mesenteries:
Anchor the small intestine to the peritoneal wall.
A 22-year-old girl presented to the emergency room for nausea, vomiting, fever, and abdominal pain. On physical examination, her abdominal pain was located to the right iliac region. The pain she was experiencing is classified as rebound tenderness, meaning when pressure is applied, there is no pain, but when pressure is released there is extreme pain. Given the location of the pain and the presentation, what would be the presumptive diagnosis?
Appendicitis
Which of the following does not occur during the cephalic phase?
Release of secretin from the small intestine
Which transporter allows glucose to move against a concentration gradient?
SGLT1
Match the following molecules with its function.
Trypsin - A peptidase that activates other peptidases Chymotrypsinogen - An inactive endopeptidase released from pancreatic vesicles Enterokinase - An enzyme of the intestinal mucosa Carboxypeptidase - An exopeptidase
What can you deduce from the fact that the large intestine wall is composed of simple columnar epithelia?
Water absorption by the large intestine does not require plicae.
Click on the location of the receptors for gastrin.
basal membrane
Which labeled structure releases bile in response to CCK?
gall bladder
Which structure contains haustra?
large intestine
Which structure is the parotid gland?
on side of face
Which structure releases HCO3 in response to secretin?
pancreas
What structure(s) in her mouth are the cause of the intense pain?
salivary gland
Which labeled structure contains rugae?
stomach
Where do the bacteria that colonize the large intestine come from in a newborn baby?
They come from breast or bottle-feeding, or when the baby puts their fingers in their mouths.
What is the role of the pharynx?
To act as a pathway for CO2 to leave the body.
Place the following regions of the stomach in the order they would be encountered by a food molecule.
- Cardiac - Fundus - Body - Pyloric
Match each of the following digestive tract structures with its general function.
- Oral cavity - Contains salivary glands - Duodenum - major site of digestion - Colon - Major site of water absorption - Esophagus - connects pharynx to stomach - Stomach - Begins enzymatic digestion of proteins - Pharynx - Connects mouth to esophagus - Rectum - terminal end large intestine
Villi formation is due to contraction of cells in the mucosal layer of the digestive tract.
True
Swallowing is controlled by which of the following nerves?
- Trigeminal - Glossopharyngeal - Vagus
Arrange the teeth in the order they would be encountered, starting at the midsagittal plane and moving laterally.
- incisor - canine - pre-molar - molar
Place the tissue layers of the digestive tract in the order you would encounter them moving from the lumen toward the abdominal cavity.
- mucosal epithelium - lamina propria - muscularis mucosa - submucosa - circular layer of smooth muscle - myenteric plexus - longitudinal layer of smooth muscle - serosa
Acid formation in the stomach is a result of _________.
Secretion
Chyme moves ___________ through the small intestine because ____________ .
Slowly; the frequency of segmentation contractions is higher in the jejunum than in the ileum
Why are three muscles used to close the jaw but only one muscle used to open it?
Strength is needed to crush food to begin the digestive process, while opening the jaw is not usually under a load.
Lacteals:
Surround capillaries, venules, and lymphatic vessels.
Which of the following is NOT associated with bile?
Synthesis in gall bladder
Why are dietary triglycerides digested to free fatty acids and glycerol, if they are then recombined to form triglycerides within the cell?
TGs cannot cross the cell membrane, while FFA can.
Why is the lumenal surface of the digestive tract lined with epithelium?
The digestive tract is in direct contact with the outside world through the food and fluids we eat and drink. It needs to protect itself in the same way as does the skin. The epithelial layer and the immune presence inside the GI tract protect against microbes that would do us harm
The intestinal phase is triggered by ____________.
The presence of chyme in the small intestine
Why is the stomach one of the few places within the digestive tract that has three layers of smooth muscle within its wall?
The stomach needs to mix (segmentation) as well as push food through the pyloric sphincter (peristalsis). This requires the extra layer of muscle and suggests that less mixing occurs in other parts of the digestive system.
What is/are the result of damage to the myenteric plexus within the wall of the GI tract?
changes in gastric motility
Which structure releases secretin?
duodenum
Which structure closes the airways during swallowing?
epiglottis
