Digestive System Flashcards
1
Q
What does the GI tract consist of?
A
- mouth
- pharynx
- esophagus
- stomach
- small intestine
- large intestine
2
Q
Why is the GI tract considered part of the external environment?
A
- the GI tract is a continuous tube extending from the mouth to the anus
3
Q
What are the accessory digestive organs?
A
- liver
- pancreas
- gallbladder
4
Q
What do accessory organs do?
A
- produce/store secretions that assist in the digestion of food
5
Q
What is digestion?
A
- the breaking down of ingested food (mechanical digestion vs. chemical digestion)
6
Q
What is absorption?
A
- the entry of nutrients into the cells lining the GI tract en route to the blood or lymph
7
Q
What is defecation?
A
- the elimination of wastes and indigestible substances
8
Q
What are the four layers of tissue surrounding the lumen in the GI tract?
A
(deep to superficial)
- mucosa
- submucosa
- muscularis
- serosa
9
Q
What is the mucosa?
A
- inner lining composed of layers of epithelial tissue, connective tissue and smooth muscle
10
Q
Discuss the epithelial tissue layer of the mucosa.
A
- contains glandular cells that serve both exocrine functions (secrete mucous and fluid) and endocrine functions (secrete hormones)
11
Q
Discuss the connective tissue layer of the mucosa.
A
- contains blood vessels and lymphatic vessels that collect absorbed nutrients
12
Q
Discuss the smooth muscle layer of the mucosa.
A
- creates folds in the lining of the stomach and small intestine that increase the surface area for digestion and absorption
13
Q
What is the submucosa?
A
- mass of connective tissue that binds the mucosa to the muscularis
- contains blood vessels, lymphatic vessels, and a plexus of neurons that belong to the enteric nervous system
14
Q
What is the muscularis made up of?
A
- layers of skeletal muscle (mouth, pharynx, upper esophagus)
- smooth muscle (the rest of the GI tract)
15
Q
What is the purpose of the muscularis?
A
- contraction of these muscles assists in the mechanical digestion and movement of food through the GI tract (“motility”)
16
Q
What is “peristalsis”?
A
- wave-like muscle contractions that moves food to different processing stations in the digestive tract
17
Q
What is the serosa?
A
- a mixture of connective tissue and epithelial tissue that forms part of the
peritoneum - helps suspend the portions of the GI tract that are located within the abdominal cavity
18
Q
What is “mesentery”?
A
- portion of the peritoneum that suspends the small intestine
19
Q
What are the role of teeth in regards to digestion?
A
- assist in the mechanical digestion of food
20
Q
What is the role of the tongue in regards to digestion?
A
- mechanical digestion of food
- taste sensations (CN VII, CN IX)
- contains glands which secrete a digestive enzyme that assists in the chemical digestion of lipids (in the stomach)
21
Q
What is the hard palate?
A
- anterior portion formed by the maxillae and palatine bones (covered by a mucous membrane)
22
Q
What is the soft palate?
A
- posterior portion formed by skeletal muscle (covered by a mucous membrane)
23
Q
What is the the uvula?
A
- muscular process that hangs off the posterior border of the soft palate
24
Q
What makes up the palate and what does it do?
A
- hard and soft palate
- uvula
- during swallowing, the soft palate and uvula are pulled superiorly to prevent food from entering the nasal cavity
25
What are salivary glands and what do they do?
- secrete saliva
| - receive sympathetic innervation and parasympathetic innervation (CN VII, CN IX)
26
What is saliva made of?
- mixture of water, ions, and a digestive enzyme
27
What are the functions of saliva?
- keep the mucous membranes of the mouth, pharynx, and esophagus moist
- assist in the chemical digestion of carbohydrates
28
What is the pharynx and what is its purpose?
- passageway for food from the mouth to the esophagus
- muscular contractions in these areas help to propel food along and prevent it
from entering the larynx (epiglottis)
29
What is the esophagus?
- muscular tube that functions as a passageway for food from the pharynx to the stomach
30
Where is the esophagus?
- descends through the thoracic cavity posterior to the trachea and enters the
abdominal cavity through the esophageal hiatus in the diaphragm
31
What is the esophagus made of?
- sphincters of smooth muscle at either end, which regulate the passage
of food into (upper esophageal sphincter) and out of (lower esophageal
sphincter) the esophagus
32
Describe the shape and location of the stomach.
- j-shaped organ located just inferior to the diaphragm in the upper left quadrant
of the abdominal cavity
33
What are the main functions of the stomach?
- assist in the mechanical and chemical digestion of food
| - store partially digested food before it enters the small intestine
34
What is the pyloric sphincter?
- a sphincter of smooth muscle, which regulates the
| passage of food into the small intestine
35
Within the stomach’s folded mucosa, there are a host of gland cells. What are their names?
- exocrine gland cells
| - endocrine gland cells
36
What do exocrine gland cells do in the stomach?
- secrete “gastric juice”, which contains acid (HCl) and digestive enzymes that assist in the chemical digestion of food
37
What do endocrine gland cells do in the stomach?
- secrete a hormone (gastrin) that stimulates gastric secretions and motility
38
What is a peptic ulcer?
- the acid that is secreted
| in the stomach erodes the mucosa of the stomach or duodenum and cause pain and bleeding
39
What are some common causes of peptic ulcers?
- bacterial infection
- chronic use of NSAIDs
- both of which inhibit the release of protective mucous secretions
40
How long is the small intestine?
- 3m
41
What is the small intestine?
- highly-convoluted tube in the middle of the abdominal cavity that connects the stomach to the large intestine
42
What is the purpose of the small intestine?
- the primary site of both digestion (mechanical and chemical) and absorption of food along the GI tract
43
What are the three parts of the small intestine?
- (proximal to distal)
- duodenum
- jejunum
- ileum
44
Describe the small intestines mucosa.
- highly folded
45
What do the exocrine gland cells in the small intestine do?
- secrete “intestinal juice”, which contains digestive enzymes that assist in the chemical digestion of food
46
What do the endocrine gland cells in the small intestine do?
- secrete hormones that:
- stimulate the release of bicarbonate (pancreas)
- stimulate the release of digestive enzymes (pancreas) and bile (gallbladder)
47
What does bicarbonate do?
- buffers the stomach’s acid in the small intestine
48
What do digestive enzymes and bile do?
- assist in the chemical digestion of food
49
What is the large intestine?
- tube that functions as a passageway for the by-products of digestion from the small intestine to the anus
50
What is flatulence?
- gas
| - farts lol
51
What is the purpose of the large intestine?
- contains an abundance of bacteria that assist in the final stages of chemical digestion, a process that produces gas (flatulence) as well as some vitamins
52
What are some functions of the large intestine?
- absorption of water, ions, and some vitamins
| - elimination of digestive wastes and indigestible products
53
List the areas of the large intestine?
- appendix
- cecum
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum and anal canal
54
What are the names of the two sphincters in the large intestine?
- ileocecal sphincter
| - anal sphincter
55
What is the ileocecal sphincter's purpose?
- smooth muscle sphincter that regulates the passage of material from the small intestine into the large intestine
56
What is the anal sphincter's purpose?
- smooth muscle (internal anal sphincter) and skeletal muscle (external anal sphincter) sphincters that regulate the passage of material out of the large intestine
57
Where is the pancreas located?
- located posterior to the stomach
58
What is the pancreas' purpose in the GI tract?
- secretes “pancreatic juice” into the GI tract (exocrine function)
59
What does “pancreatic juice” do?
- contains bicarbonate and digestive enzymes that
assist in the chemical digestion of food, is carried from the pancreas to the
duodenum by two small ducts
60
Where is the liver located?
- inferior to the diaphragm in the upper right quadrant of the abdominal cavity
61
What are the livers functions?
- secretes bile
- detoxifies the blood
- involved with the metabolism of carbohydrates, lipids, and proteins
- stores glucose (glycogen) as well as several vitamins and minerals
- produces the active form of vitamin D
62
Where is the gallbladder located?
- tucked up into the inferior surface of the liver
63
What is the purpose of the gallbladder?
- stores and concentrates the bile produced by the liver and releases it into the small intestine when needed
64
The liver receives blood from which two vessels?
- hepatic artery (a branch of the celiac trunk) – carries oxygenated blood to the liver
- hepatic portal vein – carries nutrient-rich deoxygenated blood from the GI tract to the liver
65
What is jaundice
- the liver’s ability to form bile becomes compromised (e.g., hepatitis, cirrhosis) or if
there is a blockage of the release of bile into the GI tract (e.g., gall stones), excess
bilirubin will accumulate in the blood
- results in yellowish tinge
66
Discuss the regulation of the digestive system.
- receives sensory input from the GI tract (chemoreceptors, stretch receptors)
- sends motor signals to the glands and smooth muscle of the GI tract
