The digestive system Flashcards
(102 cards)
1
Q
Digestion
A
-rendering soluble semi-solid or solid substances
2
Q
Ingestion
A
food taken into the body
3
Q
Propulsion
A
-process that moves food through the alimentary canal
a. swallowing (voluntary)
b. peristalsis (involuntary)
4
Q
peristalsis
A
-progressive, wavelike contractions that move foodstuffs through the alimentary canal
5
Q
Mechanical digestion
A
-physically breaking apart bigger particles into smaller particles
ex: chewing, churning
6
Q
chewing (mastication)
A
-breaking food into smaller pieces to increase total surface area
7
Q
churning
A
-happens in the stomach
-mix food with enzymes
8
Q
segmentation
A
-done in the small intestines
-non-adjacent segments of alimentary canal contract and relax
9
Q
hydrolysis
A
-break down of carbohydrates, proteins, or lipids into smaller usable molecules with the addition of water
-ex of chemical digestion
10
Q
Chemical digestion
A
-directed by enzymes secreted into the alimentary canal or tethered to its walls (brush border enzymes)
11
Q
Absorption
A
movement of molecules from the GI tract into the blood or lymph (through the mucosal cells)
12
Q
defecation
A
-elimination of indigestible substances from the body
13
Q
What are the two main groups of organs of digestion
A
- Alimentary Canal (GI tract)
- Accessory Organs
14
Q
Alimentary canal
A
-also called gastrointestinal tract
-a continuous tube running from mouth to anus (30ft long in cadaver)
15
Q
Accessory organs
A
-food does not pass through accessory organs
-accessory organs lay outside of the GI tract and connect to it through duct
-are also some accessory organs located in the oral cavity
16
Q
Accessory organs in the oral cavity
A
- teeth
- tongue
17
Q
Accessory organs that lay outside of the GI tract and connect to it through ducts
A
- Liver
- Gall bladder
- Pancreas
- Salivary Glands
18
Q
Tissue lining the mouth (oral cavity-buccal)
A
stratified squamous epithelium
19
Q
Structures associated with oral cavity
A
- Lips and Cheeks
- Palate
- Tongue
- Salivary glands
- teeth
20
Q
Lips and Cheek: job
A
-keeps food between teeth when we chew
-assist in speech
21
Q
Palate: job
A
-roof of mouth
- anterior = hard palate, posterior = soft palate (include uvula)
- palatine tonsils
22
Q
Tongue: Job
A
-helps with swallowing, speech, taste buds, mixes food with saliva to create bolus, repositions food between teeth
23
Q
Salivary glands: job
A
-produce saliva
-contains parotid, submandibular, and sublingual
24
Q
Parotid Glands
A
-lay anterior to ears
-secrete saliva into ducts that open near the upper second molar
25
Submandibular gland
-lay along the medial aspect of the mandibular body
-secrete saliva into ducts that open on ether side of the lingual frenulum (median fold that secretes tongue to floor of oral cavity
-under the mandible
26
sublingual glands
-lay anterior to the submandibular glands under the tongue
-secrete saliva into ducts that open into the floor of the mouth
27
saliva: what is it
-lubricates, dissolves, and chemically breaks down food
-increase in production when food enters mouth (or with sight and smell of food)
- 1-1.5 L produced per day
28
Saliva: composition
-97-99.5% H2O
Solutes:
-electrolytes (Na+, K+, Cl-)
- mucous
-lysozyme (bacteriolytic)
- metabolic wastes
-enzymes: salivary amylase (converts starch --> maltose)
lingual lipase (converts glycerides --> glycerol and fatty acids)
29
Deciduous teeth (milk or baby teeth)
-emerge between 6 mos. and 2 years of age
-20 teeth total
30
permanent teeth
-replace deciduous teeth between 6-12 years of age
-32 teeth total
31
Incisors
-8 total in your mouth
-4 per jaw
32
canines (cuspids)
- 4 in total
-2 per jaw
33
premolar (bicuspids)
-8 in total
-4 per jaw
34
Molars
-12 in total
-6 per jaw
35
crown
area above the gingiva (gum)
36
Enamel
-brittle ceramic-like substance
-hardest substance in the body
-heavily mineralized with calcium salts and densely packed mineral crystals called hydroxyapatite
-bears the force of chewing
-cells producing enamel degenerate when a tooth erupts- as a result, the enamel will not heal
37
dentin
-protein-rich bone-like material that acts as a shock absorber
-also penetrates into the root
38
odontoblast
-cells that secrete and maintain dentin
39
Pulp Cavity
-includes connective tissue, blood vessels, and nerve fibers
-collectively called pulp
-supplies nutrients to tooth
-provides tooth sensation
40
root
-area of tooth embedded in jaw bone
41
cementum
-calcified connective tissue covers the outer surface of the root
-attaches the tooth to the periodontal ligament that connects the tooth to the underlying bone
42
root canal
-where pulp cavity extends into the root
43
how to cavities form
-dental carries
1. a film of bacteria and sugar (dental plaque) sticks to the surface of teeth
2. bacterial metabolize the sugar and make acid as a byproduct
3. the acid dissolves the calcium salts of the teeth
44
How does periodontal disease progress
1. dental plaque calcifies and forms calculus (tartar)
2. as it grows the calculus pries apart the seal between the gums and tooth
3. the bacteria infect the gingiva and multiply within deep pockets between the gingiva and tooth
4. bacteria dissolve periodontal ligament and activated immune cells activate osteoclasts
5. activated osteoclast dissolves the surrounding bone
-accounts for 80-90% of tooth loss
45
Pharynx
-contains the nasopharynx, oropharynx, and laryngopharynx
-air goes into all three, but food goes into the oropharynx and laryngopharynx
46
Deglutition
-swallowing
1. tongue rises
2. uvula closes off the nasopharynx
3. epiglottis seals glottis
4. food is forced into the esophagus
47
esophagus
-the muscular tube that is 10 inches in length
-posterior to the trachea
-lined with stratified squamous epithelium
48
upper esophageal sphincter
-located at the entrance to the esophagus
-opens to let food enter during swallowing
-peristalsis begins here
49
Lower esophageal sphincter (LES)
-also called gastroesophageal sphincter or cardiac sphincter
-located where the esophagus joins the stomach
-opens to let food enter the stomach
50
Swallowing times for food
4 seconds
51
swallowing times for fluid
1-2 seconds
52
stomach
-lays in the upper left quadrant of the abdominopelvic cavity
-forms chyme (food that becomes a creamy paste)
-lined by simple columnar epithelium (all subsequent GI tract organs up until the rectum are lined with this)
-lining contains millions of gastric pits--> lead to gastric glands
53
secretory cells lining the gastric glands make what?
gastric juices
54
What are the 4 areas of the stomach?
-cardia
-fundus
-body
-pylorus
55
pyloric sphincter
-located where the stomach and small intestine join
56
duodenum
-first part of the small intestine
57
Greater curvature
-lateral curve of stomach where the greater omentum attaches here
58
lesser curvature
-the medial curve of the stomach
-lesser omentum attaches here
59
rugae
-large longitudinal folds of the inner lining that allow for distension of the stomach
60
What are the three layers of muscle in the stomach wall
1. oblique
2.circular
3. longitudinal
61
Where are secretory cells located
-in gastric pits
62
chief cells
-zymogenic cells
-produced pepsinogen (pepsin digest proteins)
63
parietal cells
-produce HCL and intrinsic factor
-HCL kills microbes and denatures (unfolds) proteins
-intrinsic factors assist with the absorption of vitamin B12 in the small intestine
64
What is the pH of the stomach
1.5-3
65
Goblet cells
-produce mucous (to protect the lining of stomach)
66
Small intestine
-named for its small diameter
-the longest segment of the digestive tract
-extends from pyloric sphincter to ileocecal sphincter (valve)
67
What are parts of the small intestine contain
1. duodenum (10ft)
2. jejunum (8ft)
3. ilium (12ft)
total 22 ft
68
plicae circulars
-circular folds
-seen in the lumen of the small intestine
-forces chyme to spiral through lumen
-slows movement and increases contact time
69
villi
-fingerlike projections of the mucosa that extend into the lumen
-increasing surface area for absorption
70
simple columnar epithelium in GI tract
-small intestine lined by one layer of column-shaped epithelial cells
-specialed for reabsorption of the nutrients-high rate of mitosis (cell division)
-renews every 2-4 days
71
microvilli
-tiny surface projections of the surface cells (columnar epithelial cells) lining the small intestines
-increases the surface area for reabsorption of nutrients
-gives the mucosal surface a fuzzy appearance (referred to as the brush border)
72
brush border enzymes
-attached to this surface (small intestine) complete the digestion of carbohydrates and proteins
73
intestinal crypts
-secrete intestinal juice (1-2 L absorbed/produced per day)
-stimulus for secretion: stretch or irritation
-mostly water and mucous
-contains few enzymes (produced by brush border)
74
Peyer's patches
-mucosa-associated lymphoid tissue present in the submucosa of the small intestine
-concentrations of white blood cells positioned to identify pathogens and initiate immune responses
75
cecum
-blind-ended pouch that hands below the ileocecal valve
76
appendix
-blind-ended tubular structure extending from the cecum
-walls contain MALT
-a storehouse for normal gut bacteria (normal flora)
-can become twisted or blockage which can lead to appendicitis
77
What are the four areas of the colon
1. ascending colon
2. transverse colon
3 descending colon
4 sigmoid colon
78
Characteristics of the large intestines
-5ft in length
-taeniae coli
79
taeniae coli
-3 longitudinal bands of smooth muscle within large intestine walls
-contraction of smooth muscle results in pocket-like sacs called haustra
80
haustra
-series of pouches
-foodstuff travels from pouch to pouch as it dehydrates and becomes feces
81
Functions of Large Intestine
-chemical digestion of non-digested carbohydrates
-accomplished by fermentation via normal flora (bacteria) --> gas (flatus)
-absorb water
-absorb vitamins B and K which are synthesize by normal flora (bacteria) here
82
What are the four lobes of the liver
1. right lobe
2. left lobe
3. caudate lobe
4. quadrate lobe
83
falciform ligament
-separates the right and left lobes and suspends the liver from the diaphragm and anterior abdominal wall
84
Liver
-each lobe is separated into lobules
85
hepatocytes
-liver cells
-main functional cells of the liver
-they process nutrient-rich blood, detoxify the blood, store glucose as glycogen, produce plasma protein, store vitamins, and irons, produce bile
86
sinusoids
-blood in sinusoids passes by hepatocytes
-allowing hepatocytes to perform blood-related functions (detoxifying)
87
Kupfer cells
-macrophages
-sweep along inside sinusoids and remove debris and worn-out red blood cells
88
central vein
-collects blood from sinusoids (blood processed by hepatocytes)
- blood from central veins ultimately delivered to hepatic veins --> inferior vena cava
89
bile canaliculi
-collect bile produced by hepatocytes
-deliver the bile to microscopic bile ducts (at 6 corners of lobule)
90
portal triad
-at each of the six corners of the lobule
91
a branch of the portal arteriole
-delivers fresh oxygenated blood into sinusoids (for oxygen delivery to the hepatocytes)
-blood of the portal arterioles ultimately originated from the common hepatic artery
92
a branch of the portal venule
-delivers nutrient-rich blood to sinusoids
-blood of the portal venules ultimately originated from the hepatic portal vein (draining the intestines)
93
bile duct
-collects bile from bile canaliculi
-these microscopic bile ducts ultimately deliver the bile to the right and left hepatic ducts (which carry the bile out of the liver)
94
carbohydrate digestion: mouth
site of action: mouth
enzyme: salivary amylase (ptyalin)
foodstuff: helps breakdown starch into oligosaccharides (dextrins)
*where digestion first starts
95
Carbohydrate digestion: small intestine
site of action: small intestine
enzyme: pancreatic amylase
foodstuff: helps breakdown starch into oligosaccharides (dextrin)
enzyme: intestinal enzymes (dextrinase and glucoamylase) (brush border enzymes)
foodstuff: breaks down oligosaccharide (dextrins) into maltose
enzyme: intestinal enzymes (lactase) (sucrase)
foodstuff: breaks down lactose into glucose and galactose
breaks down sucrose into fructose and glucose
96
Maltose: gets broken down into
enzyme: maltase
broken into: glucose and glucose
97
Sucrose: gets broken down into
enzyme: sucrase
broken into: glucose and fructose
98
lactose: gets broken down into
enzyme: lactase
broken into: glucose and galactose
99
chemical digestion of proteins: stomach
site of action: stomach
enzyme: pepsinogen which gets converted to pepsin by HCL
foodstuff: proteins get broken down into larger polypeptides
100
chemical digestion of proteins: small intestine
site of action: small intestine
enzyme: trypsinogen --> trypsin
chymotrypsinogen --> chymotrypsin
procarboxypeptidase --> carboxypeptidase
foodstuff: breaks down larger polypeptides into small polypeptides (small peptides)
* enzymes are called enteropeptidase which is secreted by the cell lining of the duodenum and activates the enzymes
enzyme: intestinal enzymes (aminopeptidase dipeptide and carboxypeptidase) are brush border enzymes
foodstuff: amino acids
101
digestion of lipids: small intestines
site of action: small intestines
enzyme: bile (not an enzyme)
foodstuff: bile emulsifies triglycerides into smaller fat droplets
enzyme: pancreatic lipase
foodstuff: lipase chemically breaks down smaller fat droplets into glycerol and fatty acids
102
lingual lipase
-formally begins digestion of lipids in mouth
