Chapter 24 Flashcards
1
Q
Digestive system and homeostasis:
A
- Breaks down food to be absorbed and used by body cells
- absorbs water vitamins and minerals
- eliminates waste from body
2
Q
Basic processes of the digestive system:
A
- ingestion
- secretion - walls of GI tract
- motility - mixing and propulsion
- digestion - mechanical and chemical
- absorption - blood and lymph
- defecation - wastes
3
Q
Organs of the GI tract:
A
- mouth
- pharynx
- esophagus
- stomach
- small intestine
- large intestine
4
Q
Accessory digestive organs:
A
- Teeth
- Tongue
- Salivary Glands
- Liver
- Gallbladder
- Pancreas
5
Q
What are the 4 basic layers of the GI tract?
A
Mucosa, submucosa, muscularis, serosa
6
Q
What are the 3 layers of the MUCOSA that lines the GI tract?
A
- Epithelium
- Lamina Propria
- Muscularis mucosae
7
Q
What parts of the mucosa in GI tract have epithelium, what kind, and what is it for?
A
Epithelium provides tight junctions to prevent leakage.
- mouth pharynx esophagus anus -> stratified squamous epithelium provides protection
- stomach, intestines -> simple columnar epithelium allows secretions and absorption
8
Q
What is the Lamina Propria in mucosa of GI tract made of and what is it for?
A
Areolar connective tissue, blood, and lymphatic vessels
it is the majority of Mucosa- associated lymphatic tissue (MALT)
9
Q
What is the musclaris mucosae of mucosa in the GI tract made of and what is it for?
A
THIN layer of smooth muscle
-mucosal fold which increase surface area for secretin and absorption
10
Q
What is the SUBMUCOSA of the GI tracts made of and for?
A
- Areolar connective tissue, blood vessels, and lymphatic vessels
- it is a neural network - submucosal plexus
11
Q
Where is the MUSCULARIS found and what is its purpose in the GI tracts?
A
- Mouth, Pharynx, upper/middle esophagus->skeletal muscle for voluntary swallowing
- External Sphincter-> skeletal muscle for voluntary defecation
- Rest of GI tract- smooth muscle -> involuntary for breakdown and mixing, inner layer circular, outer layer longitudinal
12
Q
What is the SEROSA made of and for?
A
- Areolar connective tissue and simple squamous epithelium
- covering of GI tract in abdominopelvic activity
13
Q
What types of nerves are there in the GI tract?
A
Enteric Nerves and Autonomic Nerves
14
Q
What are enteric nerves?
A
“brain of the gut”
- functions independently - “intrinsic”
- myentric plexus
- submucosal plexus
15
Q
What is the Myentric Plexus in enteric nerves for and made of?
A
- between longitudinal and circular muscle layers
- controls motility
16
Q
What is the submucosal plexus for and where?
A
- in submucosa
- motor: organ secretions
- sensory: stretch and chemoreceptors
- detects what is in the food you swallow
17
Q
Autonomic nerves in the GI tract?
A
“extrinsic” -> outside control
- parasympathetic -> action on ENS(stimulates) > increased Gi motility and secretions
- sympathetic -> action on ENS (inhibits) -> decreased Gi motility and secretions
18
Q
What are the parts of the Mouth?
A
cheeks, tongue, hard/soft palates
- Lips (or labia)
- Hard palate (anterior)
- Soft palate (posterior)
- Uvula
- Salivary Glands
19
Q
What are the types of salivary glands?
A
Major salivary glands - parotid, submandibular, sublingual
small salivary glands- labial buccal palatal lingual
20
Q
What mechanical digestion process does the MOUTH provide?
A
chewing, produces bolus
21
Q
what chemical digestion does the mouth provide?
A
salivary amylase - breakdown of starch (only monosaccarhides can be absorbed - creates sugar)
lingual lipase - breakdown of trigyclerides - activated by stomach acid
22
Q
what is bolus?
A
mushy ball of food you form in mouth before swallowing
23
Q
what does saliva do?
A
helps dissolve food for taste and contains enzymes
24
Q
what is the composition of saliva?
A
99.5% water, .5% solutes
25
what activates salivary amylase?
Cl-
26
what is in saliva and what does are there functions?
- Cl- activates salivary amylase
- icarbonate/phosphate ions – buffers – pH 6.35 -.85
- Salivary amylase – enzyme (starch)
- Bacteriolytic enzyme – lysozyme
- Immunoglobulin A –prevent microbe attachment
27
How much do you salivate daily and what is it controlled by?
- 1000-1500 ml
- controlled by autonomic nervous system
- parasympathetic- > promotes salivation
- sympathetic -> inhibits (stress)
28
What is the tongue made of and parts of the tongue?
- skeletal muscle covered in mucous membrane
- hyoid, temporal, and mandible bones
- extrinsic muscles move tongue for chewing and swallowing
- intrinsic alter shape and size of tongue for speech and swalling
- lingual frenulum- limits posterior movement
- lingual glands- secret mucous and lingual lipase (acts on triglycerides)
29
What are the parts of the teeth?
- in alveolar processes of mandible and maxillae
- Process covered by gingivae (gums)
- Inside Process – periodontal ligament
- Crown, Neck, Roots (1-3)
- Inside – Dentin – calcified connective tissue (hard)
- Crown covered by enamel (hardest body substance)
- Cementum – Anchors dentin of root to ligament
- Pulp Cavity, Pulp (Con. Tissue, Blood, Nerves, Lymph), Root canals
30
What is the pharynx and what is it made of and what does it do?
- Funnel shaped tube from mouth to esophagus.
- Skeletal muscle covered by mucous membrane.
- Muscle contractions (oropharynx, laryngopharnx) help propel bolus from mouth to esophagus
31
What is the esophagus made of?
-Collapsible muscular tube from pharynx to stomach
(via esophageal hiatus – opening in the diaphragm)
- Mucosa: stratified squamous epithalium (abrasion)
near stomach contains mucous glands
- Submucosa: blood vessels and mucous glands
- Muscularis:
1st 1/3 = Skeletal muscle
2nd 1/3 = Skeletal and Smooth muscle
3rd 1/3 = Smooth muscle
Upper Esophageal - > UES regulates movement of bolus pharynx ->
esophagus
-Lower esophagageal-> LESregulates movement
of bolus esophagus -> stomach
32
What does the esophagus do?
moves bolus, secretes mucus, no digestive enzymes, no absorption
33
What is deglutition?
Deglutition is swallowing.
- bolus is forced to back of oral cavity into oropharynx by tongue
- involves mouth, pharynx, esophagus
34
What are the phases of deglutition and what occurs?
1. Voluntary - swallowing
```
2. Involuntary phase
Bolus stimulates receptors in oropharnyx -> lowers pons
APs to deglutition center in medulla
APs from deglutition center
soft palate & uvula up (block nasopharynx)
epiglottis closes larynx
bolus through oro & laryngopharynx
UES relaxes - bolus into esophagus
```
3. Esophageal Stage
- Peristalsis: coordinated contraction/ relaxation of circulation longitudinal muscles - pushes bolus
- squeeze bolus toward stomach
- LES relaxes - bolus into stomach
- mucus secreted by esophageal glands lubricate bolus and reduce friction
35
How long does it take food to get from mouth to stomach
4-8 seconds
36
What facilitates deglutition?
secretion of saliva and mucus
37
What does the stomach serve as?
Mixing chamber/ holding reservoir
38
What are the 4 main regions of the stomach and where?
1. Cardia - surround superior opening
2. Fundus - rounded superior portion
3. Body - large central portion
4. pyloris - antrum and canal (pyloric sphincter)
39
What are the 2 stomach curvatures and where?
Lesser - concave medial border
| greater - convex lateral border
40
What are the three parts of the small intestine?
Duodenum, jejunum, ileum
41
Where is the stomach located?
Directly inferior to the diaphragm in the epigastric, umbilical, and left hypochrodriac regions of the abdomen
42
What is the digestion process in the stomach
- forces small quantity of material into small intestine on intervals
- digestion of starch continues
- digestion of proteins and triglycerides begins
- blous->liquid-> certain substances absorbed
43
What are the two parts of the pyloris?
pyloric antrum, pyloric canal
44
What is rugae?
large folds in the stomach that occur when stomach is empty
45
What are the layers of the stomach?
Mucosa - surface mucosa cells, lamina propria, muscular mucosae
46
what are the 3 types of exocrine glands in the stomach?
1. mucous and mucous neck cells - secrete mucus
2. parietal cells - Hcl & intrinsic factor ( intrinsic factor needed for absorption of B12)
3. Chief cells - pepsinogen and gastric lipase
(secretions make up gastric juice)
47
Where are gastric pits located?
gastric glands
- epithelial cells extend to lamina forming columns of gastric glands
- glands open to channels called pits - > secretions from glands go in the pits and them into lumen of stomach
48
what is the type of entroendocrine cell in the stomach
G-cell
49
What are the 3 additional layers that lie deep to the mucosa in the stomach?
1. Submucosa - areolar connective tissue
2. muscularis - 3 layers of smooth muscle, outer longitudinal layer, middle circular layer, inner oblique layer
3. serosa - simple squamous epithelial and areolar conn. tissue ; part of visceral peritoneum
50
where is the G-cell located?
pyloric antrum and secretes gastrin into bloodstream
51
Summarize the mechanical and chemical digestion in the stomach?
Food is mixed every 15-20 sec, becomes CHYME, funds primarily stores for 1 hr, salivary amylase still active, churning increases acidity, inactivates salivary amylase, activates lingual lipase, digest triglycerides into fatty acids and diglycerides, parietal cells secret HCl, activates pepsinogen, pepsin created, protein breakdown to amino acids, gastic lipase breaks short-chain triglycerides into fatty acids and monoglycerides
52
What do parietal cells do in the stomach?
kill microbes, denature proteins, stimulate hormone release to promote flow of bile and pancreatic juices
53
What is HCl secretion stimulated by in the stomach?
ACh, gastrin, and histamine (synergist)
54
How long before food is moved from stomach to duodenum and what spends the least amount of time in the stomach?
2-4 hours
| carbs
55
Digestion requires secretions from:
pancreas, liver, and gallbladder
56
What is the pancreas what is it made of?
Retroperitineal gland
Made of small clusters of glandular epithelial cells.
12-15 cm long 2.5 cm thick
57
What are the three parts of the pancreas?
Head- expanded portion near curve of duodenum
| Body & tail- superior and left head
58
Where are pancreatic juices secreted to
Small ducts that unite to form 2 big ducts the pancreatic and accessory ducts
59
Where is the pancreatic duct
Enters the duodenum as dilated common duct called hepatopancreatic ampulla
- ampulla opens in elevation of duodenal mucosa known as major duodenal papilla
60
What are the types of clusters in the pancreas?
99% are acini and constitute as the exocrine portion of organ
1% are pancreatic islets and form endocrine portion
61
what do acini secrete
picture of fluids called pancreatic juices
62
what do pancreatic islets secrete
glycagon, insulin, somatosin, pancreatic polypeptides
63
Where do exocrine pancreatic juice secrete into
pancratic duct and duodenum via common duct (with bile) or accessory duct
64
How much pancreatic juice do you form daily and what does it contain
1200-1500ml and water, salts, sodium bicarbonate, and enzymes
65
what does sodium bicarbonate do
buffers acidic gastric juice pH 7.1-8.2
| -stops action of pepsin in stomach creates proper pH
66
what are the key enzymes in pancreatic juices and functions
1. pancreatic amylase - starch digestion
2. trypsin- protein digestion
3. chymotrypsin- protein digestion
4. carboxypeptidase- protein digestion
5. elastase- protein digestion
6. pancreatic lipase - triglyceride digestion
7. ribonuclease and deoxyribonuclease- nucleic acid digestion
67
Protein digesting enzymes are produced in what form
inactive
68
What activates trypsinogen in small intestine
enterokinase
69
what activated/converts to trypsin
trypsinogen
70
what does trypsin activate
chymotrsinogen, procarboxypeptidase, proelastase -> produce chymotrpsin, carboxypeptidase, and elastase
71
what do pancreatic acinar cells secrete
protein called trypsin inhibitor which combines with any trypsin formed in the pancreas accidentally
72
What divides the two lobes and which lobe is larger
falciform ligament - which is fold of mesentery
| and right lobe is larger
73
What is the gall bladder and what does it do
pear-shaped sac inferior to liver
| - stores and concentrates bile produced in liver until needed in the small intestine
74
how much does the liver weigh
3 lbs or 1.4 kg
75
what is the liver covered by
visceral peritoneum and dense irregular connective tissue that is deep to peritoneum
76
What de hepatocytes do what are they
they are major functional cell
| they form hepatic laminas which are highly branches and irregular structures
77
what do hepatic portal veins do
bring venous blood from the gastrointestinal organ and spleen into liver
78
what do hepatic sinusoids do and what are they
they are highly permeable capillaries
they converge and deliver blood into central vein which transfers to hepatic veins which then drains into the inferior vena cava
79
What is the path of bile
bile goes into bile canaliculi then to bile ductules then to bile ducts then to the right and left hepatic ducts and to the common duct
80
what two ducts join to form the common bile duct
hepatic and cystic
81
what is the difference between hepatic artery and the hepatic portal vein
the art is oxygenated and the vein is deoxygenated
82
what is the path of the hepatic artery and portal vein
hepatic artery or hepatic portal vein -> to sinusoids(substances taken up by hepatocytes) -> central vein - > hepatic vein - > interior vena cava - > right atrium
83
what are the two sources that blood is supplied to the liver
hepatic artery and hepatic portal vein
84
what is the portal triad
vein, artery, and bile duct
85
What is partially excretory product and partially degestive secretion
bile
86
what do small lipid globules do
present large surface area that allows pancreatic lipase to more rapidly accomplish digestion of triglycerides
87
what do bile salts do
aid in absorption of lipids
88
as ____ and absorption continue in small intestine bile release _____
digestion
| increase
89
what is the role and composition of bile
800-1000 ml/ day pH 7.6-8.6
-yellow/brown/olive-green liquid
contains water, salt, cholesterol, lecithin, pigments and ions.
pigment comes from RBCs, bilirubin -> stercobili (brown color of poop)
emulsification
90
what is emulsifcation
breakdown of large lipid globules into a suspension of small lipid globules
91
what are the 9 functions of the liver
1. carb metabolism-maintain blood glucose -low glycogen to glucose/ high glucose to glycogen
2. lipid metab. -hepatocytes store tryglicerides, breakdown fatty acids for ATP, synthesize lipoproteins and cholesterol
(3) Protein Metabolism
- Deaminate amino acids for ATP production. Convert toxic ammonis produced to urea
- Hepatocytes synthesize most plasma proteins
(4) Processing of Drugs and Hormones
- Detoxification (alcohol), excretion of drugs, alter or excrete steroid hormones.
(5) Excretion of Bilirubin - absorbed by liver excreted in bile
(6) Synthesis of Bile Salts - emulsification
(7) Storage
- Glycogen, Vitamins (A, B12, D, E, K)
(8) Phagocytosis- kupffer
(9) Activation of Vitamin D-skin liver and kidney participate in synthesizing active form
92
where does most digestion and absorption occur
small intestine
93
what has large surface area circular folds, villi, and microvilli
small intestine
94
how long is the small intestine
10ft living, 21 dead
| structure adapts for function
95
what are the major parts of the small intestine
```
stomach pyloric sphincter
duodenum-25 cm
jejunum -100cm
ileum - 200 cm
ileocecal sphincter of Large intestine
```
96
What are the 4 basic layers of the small intestine that are in the GI tract
mucosa
submucosa
muscularis
serosa
97
What does the epithelial layer of the small intestine contain
i. absorptive cells
ii. goblet cells (mucus)
- -intestinal glands: i & ii. and iii. paneth cells (lysozyme) and iv. enterendocrine cells
98
what are the three types of enter endocrine cells
1. S cells - secretin
2. CCK cells - cholecytoskinin (CCK)
3. K cells - glucose dependent insulinotropic peptide (GIP)
99
What is the Lamina propria of the small intestine made of and contain
areolar connective tissue
- MALT
- secondary lymphatic nodules (peyer's patches) ->present in ileum
100
What cells secrete lysozyme (bacterialdalenzyme), and are capable of phagocytosis
PANETH CELLS
101
What type of noodles are numerous in the distal ileum
solitary lymphatic nodules
102
what does the muscular mucose of the small intestine mucose consists of
smooth muscle
103
What do the submucosa in S.I. do
secrete alkaline mucus
| helps neutralize gastric juices
104
what do circular folds in SI do
folds of mucosa and submucosa
increase surface area
encourage chyme to spiral
105
what do villi in SI do
fingerlike projections on folds
increase surface area
contain lacteals (lypmhatic. cap.)
106
what do microvilli do
projections off apical membrane of absorptive cells
| form fuzzy line called brush border
107
what are the brush border enzymes in the microvilli
(i) α-dextrinase, maltase, sucrase, lactase –(carbohydrate-digestion)
(ii) aminopeptidase, dipeptidase –(protein-digestion)
(iii) nucleosidases, phoshphatases –(nucleotide-digestion)
108
together pancreatic juices and intestinal juices provide a ____ ____ that aid _____ of substances from chyme in small intestine
liquid medium
| absorption
109
what synthesizes the brush border enzymes and insert into plasma membrane of microvilli
absorptive cells
-some enzymatic digestion occurs here
110
what are the two types of mechanical digestion movement in the S.I.
segmentations (occurs rapid in duodenum)
| peristalsis called migrating motility complex MMC
111
what is segmentations movement
localize, mixing contractions. occurs in chyme distends portions of SI. circular muscle contrations. ->segments ->chyme sloshing back and further
good for absorption
approx 12 per min in duodenum
8 per min in ileum
112
what is peristalsis MMC
from lower stomach to end of SI singlow slow wave down length of SI pushes chyme a short distances APPROX 1 MMC every 90-120 min
chyme stays in SI for approx 3-5 hours
113
how does the small intestine absorb monosaccharides
1. glucose and galactose ->secondary active transport with NA+->facilitated diffusion ->blood cap of villus
2. fructose -> facilitated diff. ->facilitated diff. -> blood cap of villus
114
how are amino acids, dipeptides, and tripeptides absorbed in small intestine
1. Amino acids- active transport or secondary active transport -> diffusion -> blood cap of villus
2. dipeptides and tripeptides ->secondary A.T. w/ NA+ -> diffusion->blood cap of villus
115
how are lipids absorbed in SI
1. short chain fatty acid-> simple diff.->diff.->blood cap
| 2. long chain and monoglycerides->simple diff. ->triglyceride ->lacteal of villus
116
What percent of absorption occurs in SI and LI and stomach
90 in SI
| 10 LI and stomach
117
all carbs are absorbed as
monosaccharides
118
amount of saliva produced, and ingestion of liquids ingested and secreted
1 liter
| 2.3 liters
119
how much gastric juice and bile ingested and secreted
2 liters
| 1 liter
120
how much pancreatic juice and intestinal juice infested and secreted
2 liters
| 1 liter
121
small intestine and large intestine amounts absorbed
8.3 liters
| .9 liters
122
total ingested and secreted
9.3 liters
123
total absorbed
9.2 liters
124
excreted in feces
.1 liter
125
Function of LI
completion of absorption
production of certain vitamins
formation/expulsion of feces
126
the ileum connects to the ___ and is how long?
anus
| 1.5m long 6.5 cm in diameter
127
What is the large intestine attached to
posterior abdominal wall by its mescaline; double layer of peritoneum
128
what are the four major regions of the large intestine
cecum
colon
rectum
anal canal
129
material from SI passes to the LI through the
ileocecal sphincter
130
what is the vermiform appendix possibly for
immune activity
131
the ascending and descending colon are _____
| the transverse and sigmoid colon are
retroperitineal
| not retroperitoneal
132
the internal and external sphincter are made of
smooth and skeletal
133
the LI is the ____ portion of the GI tract
terminal
134
inferior to the ileocecral sphincter is the _____
| appendix is also attached to this
cecum
135
epithelium of LI has
absorptive cells - mainly water
and goblet cells- secrete mucus
arranged into intestinal glands (or crypts of lieberkuhn)
136
muscularis of LI
circular and longitudinal muscle
some thick portions of longitudinal muscle forming bands(teenier coli)
-tonic contractions of bands -> gather colon into series of pouches called haustra
137
Mechanical digestion of LI
ileosphincter regulates chyme entry into cecum ( gastrin relaxes the sphincter)
- valve remains partially closed so passageway to chyme into cecum occurs slowly
- accumulation in cecum and ascending colon
- >haustral churning
- >peristalsis - slower rate then GI
- >mass peristalsis - drives content of color into rectum
138
how often does mass peristalsis occur
3-4 times a day or immediately after a meal
139
chemical digestion
digestion via bacterial activity
- >fermentation of carbohydrates, release hydrogen, CO2 and methane
- >proteins->amino acids
- >amino acids->indole, skittle, hydrogen sulfide, fatty acids
- >produce some band K vitamins
140
absorption and feces fermentation
chyme in large intenstine 3-10 hours
| feces semi-solid due to water reabsorption (90% water reabsorbed in SI)
141
Defecation reflex is
- mass peristalsis pushes fecal material into the rectum
- rectal wall dissension stimulates stretch receptors
- sensory APs to sacral spine cord
- parasympathetic motor output to descending/sigmoid colon rectum and anus
- ensuing contractions shorten rectum->increased pressure in rectum
- pressure, contractions of diaphragm/ abdominal muscles ->opening of anal sphincters->defecation
142
if defecation doesn't occur where does it get backed up
sigmoid colon
143
What are the three phases of digestion
cephalic, gastric, intestinal
144
what is the cephalic phase of digestion
- Prepares mouth and stomach for digestion.
- Smell, sight, thought, taste of food activates neuralcenters in cortex, hypothalamus and brainstem.
- Stimulates saliva, gastric juice secretion.
145
what is the gastric phase of digestion
- Begins when food is in stomach
- Distention and pH stimulate peristaltic waves and HCl secretion (negative feedback {see figure})
- Distension / high pH -> Gastrin secretion.
- Gastrin stimulates HCl secretion, enhances LES contraction, enhances stomach motility, relaxes pyloric sphincter.
146
what is the intestinal phase
- Slow stomach emptying, to prevent duodenum overload.
- Duodenum distension ->enterogastric reflex ->decreased stomach motility and pyloric sphincter contraction.
- CCK & Secretin stimulate the secretion of pancreatic juices
- Secretin also inhibits gastric juice secretion.
