Chapters 25&26 Flashcards
1
Q
What are the 6 Digestive Tract Organs?
A
- mouth
- pharynx
- esophagus
- stomach
- small intestine
- large intestine
2
Q
What are the 2 subdivisions of the digestive system?
A
- digestive tract organs
- accessory organs
3
Q
What are the 6 accessory organs of the digestive system?
A
- teeth
- tongue
- salivary glands
- liver
- gallbladder
- pancreas
4
Q
What are the 4 tissue layers of the digestive tract?
A
- mucosa (inner lining)
- submucosa
- muscularis externa
- serosa
5
Q
Mucosa
A
- inner lining
- epithelium: mostly simple columnar, some stratified squamous
- lamina propria: loose connective tissue
- muscularis mucosae: folds mucosa, increases surface area, improves digestion/absorption efficiency
6
Q
Submucosa
A
- thicker layer of loose connective tissue
- contains blood/lymphatic vessels
- submucosa plexus: part of ENS, controls muscularis mucosae movement & glandular secretion of mucosa
7
Q
Muscularis externa
A
- 2 muscular layers near outer surface
- responsible for motility (propels food & residue through digestive tract)
- inner circular layer: forms sphincters (regulates food passage through digestive tract)
- outer longitudinal layers: controls motility (propels food through digestive tract)
- myenteric plexus: between layers of muscularis externa, part of ENS, controls peristalsis & other contractions
8
Q
Serosa
A
- outside layer
- thin layer of areolar tissue w/simple squamous mesothelium on top
- begins in lower 3-4cm of esophagus & ends just before rectum
9
Q
What are the 8 anatomical structures of the mouth?
A
- oral fissure
- fauces
- cheeks & lips
- labial frenulum
- vestibule
- palate
- tongue
- teeth
10
Q
Functions of the mouth:
A
- respiration
- ingestion
- chemical digestion
- deglutition
11
Q
Oral Fissure
A
opening between lips
12
Q
Fauces
A
opening to throat
13
Q
Cheeks & Lips
A
- enclose mouth
- retain food
- manipulate food for chewing
- speech
- sucking
- blowing
14
Q
Labial Frenulum
A
attaches gums to lips
15
Q
Vestibule
A
space between cheeks/lips & teeth
16
Q
Palate
A
separates oral cavity from nasal cavity
17
Q
Tongue
A
- manipulates food
- has taste buds
18
Q
Teeth
A
masticate food
19
Q
Anatomical structures involved in deglutition
A
- tongue
- teeth
- pharynx
- upper esophageal sphincter
- soft palate
- epiglottis
- esophagus
- lower esophageal sphincter
20
Q
Stages of deglutition
A
- buccal: voluntary; food compressed into bolus
- pharyngoesophageal: involuntary; tongue root pushes bolus to pharynx, upper esophageal sphincter constricts pushing bolus down
21
Q
Extrinsic salivary gland functions
A
- secrete 1-1.5L saliva/day
- moisten mouth
- begin starch & fat digestion
- cleanse teeth
- inhibit bacterial growth
- dissolve molecules
- bins food into bolus
22
Q
What are some unique features of the stomach?
A
- vertical in tall people & horizontal in short people
- liquids enter 1-2 seconds after leaving mouth
- solids enter 4-8 seconds after leaving mouth
- empty = .5L
- can stretch to 4L
- greater & lesser curvatures
23
Q
4 areas of stomach
A
- cardial part (cardia): 3cm from cardinal orifice; near esophagus
- fundic region: dome superior to esophageal attachment
- body (corpus): greatest part distal to cardial orifice
- pyloric part: slightly narrower pouch at inferior end
24
Q
What cells are found in cardiac glands?
A
- mucous
- some enteroendocrine
- stem cells
25
What cells are found in gastric glands?
- some mucous
- parietal
- Chief
- enteroendocrine
- stem cells
26
What cells are found in pyloric glands?
- mucous
- some parietal
- enteroendocrine
- stem cells
27
Mucous cell functions
secrete mucus to protect mucosa from stomachs acidic environment
28
Parietal cell functions
- secrete HCl: activate pepsin & lingual lipase, reduce dietary iron to usable form, destroy ingested pathogens
- secrete intrinsic factor: B12 absorption
- secrete ghrelin: produce hunger
29
Chief cell functions
- secrete pepsinogen: converted to pepsin to digest protein
| - secrete gastric lipase: digests fat
30
Enteroendocrine cell functions
-secrete gut-brain peptides & hormones
•histamine: stimulates HCl secretion
•gastric: stimulates gastric glands (to secrete HCl & enzymes); stimulates intestinal motility; relaxes ileocecal valve
•secretin: response to stomach chyme acidity; stimulates liver & pancreas ducts to secrete sodium bicarbonate
•cholecystokinin (CCK): secreted by duodenum & jejunum mucosa response to fats in small intestine; stimulates pancreatic acini tips secrete enzymes; stimulates gallbladder
31
Gastric Regulation phases
- Cephalic phase: before food is ingested; vagus nerve stimulates gastric secretion
- Gastric phase: when food enters stomach; food stretches stomach, activates myenteric & vagovagal reflexes which stimulates gastric secretion
- Intestinal phase: when chyme leaves stomach & enters intestines; intestinal gastric briefly stimulates stomach then secretion, CCK, & enterogastric reflex inhibit gastric secretion & motility
32
What are 2 signals that increase gastric secretion from G cells?
- elevated pH
| - partially digested proteins
33
Liver anatomy & functions
- right lobe: posterior view; bigger than left
- left lobe: posterior view; smaller than right
- falciform ligament: mesentery sheet separating right/left lobe; suspends liver from diaphragm
- caudate lobe: posterior side of right lobe & wraps around inferior vena cava
- quadrate lobe: posterior side of right lobe & wraps around gallbladder; inferior to caudate lobe
- round ligament: fibrous remnant of umbilical vein; carries blood from umbilical cord to fetus
- porta hepatis: port of entry for hepatic portal vein & proper hepatic artery; point of exit for bile passages
- blood supply: 30% hepatic artery & 70% hepatic portal vein
34
Gallbladder anatomy & functions
- pear shaped sac under liver
- stores/concentrated bile
- 10cm long
- internally lined by highly folded mucosa
- only secreted its own mucus
- has neck, head, body
35
Pancreas anatomy & functions
- flattened, spongy
- 12-15cm long, 2.5cm thick
- head, body, & tail
- pancreatic duct: runs lengthwise in middle of pancreas & joins bile duct at hepatopancreatic ampulla
- hepatopancratic sphincter: controls bile & pancreatic juice release to duodenum
- hepatopancreatic ampulla: formed by bile duct & pancreatic duct when they meet
36
Why does the pancreas secrete enzymes in the form of zymogens?
to prevent enzymes from digesting proteins in cells where they’re made
37
What’s unique about the pancreas?
it’s an endocrine & exocrine gland
- endocrine = pancreatic islets secrete insulin & glucagon; mostly in tail
- exocrine = 99% of pancreas; secreted pancreatic juice (1,200-1,500mL/day); mostly in head
38
What are the regions of the small intestine?
- duodenum
- jejunum
- ileum
39
Duodenum anatomical features
- 1st 25cm is small intestine
- begins at pyloric valve at end of stomach
- arches around pancreas head
- ends at duodenojejunal flexure
- receives chyme & pancreatic juice
- mainly neutralizes stomach acid
- bile emulsified fat
- takes over chemical digestion
40
Jejunum anatomical features
- 1st 40% of small intestine beyond duodenum
- rich blood supply = redder
- most digestion & nutrient absorption happens here
41
Ileum anatomical features
- last 60% beyond duodenum
- ends at ileocecal junction & valve (junction between ileum & large intestines)
- contains peyer’s patches (AKA aggregated lymphoid nodules): part of immune system, monitors intestinal bacteria & prevents growth of pathogenic bacteria
- nutrient reabsorption
42
What’s the purpose of the circular folds in the small intestine?
-slow chyme progress
-make it flow on spiral path to increase...
•contact w/mucosa
•mixing
•nutrient absorption
43
What’s the purpose of the villi in the small intestine?
- enhances chyme mixing in intestinal linen
| - milks lymph down lacteal to larger lymphatics in submucosa
44
What’s the purpose of the microvilli in the small intestine?
- increase surface area
- contain brush border enzymes to carry out some final stages of chemical digestion
- not secreted into lumen, chyme contacts brush border
45
What are the 2 types of intestinal motility?
- segmentation
| - peristalsis
46
Segmentation
- most common intestinal contraction
- kneads/churns contents
- slow chyme progression toward colon
47
What’s the purpose of 2 types of intestinal motility?
- mix chyme w/intestinal juice, bile, & pancreatic juice so these fluids neutralize acid & digest nutrients
- churn chyme & make it contact mucosa for digestion & nutrient absorption
- move residue toward large intestine
48
Which enzymes are involved in carb digestion?
- amylase
- maltase
- sucrase
- lactase
49
Which enzymes are involved in protein digestion?
-proteases (peptidases): carboxypeptidase, aminopeptidase, dipeptidase
50
Which enzymes are involved in fat (lipids) digestion?
-lipases: lingual lipase, gastric lipase, pancreatic lipase
51
What’s the purpose of bile salts in fat digestion & absorption?
it breaks up fat
52
What’s the purpose of micelles in fat digestion & absorption?
transport lipids to enterocyte surface where lipids are diffused out of cell
53
What’s the purpose of chylomicrons in fat digestion & absorption?
- packaged in secretory vesicles & transported to nasal surface to release contents in core of villus
- transport lipids absorbed from intestine to adipose, cardiac, & skeletal muscle tissue
54
Where are monosaccharides & amino acids reabsorbed from the small intestine?
blood capillary
55
Where are fatty acids & lipids reabsorbed from the small intestine?
lacteal
56
What are the main functions of the large intestine?
- water & electrolyte reabsorption
| - feces storage & formation
57
Large intestine segments in order
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
58
Anatomy of large intestine
- appendix
- cecum
- ascending colon
- right colic flexure (corner)
- transverse colon
- left colic flexure (corner)
- descending colon
- sigmoid colon
- anal canal
- external anal sphincter
59
What are the beneficial functions of bacterial flora in the large intestine?
- extract nutrients we can’t get otherwise
| - help synthesize vitamins B & K
60
What’s the relationship between nutrition & metabolism?
- nutrition provides raw materials
| - metabolism uses raw materials
61
What’s the difference between anabolic & catabolic chemical reactions?
- anabolic: using food/nutrients to build cellular material
| - catabolic: breaks down food to make energy
62
What’s the only true way to satisfy hunger?
eat food w/nutrients
63
Short term appetite regulators
- ghrelin
- peptide YY (PYY)
- cholecystokinin (CKK)
64
Long term appetite regulators
- leptin
- insulin
- neuropeptide Y (NPY)
- melanocortin
65
What are the categories of lipid transporter lipoproteins?
- lipids transported through bloodstream by 4 lipoprotein categories (higher proportion
- maintain total plasma cholesterol concentration < 200mg/dL
- chylomicrons: deliver dietary lipids to cells
- VLDLs: deliver body made triglycerides to cells
- LDLs: deliver body made cholesterol
- HDLs: removes cholesterol from body
66
What are the pathways of lipid transporter lipoproteins?
- chylomicrons: lymph absorbs from small intestine ➡️ lymph drains to bloodstream ➡️ lipoprotein lipase removes lipids from chylomicrons ➡️ lipids stored in adipocytes pr used & liver disposes of chylomicron remnants
- VLDL/LDL: liver produces VLDLs ➡️ triglycerides removed & stored in adipocytes & VLDLs become LDLs containing mainly cholesterol ➡️ cells absorb LDLs by receptor-mediated endocytosis
- HDL: it’s a loop; liver produces empty HDL shells ➡️ HDL shells pick up cholesterol & phospholipids from tissues ➡️ filled HDLs back to liver ➡️ liver excreted excess cholesterol & bile acids ➡️ repeat
67
Aerobic Respiration chemical equation
C6H12O6 + 6O2 = 6CO2 + 6H20
Glucose + Oxygen = Carbon Dioxide + Warer
68
Oxidation
losing/donating electrons
69
Reduction
receiving/gaining electrons
70
What’s the told of oxygen in aerobic metabolism?
- w/O2 pyruvic acid enters mitochondria & aerobic respiration oxidizes
- oxidizes carbs, O2 atoms attach to carbon in excreted CO2 molecule
- O2 converts nutrients to CO2 & ATP
71
What are the 3 major pathways of glucose metabolism?
- glycolysis
- anaerobic fermentation
- aerobic respiration
72
Glycolysis
-in cytoplasm
-steps:
•phosphorylation: G6P produces
•priming: G6P rearranged = F6P; phosphorylated again = fructose 1,6 diphosphate
•cleavage: fructose 1,6 diphosphate layers to 2 C3 molecules called PGAL
•oxidation: PGAL oxidized (H+ pair removed); NAD+ picks up electrons & 1 proton
•dephosphorylation: ADP ➡️ ATP; C3 compound becomes pyruvic acid
-oxidizes NADH carries electrons
-end products:
•2 pyruvic acid
•2 NADH + 2 H+
•2 ATP (4 created but 2 used)
-no O2 = pyruvate ➡️ lactate & no more ATP produced
-O2 = pyruvates transported to mitochondrial matrix
73
Anaerobic Fermentation
-in cytoplasm
-end products:
•2 lactic acid
•2 NAD+
•2 ATP (from glycolysis so 4 made but 2 used)
-liver converts lactic acid back to G6P; can form glycogen for storage or remove phosphate group & release free glucose to blood
-drawbacks:
•wasteful- most energy still in lactic acid
•lactic acid is toxic & contributed to muscle fatigue
-makes as much ATP as aerobic respiration
74
What are the matrix reaction end products of Aerobic Respiration?
* 2 pyruvate + 6 H2O = 6 CO2
* 2 ADP + 2 Pi = 2 ATP
* 8 NAD+ + 8 H2 = 8 NADH + 8 H+
* 2 FAD + 2 H2 = 2 FADH2
75
How does pyruvic acid prepare to enter CAC in aerobic respiration?
- CO2 removed (C3 compound ➡️ C2 compound)
- NAD+ removes H+ from C2 compound (C2 compound ➡️ acetyl group)
- becomes acetyl-coenzyme A (acetyl group binds coA)
-other steps happen in mitochondria
76
Which steps of aerobic respiration generate exhaled CO2?
- CO2 releases from pyruvate formed in glycolysis
| - CAC: Citric Acid Cycle
77
What’s the Chemiosmetic mechanism of ATP synthesis?
- ATP synthase harnesses energy from H+ current to drive ATP synthesis
- explains functioning of electron transport chains
- transferring electrons down electron transport system through oxidation-reduction reactions release energy
78
Lipolysis
makes triglycerides from free fatty acids & glycerol
79
Lipogenesis
breakdown of triglycerides into glycerol & fatty acids
80
What’s the danger associated w/ketone bodies?
possible pH imbalance
81
Mumps
- caused by: infection of parotid gland from mumps virus
- symptoms: painful swelling of salivary glands
- treatment: control symptoms w/pain meds but allow infection to run course
82
Mucosa Ulcers
-symptoms:
•abdominal pain
•bloating
•nausea/vomiting
•appetite/weight loss
•untreated can perforate digestive tract wall = hemorrhage
-caused by:
•chronic inflammation from bacterial infection (heliobacter pylon)
•overuse of NSAIDs (Non Steroid Anti-Inflammatory Drugs; ibuprofen & other over the counter pain relievers)
•overuse of aspirin
-treatment:
•antibiotics (for bacterial infection)
•bismuth suspension (Pepto-Bismol)
83
Acid Reflux (heartburn)
-reflux is stomach acid back into esophagus
-caused by: relaxation of lower esophageal sphincter (LES) by...
•too much food in stomach
•too much pressure in stomach (like pregnancy)
•chemical relaxants in foods
•stress/lack of sleep
•smoking
-treatment:
•treat underlying causes (more sleep, less food, stop smoking, etc)
•antacids (Tums)
•drugs blocking histamine receptors
84
What’s the relationship of cholesterol to HDL & LDL levels?
- HDL high = decreased cholesterol
- HDL low = increased cholesterol
- LDL high = increased cholesterol
- LDL low = decreased cholesterol
