GI System Flashcards
What the body can process
Amino acids, monosaccharides, and fatty acids
What kind of cells line digestive mucosa to lubricate, digest, etc
Epithelial
What regulates GI secretions and motility
Intrinsic nerve plexus
What can facilitate digestion and absorption
Fluid volumes and pH changes (enzyme function)
PH of chyme in jejunum
7
Small intestine roles: 5
Enzymatic digestion, absorbs h20, organic substrates, vitamins and ions, host defense
Large intestine roles 3
Resorts water and electrolytes, host defense, dehydration/compaction for elimination
Pancreas roles 2
Secretes buffers and digestive enzymes, secretes hormones to regulate digestion
Endocrine is into what
Blood
Exocrine is into what
Gland or duct
Serosa: 2 layers and it is what
CT layer and peritoneum, innervated
2 layers of intramural plexus and where it is
Myenteric plexus and submucosal plexus. On submucosa and muscular layers
How digestive glands empty products into lumen of gi tract
Ducts
What gives nutrients from blood to GI tract
Aorta
What carriers nutrients to liver from organs
Portal vein
Myenteric plexus outside of what
Circular muscle layer
What is outside of submucosa
Submucosal plexus
Chyme is what
Food, acids, enzymes, saliva
Gastric gland cells
Mucous neck cells, parietal cells, chief cells, endocrine cells
What controls myenteric plexus and submucosal plexus, what are their roles
Both- enteric
Myenteric=- muscle, movement
Submucosal- secretions
What PNS innervates in GI
Vagal to transverse colon, pelvic nerves to anus
What acts on the enteric NS
Lumenal chemo, mechanoreceptors, and osmoreceptors
Where parts of chyme go after entering duodenum
Simple sugars, fats, and amino acids go to lacteal. Simple sugars and AA absorbed into blood capillaries of villi. Fat enters lacteal to be processed in liver
Lactose, maltose, sucrose components
Lactose is glucose and galactose
Maltose is 2 glucose
Sucrose is glucose and fructose
Process of enzymes breaking down carbs. 4 main processes in order
- Starch broken down my salivary amylase in mouth to oligo/dextrin
- Pancreatic amylase breaks them down to lactose, maltose, sucrose
- Brush border enzymes in SI break disaccharides down to mono
- Mono absorbed by capillaries in vile and trans to liver by portal vein
Steps of protein absorption 4
- Pepsin in hcl breaks proteins- proteoses and peptones
- Pancreatic enzymes break those down to dipeptides and smaller peptides in SI
- Brush border enzymes in SI break down to AA
- Abs by capillaries in villi, trans to liver by portal vein
What cells break things down in stomach
Chief and parietal cells
Digestion of fat steps
Unemulsified fats broken down in SI by bile acids, etc in SI. Pancreatic lipases also act here. Monoglycerides and FA go to lacteals in villi and go to liver. Glycerol and FA go directly into villi and portal vein like carbs and AA
2 different routes of fat from SI
MG and FA- lacteal to liver
Glycerol and FA- directly into villi to liver
Oblique muscle layer role in stomach
Aids in grinding food
Receptive relaxation: mediated by what, what causes it to start
Vagally mediated
Pushing on the stomach causes release of vasoactive intestinal peptide (VIP)
MMC role, under what control
Mixes and propulses food
Enteric
What vagotomy does to stomach as food enters
Receptive relaxation not stimulated, pressure increases as volume increases (doesnt increase volume to accommodate more food)
Emptying time/order of oleate, acid, and saline meals in stomach
Salt fastest, then acid, then oleate.
FATS TAKE LONGEST TO DIGEST IN STOMACH
MMC: when its activated. What activates it. Which nervous system control
Fasting state
Motilin
Enteric control, NOT vagal
What slow waves due, what they are
Basic electrical rhythm, set timing for when action potentials occur
What causes depolarization in GI
Stretch, ans, pns, gastrin, serotonin, sub P*
**hormones
What causes hyperpolarization in GI
NE, SNS, VIP, NO
The __ and __ stim of sensory neurons works through __ and __ motor neurons to elicit motility
Mechanical, chemical
Excitatory, inhibitory
What stimulates relaxation in peristalsis, what stimulates contraction
Relax- VIP
Contract- cholinergic motor neurons and tachykinin
Peristalsis under what kind of control
Vagal and extrinsic
What leads to receptive relaxation
MMC, propulsion by peristalsis and segmentation
Segmentation is controlled by what
Intrinsic/enteric nerve control
What stimulates gallbladder contraction
Vagal stimulation relaxes the sphincter of oddi- into duodenum. Hormone CCK+vagal stim stimulates gallbladder contraction
What movements are in 3 parts of LI
Peristalsis
Segmental propulsion, taneia coli contract
Mass movements at end
Mass movements; assoc with 3
Eating, PNS and hormonal control (gastrin and CCK)
Haustra formed by what
Contraction of taneia coli
Defecation through what
IAS reflex, voluntary relaxation EAS, valsalva maneuver
Reflexes top to bottom 7
Gastroileal Gastrocolic Ileogastric Enteroenteric/intenstinointestinal Colonocolonic Cecoileal Rectosphincteric (defecation reflex)
Secretions in mouth
Saliva, lingual lipase, salivary amylase
Esophagus secretions
Electrolytes and mucus