The Digestive System Flashcards
What are the DS accessory Organs?
Gall bladder, liver, pancreas, salivary glands, teeth, tongue
What is the Alimentary Canal?
GI tract, gut
mouth -> Pharynx -> Esophogus -> Stomach -> Small Intestine -> Large Intestine
Five Essential Activities of Digestion?
Ingestion
Propulsion and Mixing - perstalisis and segmentation
Digestion - chem/phys breakdown of polymers
Absorption - movement of momoners into blood
Elimination - defecation
What do Mechanoreceptors do?
respond to stretch
What do chemorecptors do?
Respond to changes in osmolarity, pH, and chemical composition
What do the Receptors in the DS initiate receptors to do?
stimulate smooth muscle mixing/moving lumens contents
activate digestive glands
What is the extrinsic control of the DS?
Neural
Hormonal
The outside factors
Neural - long reflexes responding to stimuli in/out of GI tract involving CNS
Hormonal - endocrine glans secrete hormones that can affect DS
What are intrinsic controls of the DS?
Neural
Hormonal?
Neural - Short Relfexes from one part of DS to other, enteric nerve plexuses initiate short reflexes in response to stimuli in GI tract
Hormonal - GI tract releases enteric hormones from enteroendocrine glands in stomach and Small intestine stimulating target cells in any DS organ
Peritonuem?
Serous membranes of abdominal cavity
Visceral - covers orgs
parietal - covers wall
What are extensions of the peritoneal Membranes?
Mesenteries
What do mesenteries function for?
anchoring body orgs to walls,
storing fat,
carrying blood/ lymph vessels, and nerve fibers
Intraperitoneal?
inside cavity, most DS orgs
Retroperitoneal?
Organs that lie posterior to peritoneum, in body wall
duodenum, pancreas, colon
Ant Surface = visceral peritoneum
Post Surface = aventita
What are the DS blood Supply?
Hepatic Portal System
Splanchnic Circulation
Where does the Splanchnic Circulation carry blood through?
What does it provide DT with?
Hepatic, splenic, left gastric, mesenteric arteries
carries O2 and nutrients to DT
Where does the Hepatic Portal System bring blood from and to for what?
blood from DT –> liver for nutrient processing
What are the four layers of the walls of the DT?
Serosa
Muscularis Externa
Submucosa
Mucosa
What Layer is the Serosa of the DT?
What kind of tissue is it made of?
What is it joined to?
what does it produce?
Outer covering, visceral peritoneum
Areolar CT and Squamous Epithelium
Mesenteries (anchors orgs.)
Serous fluid:friction free surface
What is the Adventitia?
Surrounds esophogus/body wall side of retroperitoneal organs
retroperitoneal orgs have both adventitia and serosa and it anchors orgs to surrounding tissues
What layer is the Muscularis Externa?
What kind of muscles does it contain?
What is it responsible for?
What does it contain?
2, has smooth muscle
inner(circular), outer(longitudinal)
Transportation, peristalisis, mixing, segmentation
myenteric nerve plexus
What layer are Sphincters found in of the DT wall?
Muscularis Externa
keep one way flow
circular muscle
What in the layer 2nd from the inside of the DT wall?
What kind of CT is it?
What does it supply to the Mucosa?
What kind of nerve plexus does it have?
Submucosa 2 inner
Elastic
Blood, lymph vessel and nerves
Submucosa Nerve Plexus
What is the innermost layer of The DT wall called?
What does it carry out?
What are its three sublayers?
Mucosa digestion and absorbtion lining epithilium lamina propria muscularis mucosae
What the the 3 Sublayers of The Mucosa and what are their functions?
Lining Ep: stratified squamous -> simple columnar with mucous , enzyme and hormone secreting cells
Lamina Propria - loose areolar CT with cap and lymph nodules to fight infection
muscularis mucosae - thin layer smooth muscle cells causing local movements of mucosa, pills mucosa into folds
What is the Enteric NS?
Intrisnic NS in DT which regulates by Short Reflexes
What are the two types of nerve plexuses in the Enteric NS? Where are they found? what do they do?
Submucosal Nerve Plexus: regulates gland and smooth muscle in muscoa
Myenteric: Muscularis Externa - GI tract motility
How is the Enteric NS linked to the CNS?
Long reflexes of autonomic branch, sympathetic(inhibit and parasympathetic fibers(stimulate)
What are the functions of the mouth?
ingestion, mastication, beginning of chem digestion
What is the mouth lined with, for protection of what?
mucosa is lined with stratified squamous
against abrasion by releasing defensins when damaages
What do the lips do?
assist in movement, help keep food between teeth
What does the hard palate do?
assists in forming bolus
Soft Palates function in mouth ingestion?
uvular blocks nasopharynx in swallowing
What is the tongues function?
moves and mixes food with saliva to form bolus
initiates swallowing, speech and tasting
What are the four tyoes if papillae on tongue?
Filiform Papillae: smallest, not for taste
Fungiform: Redish, all over, tastebuds
Circumvallate - v shaped row in back, tastebuds
Foliate - lateral aspects of posterior tongue, tastebuds
What are the salivary glands intrinsic Glands function?
small& scattered in mucosa, continuously provided
What do the extrinsic glands do in salivary glands? What are the three names? Where are they all found what kind of cells do they contian what are the contents of these cells?
Large, empty saliva through ducts into mouth
parotids(front of ear) - only serous cells
Submandibular/sublungual - under tongue,c ontain serous and mucous cells
serous cells: water fluid with enzymes
mucous cells - thick stick mucus for lube
What is the composition of saliva?
ph= 6.75-7 mostly h20 ions salivary amylase small amounts of metabolic waste mucin defensins
What are the functions of saliva?
Cleans mouth dissolves waste chemicals moistens/compacts foods to form bolus salivary amylase begins chem digestion Releases antibodies - IgA, lysozyme(inhibits growth) cyanide compound(poison), defensins (antibiotic and attracts WBC
How are Salivary glands controlled through extrinsic Glands?
parasympathetic fibers of ANS, reflex response
thought, smell, taste, brain, long reflex, salivary glands, increased secretion
How does intrinsic salivary glands function>?
produce small amounts all the time to keep mouth moist , inhibited during stress by sympathetic NS
What is the largest organ in the body?
Liver
What region is the liver located?
r. hypochondriac and epigastric
How many lobes is the liver separated into?
4
What ligaments support the liver?
Falciform/lesser omentum
What does the falciform do?
suspends liver to diaphragm
What does the lesser omentum do?
Suspend liver to stomach
What is the blood supply to the liver?
Hepatic art/ hepatic portal vein
What drains the blood supply of the liver?
hepatic vein
What is pw of bile drainage?
common hepatic dict and cystic duct join to form bile duct draining into hepatopancreatic sphincter and ampulla
What microscopic anatomy does the liver contain?
Lobule, sinusoid, hepatocytes, portal triads
Where are portal triads located and what do they contain?
Periphery of lobules,
arteriole - o2 rich from hepatic art
venule - nutrients from hepatic portal vein
bile duct - bile from canaliculi
What are characteristics of sinusoids?
where do they filter blood from and to?
what do they contain?
Leaky capillaries
Hepatic portal vein and artery into central vein
kupffer cells - remove debris etc from blood.
Where are hepatocytes found?
surrounding sinusoids
What are hepatocytes function?
produce bile from old rbc
process nutrients from digestive dract
store fat soluble vitamins
detoxify blood
What are examples of hepatocytes processing DT nutrients?
converting excess glucose into glycogen and store
plasma proteins from amino acids
non essential amino acids
packages fatty acids
How do hepatocytes detoxify blood?
nitrogenous wastes –> to more inert urea
destroys toxic substances
inactivates hormones
What does bile contain?
Hco3
Bile salts/pigments
cholestrol
assists faat and cholestrol absorbtion
What does Hco3 in the bile do?
neutralizes acidic chyme
what do bile salts do?
emulsify fat
What are bile pigments?
b/d product of Hb
What does emulsifying fats fdo?
increases SA for pancreatic lipase
What does enterohepatic circulation do?
recycles bile salts?
What are the functions of the gall bladder?
stores and concentrates bile by absorbing h20 and ions
What allows walls of GB to expand as fills with bile?
Rugae
What causes smooth muscles in walls of GB to contract?
CCK
What happens to the GB when fatty chyme is present in the duodenum?
cck into blood -> GB contracts -> bile in cystic duct -> Common bile duct -> sphincter of oddi opents -> major duodenal papilla -> duodenum
Secretin -> liver produces bile
what happens to GB when no chyme is present in duodenum?
bile stored in GB
Is the pancreas interperitoneal/retro?
retro
What are the pancreas’s endocrine secretions?
insulin and glucagon
What are the pancreas’s exocrine secretions essential for?
digestion
What cells make pancreatic juice?
duct cells - alkaline fluid
acinar cells - enzyme production
How does prancreatic juice get into the duodenum?
into main pancreatic duct -> sphincter -> hepatopancreatic ampulla -> sphincter of oddi
The alkaline fluid in pancreatic juice is sectreted by what type of cell, what is its function and what does it contain?
duct cells
neutralize acidic chyme
HCO3
What enzymes do the acinar cells release?
Lipase Pancreatic amylase chymotripsinogen tripsinogen procarboxipeptidase nucleases
What is trypsogen activated by?
Once activated what does it do?
brush boarder enzymess, enteropeptidase
activates all other proteases
What are hormonal regulations of pancreatic secretions?
Secretin in response to acidic chyme in duodenum, causing duct cells to secrete alkaline fluid
CCK in response to protein and fat in duodenum which causes acinar cells to release enzymes
What are neural regulation of pancreatic secretions?
vagus nerve, parasympathetic, long reflex, cephalic/gastric phases release pancreateic juice
What are the parts of the Large Intestine?
cecum, appendix ascending transverse, descending, rectum anal canal anus
transerse and sigmoid anchored by mesenteries
What are 3 unique features of LI?
Tenia Coli - long muscle - 3 strands
Haustra - formed by teni coli
Epiploic Appendages - fat on outside
The mucosa of the LI?
What kind of epithilium?
What structure does have the same epitilium
what is it abundant with?
Simple columnar
anal canal =stratified squamous
deep crypts/gob cells
What are the characteristics of motility in LI?
mostly inactive
sluggish and short lived
Types of movement in LI?
Haustral contractions
Mass Movements
What are haustral contractions and where are they found?
LI
local, every 30 mins, responsse to distentiobn
What are mass movements?
how often do they occur?
What are they triggered by?
move contents toward rectum, slow peristalsis
3-4 times daily
Gastrocolic reflex - food entering stomach
What are the 4 majors functions of the colon?
transports waste to rectum
absorbs water from indigestible foods and elminates them
reabsorbs bile salts, na, cl and others
normal bacterial flora in colon
What do the norma bacterial flora in colon do?
vitamin K & B complex
ferment undigestied carbs and increase flatus
can survie digestive process
enter through anus
What does the rectum have a complete layer of and what does it allow?
longtitudinal muscle layer
strong muscle contractions
what do the 3 valves in the rectum do?
stop feces from being passed with gas
What is the anal canal and what does it have?
What is its mucosa?
last segment of rectum
sphincters, internal (invol) external (vol)
Stratified squamous
What is the defecation reflex?
mass movements force feces in rectum and the distention of the rectum initiates spinal defecation reflex which stims parasympathetic, stimulation contraactions of sigmoid colon and rectum, internal anal sphincter relaxes, conscious control allows relaxation of external
What are glucose fructose and galactacose examples of?
monosaccrides
What are sucrose, lactose and maltose examples of?
disaccrides
What are gycogen and starch examples of?
oligosaccrides, digestion in mouth and SI
Polypeptide digestion?
stomach and small intestine
Lipid digestion?
only in small intestine
Monosaccride Absorbtion?
in ep cells facilitaed diffusion/contransport with na
carrier proteins ub nenvrabe
simple diffusion through ep cells
Facilitaed diffusion/contransport in caps
transported to liver for processing
Where are Amino Acids mostly absorbed?
duodenum/jejeunum contransport into ep cells with na facilitated diffuse into caps and vein some di and tripeptides absorbed into ep cells and hydrolysized there to amino acids go to liver
Where does lipid absorption mostly occur?
ileum
monoglycerides and free fatty acids form micelles with bile salts which then move to micro villi, lipids leave micelles and diffuse into ep cells and are resynthesized into triglycerides and formed into chylomicrons by binding with pro, phospholipids, and cholestrol which then enters blood which is then turned to fatty acids and gycerol –diffuses through cap wall into tissue for storage or ATP
Vitamin absorption? where? diet vitamins bacterial vitamins fat soluble water soluble B12
SI LI with fat into micelles diffusion intrinsic factor -->active transport
