AnatomyPhysiology IV
Terms
undefined, object
copy deck
- general roles of digestive system
- digestion of food, absorption of nutrients and water from it
- 2 main parts of digestive system
- alimentary canal (GI tract); accessory digestive organs
- components of alimentary canal
-
mouth
pharynx
esophagus
stomach
small intestine
large intestine - list the accessory digestive organs
-
teeth
tongue
gallbladder
salivary glands
liver
pancreas - list the essential activities of the digestive process
-
ingestion
propulsion
mechanical digestion
chemical digestion
absorption
defecation - def. ingestion
- taking food into the digestive tract
- def. propulsion
-
swallowing and peristalsis
peristalsis -- waves of contraction and relaxation of smooth muscle in organ walls - def. mechanical digestion
- chewing, mixing, churning food
- def. chemical digestion
- chemical breakdown of food into simple nutrients
- def. absorption
- movement of simple nutrients from GI tract to the blood or lymph
- def. defecation
- elimination of indigestible solid wastes
-
what kind of receptors are in the GI tract
they respond to what -
mechano
chemoreceptors
respond to:
stretch
osmolarity
pH - receptors in GI tract initiate what after they respond to stimuli
-
reflexes:
activate or inhibit digestive glands
speed up or slow down peristalsis - what are the main neural control systems
-
intrinsic neural control (enteric nervous sys)
extrinsic neural control
(autonomic nervous sys) - components of intrinsic neural control system
-
submucoal nerve plexus
myenteric nerve plexus - components of extrinsic neural control system
-
reflexes arising from:
within
or outside GI tract
the reflexes involve:
CNS centers
or autonomic nerves (long reflexes) - function of submucosal nerve plexus
- regulates glands and smooth muscle in mucosa
- function of myenteric nerve plexus
- major nerve supply that controls GI tract mobility
- what characterizes the processes of segmentation and peristalsis
-
large autonomic
involve local reflex arcs - relationship b/w intrinsic and extrinsic control systems
- linked by autonomic reflex arcs
- long reflexes vs. short reflexes
-
stimulus --> CNS --> local nerve plexus --> muscle effector --> response
straight from stimulus to local nerve plexus - peritoneal cavity
- abdominal cavity that contains the GI tract organs
-
what is peritoneum?
components?
gen char? -
serous membrane of abdominal cavity
visceral layer
parietal layer
contains vasc and nerve supplies to viscera
holds dig organs in place and helps store fat
lubricates dig organs and allows them to slide rel to each other -
arteries of dig sys
what organs do they serve
what are the arteries' functions -
hepatic, splenic, L gastric --> spleen, liver, stomach
inf and sup mesenteric --> S and L intestines
to get nutrients from GI tract to rest of body tissues -
what is hepatic portal circulation (compare to gen circ)
its functions -
is a diversion before gen circ
prevents spikes in blood sugar -- collects nutient-rich venous blood from stomach, S and L intestines; delivers this to liver for processing and storage of nutrients before entering gen circ - what is the same from the esophagus to the anal canal
-
walls of GI tract have same four tunics
mucosa, submucosa, muscularis, externa, serosa -
functions of mucosa
location
components in stomach in S intestine -
secretion of mucus
to protect organs from digesting themselves
eases food along tract
____ of the end products of digestion
protects against infectious diseases
contain enzyme secreting cells, hormone secreting cells (therefore endocrine and digestive functions) - char of submucosa
-
connective tissue layer with:
elastic fibers
blood and lymph vessels
lymph nodes
nerves - what is attributed to muscularis externa
- segmentation and peristalsis
- role of serosa
- protective visceral peritoneum
- function of salivary glands; location
-
produce and secrete saliva that:
cleans mouth
moistens and dissolves food chemicals
aids in bolus formation
in mouth - list the types of salivary glands
-
extrinsic
parotid
submandibular
sublingual
intrinsic - functions of extrinsic salivary glands/what activates them
-
secrete enzyme-rich saliva in resp to:
ingested food (stimulates chemoreceptors)
thought of food
secretes amylase - function of amylase
- enzyme that breaks down starches
- function, location of intrinsic salivary glands
-
keep mouth moist
scattered throughout oral mucosa - what inhibits salivation
- strong sympathetic activation
- teeth are classified how; list the categories
-
by shape/function
incisors
canines
premolars and molars - incisors
- chisel-shaped; for cutting or nipping
- canines
- conical, fangline teeth -- tear/piece
- premolars and molars
- have broad crowns with rounded tips for grinding or crushing
- what are the regions of teeth
-
crown
root - define crown; what are its components
-
exposed part of tooth above gingiva
enamel
dentin
pulp cavity - char of enamel; location
-
acellular, brittle material
made of Ca2+ salts and hydroxyapatite crystrals
hardest substance in body
on crown - definition gingiva
- gums
- char of dentin; location
-
boneline material deep to the enamel cap
forms bulk of the tooth
on crown of tooth - char of pulp cavity; location
-
cavity surr by dentin
contains pulp
on crown of tooth - components of pulp
-
connective tissue
blood vessels
nerves - definition root
- portion of tooth embedded in jawbone
- definition root canal
- portion of pulp cavity that extends into the root
- definition of dental caries; process
-
cavities - gradual demineraliz of enamel and dentin by bacterial action
dental plaque (sugar, bacteria, mouth debris) adheres to tooth
bacteria prod acid
it dissolves Ca2+ salts
salts don't protect dentin and pulp from proteolytic enzymes - definition gingivitis; effect
-
plaque accumulates, calcifies, and forms calculus
this disrupts seal b/w gums and teeth --> gums at risk for infection - definition calculus
- tartar
- definition periodontitis
-
serious gum disease from immune response
immune sys attacks bacteria and body tissues, carving pockets around teeth and dissolving bone --> causes abcess - char, location, function of esophagus
-
muscular tube
from laryngopharynx to stomach
joins stomach at cardiac orifice
travels through mediastinum, diaphragm
glands secrete mucus as bolus moves through - general events occurring in stomach
-
chemical breakdown of proteins begins
food converted to chyme - definition chyme
- liquified food
- what is muscularis; function
-
muscular part of stomach allowing stomach to churn, mix, pummel food physically
breaks down food into small fragments/chyme - epithelial lining of stomach made up of what
- goblet cells
- function of goblet cells
- produce coat of alkaline mucus that traps bicarbonate-rich fluid beneath it
- what are gastric pits? function?
-
____ (in stomach)
contain gastric glands that secrete gastric juice, mucus, and gastrin - regulation of release of gastric juice (general)
- neural and hormonal mechanisms in three phases
- phases of control of gastric secretion
-
cephalic (reflex) phase
gastric phase
intestinal phase - cephalic phase
-
part of control of gastric regulation
before food entry
excit - sight/thought of food, stim of taste/smell receptors
inhib - loss of appetite, depression - gastric phase
-
part of control of gastric secretion
once food enters stomach
excit - stomach distension, activ of chemoreceptors, caffeine, rising pH, gastrin rel in blood
inhib - pH lower than 2, emotional upset overriding parasymp nervous signals - intestinal phase
-
part of control of gastric secretion
as partially digested food enters duodenum
excit - enters duodenum, stim gastric gland activity
inhib - distension of duodenum, presence of fatty, acidic, or hypertonic chyme; irritants in duodenum - when is HCl secretion highest
- when all three ligands (ACh, histamine, gastrin) bind to parietal cells (part of gastric glands in stomach)
- what decreases HCl release; where is it released from
- antihistamines (they block H2 receptors)
-
what is the basic electrical rhythm (BER)
what initiates it -
peristaltic waves move toward the pylorus at rate of 3 waves per min
initiated by smooth muscle pacemaker cells - fate of chyme in stomach
-
delivered in small amounts to the duodenum OR
forced backward into the stomach for further mixing - what is the effect of the pyloric sphincter relaxing
- gastric emptying occurs
- what mechanisms control speed of gastric secretion and emptying
-
carb-rich chyme quickly moves from stomach to duodenum
fat-rich chyme digested more slowly causing food to remain in stomach longer - small intestine runs from where to where
- pyloric sphincter to ileocecal valve
- what are the subdivisions of the small intestine
-
duodenum
jejunum
ileum - what connects small intestine and large intestine
- ileocecal valve
- where do the bile duct and pancreatic duct flow to
- they join the duodenum at the hepatopancreatic ampulla
- what controls the entry of bile and pancreatic secretions into the s. intestine
- sphincter of Oddi
- function of cells of intestinal crypts in small intestine
-
secrete intestinal juice
rel by intestinal glands in resp to distension of irritation of the mucosa - what is the largest gland in the body
- liver
- list the divisions of the liver
-
4 lobes:
right
left
caudate
quadrate - char of intestinal juice
-
alkaline and isotonic with blood plasma
mostly water but contains some mucus - where is gallbladder in relation to liver
- rests in recess of R lobe of liver
- path of bile ducts from liver
- bile ducts fuse into common hepatic duct --> fuses with cystic duct from gallbladder --> bile duct
- function of enterohepatic circulation
- recycles bile salts
- function of gallbladder
- concentrates bile and stores it by absorbing water and ions out of the bile rel by liver cells
- what causes bile release
- acidic, fatty chyme in duodenum --> causes rel of CCK and secretin into blood --> gallbladder contracts, hepatopancreatic sphincter relaxes --> bile enters duodenum (part of s. intestine)
- functions of the pancreas
-
exocrine -- secretes pancreatic juice, which breaks down all categories of food
endocrine -- rel of insulin, glucagon, etc for glucose homeostasis - how does pancreatic juice aid in digestion
-
acini (secretory cell clusters) release zymogen granules --> they contain digestive enzymes
bicarbonate in it neutralizes stomach acid in the duocenum (part of s. intestine) - examples of enzymes in pancreatic juice
-
trypsinogen --> activated in duodenum to trypsin
procarboxypeptidase --> carboxypeptidase
active when secreted: amylase, lipases, nucleases -
secretin and CCK regulate release of what
secretin vs. CCK differences -
bile from gallbladder
pancreatic juice from pancreas
both when fatty/acidic chyme enters duodenum
for p. juice:
once CCK reaches pancreas - induces rel of enzyme-rich p.juice
once secretin reaches pancreas - induces rel of bicarbonate-rich p. juice - what, other than secretin and CCK, induces p.juice release?
- vagal (parasymp) stimulation
- what in chyme has been digested when it reaches duodenum
-
carb and protein partially
no fat digestion - required conditions for digestion; where is digestion completed
-
completed in small intestine
chyme rel slowly
diluting and mixing chyme with bicarbonate (b/c it is hypertonic and acidic)
liver and pancreas supply bile, enzymes, bicarbonate - site of nutrient absorption
- small intestine (ALL occurs there)
- enzymes used for digestion of carb
-
salivary amylase
pancreatic amylase
brush border enzymes - can all saccharides be digested
-
all but cellulose
but only mono and di can be absorbed - what facilitates absorption of carb
- glucose transports in enterocyte cell membrane by facil. diffusion
- where do carbs go when they absorbed
-
enter capillary bed in villi of small intestine
transported to liver by hepatic portal vein - enzymes used for digestion of proteins
-
pepsin (stomach)
small intestine:
p. enzymes - trypsin, chymotrypsin, c.peptidase
brush border enzymes - aminopeptidase, c.peptidases, dipeptidases - what types of proteins can be significantly absorbed
- single, di, tri peptides
- where do amino acids go after absorption
-
enter capillary bed of villi in small intestine
transported to liver by hepatic portal vein
(just like carb) - what other than enzymes is req for digestion of fats
- bile salts in high enough concen to fully solubilize fats (the critical micellar concentration)
- enzymes/chemicals needed for digestion of fats
-
bile salts
pancreatic lipases - absorption process for fats
-
simple diffusion into intestinal cells
combine w/ proteins - rel as chylomicrons into lymphatic lacteals
chylomicrons transported to systemic circ via lymph - enzymes req for absorption of nucleic acids
-
pancreatic ribonucleases
deoxyribonuclease in small intestine - what form of nucleic acids can be absorbed
- must be as single nucleic acids
- absorption process for nucleic acids
- active transport via membrane transport proteins
- absorption of fat-soluble vitamins (which vit are these)
-
A, D, E, K
co-solubilized and co-absorbed with fats -- req bile salts for significant absorption - absorption of water-soluble vitamins (which vit are these)
-
B, C
by facilitated diffusion through transport proteins
except for B12 --> must be bound to intrinsic factor (prod by stomach) for efficient absorption by s. intestine - Ca2+ absorption regulated how
-
related to blood levels of Ca
regulated by vit D and parathyroid hormone - absorption of electrolytes and ions (Na+, Fe, anions)
-
most actively absorbed along the entire small intestine
Na+ - with glucose and AAs
iron - transported into mucosal cells; binds to ferritin
anions - passively follow elect gradient estab by Na+ - water absorption
-
85% of water is absorbed in smalll intestine
moves in both dir across intest mucosa, but
net osmosis occurs when concen gradient is estab by active transport of solutes INTO mucosal cells
kidneys elim approp amount of water to maintain the proper balance - what can cause malabsorption of nutrients
-
anything interfering with delivery of bile or p.juice
damage to intestinal mucosa (bacterial infection)
gluten enteropathy (damages villi and reduces length of microvilli) - subdivisions of the large intestine
-
cecum
appendix
colon
rectum
anal canal - where does ileum join the large intestine
- at the cecum
- what contains the appendix
- cecum
- regions of the colon
-
ascending colon
hepatic flexure
transverse colon
splenix flexure
descending colon
sigmoid colon - what part of the colon joins the rectum
- sigmoid colon
- list the sphincters of the anus
-
internal (involuntary control)
external - when are sphincters closed? is this contracted or relaxed?
- all times other than during defecation - contracted
- what are hemorrhoids
- inflammation of superficial venous plexuses assoc with the anal canal that cause itchiness
- what/where are bacterial flora
-
bacteria surviving the small intestine that enter cecum
bacteria entering via anus - actions of bacterial flora
-
colonize the colon
ferment indigestible carb
and therefore rel irritating acids and gases
synthesize B complex vitamins and vit K - actions of large intestine
-
absorption of water and electrolytes
propulsion of fecal material toward the anus - does digestion occur in the large intestine
- no (other than by bacteria)
- what causes diarrhea
- lack of absorption of water and electrolytes by large intestine
-
what are haustral contractions
how do they occur -
slow segmenting movements in large intestine that move the contents of the colon
haustras contract sequentially as stimulated by distension - what stimulates defecation
- rectal walls fill with feces --> walls are distended --> stimulates contraction of rectal walls and relaxation of internal sphincter --> voluntarily the external sphincter is relaxed
- compare gastric and duodenal ulcers (general)
-
erosion of mucosal lining of stomach
erosion of mucosal lining of upper duodenum - cause and treatment of gastric ulcer
-
insufficient protection of mucosa or excessive HCl prod
treat by decreasing HCl prod (histamine H2 receptor blockers like Pepsid) or neutralize gastric acid (antacids) - cause and treatment for duodenal ulcers
-
infection of mucosa by H.pylori bacteria
antibiotics and acid reducing medications; bismuth s. (Pepto-Bismol) - what are gallstones? what are they made up of?
-
precipitation or crystalliz. of some of components of bile in gallbladder
cholesterol, bile salts/pigments, calcium salts, or mixture - location of gallstones
- stay in gallbladder or get lodged in one of ducts between gallbladder and small intestine
- effect of backed up bile
-
into liver or pancreas -- infection and inflammation --> hepatitis, pancreatitis, cancer
from liver, eventually through blood and into tissues --> jaundice - add card about cancers!
- d