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155 terms

Digestive system

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Digestion
the process by which food substances are changed into forms that can be absorbed through cell membranes
organs of alimentray canal or GI tract
mouth(oral cavity); pharynx;esophagus;stomach;small intestines; large intestines
accessory organs
lips; teeth; tongue; salivary glands; liver; gallbladder; pancreas
layers of wall of GI tract
mucosa; submucosa; muscular layer; serosa;
mucosa
innerlining, made of mucosus membrane and thin layer of smooth muscle functions as protection underlying tissue and carrying on the processes of absorption and secretion
submucosa
made of loose connecctive tissue and many blood vessels, lymph vessels, nerves; functions of transporting newly-absorbed nutrients
muscular layer
inner layer encircles the GI tract and is responsible for the action of mixing the outer layer runs lengthwise along the GI tract and is responsible for the action of peristalsis
serosa
outer layer of the GI tract makes up the visceral peritoneum functions as lubrication so visceral organs can slide freely against one another
mixing movements and propelling movements
the motor functions of the alimentary canal
segmentation
a type of movement that aids mixing by alternately contracting and relaxing the smooth muscle in nonadjacent segments of the organ
peristalis
propelling movement that includes a wavelike motion in which a ring of contraction occures in the wall of the tube
submuscosal plexus
postaganglionic fibers located in the wall of the canal is important in controlling secretions by the GI tract
myenteric plexus
musclcular layer controls the GI motility inclued sensory neurons
parasympathetic impluses
these nerve impluses increase the activities of the digestive system
sympathetic impulses
these nerve impluses decrease the activites of the digestive system
mouth
first portion of the alimentary canal that recieves food and begins digestion
mastication
mechanically breakin up solid particles into smaller pieces and mixing them with saliva
lips
judge temperature and texture of foods
tongue
a thick muscular organ that occupies the floor of the mouth and nearly fills the oral cavity when mouth is closed
lingual frenulum
mucous membrane covers the tongue and a membranous fold
papillae
rough projections that are on the surface of the tongue, some that contain taste buds
lingual tonsils
cover with rounded masses of lymphatic tissue
hyoid bone
where is the tongue anchored to
palate
forms the roof of the oral cavity and consists of hard anterior part and a soft posterior part
uvula
the soft palate forms a muscular arch which extends posteriorly and downward as a cone shaped projection
palatine tonsils
in the back of the mouth on either side of the tongue and closely associated with the palate are masses of lymphatic tissue
pharynegeal tonsils or adenoid
on the posterior wall of the pharynx above the border of the soft palate if enlarged may block the passage between the nasal cavity and pharynx
teeth
the hardest structure in the body
primary or deciduos teeth
first set usually erupts througth the gums between 6 mth and 24 month or 2 1/2 years
gingiva
gums
what happens to the root of the decidous teeth
the roots are absorbed and then the tooth is pushed out of its socket by a permant tooth
when do permant tooth come in
starts about 6 yrs old
20
the amount of decidous teeth there is
incisors
2 in each quater of the upper and lower jaw= 8
canines
1 in each quater of the upper and lower jaw=4
permolars
2 in each quater of the upper and lower jaw=8
molars
3 in each half of upper and lower jaws=12
32
the total amount of permant teeth
crown
covered with enamel, superior to the gum
root
anchored b periodontal ligament; cementum encloses root and anchors bone to the jaw
dentine
the layer beneath enamel
pulp cavity
surrounded by dentine; containg blood vessels, nerves connective tissue
cavities
prodeced by bacteria that convert carbohydrate to acid
gingivitis nd peridontitis
gum disease or inflammation of the gums
neck
portion of where the gum comes and meets the tooth
root
below the gum
layers of the tooth
enamel ; dentine ; cementum; periodontal membrane or ligament
salivary glands
parotid (2), submandibular (2), sublingual glands(2)
parotid glands
anteior to each ear; largest salivary gland
mumps
enlargement of the parotid caused a virus
serous cells
the cells that secret salivary amylase which begins digestion of carbohydrates
submandibular glands
located in the floor of the mouth on the inside surface of the lower jaw....contains mostly serous cells which secrete amylase and a few mucous cells which secrete muscus
sublingual glands
the smallest of the major salivary glands located on the floor of the mouth inferior to the tongue. primarly serect muscus cells
movements of the GI tubes
mixing and propelling by peristalsis
pharynx
located behind mouth ; connects nasal aond oral cavities
masopharynx
pharyngeal tonsils , openings of internal nares and eustachian tubes
oropharynx
palatien tonsils
laryngopharynx
lingual tonsils and larynx
swallowing mechanism
sesory receptors in teh pharynx ssend impulses over vagus nerve, triggering this reflex
tonge in swallowing mechanism
raised against palate; noves blous of food into pharynx
soft palate
raises to close the internal nares
epiglottis
cove glottis to prevent food from entering trachea
esophagus
opens
peristalitc wave
forces the food into the esophagus
esophagus
lies posterior to the trachea
esophagus
enters stomach via esophageal sphincter whch prevent regurgiatation
reflux heart burn
occurs if the the esophageal sphincter doesn't close and allow reflux of gastric juices into esophagus
stomach
J-shaped organ that lies under the diaphragm
rugae
innter lining of stomach that has fold allow for expansion
function of stomach
mix food with gastric juices (chyme) to initiate protein digestion
cardiac
part of the stomach that surround the lower esophageal sphincter
fundus
rounded portion above and to the left of teh cardiac
body
large central portion of the stomach
pylorus
inferior region which leads into the pyloric sphincter
cells produced by gastric glands
mucous cells; chief cells; parietal cells
mucous
the cells of the gastric glands that secrete protective coating of mucus
chief cells
the cells of the gastric gland that secrete pepsinogen
parietal cells
the cells of the gastric gland that secrete HCl
pepsin
pepsinogen plus HCl form
pepsin
initates protein digestion
regulation of gastric secretion
cephalic, gastric, intestinal, and inhibition of gastric secretion
cephalic phase
this is initated by tase, smell or thought of food. Causing the reflex center in the Medulla Oblongata to initiate nerve impluses that travel on the PNS whick innervate the stomach
cells involed in the cephalic phase
gastric cells that secrete pepsin for protein digestion and endocrine cells of the stomach that secrete hormones
gastrin
secreted by the endocrine cells in the stomach, which stimulates the gastric glands
gastric phase
initiated by the presence of food in the stomach. Distetnsion stiumlated the stoamch mechanoreceptor. Impulse sare sent to ethe medulla Oblongata to stimulate the release of gastrin for mteh stomach
what controls the release of gastrin
the medulla Oblongata
intestinal phase
intiated by the presence of acidic chyme entering the duodenum
gastrin
this is secreted by duodenum to travels to the stomach and stimulate the gastric glands
secretion
secreted by duodenum which inhibits gastric juice secretion
inhibition of gastric secretion
duodenum release secretion, secretin inhibits gastric glands of stomach , fatty acids in teh duodenum case the relase of cholecystokinin
cholecystokinin
release by the duodenum by fatty acids causing the inhibition of gastric juices
location of ulcers in the stomach
gastric and duodenal
causes of ulcer
stress, H.pylori, drugs
mixing and emptying action of the stomach
1. food mixed with gastric juice called chyme 2 fluid pass more readily than soilds, carbohydrates pass more readily than proteins which pass more readily thant fats
vomiting
initiated from reflex in the medulla oblongota, triggered by irritation or distension in the stomach, some drugs, toxins and sometimes rapid change in body motion
pancreas
an exocrine and endocrine gland
where doese the pancrease secret substances
as and exocrine gland it secrets pancreatic juices into the duodenum
pancreatic amylase
breaks down starches and glycogent into disaccharides
pancreatic lipase
breasks down fats into fatty acids and glycerol
trysin, chymotrypsin
breaks down proteins or partially disgested proteins into peptiedes
carboxypeptdiase
breaks down peptides into amino acids
nucleases
breaks down nucleica acids into nucloetides
pancreatic juice
from outline: pancreatic amlases, lipase, proteinase, nucleases
regluation of the pacreatic secretions
PNS by impluses that stimulate release pancreatic juice and the endocrine system with secretin a hormone tha release of pancreatic juices in response to acid chyme entering the duodenum
mouth
this is where the digestion of carbohydrates begin, with the amylase secretions
stomach
this is where the digestion of proteins begin with the secretion of pepsin
how is pepsin made
the chief cells in stomach secrete pepsinogen and the parietral cells of the stomach secrete HCl and the two combine and form pepsin
what is the puprose for pepsin
itinates the digestion of protein in the stomach
liver
this is the largest gland of the body located in the right hypochondriac and epigastric regions
how many and what are the lobes of the liver
4 lobes, right lobe , left lobe , caudate and quadrate lobes
hepatic lobules
the unctionsl units of the liver
hepatic sinusoids
instead of typical capillaries these are the vascular channels that get nutrients and oxygen form the hepatic portal vein and heaptic artery
kupffer cells
these are the cells that are located in the hepatic sinusoids that pagocytize bateria from the blood
jaundice
if the hepatic duct or the common bile duct become obstructed this occurs
liver
this functions to manufactor bile salt,breaks down toxic substances from the blood, manufactures plasma proteins and heparin, stores substances such a iron, copper, and vitamins A,D,E,K and B12
hepatic cells
the cells of the liver that secreted bile
7.6- 8.6
alkaline pH of bile
1 quart
the amount of bile made daily
bile
contains emulsified fats, pigment for the breakdown of RBC's cholesterol and electorlytes
cholerterol
remains in the bile solution and can precipitate and crystalize to form gallstones, if wedged in the bile duct the gallbladder may need to be removed
kupffer cells
cells in liver phagoctyize blood cell debris and bacteria
gallbladder
a pear shaped sac, connected to hte posterior side of teh liver by the cystic duct..
hepatic and cystic ducts
the ducts tha combine to forn teh common bile duct
funciton of the GB
stores and concentrates bile; release the bile inot small intestine to emulsify fats
cholecystokinin
when fatty acied are in the small intestines this is released by the small intestines , it stimulate the gallbladder to relase bile which helps emulsify fats
gallstones
when cholesterol in teh bile precipitates out and forms cyrstals
jaundice and pain
if stones leave the gallbladder and get lodged in the bile duct
part of the small intestines
duodenum, jejunum and ileum
duodenum
the smallest portion of the small intestines, that has numerous villi and contain mucus secreting glands whic form a pretective coating to protect the linging from gastric acids
ileum
extens for the jejunum to the ileocceal sphincter, has numerous lymph nodes called Peyer's patches
mesentery
the supportive tissue that suspends the duodenum and the ileum
Villi
1 mm finger like progjections of the mucose layer of teh small intestinal wall to enlarge surface space to amplify intestines absorption function
lacteal
the lumphatic vessels that is contained in the villi capillaries for nutrient absorption for fat
microvilli
cilia like projections on the villi that contain intestinal digestive enzymes
carboydrate digestion
begins in the mouth with salivary amylase and is completed in the small intestines with pancratic amylasea nd intestinal enzymes maltase, sucrase, and lactase
what happens to simple sugars in the small intestins
glucose and fructose are basorbed by e facilitated diffusion or active transport
protein digestion
begins in the stomach with pepsin, and is completed in the small intestines with the pancreatic proteinases, and peptidases, and intestial peptidase that break proteins down into amino acids
AMINO ACIDS
after protein is broken down this is absorbed into the villi via active transport into capillaries of villi where they are carried way by the blood
small intestines
where does fat digestion begin
fat digesion
beginning in the small intestion with the enzyme pancratic lipase, and completed with intestinal enzyme intestinal lipase producing fatty acids (FA)
short chain
the fatty acid chain that is absorbed by the villi via diffusion
long chain of FA
the fatty acid chain that is reorganized into triglcerides,
lipoprotein
the triglycerides become incased in the portein to produce this, the protein help transport the lipid...it get transported to the tissues for membrane and hormone synthesis
atherosclerosis
if cholesterol gets deposited in arteries in route to tissue memberanes it leads to
movement of the small intestines
weak peristalic contraction of movement that takes chyme 3-5 hours to move through the intesines
large intestinal movement
massive movement of peristalitc waves that occure only 2-3 times per day and pushes resiude toward the
patrs of teh large intestine
begin where ileum joint the cecum (ileocecall valve): colon asending, transverse, desending, sigmoid, rectum
rectum
contain the anal canal, internal sphincter that is under involuntary control, external sphincter that is under voluntary control and anus
large intestine
very little digestive function, some rsidue is digested by baceria to produc some vitamins, absorbs much of the water and electorlytes, mucus and bacteria
fecal color
color results in the bile pigment
fecal odor
results from compounds that are producted by bacteria
defecation
distension stimulates pressorreceptor, under contral of teh PNS, internal pressure builds and forces internal sphinceter to open and feces expelled throught the anus
ulcerative cloitis
affects the mucosa nd submuscosa of the distal large intestines and the rectum causing bouts of bloody BM, diarrhea, cramps for day or weeks can be frequent or ral. sever diarrhea lead to wgt loss and elecotyrole imbalance
diverticulitis
parts of teh intestinal wall that are weaken and inflammed, thought to be from a diet that lacks fiber
colorectal cancer
4th most pevalent, of the large intestine or rectum, sx: change in BM, bloody stools, wgt loss, fatigue, abdominal discomfort or pain