Chapter 25: Digestive System Flashcards
What is Digestion?
process whereby food is changed into a form that can be absorbed
- breakdown of ingested food
- absorption of nutrients into blood
What is metabolism?
production of atp
anabolic and catabolic cellular activities
what makes up the Alimentary canal?
Mouth, pharynx, esophagus, stomach, intestines, rectum, anus
what are the accessory organs to the digestive system?
Salivary glands, liver, gallbladder, pancreas
what are the four layers of the digestive tract?
Mucosa
Submucosa
Muscularis
Serosa
the inner most layer of the digestive tract is what?
Mucosa
what are the three layers of the Mucosa?
- ) Mucosal epithelium
- ) Lamina propria
- Blood vessels, sensory nerves, lymph vessels, M.A.L.T. - ) Muscularis mucosa
- Smooth muscle and elastic fibers
- Two layers
- Circular and longitudinal
the mucosa may have ______ to increase surface area
fold
the mucosa may also have glands that create what enzymes?
digestive and mucous enzymes
what are the functions of the mucosa?
protection
absorption & secretion
what is the submucosa made up of
loose CT, glands, BV, lymph vessels & nerves
what are the functions of the submucosa?
nourish surrounding tissues
carry away absorbed materials
describe the muscularis
layers of visceral smooth muscle inner = circular -decrease diameter when contracted outer = longitudinal -shorten tube when contract
describe the serosa
-A.k.a visceral peritoneum
-does not exist superior to the diaphragm
Instead there is adventitia
-epithelium & CT
what are the functions of the serosa?
protection
secrete serous fluid
the peritoneum is a ………
series of membranes in the abdominal cavity
- Are continuous with one another
- Peritoneal cavity in between
what are the two membranes of the peritoneum? where do they adhere?
Visceral
-Adheres directly to the internal organs
Parietal
-adheres to the abdominal wall
describe mesentaries
Sheets of peritoneum connected to organs
Access route for vessels and nerves
Stabilize position
what connects the stomach to the liver?
lesser omentum
describe the greater omentum
Starts at stomach
descends inferior
then ascends to form a pouch or “apron” (filled with adipose)
attaches to the colon
what attaches to the majority of the small intestine
mesentery proper
what attaches to the large intestine?
mesocolon
what do both the mesentery proper and the mesocolon allow for?
Both allow for nerves, BV, and lymphatics to connect to intestines
describe peristalsis
Propels bolus (food) down the tract Circular muscles contract first -Prevents bolus from moving back Longitudinal next -Advances it down the tract
describe segmentation
No net movement in any particular direction
Goal is to fragment bolus
Mostly circular muscle contractions
what are 5 functions of the mouth?
Mastication/Mixing Lubrication Speech Taste/evaluation Limited digestion
what are the 2 palates in the mouth? describe them
1.) Hard palate Palatine bone on roof of mouth 2.) Soft Palate CT extension of the palate -->Uvula *Dangles at the end of the soft palate *Prevents food from going down prematurely
what do salivary glands produce? describe
Saliva
- mucous + serous fluid
- form food bolus
- make salivary amylase
- starch digestion
- dissolve chemicals for taste
what are the three salivary glands
parotid
sublingual
submandibular
what is the function of having teeth?
mastication (mechanical breakdown)
what are the different types of teeth and what are they used for?
Incisors -cutting Cuspids (Canines) -tearing Bicuspids (premolars) -crushing & grinding Molars -crushing & grinding
what are the four tooth regions? describe
- ) Crown
- Exposed region of the tooth; covered in enamel - ) Root
- Base; within host bone - ) Neck
- boundary between root & crown - ) Gingiva
- gums
- gingival sulcus–>where gum & tooth meet
describe the two dental successions
- ) Primary or Deciduous teeth
- 20 total
- incisors, cuspid, 1st & 2nd molars - ) Secondary or Permanent Teeth
- 32 total
- incisors, cuspid, 1st & 2nd bicuspid, 1st, 2nd & 3rd molars
describe the movement through the pharynx
is enabled by swallowing
Bolus enters the Oropharynx
Passes the laryngopharynx
swallowing is known as what?
deglutition
what are the three stages of swallowing?
buccal phase
pharyngeal phase
esophageal phase
describe the esophagus
Straight, collapsible tube
penetrates diaphragm through esophageal hiatus
what is the function of the esophagus
passageway for food; only to stomach
describe the unique histology of the esophagus
Mucosa -stratified squamous -large folds (expansion) Muscularis -skeletal muscle in superior regions Adventitia (no serosa)
what are the 5 functions of the stomach
storage mechanical breakdown -churning, mixing chemical breakdown of protein delivers chyme to small intestine Little absorption of nutrients -alcohol, aspirin, water
what are the 2 general shapes of the stomach and what are the four major regions?
General shape: -lesser curvature -greater curvature Major regions: -Cardia: meets esophagus -Fundus: superior region -Body: largest region -Pyloris: meets small intestine
describe the unique histology of the stomach
Mucosa -folded into rugae for expansion during a full stomach Muscularis -THREE muscle layers: *Outer: longitudinal *Middle: circular *Inner: oblique
what do gastric glands do?
make gastric juice
for the gastric glands what are the secretory cell types? describe them (3)
- ) Parietal Cells
- HCl (lowers pH)
- Intrinsic factor (absorbs B12) - ) Chief Cells
- Pepsinogen (Breaks down proteins) - ) Enteroendocrine cells
- Secrete the hormone gastrin
True or False: the small intestine is a major digestive organ
true
what are the parts/regions of the small intestine?
describe them
Duodenum -25 cm -Digestive secretions from liver and pancreas Jejunum -2500 cm -Most digestion and absorption Ileum -3500 cm
what are the four functions of the small intestine?
completes digestion of chyme
receives secretions from pancreas & liver
absorbs products of digestion (majority of absorption)
transports remaining residue to large intestin
three things contribute to increasing the surface area of the small intestine. What are they and describe them
- ) Plicae circulares
- Folds in lining - ) Intestinal villi
- Fingerlike projections of mucosa - ) Microvilli
- Fingerlike extensions of cell membranes
what are the functions of the large intestine?
NO digestive enzymes NO nutrient absorption Bacteria here digest remaining nutrients (Remaining water & vitamins K & B absorbed) Remaining materials: -defecated as feces -Slow, infrequent peristalsis -Enabled by mucus production
what are the regions of the large intestine? describe them
slide 34-36
what are the 6 functions of the liver?
- ) Carbohydrate and lipid metabolism
- synthesizes lipoproteins, phospholipids & cholesterol
- converts carbohydrates & proteins to fat - ) protein metabolism
- make blood proteins - ) Storage
- glycogen, vitamins, iron - ) blood filtering
- ) detoxification
- ) secretes bile
the liver is divided into lobes by the what?
falciform ligament
___________attaches liver to diaphragm
coronary ligament
the largest lobe is the________
right
describe hepatic lobules
Functional unit Hepatocytes around central vein -remove toxins -produce bile Hepatic sinusoids -vascular channels -receive blood from portal veins Kupffer cells fixed macrophages
where is the gallbladder located?
the inferior surface of the liver
what is the function of the gallbladder?
store bile
concentrate bile by reabsorbing water
release bile into duodenum
slide 41
flow chart on flow charts
Pancreatic juice goes into the duodenum via……
Pancreatic duct
Hepatopancreatic sphincter
pancreatic juice is produced by……
pancreatic acini
pancreatic juice is composed of what?
Pancreatic amylase: starch Proteinases & trypsin: protein Lipase: fat Nucleases: nucleic acids Alkalines: neutralizes acidic chyme
