Chapter 25- The Digestive System Flashcards
(51 cards)
1
Q
digestion
A
- process whereby food is changed into a form that can be absorbed
- -breakdown of ingested food
- -absorption of nutrients into blood
2
Q
metabolism
A
- production of ATP
- anabolic and catabolic cellular activities
3
Q
digestive system
A
- alimentary canal
- -mouth, pharynx, esophagus, stomach, intestines, rectum, anus
- accessory organs
- -salivary glands, liver, gallbladder, pancreas
4
Q
layers of the digestive tract
A
structure of the wall
- 4 layers:
- mucosa
- submucosa
- muscularis
- serosa
5
Q
mucosa
A
- inner most layer
- consists of three layers
- -mucosal epithelium
- -lamina propria: blood vessels, sensory nerves, lymph vessels, MALT
- -muscularis mucosa
- –smooth muscle and elastic fibers
- –two layers: circular and longitudinal
6
Q
mucosa cont.
A
- may have folds to increase surface area
- may have glands
- -mucous and digestive enzymes
- functions
- -protection
- -absorption and secretion
7
Q
submucosa
A
- loose CT, glands, BV, lymph vessels and nerves
- functions:
- -nourish surrounding tissues
- -carry away absorbed materials
8
Q
muscularis
A
- layers of visceral smooth muscle
- -inner=circular
- –decrease diameter when contracted
- -outer=longitudinal
- –shorten tube when contract
9
Q
serosa
A
- aka visceral peritoneum
- -does not exist superior to the diaphragm
- –instead there is adventitia
- epithelium and CT
- function
- -protection
- -secrete serous fluid
10
Q
peritoneum
A
a series of membranes in the abdominal cavity
- visceral: adheres directly to the internal organs
- parietal: adheres to the abdominal wall
- are continuous with one another
- peritoneal cavity in between
11
Q
peritoneum: mesentaries
A
- sheets of peritoneum connected to organs
- access route for vessels and nerves
- stabilize position
12
Q
peritoneum: lesser and greater omentum
A
lesser omentum: -connects the stomach to the liver greater omentum: -starts at stomach -descends inferior -then ascend to form a pouch or "apron" --filled with adipose -attaches to the colon
13
Q
peritoneum: mesentery proper and mesocolon
A
mesentery proper
-attaches to the majority of the small intestines
mesocolon:
-attaches to large intestine
both allow for nerves, BV and lymphatics to connect to intestines
14
Q
peritoneum types
A
- mesenteries
- lesser omentum
- greater omentum
- mesentery proper
- mesocolon
15
Q
motor functions
A
- peristalsis
- segmentation
16
Q
peristalsis
A
- propels bolus down the tract
- circular muscles contract first
- -prevents bolus from moving back
- longitudinal necxt
- -advances it down the tract
17
Q
segmentation
A
- no net movement in any particular direction
- goal is to fragment bolus
- mostly circular muscle contractions
18
Q
mouth: functions
A
- mastication/mixing
- lubrication
- speech
- taste/evaluation
- limited digestion
19
Q
mouth structures
A
- hard palate
- -palatine bone on roof of mouth
- soft palate
- -CT extension of the palate
- -uvula: dangles at the end of soft palate, prevents food from going down prematurely
20
Q
salivary glands
A
produce saliva
- mucous and serous fluid
- form food bolus
- make salivary amylase (starch digestion)
- dissolve chemicals for taste
21
Q
glands
A
- parotid
- submandibular
- sublingual
22
Q
teeth: functions
A
mastication
-mechanical breakdown
23
Q
types of teeth
A
- incisors
- cutting - cuspids (canines)
- tearing - bicuspids (premolars)
- crushing and grinding - molars
- crushing and grinding
24
Q
tooth regions
A
- crown
- exposed region of the tooth; covered in enamel - root
- base; within host bone - neck
- boundary between root and crown - gingiva
- gums
- gingival sulcus: where gum and tooth meet
25
dental succession
- primary or deciduous teeth
- -20 total
- -incisors, cuspids, 1st and 2nd molars
26
secondary or permanent teeth
- 32 total
| - incisors, cuspids, 1st and 2nd bicuspid, 1st, 2nd, 3rd molars
27
pharynx
movement through the pharynx
- enabled by swallowing
- bolus enters the oropharynx
- passes the laryngopharynx
28
swallowing
- known as deglutition
- 3 stages
- -buccal phase
- -pharyngeal phase
- -esophageal phase
29
esophagus
- function: passageway for food only to stomach
- straight, collapsible tube
- penetrates diaphragm through esophageal hiatus
30
histology of esophagus
```
mucosa
-stratified squamous
-large folds (expansion)
muscularis:
-skeletal muscle in superior regions
adventitia (no serosa)
```
31
stomach: functions
- storage
- mechanical breakdown
- -churning, mixing
- chemical breakdown of protein
- delivers CHYME to small intestine
- little absorption of nutrients
- -alcohol, aspirin, water
32
stomach: general shape
- lesser curvature
| - greater curvature
33
major regions
- cardia: meets esophagus
- fundus: superior region
- body: largest region
- pyloris: meets small intestine
34
stomach: histology
- mucosa
- -folded into rugae for expansion during a full stomach
- muscularis:
- -three muscle layers:
1. outer: longitudinal
2. middle: circular
3. inner: oblique
35
gastric glands
```
-make gastric juice
secretory cell types:
-parietal cells
--HCL: lowers pH
--intrinsic factor: absorbs B12
-chief cells:
--pepsinogen: breaks down proteins
-enteroendocrine cells
--secrete the hormone gastrin
```
36
small intestine: regions
- duodenum
- -25cm
- -digestive secretions form liver and pancreas
- jejunum
- -2500cm
- -most digestion and absorption
- Ileum
- -3500 cm
37
functions of small intestine
- completes digestion of chyme
- receives secretions from pancreas and liver
- absorbs products of digestion
- -majority of absorption
- transports remaining residue to large intestine
38
Small intestine: how it increases surface area
- plicae circulares: folds in lining
- intestinal villi: fingerlike projections of mucosa
- microvilli: fingerlike extensions of cell membranes
39
large intestines: functions
- NO digestive enzymes
- NO nutrient absorption
- bacteria here digest remaining nutrients
- -remaining water and vitamins K and B absorbed
- remaining materials:
- -defecated as feces
- -slow, infrequent peristalsis
- -enabled by mucus production
40
large intestine: regions
- cecum
- -dialated, pouch-like structure
- veriform appendix
- -narrow tube with closed end
- -hangs down from cecum
- -lymphatic tissue but no digestive function
41
large intestine: regions (colons)
- ascending colon: travels upward along posterior wall to just below liver
- transverse colon: turns at right colic flexture and go towards spleen
- descending colon: turns downward at left colic flexture
- sigmoid colon: S-shaped part near terminal end
42
large intestine: regions (exits)
- rectum:
- -follows curvature of sacrum
- -leads to anal canal
- anus
- -opening to outside
- -guarded by 2 sphincters
- --internal: smooth muscle
- --external: skeletal
43
liver: functions
- carbohydrate and lipid metabolism
- -synthesizes lipoproteins, phospholipids and cholesterol
- -converts carbohydrates and proteins to fat
- protein metabolism: makes blood proteins
- storage: glycogen, vitamins, iron
- blood filtering
- detoxification
- secretes bile
44
liver: structure
- divided into loves by falciform ligament
- coronary ligament attaches liver to diaphragm
- largest lobe on right
45
Liver: structure cont. (hepatic lobules)
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
46
gall bladder: location
-inferior surface of liver
47
gall bladder: function
- store bile
- concentrate bile by reabsorbing water
- release bile into duodenum
48
see path of bile diagram
s
49
pancreas
- structure: head, body, tail
- pancreatic juice goes into the duodenum via:
- -pancreatic duct
- -hepatopancreatic sphincter
50
pancreatic juice: produced by
-produced by pancreatic acini
51
pancreatic juice: composed of
- pancreatic amylase: starch
- proteinases and trypsin: protein
- lipase: fat
- nucleases: nucleic acids
- alkalines: neutralizes acidic chyme
