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Module 2 > Digestive Tract > Flashcards

Flashcards in Digestive Tract Deck (65):
1

Peristalsis

Rhythmic contractions of adjacent segments of the digestive tract that propel material forward.

2

Segmentation

Non-adjacent segments of the digestive tract contract and relax, moving material forward and backwards, resulting in mechanical mixing waves

3

Bile

Made of water, ions, bilirubin, cholesterol, and bile salts

4

Emulsification

Bile salts break apart lipid droplets into smaller ones

5

Haustra

Pouches of the large intestine that permit distinction and elongation

6

Varices

Distended collateral veins in lower esophagus, upper stomach, and rectum

7

Ascites

Increased hydrostatic pressure in mesenteric tributaries of hepatic portal veins

8

Splenomegaly

Enlarged spleen resulting from engorgement with blood

9

Hepatic encephalopathy

Increased metabolic waste in blood ( elevated ammonia), can cause AMS

10

Hepatic portal system

Direct transport of materials absorbed from GI tract to the liver for processing prior to entry into general circulation

11

Portal hypertension

Elevated blood pressure of the portal system resulting from cirrhosis or chronic hepatitis / causes collateral circulation to develop which results in blood bypassing the liver and circulating metabolic waste.

12

Mesentery

Double sheets of serous membrane that anchor points of the digestive tract and provide a pathway for blood vessels and nerves

13

Digestive tract

Mouth/Teeth/Tongue
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Rectum/Anus

14

Accessory organs

Salivary glands
Gallbladder
Liver
Pancreas

15

Digestive Function
1) Ingestion

Food enters mouth & digestive tract

16

Digestive Function
2) Mechanical processing

Physical manipulation of solid food

17

Digestive Functions
3) Digestion

Chemical breakdown of food into small organic fragments

18

Digestive Functions
4) Secretion
(Usually occurs from Accessory organs)

Release of water, acids, enzymes, buffers

19

Digestive Functions
5) Absorption
(Usually occurs in the small intestine)

Movement of small molecules, electrolytes, vitamins and water across the digestive lining

20

Digestive Functions
6) Excretion
(Occurs with Large intestine, rectum, and anus)

Removal of waste products from the body

21

4 Main Layers of the digestive tract

Mucosa
Sub-Mucosa
Muscularis externa
Serosa

22

Mucosa

Inner lining of the digestive tract

23

Plica

Increase the surface area of the inner lining

24

3 Parts of the mucosa

Mucosal Epithelium
Lamina Propria
Muscularis mucosae

25

Mucosal Epithelium

-Stratified squamous (oral cavity, pharynx, Esophagus)
-Simple columnar( stomach, large and small intestine)

26

Lamina Propia

Areole connective tissue containing blood vessels, nerve ending, lymphatic vessels, SMC, secretory mucous glands

27

Muscularis mucosae

Two concentric layers of SMC

28

Sub mucosa

Dense irregular connective tissue that binds he mucosa to the muscularis externa, contains blood vessels, lymphatic vessels, nerve fibers, and glands

29

Muscularis Externa

Two concentric layers of SMC ( inner circular/ outer longitudinal) separated by sensory, and inter neurons of enteric NS

30

Serosa

Covers muscularis externa along portions of the digestive tract within the peritoneal cavity ( is the visceral peritoneum)

31

Digestive tract aka

Alimentary canal

32

Local Control of Digestive tract

Chemicals are released into interstitial fluid that affect only a small segment of the digestive tract.
*Paracrine as opposed to endocrine
Ex. Histamine , stomach, release of acid

33

Neural control of the digestive tract

Enteric Nervous system - sub mucosa and muscular externa contains nerve fibers.
-Enteric neurons utilize pacemaker cells and local reflex Arcs to generate GI tract motlity.
-ANS interacts with ENS

34

Hormonal control of the digestive system

At least 18 different hormones are produced by enterendocrine cells (cells of GI tract)
Hormones can increase or decrease sensitivity of SMC to neural command

35

Oral cavity

Receives food/lined by mucous membranes

36

Tongue

Mechanical processing of food, physical manipulation for cheering sensory analysis

37

Teeth

Chewing (mastication)

38

Salivary Glands

Parotid
Sublingual (salivary amylase - enzymes that breaks down starches)
Submandibular

39

Pharynx

Common passage way for air and food to the digestive tract
Stratified squamous epithelium cells
Contains muscles necessary for swallowing

40

Esophagus

10 inch long
Upper esophageal sphincter
Superior is skeletal
Middle is skeletal/smooth
Inferior is smooth
Lower esophageal sphincter ( cardiac spincter)

41

Esophageal hiatus

Whole in diaphragm that allows esophagus to pass through

42

Swallowing (Degulation)

Voluntary then becomes involuntary
Tongue compacts debris into bolous
Oral phase - compression of bolous against hard plate
Pharyngeal phase - Bolus compacts sensory E in pharynx, initiates contact, forcing food through esophongeal sphincter
Esophageal phase - Bolus is pushed toward stomach (peristalsis)

43

Stomach

Rugae - inner folds in empty stomach
Full stomach 1-1.5L
3 muscle layers - oblique, circular, longitudinal

44

4 Functions of the stomach

1. Temporary storage of ingested food
2. Mechanical breakdown of ingested food
3. Breakdown of chemical bonds by acids and enzymes (digestion)
4. Production of intrinsic factor
- Facilitates with B12 absorption

45

Parietal cells

Responsible for secretion of HCL
30-40% is mitochondria (there going to produce CO2 by product)
They utilize it in a certain different way, they convert it to carbonic acid then hydrogen ions
-Histamine and ACH potentates to further release hydrogen ions

46

Zymogen

Non functional enzyme

47

Another chemical is released from partial cells is

Intrinsic factor

48

Pepsinogen with hydrogen ions =

Pepsin (which breaks down protein)

49

Phases of gastric secretion

1st phase (Cephalic phase)
2nd phase (Gastric phase)
3rd phase (Intestinal phase)

50

1st phase (Cephalic phase)

There are sensory triggers the Initial gastric secretion to get ready (vagus stimulation)
-Sight, sounds, smells, of food stimulate vagus nerve - secretion of gastric juice (chyme) mucous, HCL, pepsin(ogen).
-Lasts a couple of minutes
-Oral phase = food enters mouth

51

2nd phase (Gastric Phase)

-Arrival of food to stomach
-Causes stretch, activation of chemoreceptors which triggers mixing waves, generates release of Gastrin (hormone) which causes a release of mucous, HCL, and pepsinogen
-Causes positive feedback response

52

3rd phase (Intestinal phase)

Pyloric sphincter ( separates stomach and first section of small intestine duodenum)
-when there's enough stretch it puts pressure on pyloric sphincter it opens
-The cells of duodenum causes release of somatostatin (GHIH) which inhibits Gastrin and causes a negative feedback of mucous, HCL, and pepsinogen.
-it also releases bicarbonate

53

Small intestine

-20ft long
-90% nutrient absorption

54

retroperitoneal
Receives chyme from stomach (which drops the PH), which causes stretch.
Presence of lipids and proteins causes release of CCK
Receives pancreatic, liver, gallbladder secretions
-10 in long
-upper GI

Duodenum

55

8ft long
-chemical digestion
-nutrient absorption (pepsin breaks down proteins, lipids carbohydrates) then travels to liver for processing
Monosaccharides
Disaccharides
Polysaccharides

Jejunum

56

Iileocecalvalve connects small intestine to the large intestine
*Secretions of small intestine in preparations for food arrival
*Inhibited by sympathetic activation

Ileum

57

99% exocrine function
1% endocrine function
-pancreatic juice = enzymes and buffers (NaHco3)
Carbohydrates -(carbohydrases)
Lipids - lipase (responsible of lipid breakdown)
Protease - proteins
Nuclei acids - nuclease
**they all enter through pancreatic duct

Pancreas

58

Released due to presence of lipids or partially digested proteins from intestine epithelium cells, then causes the hepatic pancreatic sphincter to open, causes pancreatic enzymes to enter the duodenum to digest proteins, lipids, carbohydrates

CCK (cholecystokinin)

59

Glucose, fructose, galactose

Monosaccharides

60

Lactose, sucrose, maltose

Disaccharides

61

Starches, glycogen, cellulose

Polysaccharides

62

Aka colon
5ft long
Recieves waste from ileocecavalve
Appendix is attached from colon
1st is ascending colon
2nd is transverse colon
3rd is descending colon
Stanoid colon
Rectum
Anus

Large intestine

63

Re absorption of water
Compaction of fecal matter
Temporary storage of fecal matter
Absorption of bile salts and vitamins
Absorptions of toxic ( ammonia, hydrogen sulfide, nitrogen, bilirubin)

Function of colon

64

1. Sensory (stretch)
2. Motor (parasympathetic contraction)
3. Distention (stretch positive feedback)
Internal anal sphincter involuntary control
External anal sphincter voluntary control
Absorption, movement, defection

Defecation

65

Performs most of the livers functions
Metabolism, storage, digestion, and bile production

Hepatocytes