Digestion 1: Function & Structure Flashcards Preview

PSL301 > Digestion 1: Function & Structure > Flashcards

Flashcards in Digestion 1: Function & Structure Deck (126):
1

What are the functions of the digestive system?

1) supply: water, electrolytes, nutrients to the body
2) motility: move materials from 1 part to another, remove waste
3) absorption
4) defense: prevent infection & autodigestion

2

majority of the lymphoid tissues is found...

scattered throughout the Gi tract

3

we have ___ and ____ at the back of the throat for defense

tonsils;
lymphoid tissues

4

GALT

gut associated lymphoid tissues

5

What structures make up the digestive system?

1) tubular GI tract: esophagus, stomach, small & large intestines
2) accessory organs: teeth, tongue, salivary glands, liver, gall bladder, pancrease

6

Purpose of the mouth

receptacle for food

7

what happens in the mouth?

- tongue: taste & guide food to pharynx
- teeth: mechanical digestion
- salivary amylase & salivary lipase (minimal digestion)
- forms bolus

8

what secretes saliva?

salivary glands

9

what does saliva contain?

- antibacterial factors
- mucus
- salivary amylase & salivary lipase

10

pharynx is located...

at the back of the throat

11

purpose of pharynx

push food into esophagus

12

___ protects the larynx during swallowing

epiglottis

13

the swallowing reflex begins at...

pharynx

14

what feature of the pharynx makes swallowing very easy?

epithelial walls are closely adherent to the sides, making the lateral surface very flexible

15

function of esophagus

moves food into stomach (peristalsis)

16

which muscles are present in the esophagus?

beginning: striated muscles (voluntary)
end: smooth muscles (involuntary)

17

sphincters of the esophagus

beginning: upper esophageal sphincter
end: lower esophageal sphincter

18

sphincters of the esophagus control...

movement of materials through the esophagus

19

esophagus passes through the ___. what are the implications?

thorax;
inhaling will suck food upwards -> this is prevented by the esophageal sphincters

20

functions of the stomach

- temporarily stores ingested food
- secretes enzymes for digestion
- mechanical digestion
- slowly empties chyme into small intestines

21

the entire GI tract has a layer of ____ and ___ muscle

circular;
longitudinal

22

stomach muscles

- circular layer
- longitudinal layer
- oblique muscle layer

23

exit of chyme into the small intestines is controlled by...

pyloric sphincter

24

the pyloric sphincter checks .... before allowing food to exit the stomach

- pH
- liquid content
- size of particles
...in chyme

25

sections of the small intestines

1. duodenum
2. jejunum
3. ileum

26

how does food move forward in the small intestines?

- peristalsis
- segmentation

27

main area of digestion and absorption?

small intestines

28

most of the enzymes secreted in the small intestines break down ____

macromolecules

29

absorption of nutrients occurs passively // actively

passively, once the micromolecules are small enough

30

amount of absorption depends on...

time that is spent in small intestines

31

digestion in the small intestines is aided by secretions of...

- liver (via gall bladder) → bile salts
- pancreas → pancreatic enzymes, bicarb

32

liver is connected to gall bladder by...

common hepatic duct

33

gall bladder secretes things into the small intestines by...

common bile duct

34

entrance of material from gall bladder & pancreas to small intestines is controlled through...

sphincter of oddi

35

secretions of the pancreas & gall bladder is influenced by...

hormones

36

segments of the large intestines

1. ascending colon
2. transverse colon
3. descending colon
4. sigmoid colon
5. rectum

37

how is fecal matter moved in the large intestines?

- segmentation
- mass movement

38

what happens in the large intestines?

- absorption of water & electrolytes
- storage of fecal material for expulsion

39

entrance to the large intestine is controlled by...

illeocecal VALVE (not sphincter)

40

the small intestine is large in ____, while the large intestine is large in ____

length;
diameter

41

how is excretion of poop controlled?

internal & external sphincters

42

muscles of the large intestine

- circular layer
- 1 strip of longitudinal muscle = taenia coli

All circular muscles gather along taenia coli, forming haustra (bulges)

43

bulges in the large intestine =

haustra

44

layers of the GI tract

1. mucosa
2. submucosa
3. muscularis externa
4. serosa

45

mucosa is made up of...

- epithelial walls
- lamina propria
- muscularis mucosae

46

lamida propria

thin layer of connective tissues that have fibroblas, myofibroblasts

47

muscularis mucosae

- waves the villi
- helps more mucus come out

48

submucosa is made up of...

- Thick, dense layer of connective tissue
- Blood vessels
- Embedded glands

49

muscularis externa is made up of...

longitudinal & circular muscles
- partial oblique muscle in stomach only

50

serosa layer is made up of...

mesentary system

51

2 components of the enteric nervous system

- submucosal plexus
- myenteric plexus

52

mesentary system

double membrane tissue that surrounds the GI tract and attaches it to the rear wall of abdominal cavity

53

specialized cells of the mucosa

- epithelial cells / transport cells (parietal, goblet, paneth cells)
- enteroendocrine cells
- exocrine cells (goblet cells, paneth cells)

54

epithelial cells in the mucosa are responsible for...

- secretion: acid, bicarb
- absorption: nutrients, water, vit

55

enteroendocrine cells

cells that secrete hormone in the GI tract

56

exocrine cells of the mucosa are responsible for...

secreting enzymes, mucus, anti-microbials, etc.

57

goblet cells

secrete mucus

58

paneth cells

secrete anti-microbial compounds

59

parietal cells

secrete HCl

60

where are paneth cells olcated?

at the bottom of the crypt

61

what cell is responsible for immunity/defense in the GI?

paneth cells

62

cells in the GI have a short // long lifespan?

short

63

what is used to replace cells in the GI? Where are they located?

stem cells;
bottom of crypt → move to top of crypt as it differentiates

64

ENS

enteric nervous system

65

neurons in the ENS

- sensory
- interneuron
- parasympathetic ganglia
- sympathetic postganglionic fibres

66

myenteric plexus

regulates motility

67

myenteric plexus is also known as...

Auerbach's plexus

68

submucosal plexus is also known as...

Meissner's plexus

69

submucosal plexus

regulates secretion and absorption

70

2 main networks of the ENS

1. myenteric plexus
2. submucosal plexus

71

where is the myenteric plexus located?

between the circular & the longitudinal layer

72

where is the submucosal plexus located?

in the submucosa

73

How is the activity of the digestive system regulated?

short (ENS) & long (CNS) reflexes

74

receptors/sensors in the ENS

- mechanoreceptors: stretching of stomach
- chemoreceptors: sense digestion products

75

how does the stomach send information to the CNS (long reflex)?

vagus nerve

76

response from long reflex

- enhance secretion & motility
- change motility & secretion pattern

77

response from short reflex

- enhance secretion & motility
- change motility & secretion pattern

78

2 ways the ENS/CNS can be stimulated

1. presence of food
2. cephalic phase of digestion (thinking/smelling/seeing food)

79

smelling food sends information to ___ receptors, which then sends info to ___

sensory;
the cephalic brain

80

how does the cephalic brain send information to secretory cells of the stomach & small intestines?

via neurons of the myenteric & submucosal plexus

81

release of insulin & glucagon is controlled by the short // long reflex?

long

82

parasympathetic control is divided into...

1. cranial division (vagus nerve)
2. sacral division (Pelvis nerve)

83

PNS has what effect on digestion?

increase digestion
- increased motility & secretion
- relaxes sphincters

84

cranial division of PNS connects to...

1. esophagus
2. stomach
3. small intestines

85

sacral division of PNS connects to...

1. large intestines
2. rectum & anus

86

Steps of PSN control, starting with preganglion neurons and ending with NT secretion

1. pre-ganglion neurons synapse on ganglionic neurons in ENS
2. post-ganglionic fibres secrete ACh

87

distribution of SNS control

evenly distributed throughout GI

88

SNS post-ganglionic fibres release...

noradrenaline

89

SNS generally has what effect on digestion?

- inhibit gut movement
- reduce secretions
- cause sphincters to contract

90

SNS pre-ganglionic fibres release...

ACh

91

the SNS pre-ganglionic fibres connects to...

prevertibral ganglia
- celiac
- superior mesenteric
- inferior mesenteric

92

what changes in the GI regulate activity?

Local factors → secretory & enteroendocrine cells
- pH
- physical / chemical stimuli

Hormones → secretion & motility patterns

Neural mechanisms (myenteric/submucosal plexus)
- short reflex: input from stretch & chemoreceptors
- long reflex: input from CNS

93

first layer of control in the ENS is by...

local stimuli

94

sweet taste receptors activate ___, which increase of ___ (this increases glucose uptake from intestinal lumen)

G-proteins;
incretins

95

GIP

glucose-dependent insulinotropic peptide

96

GLP-1

glucagon-like peptide

97

enterocytes

epithelial cells found in the GI tract

98

2 peptides which stimulates the release of insulin

1) GIP
2) GLP-1

99

Sweet taste receptor is...

dimer of T1R2 and T1R3

100

sweet taste receptors can be found...

- in the mouth
- on enteroendocrine cells in the stomach

101

INCRETINS

general term for GI hormones that stimulate insulin release

102

incretins are secreted by ___ cells

enteroendocrine

103

Where does incretins act?

goes through circulatory system → pancrease

104

local effect of incretin

influence local enterocytes:
- more Na/glucose transporters
-more glucose uptake
- bring more glucose to enterocytes

105

___ circulation = blood flow from heart to digestive system

splanchnic circulation

106

what vessels bring blood to and from the digestive system?

- hepatic artery / hepatic vein
- digestive tract arteries / hepatic portal vein

107

SPLANCHNIC

general term for internal orgains

108

PORTAL SYSTEM

circulatory system from 1 capillary bed to another

109

all blood from the digestive tract passes through the ____ before entering the ____ → ____

liver;
hepatic vein;
inferior vena cava

110

arteries leading to stomach

celiac artery (left & right gastric arteries)

111

arteries leading to small intestines

- superior mesenteric artery
- hepatic artery (→liver)
- small artery that goes to gall bladder

112

arteries leading to large intestines

superior & inferior mesenteric arteries

113

____ artery supplies blood to majority of the small & large intestines

superior mesenteric

114

___ arteries supply blood to most of the digestive system (though not a main force)

inferior mesenteric

115

capillaries in the villi is used for...

- gas exchange
- transport soluble nutrients
- transport water & electrolytes

116

what is used for fat absorption? where does it go?

central lacteal;
lymphatic system

117

LACTEAL

projections of the lymph system

118

function of hepatocytes

- remove potentially harmful agents
- filters & processes the blood

119

blood from the hepatic portain vein & hepatic artery pools in the ____ → _____ vein → drain into ______

sinusoid;
central;
hepatic vein

120

SINUSOIDS

slight enlargement of capillaries

121

bile exits hepatocytes through ___, which then drains into ___ and is stored in the gall bladder

bile canaliculi;
bile ductules

122

functions of the liver

- glucose & fat metabolism
- protein synthesis
- hormone synthesis
- urea production
- detoxification
- storage

123

liver sends ... via the hepatic vein

metabolites to peripheral tissues
- glucose
- plasma proteins (albumin, clotting factors, angiotensionogen)
- urea
- vit D, somatomedins
- metabolites for excretion

124

liver sends ... via the bile duct

things secreted into duodenum
- bile salts
- bilirubin
- water, ions
- phospholipids

125

.... enters the liver via hepatic portal vein

things absorbed from GI tract
- bilirubin
- nutrients
- drugs
- foreign substances

126

... enters the liver via hepatic artery

metabolites & drugs from peripheral tissues
- bilirubin
- metabolites of hormones & drugs
- nutrients