gastrointestinal tract Flashcards

1
Q

how are carbohydrates dealt with?

A

broken first down by enzymes
amylase in saliva
then further down into simpler foms such as disaccharides

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2
Q

maltose is broken down by…

A

maltase

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3
Q

sucrose broken down by…

A

sucrose

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4
Q

how are proteins broken down?

A

peptidase

into amino acids

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5
Q

how are lipids broken down

A

lipase

fatty acids removed from glycerol back bone

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6
Q

how is food energy measured?

A

how much every can be derived from it

calories

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7
Q

what is BMI

A

weight relative to height

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8
Q

what should BMI be coupled with to make it more representative

A

skin fold measurements
upper arm circumference
ketones in urine
nitrogen balance

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9
Q

high BMI =

A

higher risk of comorbidity

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10
Q

steps of the digestive process

A
ingestion
propulson
mechanical and chemical igestion
apsorption
defecation
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11
Q

what is propulsion

A

swallowing, oesphagus, peristalsis

pushing of food through the tract

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12
Q

histological features of the digestive tract

A
outside to in
serosa
muscularis exerna
submucosa
mucosal layer
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13
Q

what is the serosa

A

connective tissue and epithelial layer
cntinuous with outer
forms visceral layer

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14
Q

what is the muscularis externa

A

longitudinal muscle outer
circular muscle inner
sandwiched between the muscles is the nerves/plexus

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15
Q

what is the mucosal layer

A

layer of epithelial celss that protect the gut from abrastion

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16
Q

features of the mucosal layer

A

gastric gland here secretes enzyemes
enteroendocrine cells release hormomes
absrbs material into capillaries

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17
Q

what is the lamina propria

A

part of the mucosa
connective tissue
contains: capillaries, lymph vesles, lymphoid folicles

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18
Q

features of the submucosa

A

contains blood and lymph vessels

deep within is the sensory neurones: plezus

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19
Q

features of the muscularis exerna

A

smooth muslce is longlitudinal
circular muscle inside
can produce waves of contraction
myenteric plexus found here

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20
Q

what forms the ENS

A

network of neurones connected t the submucosal plexus

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21
Q

what two tyes of contraction can the muscularis externa help with

A

peristalsis or segmentation

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22
Q

what is the function of the mouth

A

reduced food sie
prepares it for swallowing
starting point for chemical breakdown

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23
Q

what is the tongue

A

skeletal muscle
upper surface is keratinised stratified squamous epthelium
bottom is non-keratinised mucus membrane

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24
Q

what is saliva pH

A

pH7
hypotonic
mainly water

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25
Q

what are the three salivary glands

A

paratoid
submanidubular
sublingual

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26
Q

what is the paratoid salivary gland

A

serous cells
mainly watery
contains enzymes, electrolytes and mucin

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27
Q

what are the submandibular and sublingual salivary glands

A

serous and mucosal cells

thicker saliva

28
Q

functions of saliva

A
protection
temp control
acid neutralisation
defence
taste
lubrication
digestion enzymes
29
Q

function of the osephagus

A

moves bolus to to stomach

delivery shute

30
Q

features of osephagus

A

secretes mucus
strited muscle at top for voluntary functions
smooth at bottom for involuntary

31
Q

what is peristalsis

A

propulsion of food along the tract

circular and longitudinal muscles have waves of contraction and relaxation moving the bolus

32
Q

function of the stomach

A

strores the food
digests it chemically
digests it physically using grinding

33
Q

what are rugae

A

foldings on the inner lining of the stomach

allow it to expand

34
Q

anatomy of the stomach, name the parts

A

cardia
fundus
bod
pyloric region

35
Q

which parts of the stomach expand?

A

fundus and body

36
Q

what is the function of the pyloric region

A

chruning and empying flood

strong contractions needed here and thick mucles

37
Q

describe the passage of food in the stomach

A
food in and stored
mixed with water mucus and gastric secretory products 
grinding
food into pylorus
passes to duodenum
38
Q

what affects the rate of stomach emptying

A

volume of food in stomach and its contents

more food means stronger contractions

39
Q

what slows down digestion

A

but fat and acidic foods result it less stronger cntractions as these need longer to be digested and neutralised

40
Q

what are gastric pits

A

the lead to gastric glands in the surface of the stomach

41
Q

what is released from gastric glands

A

mucus
HCL
intrinsic factors
hormones

42
Q

what are exocrine gland cell

A

secrete into ducts and the stomach lumen gastric juice

43
Q

examples of exocine things secreted into he stomach

A

mucus
pepsinogen
HCL
intrinsic factors

44
Q

endocrine

A

secrete into the blood system

pyloric regions

45
Q

paracrine

A

secretions acting on neighbouring cels
histamine
stomatastin

46
Q

what does a parietal cell release

A

HCL gastric juice and intrinsic factor

47
Q

what do chief cells release

A

pepsinogen and gastric juice lipase

48
Q

what do G cells release

A

hormone gastrin which stimulates gastric acid secretion

49
Q

what do paracrine cells do

A

stimulate gastric juice secretion

50
Q

what do D cells do

A

secrete stomatostain which inhibits gastric acid secretion

51
Q

what secreted HCL

A

parietal cells

fundus and body

52
Q

functions of HCL

A

breakdown of connective tissue and muscle fibres of ingested meat
activate pepsinogens
kills microorganisms

53
Q

how is HCL made in the stomach?

A
CO2 transprted into parietal cells
carbonic acid dissociates
bicarbonate to bloo
exchange for chloride into the lumen
H into gastric gland in exchange for K 
K into blood
blood more alkaline due to bicarbonate there
H= with chloride forms HCL released into stomach
54
Q

what is pepsinogen

A

made by chief cells
an enzyme in gastric cells
a group of proteolytic proenzymes
hydrolyses peptide bond

55
Q

what is pepsin

A

protease

hydrolyses peptide bond within proteins

56
Q

how does the stomach not digest itself

A

mucus is key
outer layer is physical protection
water layer acts as buffer for neutralisation

57
Q

causes of gastric ulcers

A

coffee
nicotine
asprin
low bicarbonate

58
Q

how does helicobacter pylori cause

A
swims to mucus layer, gets into epthelium
enzyme urease released
neutralises gastric acid,
ammonia breaks down musuc layer
pylori breaches layer 
inflamation of the cells
59
Q

why is vitamin B12 needed?

A

maintanence of CNS and metabolism and maturation of RBC

lack can lead to anaemia

60
Q

how is vitamin B12 absorbed

A

intrinsic factor

61
Q

describe the process of vitami B12 beng absorbed

A

cobalmin is bound to proteins in food
acid pH ad pepsin release colbalamin from protein
gastric glands ecrete molecule to bind with this calalamn
gastric parietal cells secrete intrinsic factor
pancrease secretes proteases and alkaline
cobalamin is released after the degredation of the molecule

62
Q

name the three stages of gastri secretion

A

cephalic
gastric
intestinal

63
Q

what is the cephalic stage of digestion

A

CNS stimulated through sight and smell
signal the submucosa plexus to release Ach
mucus, pepsinogen and HCL secreted, gastrin also secreted

64
Q

what is the gastric phase of digestion?

A
food into th stomach
stretch receptors stimulated
message to submucosal and myenetic plexus
mucus, pepsinogen and HCL stimulated
waves of contraction
gastin stimulated too
food broken down
stomatastin produced
things shut down ready for next stage
65
Q

what happens in the intestinal stage of digestion

A
food moved to duodemun
plexus inhibited
stomach less stretched
lesss grnding
cell secretion inhibited
chyme is acidic, CCK, secretein stimuated
peristalis stopped
everything slowed down and stopped