Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GI lectures - semester 3 > week 1 - basic structures and processes > Flashcards

week 1 - basic structures and processes Flashcards

1
Q

how many layers does gut wall have? name them inner to out?

A 
4 layers:
Mucosa (innermost)
Submucosa
Muscularis externae
Serosa (outermost)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what does mucosa contain?

A

epithelium, lamina propria, muscularis mucosae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the submucosa layer?

A

CT layer with glands, nerves, veins and arteries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what does the muscularis externae layer contain?

A

2 smooth muscle layers:
outer longitudinal
inner circular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the serosa layer?

A

outermost serous membrane:
CT (inner), simple squamous epithelium (outer) – mesentery between 2 layers lubricate on containing arteries, veins, nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the overall process of GI?

A

Point of entry for food into body
Mechanically breakdown food
Temporary store food – stomach
Chemically digest food: salivary amylase & lipase, pancreatic amylase
Kill pathogens in food
Move food along GI tract – cilia
Absorb nutrients from resultant solution – small intestines
Eliminate residual waste materials – rectum & anus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is digestion?

A

conversion of what we eat by physical & chemical disruption, into a sterile, neutral pH, isotonic solution (absorb), from which we absorb nutrients (sugars, fatty acids, AA, minerals, vitamins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what does the alimentary canal contain within GI?

A

Mouth, tongue, pharynx, oesophagus, stomach, small intestine, colon of large intestine, appendix, rectum, anus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are accessory organs of the GI?

A

liver, gallbladder, pancreas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the function of the mouth in digestion?

A 
Saliva: Starts digestion (salivary amylase & lipase - chemical), bacteriostatic (IgA), high Ca2+ (protect teeth), assists swallowing
Physical: teeth, tongue, muscles of mastication (chewing)
Forms bolus (chewed food) to enter oesophagus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

oesophagus - function in digestion?

A

Upper end oesophagus (voluntary), lower end oesophagus (involuntary)
Rapid peristaltic transport (mouth to stomach in 8-9 seconds)
Fastest GI transport: oesophagus (entry) & rectum/anus (exit)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

structure of oesophagus?

A

mucosa (epithelium, lamina propria, muscularis mucosae), submucosa, muscularis externa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

innervation of oesophagus?

A

myenteric plexus (between 2 layers of muscularis externae), submucosal plexus (between submucosa and muscularis externae)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

stomach - how does it digest food??

A

Physical: churning (3 muscle layers & mucosal rugae)
Chemical: acid (HCl) & enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

function of the stomach?

A

Acts as food store – eat faster than digest
Contracts rhythmically: mix & disrupt food
Secretes acid & proteolytic enzymes – breakdown tissues & disinfect
Protects epithelium – secreting mucus
Produce hypertonic chyme – combined action of acid, enzymes & agitation (stir disturbance) (hypertonic: more molecules greater osmotic strength)
Brings incompletely digested chime to duodenum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is receptive relaxation of the stomach?

A

wall relaxes - pressure doesn’t rise as volume increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

structure of stomach (from lumen out)?

A

rugae, gastric mucosa, muscularis mucosae, submucosa, muscularis externa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is rugae?

A

folds of gastric mucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the function of the gastric mucosa in stomach?

A

secretes acid, digestive enzymes & hormone gastrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

describe the muscularis externa in stomach

A

3 layers of smooth muscle: oblique, circular, longitudinal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

which epithelium lines the stomach?

A

Simple columnar epithelium all the way along stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what does liver secrete? into where?

A

Liver secretes bile into duodenum (of small intestine – pylorus end of stomach), some bile stored in gallbladder

23
Q

what does pancreas secrete? where into? via?

A

pancreas secretes pancreatic juice into duodenum (pancreatic duct)

24
Q

where does pancreas and liver secrete into? why?

A

All into 2nd part of duodenum (major duodenal papilla)

all alkali to neutralise acid chyme

25
Q

function of duodenum?

A

dilation & neutralisation of chyme

26
Q

structure of duodenum?

A

Structure: 25cm, C-shaped, proximal SI, curves round head of pancreas

27
Q

what does bile contain?

A

water, alkali (isotonic balance acidic HCl), bile salts (emulsify fat)

28
Q

what happens in terms of the undigested food in the duodenum?

A

Water drawn in from ECF to render hypertonic chyme, isotonic
Liver release bile (from gall bladder)
Pancreas, liver & intestine secrete enzymes: act with bile to complete digestion of chyme

29
Q

how does enzymes form pancreas and intestine complete digestion?

A

Cleave peptides to AA
Cleave polysaccharides to monosaccharides
Breakdown & re-form lipids
Breakdown nucleic acids

30
Q

what does absorption require in order to occur properly?

A

active process – requires lots of energy
Requires large SA
Good blood supply / drainage – energy (glucose, ATP), oxygen etc.

31
Q

how does the gut provide a large surface area?

A

gut is folded/villi/micro-villi, adequate contact time (control gut transit)

32
Q

structure of the jejunum (from in to out)?

A 
Plicae circulares (end of villi, circular folds of mucosa & submucosa project into gut lumen)
Jejunal mucosa
Muscularis mucosae, submucosa, muscularis externa (inner circular, outer longitudinal)
33
Q

what does microvilli contain?

A

goblet cells

34
Q

what does jejunal mucosa contain?

A

simple columnar epithelium, lamina propria, MM

35
Q

what has happened by small intestine (duodenum / jejunum / ileum)?

A

most active absorption proximally, by terminal ileum (nutrients absorbed, water still to be absorbed)

36
Q

describe the large intestine (structure) from appendix end

A

caecum, ascending colon, (right hepatic flexure), transverse colon, (left splenic flexure),descending colon, sigmoid colon, rectum

37
Q

structure of large intestine?

A

Mucosa, submucosa, muscularis externa

38
Q

what does mucosa of large intestine contain?

A

has crypts of Lieberkühn – simple columnar epithelium – produce mucus & absorb water & electrolytes

39
Q

what is the function of the large intestines?

A

continues water recovery – contents semi-solid by end of large intestine
Contents await expulsion in colon (not yet rectum)

40
Q

how do contents travel from colon to rectum?

A

At certain times, rapid propulsion into the rectum (stretches rectum gives the urge to defaecate)

41
Q

fluid balance of gut - how many litres of fluid in 1kg of ingested food?

A

Ingest 1kg: mouth 1.5L saliva, stomach 2.5L gastric secretions, small intestine 9L of water/alkali – making a total of 14L (including ingested 1kg)

42
Q

of the 14L, how much is reabsorbed and how much is excreted?

A

small intestine: absorb 12.5L, large intestine: absorbs 1.35L
Leaving 0.15kg faeces

43
Q

what does decrease absorption / increase secretion results in?

A
  • Life threatening dehydration (depletion of body fluids, not just what we drank because of osmosis (hypertonic, isotonic))
  • Life threatening electrolyte imbalance
44
Q

Motility & secretion precise control by what?

A

neural (nerves), paracrine & endocrine

45
Q

how does the neural control function?

A

divided into somatic and ANS

46
Q

what does somatic neural control?

A

Somatic (innervates striated muscle): ingestion (mouth & first 1/3 oesophagus), excretion (last sphincter of anus)

47
Q

what does ANS neural control?

A

ANS controls the rest:

a. Post ganglionic neurones from plexuses
b. ‘gut nervous system’ – gut brain
c. range of neurotrasmitters

48
Q

describe the post ganglionic neurones from plexus (control of ANS neural on the gut)

A
  1. Submucosal plexus: between muscle layers of gut (ME)

2. Myenteric plexus: beneath muscle but on top of submucosa

49
Q

what are the paracrine control over the gut

A

Paracrine control (act locally):

  1. histamine
  2. vasoactive substances
50
Q

what does histamine control?

A

control acid production in stomach

51
Q

what do vasoactive substances control?

A

affect blood flow in gut

52
Q

describe endocrine control over the gut

A

Range of hormones control:

  1. secretion of stomach acid
  2. alkali secretion from liver & pancreas
  3. enzyme secretion
53
Q

what do all hormones of the gut belong to?

A

All hormones are peptides of 2 structurally related families (gastrin & secretin groups)

GI lectures - semester 3 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions