Midgut and Hindgut Flashcards

1
Q

Describe midgut generally

A

Starts in 2nd portion duo
Part of gi tract forming ost of intestines

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2
Q

What supplies midgut

A

Superior mesenteric a = 2nd unpaired branch aorta

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3
Q

Describe content midgut

A

Duo - distal 1/2
Jejunum
Ileum
Cecum and appendix
Ascending colon
Transverse colon - prox 2/3

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4
Q

Describe hind gut Gen

A

Distal portion gi
Shortest portion

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5
Q

What supplies hindgut

A

Inferior mesenteric a

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6
Q

Describe contents hindgut

A

Transverse colon = distal 1/3
Descending colon
Sigmoid colon
Recto
Anal canal (upper part)

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7
Q

Describe transition to midgut

A

In 2nd portion duo = blood supply changes

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8
Q

Describe transition from duo to jejunum

A

Duodenal flexure
Si = intra

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9
Q

Describe arterial supply duodenum - anastomoses

A

Superior pancreaticoduodenal (gastroduodenal - common hepatic - celiac trunk) and inferior pancreaticoduodenal (sma) arteries anatomose

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10
Q

Describe jejunum

A

2nd portion si
Makes proximal 2/5 si
Specialized in nutrient absorption

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11
Q

What is location of jejunum

A

From duo at duodenojejunal flexure
(Made by suspensory muscle/lig of duo = treitz)
To ileum

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12
Q

Is there a clear anatomical distinction between duo and jejunum

A

No

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13
Q

What is treitz

A

Extension so do not regurgitate in mouth, Smooth muscle fibers to help contract

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14
Q

What is purpose of suspensory ligament of jejunum

A

Jejunum heavy
When Breathe in = increased pressure produced by diaphragm, contract les and pull on treitz = reduce this increased pressure

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15
Q

What is found in jejunum - folds

A

Plicae circulares = numerous circular folds in its lumen
Increased surface area for absorption
Rugged wall, 1st portion received a much richer bolus

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16
Q

Describe arterial supply distribution jejunum

A

Less prominent arterial arcades
Long vasa recta (straight arteries)

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17
Q

Compare jejunum and ileum - muscle

A

Ileum = Less plicae, more smooth, peyers patches

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18
Q

Describe ileum

A

Final section si
Makes distal 3/5 of si
Longer than jejunum

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19
Q

Describe location of ileum

A

From jejunum (suspended in mesentery) to ileocecal junction - forms sphincter like end

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20
Q

Describe anatomical distinction of ileum

A

Contains lymphoid nodules = peyers patches
Plicae circulares = low and sparse
Denser arterial arcades and shorter vasa recta

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21
Q

Compare arterial supplies of jejunum and ileum

A

Jejnum = long vasa recta, proximal
Ileum = short vasa recta, many of arterial arcades, distal, I LOVE ARCADE FIRE

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22
Q

Describe mesentery of si

A

Ileum and Jejunum suspended in mesentery = peritoneal fold that carries blood vessels, lymphatics and nerve fibers
Link post abd wall to organ

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23
Q

Describe arterial supply midgut - Gen

A

From sma
Gives jejunal and ileal arteries
Ends in arterial arcades and vasa recta

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24
Q

What is root of mesentery

A

Entry/exit vasculature

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25
Q

Describe large intestine

A

1.5m long and large diameter
Extends from cecum to anal canal
Converters liquid feces to semi solid state
Absorbs water, salt and electrolytes

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26
Q

Describe parts of li

A

Cecum, appendix, colon (ascending, transverse, descending, sigmoid), rectum, anal canal
Transition to hind gut = in transverse colon

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27
Q

Describe flexures of li

A

Right colic flexure - hepatic
Left colic flexure - splenic
(Hits organ and changes direction)

28
Q

Describe Taenia coli of li

A

Longitudinal band Smooth muscle fibers - helps contract - peristalsis
3 of them = ribbon smooth muscle, organized each side li, converge onto appendix
When contract = makes colon fold on itself

29
Q

Describe omental appendices of li

A

Peritoneal covered fat lobules
NOT ON RECTUM
Fat storage?
Depends on bmi

30
Q

Describe haustra of colon

A

Pouches like sacculations
Give Segmented appearance to colon
Due to contractions of Tenia coli

31
Q

Describe cecum

A

1st part li
Inf to ileocecal opening
Removes water and salts, secreted mucus to lube stool

32
Q

Describe location of cecum

A

Right iliac fossa

33
Q

Is cecum retro

A

NOOOOOOOOOOOOOO
INTRA
But not suspended in mesentery
Tenia coli = from appendix up
Continuous with ascending colon

34
Q

Describe appendix

A

Mobile
Narrow, hollow, blind ended tube connected to cecum
Contains large aggregation of lymphoid tissue
Location highly variable = retrocecal or subcecal

35
Q

Describe Clinical- mcburney’s point

A

1/3 of from Asis to umbilicus
Tenderness at this point = acute appendicitis
Surgery needed, if burst = infection would spread in abd region, not contained, could lead to peritonitis

36
Q

Describe iliocecal opening

A

Passage of si to li, sphincter= ileocecal
Gastrointestinal reflex = activates peristalsis

37
Q

Describe ascending colon

A

Behind liver

38
Q

Describe location of ascending colon

A

From cecum to hepatic flexure
Under right lobe of liver

39
Q

Is ascending colon retro

A

YES
Creates paracolic gutters

40
Q

Describe paracolic gutters - ascending colon

A

Folding of peritoneum forms paracolic gutters
Between colon and posterolateral abdominal wall
Allows passage and accumulation of fluids from diff abd regions
If infection = would accumulate here
*serous fluid, peritoneum

41
Q

Describe transverse colon

A

Longest and move movable part of colon
Jump form right side to other
Intra, fixed where spleen is and where liver is but then suspended by mesentery

42
Q

Is transverse colon in midgut or hindgut

A

Marks transition between 2

43
Q

Describe location of transverse colon

A

Crosses abdomen from hepatic flexure to splenic Flexure

44
Q

Is transverse colon Intra or retro

A

INTRA
Completely invested by peritoneum
Connected to post abd wall (over pancreas) by transverse mesocolon
Ant layer of mesocolon adherent to post layer of greater omentum

45
Q

Describe midgut blood supply - Gen

A

Branches named by region they supply
Series of branches along sma

46
Q

Describe midgut blood supply - branches

A

Jejunal arteries
Ileal arteries
Ileocolic artery (terminal branch sma) = ileocecal junction
Right colic artery = ascending colon
Middle colic artery = midgut section of transverse colon

47
Q

Describe marginal artery - midgut blood supply

A

runs along mesenteric border of large intestine: Connects iliocolic, right, middle from SMA & left colic from inferior mesenteric artery (IMA)

48
Q

Where is descending colon

A

From splenic flexure to sigmoid colon
Attached to diaphgram through phrenicocolic ligament

49
Q

What is splenic flexure - descending colon

A

More acute bend, higher and more posterior than hepatic flexure

50
Q

Is descending colon Intra

A

NO retro
Folding of peritoneum forms paracolic gutters
Between colon and posterolateral abdominal wall

51
Q

Describe clinical case - right and left paracolic gutters

A

Possible to mobilize colon by cutting peritoneum along peritoneal reflection - white line of toldt
Cut and move it over, so can get to abd aorta first

52
Q

Describe sigmoid colon

A

S shaped portion colon
Last portion
When hits iliac bone on left

53
Q

Describe sigmoid colon Location

A

Crosses iliac fossa to join rectum in pelvis

54
Q

Describe sigmoid colon - INTRA OR RETRO

A

INTRAAAAA
Suspended in sigmoid mesocolon
Quite mobile since suspended in mesocolon
Contains inferior mesenteric vessels

55
Q

DESCRIBE RECTUM

A

12 cm long
NO TENIA coli, just smooth muscle
Accumulates feces, not much absorption

56
Q

Describe rectum location

A

From sigmoid colon at rectosigmoid junction (level s3) to anal canal as it passed through pelvic floor (ends at anorectal ring)

57
Q

Describe rectum - Dilations/diameter

A

First portion is extension of sigmoid colon = same diameter
Rectal ampulla = dilated portion near its end, stores feces before release via anal canal

58
Q

Is sigmoid colon retro or intra

A

RETRO - needs to be stable, accumulates Weight

59
Q

Describe anal canal

A

2.5-4cm long
Terminal part li
Differentiated from rectum by transition of its internal surface = from endodermal to skin like ectodermal

60
Q

Where is location anal canal

A

Below pelvic diaphragm
From anorectal junction (more constricted here) to anus (external opening of rectum)
Surrounded by inner involuntary and outer
voluntary sphincters

61
Q

Describe clinical - cancers, hemorrhoids

A

Internal hemorrhoids = no sensory info (simple columnar epi)
External hemorrhoids = can feel (stratified squamous epi)
Cancers will be diff if on inside or outside

62
Q

Describe hind gut blood supply - Gen

A

Branches named according to region
All from inferior mesenteric artery

63
Q

Describe branches of Hindgut blood supply

A

Left colic = descending colon
Sigmoid arteries = sigmoid colon (in sigmoid mesocolon)
Superior rectal artery = terminal branch for superior rectum

64
Q

Describe marginal artery - hind gut

A

runs along mesenteric border of large intestine: Connects iliocolic, right, middle from SMA & left colic from inferior mesenteric artery (IMA)

65
Q

Describe what blood supply is to rectum

A

Superior rectal (inf mesenteric artery)
Middle rectal (internal iliac artery)
Inferior rectal (internal pudenal artery)