7: Intestines Flashcards

1
Q

What is the difference in MOBILITY between the Small and Large intestines?

A

Small

  • Duodenum NOT mobile
  • Jejunum / Ileum mobile

Large

  • Ascending & Descending colon NOT mobile
  • Caecum NOT mobile
  • Transverse colon mobile
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2
Q

What is the difference in Lumen Diameter between the Small and Large intestines?

A

Small: Smaller

Large: Larger

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3
Q

What is the difference in Logitudinal Muscle between the Small and Large intestines?

A

Small: Continuous layer

Large: 3 bands: teniae coli

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4
Q

What is the difference in FATTY TAGS between the Small and Large intestines?

A

Small: NONE

Large: Attached to wall

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5
Q

What is the difference in the WALLS between the Small and Large intestines?

A

Small: Smooth

Large: Sacculated (sac formation), forms Haustra (small pouches)

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6
Q

What is the difference in the Mucous Membrane between the Small and Large intestines?

A

Small: Permanent folds = plicae circularis

Large: Incomplete folds may be present

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7
Q

What is the difference in LYMPHATIC TISSUE between the Small and Large intestines?

A

Small: = lymphatic tissue

Large: NONE

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8
Q

What is the blood supply of the DUODENUM? (2 things)

A

Duodenum derived from Foregut & Midgut

  1. Foregut supplied by Coeliac Trunk

Coeliac Trunk → Gastroduodenal Artery → Sup Pancreaticoduodenal Artery

  1. Midgut supplied by Sup Mesenteric Artery (SMA)

Abd. Aorta → SMA → Inf Pancreaticoduodenal Artery

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9
Q

What is the blood supply of the Jejunum and Ileum?

A

Jejunum & Ileum derived from Midgut

Midgut supplied by Sup Mesenteric Artery (SMA)

  • Abd Aorta → SMA → Jejunal Arteries
  • Abd Aorta → SMA → Ileal Arteries

Jejunal Arteries unite → form Arterial Arcades (loops)

Arterial Arcades give rise to Vasa Recta (straight arteries)

(Ileal arteries do same thing)

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10
Q

What is the venous drainage of the Duodenum? (2 points)

A
  1. Veins of duodenum follow arteries
  2. Drain → Hepatic Portal Vein:
  • Directly
  • Through Sup Mesenteric & Splenic Veins
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11
Q

What is the difference in COLOUR between the Jejunum and Ileum?

A

Jejunum: Deep red

Ileum: Paler pink

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12
Q

What is the difference in VASA RECTA between the Jejunum and Ileum?

A

Jejunum: Long

Ileum: Short

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13
Q

What is the difference in PLICAE CIRCULARIS FOLDS between the Jejunum and Ileum?

A

Jejunum: Large + Tall + Closely packed

Ileum: Low + Sparse + Absent in distal part

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14
Q

What is the difference in LYMPHOID NODULES (PEYERS PATCHES) between the Jejunum and Ileum?

A

Jejunum: Few

Ileum: Many

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15
Q

What is the difference in FAT IN MESENTRY between the Jejunum and Ileum?

A

Jejunum: Less

Ileum: More

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16
Q

What is the difference in LOOPS between the Jejunum and Ileum?

A

Jejunum: Few LARGE loops

Ileum: Many SHORT loops

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17
Q

What is the difference in VASCULARITY between the Jejunum and Ileum?

A

Jejunum: Greater

Ileum: Less

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18
Q

What is the difference in DIAMETER between the Jejunum and Ileum?

A

Jejunum: Thick and heavy

Ileum: Thin and light

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19
Q

What are the 8 parts of the large intestine?

A
  1. Caecum
  2. Appendix
  3. Ascending Colon
  4. Transverse Colon
  5. Descending Colon
  6. Sigmoid Colon
  7. Recum
  8. Anal Canal
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20
Q

What is the blood supply of the Caecum?

A

Caecum is Midgut derived

Midgut supplied by Sup Mesenteric Artery (SMA)

Abd Aorta → SMAIleocolic Artery

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21
Q

What is the blood supply of the Appendix?

A

Appendix is Midgut derived

Midgut supplied by Sup Mesenteric Artery (SMA)

Abd Aorta → SMA → Ileocolic Artery → Appendicular Artery

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22
Q

What is the venous drainage of the Caecum and Appendix?

A

Through Ileocolic Vein → Sup Mesenteric Vein (SMV) → Portal Vein

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23
Q

What is the blood supply of the Ascending Colon and Right Colic Flexture?

A

Ascending Colon and RCF derived from Midgut

Midgut supplied by Sup Mesenteric Artery (SMA)

  • Abd Aorta → SMA → Ileocolic Artery (AC)
  • Abd Aorta → SMA → Right Colic Artery (RCF)
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24
Q

How is the Marginal Artery of the large intestine formed?

A

3 arteries:

  • Ileocolic Artery (supplies AC)
  • Right Colic Artery (supplies RCF)
  • Right branch of Middle Colic Artery (supplies TC)

Arteries anastamose with each other → Anastomotic Arcade

Asatomotic Arcade continues round large intestine to form a continuous arterial channel: Marginal Artery

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25
Q

What is the venous drainage of the Ascending Colon and Right Colic Flexture?

A

Ileocolic + Right Colic Veis → drain into Sup Mesenteric Vein (SMV) → Portal Vein

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26
Q

What is the blood supply of the Transverse Colon?

A

Transverse Colon is Midgut & Hindgut derived

Midgut supplied by Sup Mesenteric Artery (SMA)

Abd Aorta → SMA → Middle Colic

Abd Aorta → SMA → Right Colic

Hindgut supplied by Inf Mesenteric Artery (IMA)

Abd Aorta → IMA → Left Colic

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27
Q

What is the venous drainage of the Transverse Colon?

A

Middle colic vein → SMV → Portal vein

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28
Q

What is the blood supply of the Descending and Sigmoidal colons?

A

Descending and Sigmoidal colons are Hindgut derived

Hindgut supplied by Inf Mesenterc Artery (IMA)

Abd Aorta → IMA → Left Colic Artery (Desc)

Abd Aorta → IMA → Sigmoid Arteries (Sigmoid)

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29
Q

What is the venous drainage of the Descending and Sigmoid Colons?

A

Left Colic + Sigmoid Veins → Inf Mesenteric Vein (IMV) → Splenic & Portal Veins

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30
Q

What is the blood supply of the Rectum & Anal Canal?

A

Proximally: Rectum & Anal Canal are Hindgut derived (IMA)

Hindgut supplied by Inf Mesenteric Artery (IMA)

Abd Aorta → IMA → R & L Sup Rectal

Distally: Common Iliac Artery (CIA)

Abd Aorta → CIA → R & L Internal Iliac

  • R & L Internal Iliac → R & L Middle Rectal
  • R & L Internal Iliac → Inf Pudendal → R & L Inf Rectal
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31
Q

What is the venous drainage of the Rectum and Anal canal?

A

Sup + Middle + Inf Rectal Veins

  • Sup Rectal Vein → Inf Mesenteric Vein (IMV) → Splenic + Portal Veins
  • Middle + Inf Rectal Veins → Systemic System
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32
Q

What are the paracolic gutters?

A

Spaces between colon and abdominal wall

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33
Q

What does the Duodenum secrete? (5 things)

A
  1. HCO3-
  2. Water
  3. Bile
  4. Protease / Carbohydrase
  5. Secretin / Gastrin / Cholecystokin (CCK)
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34
Q

What does the Duodenum absorb?

A

Iron

35
Q

What does the Jejunum secrete? (2 things)

A
  1. Protease / carbohydrase
  2. Secretin, Gastrin, Cholecystokinin (CCK)
36
Q

What does the Jejunum absorb? (6 things)

A
  1. Carbs
  2. A.a
  3. F.A
  4. Vitamins & Minerals
  5. Electrolytes
  6. Water
37
Q

What does the Ileum secrete? (2 things)

A
  1. Protease / carbohydrase
  2. Secretin / Gastrin / Cholecystokinin
38
Q

What does the Ileum absorb? (2 things)

A
  1. Vitamin B12
  2. Bile
39
Q

What does the Large Intestine secrete?

A

NOTHING

40
Q

What does the Large Intestine absorb? (2 things)

A
  1. Water
  2. Vitamin K, B12, Thiamine, Riboflavin
41
Q

What form are Carbs ingested in?

A
  1. Amylose = straight chain with alpha 1-4 bonds
  2. Amylopectin = branched with alpha 1-6 bonds
42
Q

What enzyme is in the saliva and pancreas?

A

Alpha-amylase

43
Q

What does alpha-amylase breakdown?

A

alpha 1-4 bonds

Amylose → Glucose / Maltose

44
Q

What enzymes are on the Intestinal Brush Border? (4 things)

A
  1. Isomaltase
  2. Maltase
  3. Sucrase
  4. Lactase
45
Q

What does Isomaltase breakdown?

A

alpha 1-6 bonds

46
Q

What does maltase breakdown?

A

Maltose → Glucose

47
Q

What does sucrase breakdown?

A

Sucrose → glucose / fructose

48
Q

What does lactase breakdown?

A

Lactose → glucose / galactose

49
Q

How is glucose absorbed in the intestines? (3 steps)

A
  1. Na concentratient gradient formed using Na/K-ATPase in basolateral membrane
  2. Na enters Epithelial cell down concentration gradient WITH GLUCOSE through Na-Glucose Symporter
  3. Glucose leaves Epithelial cell into BLOOD through GLUT2 transporter (facilitated diffusion)
50
Q

How are Amino Acids absorbed in the intestines? (2 things)

A
  1. 5 active transport Na/A.A cotransporters
  2. Facilitated diffusion
51
Q

How are fats absorbed in the intestines? (3 steps)

A
  1. Bile acids (in duodenum) incorporate fats → micelles (fat inside, bile acids outside)
  2. Micelles carry fats into “unstirred layer” next to mucosa
  3. F.A released and slowly diffuse into epithelial cells
52
Q

How are sat and water absorbed in the intestines?

A
  1. Na → diffuses into cell → actively transported across basolateral membrane
  2. Cl- follows Na+ movement (down electrical gradient)
  3. Ion movement forms osmotic gradient → water uptake
53
Q

What is Oral Rehydration Therapy?

A

Give patient mixture of glucose and NaCl

  • Na uptake = generates osmotic gradient → water follows
  • Glucose uptake = stimulates Na uptake + generates own osmotic gradient → water follows
54
Q

What is Segmenting of small intestine? (4 points)

A
  1. NOT peristalsis
  2. Contents moved very slowly
  3. Gently agitated
  4. Ensures: effective absorbtion
55
Q

What is the intestinal gradient?

A

Small intestine divided into sections: each section has own pacemaker

Intestinal gradient: frequency of pacemakers get less from Duodenum (12 / min) → Terminal Ileum (8 / min)

56
Q

What do pacemakers in the sections of the intestine cause?

A

Intermittent contraction of SM in that section

57
Q

What are the different types of motility in the intestines? (3 things)

A

Small Intestine

  1. Segmenting

Large Intestine

  1. Haustral Shuffling
  2. Mass Movement
58
Q

What is Haustral Shuffling of the large intestine? (3 points)

A
  1. Large intestine divided into segments called Haustra
  2. Contractions of SM in Haustra walls shuffle contents back & forth
  3. Causes slow absorbtion of remaining water → forms faeces
59
Q

What is Mass Movement of the large intestines?

A
  1. Perstaltic pattern from Transverse colon → Descending colon
  2. Forces faeces rapidly → Rectum
  3. Faeces in Rectum induces urge to defecate via Pressure Receptors

Happens 1 or 2 times a day

60
Q

What is Mass Movement of the large intestine triggered by?

A

Gastro-colic reflex

61
Q

What is the mechanism of defecation? (4 steps)

A
  1. Mass Movement fills rectum + induces urge to defecate
  2. PS control → relaxes Internal Anal Sphincter (SM)
  3. Voluntary control → relaxes External Anal Sphincter (voluntary straited muscle)
  4. Once both sphincters relax → intra-abdominal pressure increases → faeces expelled
62
Q

What are the types of Inflammatory Bowel Disease? (5 causes)

A
  1. Ulcerative Colitis
  2. Crohn’s Disease
  3. Diversion Colitis
  4. Diverticular Colitis
  5. Radiation / Drugs / Infectious / Ischaemic Colitis
63
Q

What are the clinical features of Ulcerative Colitis? (3 things)

A
  1. Rectal bleeding
  2. Diarrhoea
  3. Abdominal pain
64
Q

What are the clinical features of Upper GI Crohn’s disease? (3 things)

A
  1. Nausea & vomiting
  2. Dyspepsia (indigestion)
  3. Loose stools
65
Q

What are the clinical features of Colonic Disease Crohn’s? (2 things)

A
  1. Diarrhoea
  2. Passing blood
66
Q

What things trigger Inflammatory Bowel Diseases?

A
  1. Abx → Gets rid of normal flora
  2. Diet
  3. Acute infammation
  4. NSAIDs
  5. Smoking (Increases Crohn’s risk)
  6. Stress
67
Q

What are the investigations for Inflammatory Bowel Disease? (6 things)

A
  1. Colonoscopy
  • Biopsy of involved mucosa
  • Check for ulceration
  1. Stool analysis
  • Parasites
  • Clostridium difficile
  • Culture
  1. Barium radiography
  2. CT scan
  3. Capsule endoscopy
  4. X-Ray
68
Q

What are the MACROSCOPIC changes of Ulcerative Colitis? (3 things)

A
  1. Red + inflammed mucosa
  2. Mucosa bleeds easily
  3. Ulceration (if severe)
69
Q

What are the MICROSCOPIC changes of Ulcerative Colitis? (4 things)

A
  1. Superficial inflammation
  2. Chronic inflammatory cells infiltrate Lamina Propria
  3. Crypt abcess
  4. Goblet cell depletion
70
Q

What are the MACROSCOPIC changes of Crohn’s Disease? (3 things)

A
  1. Thickened + Narrowed bowel
  2. Deep ulcers + fissures (tears) in mucosa (Cobblestone appearance)
  3. Fistulae + Abcesses (if penetrating disease)

Pic is Crohn’s Cobblestones

71
Q

What are the MICROSCOPIC changes of Crohn’s Disease? (4 things)

A
  1. Inflammation through all bowel layers
  2. Increase in chronic inflammatory cells
  3. Lymphoid hyperplasia
  4. Granulomas
72
Q

What are the investigations for Crohn’s disease? (5 things)

A
  1. Colonoscopy
  2. Upper GI Endoscopy
  3. Small Bowel Imaging
  4. Perineal MRI / Endoanal US
  5. Capsule endoscopy
73
Q

When should colonoscopy be done for Crohn’s disease?

A

If colonic involvement suspected

74
Q

When is Upper GI Endoscopy required for Crohn’s disease patients?

A

To exclude Oesophageal + Gastroduodenal diseases in patients with relevant symptoms

75
Q

When is Small Bowel Imaging requried?

A

Mandatory if suspected Crohn’s

76
Q

What are the different types of Small Bowel Imaging?

A
  1. Barium
  2. CT scan with oral contrast
  3. US
  4. MRI
77
Q

What are the findings Small Bowel Imaging for Crohn’s disease? (3 things)

A
  1. Asymmetrical alteration in mucosal pattern
  2. Deep ulceration
  3. Areas of narrowing
78
Q

Why is Perineal MRI / Endoanal US used for Crohn’s?

A

To evaluate perianal disease

79
Q

When is Capsulse endoscopy needed for Crohn’s patients?

A

For Crohn’s disease patients with NORMAL radiological exam

80
Q

What are the investigations for Ulcerative Colitis? (2 things)

A
  1. Colonoscopy (gold standard for UC)
    * Assesses disease activity + extent
  2. X-Ray → to exclude colonic dilation
81
Q

What are the treatments for Crohn’s disease for:

  1. Induction of Remission (3 things)
  2. Maintenance of Remission (2 things)
  3. Perianal disease (2 things)

(Remission = diminution in severity)

A

API

Azathioprine (immunosuppresant)

Prednisolone (oral) / Hydrocortisone (IV) (corticosteroids)

Infliximab (monoclonal antibody)

  1. Induction of Remission
  • Oral / IV Glucocorticoids
  • Enteral Nutrition (artificial)
  • Anti-TNF antibodies
  1. Maintenance of Remission
  • Methotrexate
  • Anti-TNF antibodies
  1. Perianal disease
  • Azathioprine
  • Anti-TNF antibodies
82
Q

What are the treatments for Ulcerative Colitis for:

  1. Distal disease (1 thing)
  2. Extensive disease (2 things)
A
  1. Mesalamine (5-ASA)
  2. Azathioprine (immunosuppresant)
  3. Prednisolone (oral) / hydrocortisone (iv) (corticosteriods)
  4. Infliximab (monoclonal antibody)

MAPI

83
Q

What should be done for Ulcerative Colitis and Crohn’s if there are complications and the treatments are working?

A

Colectomy