Block 3 W2 Flashcards

1
Q

What are the foregut derivatives?

A

Oesophagus, stomach, proximal duodenum, liver, gall bladder and pancreas.
Coeliac artery

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2
Q

What are the midgut derivatives?

A

Distal duodenum, jejunum, ileum, caecum, vermiform appendix, proximal 2/3 transverse colon.
Superior mesenteric artery

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3
Q

What are the hindgut derivatives?

A

Distal 1/3 transverse colon, descending colon, sigmoid colon, rectum, proximal anal canal.
Inferior mesenteric artery

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4
Q

Describe the layers of the anterolateral abdominal wall.

A

Skin -> superficial fascia (fatty Camper’s fascia) -> superficial fascia (membranous Scarpa’s fascia) -> external oblique muscle -> internal oblique -> transverses abdominus -> transversalis fascia -> extraperitoneal fascia -> parietal peritoneum.

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5
Q

What is the origin and insertion of the external oblique?

A

Origin - 8 digitation from inferior 8 ribs
Insertion - linea alba, iliac crest, public tubercle
Aponeurotic anteriorly
Inferomedial fibre orientation

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6
Q

What is the origin and insertion of the internal oblique?

A

Origin - lumbar fascia, iliac crest and lateral 2/3 inguinal ligament
Insertion - linea alba, pecten pubic and ribs 10-12
Aponeurotic anteriorly
Supermedial fibre orientation

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7
Q

What is the origin and insertion of the transversus abdominus?

A

Origin - lumbar fascia, iliac crest, costal cartilages 7-12 and lateral 1/3 inguinal ligament
Insertion - xiphisternum, linea alba, pubic crest
Aponeurotic anteriorly
Transverse fibre orientation

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8
Q

What is the origin and insertion of the rectus abdominus?

A

Origin - pubic crest and pubic symphysis
Insertion - costal cartilages 5-9, xiphisternum
3 tendinous insertions -> 6 pack

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9
Q

Describe the arrangement of rectus sheath above arcuate line.

A

External oblique covers rectus abdominus anteriorly.
Internal oblique splits and covers anterior and posterior.
Transversus abdominus covers posteriorly.

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10
Q

Describe the arrangement of rectus sheath below arcuate line?

A

All aponeurosis of each muscle covers the rectus abdominus anteriorly only.
Enables blood supply - inferior epigastric artery - passes through rectus to supply the muscles.
Nerve - intercostal and subcostal nerves.

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11
Q

Where does the inguinal canal begin and end?

A

Begins - deep inguinal ring (transversalis fascia)

Ends - superficial inguinal ring (aponeurosis of external oblique).

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12
Q

What does the inguinal canal carry?

A

Transmits the spermatic cord/round ligament of the uterus and genital branch of genitofemoral nerve.
Pathway by which structures passes from abdomen to external genitalia.

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13
Q

Describe the boundaries of the inguinal canal.

A

Floor - inguinal and lacunar ligament
Roof - transversus abdominus, internal oblique and transversalis fascia.
Anterior - aponeurosis of external oblique and internal oblique
Posterior - transversalis fascia

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14
Q

Define inguinal hernia.

A

Arises when a portion of intestine protrudes through weak spot in the inguinal canal.
Indirect - protrudes through deep inguinal ring.
Direct - protrudes through posterior wall of inguinal canal.

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15
Q

What are the functions of the anterolateral abdominal wall?

A

Moves trunk
Depress the ribs
Increases intra-abdominal pressure (valsalva)
Supports intestines

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16
Q

Define peritoneum.

A

Serous membrane lined by mesothelial cells.

Consists of parietal peritoneum and visceral peritoneum.

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17
Q

Define parietal peritoneum.

A

Serous membrane lining abdominal, pelvic walls and inferior surface of diaphragm.

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18
Q

Define visceral peritoneum.

A

Serous membrane lining abdominal organs.

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19
Q

Define peritoneal cavity.

A

Potential space, allows organs to be loose for movement in GI tract.

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20
Q

Define infra-, retro- and intraperitoneal.

A

Intraperitoneal - structures lying within visceral peritoneum.
Retroperitoneal - structures lining outside parietal peritoneum e.g. kidneys, 1st part of duodenum.
Infraperitoneal - structures lying below parietal peritoneum.

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21
Q

Define omentum.

A

Fold of peritoneum connecting stomach with other abdominal organs.

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22
Q

Define lesser omentum.

A

Double layer of peritoneum connecting the porta hepatis to the stomach (the lesser curvature) and the beginning of duodenum.
Consists hepatogastric and hepatoduodenal ligaments and forms the anterior wall of lesser sac.

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23
Q

Define greater omentum.

A

Double layer of peritoneum connecting the stomach (greater curvature) to transverse colon.
Lines and covers abdominal contents and has fat deposits + blood supply.

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24
Q

Define mesentery.

A

Fan-shaped double fold of peritoneum that suspends jejunum and ileum from the posterior abdominal wall and transmits nerves and blood vessels to and from the small intestines.
Forms a root that extends from duodenojejunal flexure to right iliac fossa (15cm).

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25
Q

Describe the transverse mesocolon.

A

Connects posterior surface of transverse colon to posterior abdominal wall. Fuses with greater omentum to form gastrocolic ligament.

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26
Q

Describe the sigmoid mesocolon.

A

Connects sigmoid colon to pelvis wall.

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27
Q

Describe the mesoappendix.

A

Connects appendix to mesentery of ileum.

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28
Q

Describe gastrolienal (gastrosplenic) ligament.

A

Connects greater curvature of stomach to hilus of spleen.

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29
Q

Describe lienorenal (splenorenal) ligament.

A

Connects hilus of spleen to left kidney.

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30
Q

Describe gastrophrenic ligament.

A

Connects greater curvature of stomach to diaphragm.

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31
Q

Describe gastrocolic ligament.

A

Connects greater curvature of stomach to transverse colon.

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32
Q

Describe phrenicocolic ligament.

A

Connects left colic flexure to diaphragm.

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33
Q

Describe the falciform ligament.

A

Sickle-shaped peritoneal fold connecting liver to diaphragm and anterior abdominal wall.

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34
Q

Describe the ligamentum teres hepatis.

A

Round ligament of liver
Lies in free margin of falciform ligament and ascends from umbilicus to inferior surface of liver.
Remnant of left umbilical vein.

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35
Q

Describe the coronary ligament.

A

Connects diaphragmatic surface of liver to diaphragm and encloses the bare area of liver.

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36
Q

Describe the ligamentum venosum.

A

Remnant of ductus venosus.

On fissure on inferior surface of liver

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37
Q

Describe the lesser sac (omental bursa).

A

Close sac of space behind liver, lesser omentum and stomach.
Communicates with greater sac through epiploic foramen.
3 recesses:
- superior recess -> behind stomach, lesser omentum and left lobe of liver.
- inferior recess -> behind stomach and greater omentum.
- splenic recess -> extends to left hilus of spleen.

38
Q

Describe the greater sac.

A

From diaphragm to pelvic floor
3 recesses:
- subphrenic (supra hepatic) recess -> between diaphragm and liver
- sub hepatic recess (Morrison pouch) -> deep, between liver and kidney.
- paracolic recesses (gutters) -> lie lateral to ascending and descending colon.

39
Q

What are the components of the posterior abdominal wall?

A

Quadratus lumborum
Psos major
Illiacus

40
Q

Describe the innervation, vasculature and epithelia of small intestine.

A

Simple columnar epithelium
Vagus nerve
Superior mesenteric arteries.

41
Q

Describe the jejunum.

A

Proximal 2/5 of SI
Thicker walls
Main site for absorption - prominent plicae circularis increases SA.

42
Q

Describe the ileum.

A
Distal 3/5 of SI
Thinner walls
Less absorption (B12, bile salts, H2O and lipids)
Less plicae circularis 
More Peyer's patch
43
Q

Differentiate between the mesentery of the jejunum vs. ileum.

A
Jejunum
- long vasa recta
- short/less arterial arcades
- low fat
Ileum
- short vasa recta
- long/more arterial arcades
-high fat
44
Q

Define Meckel’s diverticulum.

A

Slight bulge in small intestine present at birth - vestigial remnant of vitelline duct:

  • present in 2% populations
  • 2 inches
  • found 2 feet away ileocecal junction
  • 2 types of common ectopic tissue (gastric/pancreatic)
45
Q

Describe the large intestine.

A

5 feet long
Major site of H2O, electrolyte and drug absorption
Contains bacteria
2 flexures - right and left colic flexures

46
Q

Differentiate between retro and intraperitoneal structures of LI.

A

Caecum - mesentery -> intraperitoneal
Ascending colon - attached to posterior abdominal wall -> retroperitoneal
Transverse colon - mesentery ->intraperitoneal
Descending colon - retroperitoneal
Sigmoid colon - retroperitoneal

Intraperitoneal structures are more flexible for movement.

47
Q

Describe the characteristic structures of the LI.

A

Taeniae coli - 3 longitudinal muscular strands that contract for movement of faecal matter.
Haustra - bulges
Appendices epiploicae - deposits of fat

48
Q

Describe the caecum.

A

1st part of LI where chyme enters from ileum -> faeces.
Ileocecal valve -> opening from ileum to caecum.
Orifice of appendix -> opening from vermiform appendix to caecum, 2cm below valve.

49
Q

Describe the vermiform appendix.

A
6-9cm
Variable position - retrocaecal/retroileal.
Mesoappendix
Supplied by appendicular artery
Taeniae coli fuse at base
Large aggregations of lymphoid tissue
50
Q

Define appendicitis.

A

Inflammation of appendix resulting from bacteria/virus trapped by obstruction of the lumen by faeces.
Referred pain to umbilicus region, max pain -> McBurney point (lateral 1/3 between right ASIS and umbilicus).

51
Q

What is the role of the sigmoid colon?

A

Stool completes solidification and moves stool into rectum.

Stores faeces.

52
Q

Describe the rectum.

A

Rectal ampulla - stores faeces
No appendices epiploicae/haustrations and taeniae coli fuses here.
Transverse rectal folds (circular muscle) (Houston valve)- supports faecal mass.

Peritoneum:

  • prox 1/3 -> anterior and bilateral parietal peritoneum
  • mid 1/3 -> anterior
  • dis 1/3 -> infraperitoneal
53
Q

How is the anal canal divided?

A

Upper 2/3 - visceral part belonging to intestine.

Lower 1/3 - somatic part belonging to perineum.

54
Q

Define anal columns and anal valves.

A

Anal column - 5-10 longitudinal folds of mucosa.

Anal valve - present-shaped mucosal folds that connect lower ends of anal columns.

55
Q

Define anal sinuses.

A

Series of pouch-like recesses at lower end of anal column in which anal glands open.

56
Q

Distinguish between internal and external anal sphincters.

A

Internal - thickening of circular smooth muscle
External - skeletal muscle
Separated by a groove, Hilton white line.

57
Q

Define pectinate (dentate) line.

A

Point of demarcation between visceral and somatic portions. Different embryological origin:

  • somatic -> ectoderm
  • visceral -> endoderm
58
Q

Describe the change in epithelia in the anal canal.

A

Above - columnar or cuboidal

Below - keratinised stratified squamous

59
Q

Describe the change in vasculature in the anal canal.

A

Above - superior rectal artery and veins (portal venous system)
Below - middle and inferior rectal artery and veins (canal system)

60
Q

Describe the change in lymphatics in the anal canal.

A

Above - internal iliac nodes

Below - superficial inguinal nodes

61
Q

Describe the change in innervation in the anal canal.

A

Above - visceral innervation via inferior hypogastric plexus

Below - somatic innervation via inferior anal nerve (pedendal nerves)

62
Q

Describe the innervation of the smooth muscle of rectum and anal canal.

A

Parasymp. nerve from S2, S3 and S4 (pelvic splanchnic nerve)

Symp. nerves from T11-L2 (inferior hypogastric plexus)

63
Q

Describe the process of defaecation.

A
  1. faeces stretches rectum and stimulates stretch receptors, which transmit signals to spinal cord.
  2. spinal reflex stimulates contraction of rectum -> passes faeces towards anal canal.
  3. spinal reflex also relaxes internal anal sphincter (involuntary).
  4. impulses from brain prevent untimely defaecation by keeping the external anal sphincter contracted.
  5. defaecation occurs when external sphincter relaxes (voluntary).
64
Q

Define the valsalva manoeuvre.

A

Close off oral cavity and nasopharynx to increase intra-abdominal pressure to allow defaecation.

65
Q

What nutrients does fat contain?

A

Fat-soluble vitamins ADEK, essential w-6 and w-3 fatty acids, linoleum acid and linolenic acid.

66
Q

Define triglycerides.

A

Triacylglycerol -> 3 fatty acids ester bonded to glycerol.

67
Q

What other lipids are there?

A

Phospholipids, cholesterol ester and cholesterol.

68
Q

What are the solutions to TAG digestion and transportation in blood?

A

TAG is large - can’t be absorbed straight away and is immiscible with water.
Digestion: emulsification into small droplets and stabilised by bile salts and amphipathic lipids for enzyme action.
Transportation: coat TAG with amphipathic lipids.

69
Q

Describe the digestion of fat.

A

Starts in mouth and stomach, bulk lipids are emulsified into smaller droplets -> increases SA for enzymatic attack.
Lingual lipase digests some TAG.

Biles salts from gallbladder and amphipathic lipids coat small emulsion particles to prevent re-aggregation into bulk TAG in small intestine.

Pancreatic lipase degrade TAG and bile salts solubilise products into micelles to facilitate uptake into enterocytes.

70
Q

What are the sources of lipase?

A

Lingual lipase - Ebner’s gland on tongue
Gastric lipase - cleaves 20% TAG, churning action of stomach at 37degreesC emulsified bulk TAG.
Pancreatic lipase, phospholipase, cholesterol esterase.

71
Q

Describe the absorption process of fat.

A

Small intestine:

  • micelles travel to apical brush border of enterocytes and release products of digestion
  • fatty acids, monoglycerides and cholesterol diffuse into the cell
  • within, lipid products are re-esterified to TAG, cholesterol ester and phospholipids
  • re-esterified lipids with apoproteins form chylomicrons
  • chylomicrons exocytose from enterocytes into lacteals -> thoracic duct -> blood.
72
Q

How are bile salts recycled?

A

Recirculated from ileum to liver via enterohepatic circulation.
Some lost through faeces.

73
Q

Define steatorrhoea.

A

Malabsorption of lipids due to insufficient release of pancreatic lipase.
Causes: excessive alcohol, pancreatic disease, hyper secretion of gastrin, ileal resection.

74
Q

Where is bile formed and concentrated?

A

Bile continuously formed by liver and secreted to gallbladder, where it is stored and concentrated.

75
Q

What is the composition of bile?

A

Water (97%) + bile salts (0.7%) + bile pigments

Breakdown products of cholesterol

76
Q

Differentiate between primary and secondary bile salts.

A

Primary - cholic and chenodeoxycholic acids, made by liver (80%)
Secondary - formed by bacterial action in intestine (20%)

77
Q

Describe the structure of bile salts.

A

Have planar structure with all polar groups on one face and non-polar on another - amphipathic.

78
Q

Describe the role of CCK in the release of bile.

A

CCK released from duodenal mucosa when chyme enters duodenum -> stimulates gall bladder to release bile by contraction of gall bladder and relaxation of sphincter of Oddi (normally closed).

79
Q

Define cholelithiasis and the types.

A

Gallstones
Choledocholithiasis - stones in ducts of biliary tree

Cholesterol stones - very large, 80% cholesterol
Pigment stones - excess insoluble unconjugated bilirubin.
Mixed stones - mix of cholesterol and Ca2+.

80
Q

What are the risk factors of gallstones?

A

Female factor forty

Caucasians, females, forty, low fibre, high cholesterol, starchy diet, overweight.

81
Q

Why is digestion of TAG and phospholipids usually incomplete?

A

1st fatty acid removal - gastric lipase - fast reaction.
2nd - pancreatic lipase - fast reaction
3rd - ester hydrolase - slow reaction, only occurs if food remains in duodenum.

82
Q

Explain why micelle transport to enterocytes.

A

Micelles transport products of fat digestion across the unstirred water layer at enterocyte surface, where they are taken up by carrier-mediated or passive diffusion.

  • without bile salts, absorption very slow
  • unstirred water gives direction to products towards tips of villi.
83
Q

Describe the process of TAG reassembly in the enterocyte.

A
  • Reassembly of TAG occurs in ER of enterocytes.
  • Phospholipids and protein is added as TAG droplet passes from ER to Golgi where glycosylation occurs.
  • Cholesterol, cholesterol ester and fat-soluble vitamins added to chylomicrons -> exocytosed.
84
Q

Describe the difference between chylomicrons and HDL.

A
  • Chylomicrons biggest lipoprotein, HDL smallest.
  • Chylomicrons more TAG, HDL lowest
  • Chylomicrons lowest protein, HDL highest
85
Q

Where are apoproteins synthesised?

A

Liver

86
Q

Describe the metabolism of chylomicrons.

A

Dietary TAG -> nascent chylomicrons + apoproteins -> mature chylomicrons -> delivered to muscles, adipose tissue and heart for energy production -> digested into fatty acids as lipoprotein lipase on capillary surface -> chylomicron remnant -> go to liver for recycling.

87
Q

What is omega-3 important for?

A

Blood clotting, growth, anti-carcinogenic, anti-inflammatory.
Fatty fish, green veggies.

88
Q

What is omega-6 important for?

A

Brain functioning, development, skin and nail growth, pro-inflammatory.
Vegetable oils, nuts.

89
Q

What is omega-7 and omega-9 important for?

A

7- reduces inflammation and insulin resistance.

9 - reduces inflammation and improves healing.

90
Q

What are the health benefits of conjugated linoleic acid (CLA)?

A

Lowers body fat content - lipolytic action and anti-carcinogenic.
Cheddar, milk, cooked meat.