Large Intestine

Question 1

Structures of the large intestine

Answer 1

Appendix
Caecum
Ascending colon
Transverse colon
Descending colon
Rectum
Anal canal

Question 2

Large intestine functions

Answer 2

Absorption of the remaining water, electrolytes (NaCI) vitamins and minerals (most water absorption in ascending colon)

Digestion

Propulsion

Defecation

Question 3

What forms the ileocaecal valve?

Answer 3

The superior and inferior ileocaecal folds

Question 4

Is the caecum intraperitoneal or retroperitoneal?

Answer 4

Intraperitoneal (but has no mesentery)

Question 5

What is the function of the appendix?

Answer 5

Contains masses of lymphoid tissue which functions to produce and store lymphocytes.

Also acts as a reservoir for beneficial gut bacteria

Question 6

Appendix arterial supply

Answer 6

Appendicular artery (branch of the ileocolic artery)

Question 7

Caecum blood supply

Answer 7

Ileocolic artery (branch of SMA)
Caecum & appendix drained by the ileocolic vein

Question 8

What veins from the portal vein?

Answer 8

SMA and splenic vein

Question 9

Caecum nerve supply

Answer 9

Intrinsic- ENS
Extrinsic - para: vague
symp: abdominopelvic splanchnic

Question 10

Phrenicocolic ligament attachments

Answer 10

Splenic flexor to diaphragm

Question 11

Ascending colon intraperitoneal or retroperitoneal

Answer 11

secondary retroperitoneal: - Lies on posterior abdominal wall and covered by peritoneum anteriorly and laterally

Question 12

Transverse colon intraperitoneal or retroperitoneal

Answer 12

intraperitoneal

Question 13

Descending colon intraperitoneal or retroperitoneal

Answer 13

retroperitoneal and covered with peritoneum anteriorly and laterally

Question 14

Where does the sigmoid colon join the rectum

Answer 14

~S3

Question 15

how can you identify the termination of the sigmoid or the rectosigmoid junction?

Answer 15

termination of the teniae coli

Question 16

sigmoid colon intraperitoneal or retroperitoneal

Answer 16

intraperitoneal

Question 17

Describe three macroscopic features that are unique to the colon

Answer 17

Teniae coli
Haustra
Omental appendicies

Question 18

Characteristics of the large intestine mucosa

Answer 18

simple columnar epithelia

• Thicker mucosa & deeper crypts compared to rest of GIT
• These crypts contain abundant goblet cells: which produce mucous to protect the wall and allow ease of passage of faeces
• Unlike the small intestine the large intestine has no circular folds, villi or brush like border

Question 19

What type of cell is abundant in the crypts of the colonic mucosa? What is their purpose?

Answer 19

goblet cells: which produce mucous to protect the wall and allow ease of passage of faeces

Question 20

Differentiate a haustral contraction from a mass movement

Answer 20

Haustral contractions (every 30mins)
• Short-lived, slow contractions – mainly in ascending & transverse colon
• Initiated by ENS when individual haustra fill with food residue
Mass movements (3-4 times/daily)
• Powerful, prolonged contractile waves that force contents towards rectum

Question 21

List five (5) risk factors for constipation

Answer 21

• Dietary factors
• e.g. diets low in fibre or water
• Lifestyle factors
• e.g. sedentary lifestyles
• Medication side effects
• e.g. analgesics, anti-depressants, iron supplements, diuretics
• Psychological & neurological factors
• e.g. chronic stress, ignoring the urge to defecate
• Organic diseases & metabolic problems
• e.g. diverticular disease, GIT malignancies, IBD, hypothyroidism

Question 22

which ligament connects the liver to the anterior abdominal wall and diaphragm

Answer 22

Falciform ligament

Question 23

Portal vein is formed by the union of?

Answer 23

superior mesenteric vein and splenic vein

Question 24

Which of the following bile components assists in the process of digestion?

Answer 24

bile salts and phospholipids

Question 25

Neonatal jaundice is an example of?

Answer 25

Hepatic jaundice

Question 26

gall stone in the bile duct is referred to as?

Answer 26

choledocholithiasis

Question 27

Is the rectum intraperitoneum or retroperitoneal

Answer 27

Retroperitoneal: - sup: covered anteriorly and laterally by peritoneum - Mid: covered anteriorly - Inf: no covering as it is subperitoneal

Question 28

Arterial supply to the proximial rectum:

Answer 28

Superior rectal artery (IMA)

Question 29

Arterial supply to the mid and inf rectum:

Answer 29

Middle rectal artery

Question 30

Arterial supply to the a no rectal junction:

Answer 30

Internal rectal artery

Question 31

2 types of cells in the colon:

Answer 31

Absorptive cells and goblet cells

Question 32

When would constipation warrant special concern or referral?

Answer 32

- onset in middle or old age - PR bleed, melena/mucous - weight loss, fever, rectal pain, anorexia, nausea - family history of colorectal cancer

Question 33

Acute diarrhea vs chronic diarrhea?

Answer 33

Acute: sudden onset of >3 loose stools for less than 14 days chronic: at least 4 weeks

Question 34

What is diverticulosis?

Answer 34

The formation of outpouches in the wall of the colon