Intestines, rectum and anus

Question 1

Name the 3 components of the small intestine, in order

Answer 1

Duodenum, jejunum, ileum

Question 2

Name the 3 components of the large intestine, in order

Answer 2

Caecum, colon, rectum

Question 3

Name the 4 functions of the intestines (hint if needed: movement, major site of ____, absorption of ___,___,___ and to _____/_____ residues)

Answer 3

1. Movement of ingesta from stomach -> anus
2. Major site of ingestion
3. To absorb water, ions and products of digestion
4. To concentrate and lubricate indigestible residues

Question 4

What type of species would a caecum be relevant to digestion?

Answer 4

Herbivores or high plant material diets -> for fermentation

Question 5

Name the parts of the duodenum (in order)

Answer 5

Cranial part, cranial flexure, descending duodenum, caudal flexure, ascending duodenum

Question 6

Which part of the duodenum is most closely associated with the liver/ pancreas, receives bile and pancreatic ducts

Answer 6

Cranial flexure

Question 7

The cranial flexure is attached to the liver via the ______

Answer 7

Hepatoduodenal ligament

Question 8

What is the name of the flexure where the ascending duodenum/ jejunum merge?

Answer 8

Duodenojejunal flexure

Question 9

What structure connects the ascending duodenum to the descending colon?

Answer 9

Duodenocolic fold of the mesentery

Question 10

What structure is the longest in the small intestine?

Answer 10

Jejunum

Question 11

What mesentery supports the jejunum?

Answer 11

Mesojejunal mesentery

Question 12

Which artery, when combined with the mesenteries, forms the ‘root/ origin of the mesenteries’?

Answer 12

Cranial mesenteric a.

Question 13

Is the junction between the ileum and jejunum well distinguished? ELABORATE

Answer 13

No, but can be defined by the presence of the antimesenteric ileal branch

Question 14

what structure attaches the ileum to the caecum?

Answer 14

Ileocaecal fold

Question 15

What structure does the ileum terminate at, and what structure does this lead into?

Answer 15

Ileal orifice -> caecocolic junction

Question 16

What is the name of the sphincter located at the caecocolic junction?

Answer 16

Ileocolic sphincter

Question 17

What is the function/ benefit of the ileocolic sphincter

Answer 17

Prevention of reflux of LI contents into ileum

Question 18

At the pylorus, on a histology level, what structures disappear, and what appear

Answer 18

Pyloric glands disappear, crypts of lieberkuhn (intestinal glands) and duodenal glands (of Brunner), villi appear

Question 19

How is absorption facilitated in the small intestine?

Answer 19

Increased surface area (by surface folds) and villi (lamina propria projections)

Question 20

Name the layers of the GIT from the inside out

Answer 20

Tunica mucosa, tunica submucosa, tunica muscularis, tunica serosa/ adventitia

Question 21

Name the 3 types of cells located within the epithelium of the tunica mucosa (of the GIT)

Answer 21

Enterocytes (absorptive cells), goblet cells, enteroendocrine cells

Question 22

Describe the layer the enterocytes form in the tunica mucosa epithelium.

Answer 22

Enterocytes form an absorptive layer of simple columnar epithelium with a border of microvilli (in a protective coat of mucopolysaccharide - which contains glycocalyx, a digestive enzyme)

Question 23

Describe the function of goblet cells.

Answer 23

Secrete mucin/ mucigen helping to form a barrier

Question 24

Within the tunica mucosa, what is the layer of loose connective tissue containing elastic fibres.

Answer 24

Lamina propria

Question 25

What material makes up the core of the villi, as well as fills in the spaces between them?

Answer 25

Lamina propria

Question 26

What structures are located within the lamina propria

Answer 26

Crypts of lieberkuhn (intestinal glands), blood and lymph vessels, and lymphatic tissue

Question 27

What vessel drains each villus?

Answer 27

Central lymph vessel (or 'lacteal)

Question 28

What are the nodules of lymphatic tissue called when located in the Ileum, and which layer/s are they located in (tunica ___)

Answer 28

Peyer's patches -> may extend through the muscularis mucosa into the submucosa

Question 29

The anti-mesenteric wall will always contain nodules called what?

Answer 29

Peyer's pathches

Question 30

Describe the epithelial cells overlying the peyer's patches

Answer 30

Flattened, with long microvilli, no villi or glandular crypts

Question 31

What are the 3 components in the tunica mucosa

Answer 31

Lamina propria, muscularis mucosae, epithelium

Question 32

Within the muscularis mucosae (of the tunica mucosa), the circular muscle layer is _____, and the longitudinal layer is _____ (outer, inner).

Answer 32

Circular -> inner Longitudinal -> outer

Question 33

Brunner (duodenal glands): Type of gland (secretion and structure)

Answer 33

Alkaline, mucoid gland Simple, branched tubulo-acinar or alveolar glands

Question 34

What is the prominent plexus located in the tunica submucosa

Answer 34

Meissner's

Question 35

What are the 2 main functions of the tunica muscularis layer?

Answer 35

To propel food caudally + to mix contents

Question 36

A thin layer of connective tissue divides the inner circular layer and outer longitudinal layer (of the tunica muscularis), which plexus is located within here?

Answer 36

Myenteric (auerbach's)

Question 37

Describe the structure of the tunica serosa.

Answer 37

Simple squamous epithelia which overlies 3 layers of connective tissue (2 collagen layers sandwiching 1 layer of elastic fibres).

Question 38

What structure joins the colon to the caecum?

Answer 38

Ileocaecal orifice

Question 39

Name the 3 parts of the colon.

Answer 39

Ascending colon, transverse colon, descending colon

Question 40

Is the small or large intestine absent of villi? And do the number of goblet cells increase as you move caudal or cranial? Do the crypts of lieberkuhn become deeper or more shallow as you move caudally from SI -> LI

Answer 40

Large intestine is absent of villi Goblet cells increase as you move caudal Crypts become deeper as you move caudal from SI -> LI

Question 41

Name the 3 zones in the mucosa and submucosa region of the anus

Answer 41

Columnar, intermediate, cutaneous

Question 42

Which zone are the anal glands located in, and which zone do they continue into?

Answer 42

Columnar zone, and continue into the intermediate zone

Question 43

Name the 3 unpaired a.s that arise from the aorta in the abdomen, where each supplies part of the intestine.

Answer 43

Coliac, cranial mesenteric, caudal mesenteric

Question 44

What organs are supplied by the cranial mesenteric a.?

Answer 44

Supplies intestine from distal duodenum -> transverse (middle) colon

Question 45

What organs are supplied by the caudal mesenteric a.?

Answer 45

Supplies the descending colon ->proximal rectum

Question 46

What a. supplies the distal rectum/ anus?

Answer 46

Internal pudendal a.

Question 47

Describe the venous drainage from the intestines

Answer 47

The blood from the intestines flow through progressively larger veins -> hepatic portal vein -> liver

Question 48

Lymph from the area supplied by the cranial mesenteric a. (say which area this is again) drains to what lymph node centre?

Answer 48

Area supplied by cranial mesenteric a.: distal duodenum -> transverse colon. Drains to cranial mesenteric lymph centre

Question 49

Lymph from the area supplied by the caudal mesenteric a. (say which area this is again) drains to what lymph node centre?

Answer 49

Area supplied by caudal mesenteric a.: descending colon -> proximal rectum Lymph centre: Caudal mesenteric lymph centre

Question 50

Where do efferent lymphatics drain to?

Answer 50

Intestinal or lumbar trunks