Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GI > Large intestine > Flashcards

Large intestine Flashcards

1
Q

Describe the innervation of the large intestine

A
  • Complex system, intramural ganglia
  • Plexuses in submucosal layer (submucosal plexus) and in muscular layer (myenteric plexus)
  • Connected to CNS by fine network of nerve fibres
  • Belong to ANS, under sympathetic and parasympathetic control
  • Responsible for muscular and secretory activity of gut
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the blood supply of the large intestine

A
  • Mainly cranial and caudal mesenteric arteries
  • Also abdominal aorta
  • Internal pudendal artery supplies caudal part of rectum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the venous drainage of the large intestine

A
  • Veins parallel to artiers, most supply portal vein

- Veins of caudal rectum and anal region join caudal vena cava

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the divisions of the large intestine?

A
  • Caecum
  • Colon
  • Rectum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the histological features of the large intestine

A
  • Caecum, colon, rectum very similar
  • Mucosa, submucosa, muscularis and serosa (same as SI)
  • No villi, only crypts
  • Crypts are tubular glands, deeper than SI
  • Many goblet cells
  • Presence of variable GALT within mucosa and submucosa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the difference in goblet cell density through the large intestine

A
  • Density increases from beginning to end
  • Goblet cell density:
    Rectum >colon>caecum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the appearance and location caecum

A
  • Blind tube that communicates with ileum and colon
  • Left of abdomen in pigs
  • Right of abdomen in carnivores, ruminants and horse
  • In dog short and drawn into spiral
  • In cat shorter and comma shaped
  • Very large in horse
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the caecum of the horse

A
  • Large capacity (30L, 1m long)
  • Base (dorsally located)
  • Body
  • Blnd ending apex pointing cranioventrally (close to xiphoid cartilage, ventral abdominal floor)
  • 4 taenia (medial, lateral, dorsal, ventral) over most of horse caecum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the caecum of pigs

A
  • Cylindrical blind sac laying on left of abdomen
  • Apex caudoventrally
  • 3 taenia (lateral, medial ventral)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the caecum of ruminants

A
  • Relatively small

- No taenia or haustra

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are taenia?

A

Visible bands of smooth muscle and elastiv fibres on external surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are haustra?

A

Sacculations between taenia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the structure and appearance of the colon

A
  • Divided into ascending, descending, transverse
  • Short ascending, passes cranially on right
  • Transverse right to left, cranial to root of mesentery
  • Long descending, passes left of mesenteric root caudally
  • Continues as rectum in pelvic cavity
  • Form and topography complex in some animals
  • Ascending can have many modifications
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the colon of the horse

A
  • Ascending arranged in 2 U-shaped loops on top of each other
  • Short transverse, long ascending
  • Ascending referred to as large colon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the large colon of the horse

A
  • 4 limbs 3 flexures
  • Is same as ascending colon
  • right ventral colon -> sternal flexure -> left ventral colon -> pelvic flexure -> left dorsal colon -> diaphragmatic flexure -> right dorsal colon
  • RVC and LVC: 4 taenia
  • LDC: 1 taenia
  • RDS: 3 taenia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the clinical importance of the the flexures in the large colon of the horse?

A

Sudden changes in diameter, likely sites of impaction causing colic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the colon of the pig

A
  • Big, cone shaped coiled ascending colon
  • BAse attached to left abdominal roof, apex pointing ventrally
  • 2 taeniae, 2 rows of haustra
  • External loops have 2 taeniae, not present on internal loops
18
Q

Describe the colon of ruminants

A
  • Long ascending, 2 sigmoid flexures, double spiralled area
  • Short transverse, straight descending
  • Sigmoid flexure at end
  • No taenia or haustra
19
Q

Describe the structure and appearance of the rectum

A
  • Desceding colon enters pelvis, becomes rectum
  • Most dorsal pelvic viscera
  • Joins anal canal (terminal part of alimentary tract) opens outside with anus
20
Q

Describe the structure and appearance of the anus

A
  • Mucosa of anal canal keratinised at ends, continuous with skin
  • Circumanal galnd only present in canidae and humans
  • Anal sacs present in carnivores
21
Q

Describe the anal sacs of carnivores

A
  • Paired diverticula
  • Located within lamina propria/submucosa
  • Contain apocrine glands and ducts opening into anal canal
  • Prone to occlusion in dogs
22
Q

Descrieb the large intestine of the dogs and cats

A
  • Caecum between SI and LI
  • A, T and D parts
  • Caecum small
  • Caecum no direct connection with ileum
  • Caecum into spiral, held against ileum by fold of peritoneum
  • Caecum to colon beyong ileocolic junction
  • Guarded by ileocolic sphincter
  • Colon suspended by mesocolon
  • Transverse R to L of body
  • Stomach cranially, SI and cranial mesenteric artery caudally
  • Descending is lonest part, to pelvic cavity
  • Then is rectum
  • LI smooth, villi lacking, many scattered lymph nodules, noo mucosal folds
23
Q

Describe the large intestine of the pig

A
  • Coiled LI
  • Spiral ascending colon
  • Sacculated
  • 2 taenia on colon, 3 on caecum
  • Caudal limp of loop (incl, cecocolic junction) sisto left of mesenteric axis
  • Ascending on left, transverse on right due to reversal of course of coil
  • Caecum and colon considered together as combine in conical, ventrally tapering mass suspende from roof of abdomen
  • Caecum has origin below left kidney, extends ventrally agains left flank
  • Rounded blind apex
  • Ascending colon arranges around mesentery in cone
  • Outer part wide sacculatied continuing from caecum
  • Pirals ventrally clockwise centripetally before reverse at apex to ascend in narrower, smoother and tighter centrifugal coils
24
Q

Describe the large intestine of ruminants

A
  • Colonn divided into ascending, transverse and descending
  • Ascending wound in complex manner
  • Narrows, turns ventrally, 2 centripetal turns, then 2 centrifugal turns
  • Joins short transverse crossing midline in front of mesenteric artery, leads to descending
  • No taeniae or haustra
  • Smaller ruminants 3 or 4 turns in each direction, centrifugal turns pearl necklace appearance = segmentation of pellets
25
Q

Describe the large intestine of horses

A
  • Ascending divided into RVDC, LVC, LDC, RDC
  • Sternal, then pelvic then diaphragmatic flexures
  • RVC, caecum and LVC have 4 taenial bands
  • LDC has 1
  • RDC has 3
  • Descending has 2
  • Caecum on RHS
  • Apex more ventral, curled like shell
  • 4 taenia - medial, lateral, dorsal and ventral
  • Short transverse and long descending
26
Q

Describe water exchange in the GI tract

A
  • Continuous water exchange (secretion and absorption ongoing)
  • Essential for digestion and absorption
  • Intracellular and extracellular water in body
  • Most water absorbed from GIT is from intestinal secretions
  • Most water secreted in proximal SI, absorbed in SI and LI
27
Q

Define the muscularis layer of intestine

A
  • Beneath submucosa, 2 layers smooth muscle, inner circular outer longitudinal
28
Q

Define chyme

A

The mixture of feed and digestive secretions in the lumen of the digestive tract

29
Q

Define peristalsis

A

Circular contractions travelling along the wall of a tube

30
Q

Define anti-peristalsis

A

Contractions that propagate in the opposite direction to peristalsis

31
Q

Define segmentation

A
  • Causes content to move back and forth, while at same time is transported distally
  • Most common form of motility in caecum and colon, lower frequency in intestines
32
Q

Define mass movements

A
  • At intervals of 3-5 minutes segmentation replaced by movements where larger sections of caecum contract simultaneously
  • Represent form of peristalsis, distinguished from that in that contractions of individual muscule cells lasts longer
  • Forces caecal content into colon
33
Q

Explain why regions of the large intestine have haustra/sacculations

A
  • In horses do not have continuous longitudinal muscle layer
  • Instead have powerful muscle bands
  • Causes series of sac like invaginations = haustra
  • Contribute to mixing of colonic content
  • Delays transport of chyme
34
Q

What are the anatomical openings in the large intestine?

A
  • Ileocaecal (between ileum and caecum)
  • Ileocolic (between ileum and colon)
  • Caecocolic between caecum and colon)
35
Q

Describe digestion and absorption in hind-gut fermenters

A
  • Adapted to high roughage diet
  • Development of large intestine
  • Major siteof microbial digestion and water absorption
  • LI does not produce digestive enzymes
  • Microbial fermentation of fibre, starcha and protein = VFAs and lactic acid
  • Fermentation of fructans = fructose and lactic acid
  • Absorption of VFAs accompanied by absorption of water and electrolytes
36
Q

Why do hind gut fermenters require microbial digestion?

A
  • LI does not have digestive enzymes
  • Up to have fibre in grass cannot be digested in horse without microbial digestion
  • Bacteria snthesise essential AAs
  • Microbial digestion produces water soluble B and K vitamins
  • Rabbits and rats coprophagic to increase intake of protein AAs and B vitamins
37
Q

What factors are important in digestion in hind-gut fermenters?

A
  • Type of bacteria present
  • Correct pH 5-6
  • Anaerobic environment
  • Fluid movement
  • Retention of food (up to 65 hours)
38
Q

Where does most microbial digestion and absorption occur in the horse?

A
  • Caecum

- Ventral colon

39
Q

Where does most microbial digestion and absorption occur in the rabbit?

A

Caecum

40
Q

What are the effects of infrequent feeds in horses?

A
  • Decrease in pH and increased lactate
  • Massive influx of water rather than continuous low level
  • Large concentrate meal can cause 15% change in circulating fluid volumes

GI (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions