Jejunum, Ileum and Colon Flashcards by Emily McGrath

Deglutition

swallowing

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Divisions of small intestine

duodenum
ileum
jejunum

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measurement of:
duodenum
ileum
jejunum

first 25cm

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ILEUM

Feels like
colour
located

single wall
paler (Peyers patches)
Mainly in the lower R quadrant

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Modifications to Increase Surface Area

Plicae circulares
Villi
Microvilli

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Plicae circulares

circular folds

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villi contain

capillaries and lacteals.

Folds of the mucosa

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Microvilli:

folds of cell membranes of absorptive cells

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Lacteal

network of blood and lymph capillaries found in villi

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how do carbs and proteins get into blood to liver

via hepatic portal vein

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-Fat into lymph

fat-soluble toxins circulate systemically b4 going to liver for
detoxification

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Arterial supply

Terminal branches of SMA
→ arterial arcades
→ vasa recta

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Venous drainage

tributaries of SMV

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Lymphatic drainage

SM lymph nodes.

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LARGE INTESTINE
extends from
consists of

from ileocecal junction to anus

cecum, colon, rectum, anal canal

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features of large intestine

✓ Absence of villi
✓ Presence of goblet cells
✓ Deep intestinal glands

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large intestine movements are

sluggish (18-24 hours)

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large intestine function

Absorption of water and salts,
secretion of mucus
extensive action of microorganisms.

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how much chyme enter the cecum

1500 mL

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% of volume reabsorbed

yielding

80-150mL of faeces

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large intestine absorbs

water and electrolytes

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Ileocaecal fold

where Ileum joins the large intestine

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Ileo-caecal valve

sphincter formed by the extension of smooth muscle from the ileum

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position of caecum

inf to the ileocaecal opening.

Appendix is attached to the

postero-medial wall of the caecum

Blood supply to caecum and appendix is derived from

SMA

Teniae coli

: 3 longitudinal muscle bands

Appendices epiploicae

short peritoneal fold filled with fat

peritoneal folds that have mesentery

Appendix, transverse & sigmoid colon

Cecum covered..

completely by peritoneum, but has no mesentery

Ascending & descending colon covered

by peritoneum anteriorly & on the sides

Ascending, transverse, descending and sigmoid colon | Arterial supply

Ascending and proximal two-thirds by SMA - Ileocolic - Right colic - Middle colic

Ascending, transverse, descending and sigmoid colon | Venous drainage

tributaries of SMV & IMV

Lymphatic drainage

- Lymph channels follow the arteries | SM and IM lymph nodes.

RECTUM located description follows

S3 thick muscular tunic 15 cm long sacrococcygeal curve

rectum: concavity is maintained by

puborectal sling

Houston's valves what are they what do they do

semi-lunar transverse folds of rectal wall | protrude into the rectum and overlap

Houston's valves function

support weight of faecal matter

Houston's valves - width - made of - supplied by

12mm circular muscle coat of the rectum sup,middle ,inf. rectal arteries

where does the anus begin

where muscles pass through pelvic diaphragm

Muscles of the anus are

(1) The external sphincter. (2) The pubo-rectalis muscle (3) The longitudinal muscle of the rectum. (4) The internal sphincter.

In Anal canal superior epithelium is inferior epithelium is

simple columnar | stratified squamous

Internal anal sphincter muscle is

smooth

External anal sphincter muscle is

skeletal muscle

what is Hemorrhoids

Vein enlargement or inflammation

Colon/Rectum covered by peritoneum

– Cecum – Transverse – Sigmoid – Anterior descending and ascending

Colon/Rectum NOT covered by peritoneum

post ascending and descending

Secretions of the Small Intestine

Mucus Digestive enzymes Brunner’s glands

function of mucus

Protects against digestive enzymes and stomach acids

Brunner’s glands aka what are they Stimulated by

- Duodenal glands - tubular mucous glands of the submucosa - vagus nerve, secretin, chemical or tactile irritation of duodenal mucosa

Intestinal crypts (of Lieberkuhn) - what - where - cells divide - secrete

- tubular glands in mucosa - inbetween villi - every 3-6 days to renew epithelium - watery intestinal juice which mixes with chyme

Intestinal flora - what is it - produce

permanent normal bacteria | vitamins, e.g. K, which get absorbed

Hormones Cholecystokinin stimulates... to release.... Secretin stimulates... to release....

GB and pancreas to release stored bile | pancreatic ducts to release acid neutralizer

Cells of mucosa

Absorptive cells Goblet cells Endocrine cells Granular cells (paneth cells)

Absorptive cells w micro villi what do they do where

produce digestive enzymes and absorb digested food | small intestine

goblet cells produce where

protective mucus | colon

Endocrine cells produce

regulatory hormones

Granular cells (paneth cells): function

protect from bacteria

JEJUNUM feels like contains located

double wall..thicker than ileum plicae circulares mostly upper left quadrant