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74 Cards in this Set
- Front
- Back
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small intestine 7m the longest region of alimentary tract is divided into three regions: |
- duodenum - jejunum - ileum
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modifications of luminal surface (area of intestinal lumen is enlarged by the formation of): |
*pilcae circulares
*villi
*microvilli
*crypts of Liberkuhn |
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Pilcae circulares = |
valves of Kerckring |
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Pilcae circulares: |
- transverse folds of submucosa and mucosa, that form elevations
- permanent fixures of duodenum and jejunum, end in proximal half of ileum
- increase surface area by 2-3
- decrease velocity of movement of chyme along the alimentary canal |
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Villi: |
- epithelial covered, finger-like, leaf-like protrusions of the lamina propria
- core with capillary loops, a blindly ending lymphatic channel -lecteal
- their number is greater in duodenum than in jejunum or ileum
- increase surface are of small intestine by factor of 10 |
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Microvilli: |
- modification of apical plasmalemma of epithelial cells
- increase the surface area of small intestine by a factor of 20 |
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Crypts of Lieberkuhn: |
- invaginations of epithelium into lamina propria between villi form interstitial glands
- also augment surface area of small intestine |
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all surface area due to modifications is bigger by... |
factor 400-600 !!! |
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Intestinal MUCOSA three layers: |
- simple columnar epithelium - lamina propria - muscularis mucosae
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Epithelium of intestinal mucosa: |
- simple columnar epithelium covering villi - posses surface absorptive cells, goblet cells, DNES cells |
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Surface absorptive cells: |
- tall columnar cells
- function: terminal digestion, absorption of water and nutrients
- most numerous cells of epithelium
- they make- brush-border
- posses microvilli with glycocalyx and all zonulae and junctions |
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Goblet cells: |
- unicellular glands
-duodenum has the smallest number, it increases toward the ileum
- manufacture mucinogen, (mucin) component of mucus- making protective layer
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DNES cells: |
- production of paracrine, endocrine hormones
- small amount |
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M cells (Microfold cells): |
- phagocytose and transport antigenes from lumen to the lamina propria
- squamous-like, where lymphoid nodules
- belong to mononuclear phagocyte system |
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LAMINA PROPRIA (loose CT) housing: |
- numerous tubular intestinal glands, Crypts of Lieberkuhn, lymphoid cells |
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Crypts of Lieberkuhn: |
- increase the surface area of intestinal lining
- composed of DNES cells, surface absorptive cells, goblet cells, regenerative cells and Paneth cells
- simple/ branched tubular glands |
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Regenerative cells of small intestine: |
- stem cells
- repopulate: crypts, mucosal surface, villi |
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Paneth cells: |
- clearly distinguishable because of presence of large, eosinophilic apical secretory granules
- pyramid-shaped, occupy the bottom of the crypt
-manufacture antibacterial agent- lysozyme, proteins- defensin, tumor necrosis factor -alfa
- unlike others long life span 20 days |
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Muscularis mucosae: |
composed of:
- inner circular layer and outer longitudinal layer of smooth m.m cells
- rhythmic contraction during digestion |
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Submucosa: |
- dense irregular fibroelastic CT with rich lymphatic and vascular supply
- posses innervation: *parasympathetic : submucosal Meissner's plexus |
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why submucosa of duodenum is unusual ? |
it houses glands known as:
Brunner's glands (duodenal glands) |
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Brunner's glands: |
- produce a mucous, bicarbonate rich fluid as well as urogastrone (human epidermal growth factor) - inhibits HCl
-branched tubulo-alveolar with mucous acini |
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Muscularis externa of small intestine: |
- inner circular -outer longitudinal layer - between Auerbach's myenteric plexus
-responsible for peristaltic activity of small intestine |
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adventitia: |
second and third par of duodenum
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serosa: |
entire small intestine |
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lymphatic draining in small intestine: |
blindly ending lacteals -->submucosal lymphatic plexus--> lymph nodes--> torasic duct---> circulatory system |
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blood supply of small intestins: |
- submucosal vascular plexus --> hepatic portal vein |
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the shortest segment of small intestine? |
duodenum |
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recives bile from the liver, digestive juces from pancreatic ducts which open in to a lumen of duodenum at the... |
duodenal papilla (of Vater) |
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jejunum: |
- posses the most Goblet cells
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ileum: |
- posses the smalles amount of villi
- houses permanent clusters of lymphoid nodules known as Peter's patches |
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immunological activity of the lamina propria: |
- immunoglobulin A produced by plasma cells in the lamina propria is recirculated through the liver and gallbladder
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IgA-protein complex is transported into the lumen via... |
TRANSCYTOSIS |
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glands of small intestine produce... |
2 L of slightly alkaline fluid per day |
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small intestine participates in two types of contraction: |
- mixing
- propulsive (peristaltic waves) <--- gastroenteric reflex <--- myenteric plexus |
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cholecystokinin, gastrin, motilin, substance P, serotonin.... |
increase intestinal motility |
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secretin and glucagon... |
decrease intestinal motility |
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when muscularis externa is irritated it undergoes intense, swift concrations known as...
they propel chyme into colon within minutes for elimination as... |
Peristaltic rush
diarrhea |
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propel |
napedza |
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final breakdown of protein and carbohydrates occurs at the... |
microvilli
(where dipeptides and disacharides adhere to glycocalix....monomers...transport) |
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lipids are emulsified by bile salts into small fat globules that are split into... |
monoglycerides and fatty acids ---> micelles --> diffusion |
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absorption small intestine in numbers: |
6-7 l of fluid 30-35 g of sodium 0.5 kg carbohydrates and proteins 1 kg of fat are absorbed each day !!! |
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long chain fatty acids and monoglycerudes --> SER of surface absorptive cell --> reestrification --> triglycerides---> Golgi + lipoprotein coat --> RER---> |
CHYLOMICRONS |
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chylomicrons- |
large lipoprotein droplets ---> lymphatic vessels--> lipid-rich substance -CHYLE |
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short fatty acids do not enter SER for...
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reestrification |
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cholera toxin |
10L per day because of diarrhea! + electrolytes |
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Malabsorption (sprue) |
example gluten enteropathy (nontropical sprue)
- gluten -->allergic reaction |
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sprue |
wylew |
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LARGE INTESTINE subdivision: |
* cecum---> appendix * colon (ascending, transverse, descending, sigmoid) * rectum * anus
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large intestine function: |
- it absorbs most of the water and ions, gases from chyme, compacts chyme into feces for elimination |
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cecum and colon are... |
indistinguishable histologically |
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colon receives chyme from the ileum at the... |
ileocecal valve - anatomical and physiological sphincter that prevents reflux |
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Colon components: |
- no villi - richly endowed with crypts of Lieberkuhn (similar to those in small intestine except absence of Paneth cells - goblet cells, DNES cells |
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Muscularis externa is unusual in large intestine that the... |
outer longitudinal layer is not continuous thickness along the surface instead most of it is gathered into three narrow ribbons of muscle fibers known as TAENIAE COLI |
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constant tonus maintained by the taeniae cili puckers the large intestine into sacculations called... |
haustra coli |
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serosa: |
displays numerous fat-filled pouches called appendices epiploicae |
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bacterial flora of large intestine produce: |
* indole, hydrogen sulfide, mercaptans
*by products: riboflavin, thiamin, vit. B12, vit. K * gases: CO2, methane, H2---> flatus
*mucus and HCO3- |
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Pseudomembranous colitis- |
inflammatory disease of bowel, most frequently due to prolonged antibiotic therapy |
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bowel |
jelita |
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enteritis- |
irritation of colonic mucosa ---> diarrhea |
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rectum and anal canal display longitudinal folds- |
anal columns, (rectal columna of Morgagni) |
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anal columns (rectal columns of Morgagni) form pouch-like outpocketings: |
anal valves with anal sinuses |
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pouch |
kieszonka, torebka, etui |
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Anal mucosa: |
epithelium: - simple cuboidal - stratified squamous nonkeratinized - stratified squamous keratinized
lamina propria: - fibroelastic CT - houses anal glands, circumanal glands, hair follicles, sebaceous glands
muscularis mucosa: -inner circular layer and outer longitudinal layer |
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simple cuboidal epithelium: |
from retcum to pectinate line |
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stratified squamous nonkeratinized |
from pectinate line till external anal orfice |
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stratified squamous keratinized (epidermis) |
at the anus |
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submucosa of anal canal- content: |
- fibroelastic CT - two venous plexuses: internal and external hemorrhoidal plexuses |
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muscularis externa of the anal canal: |
inner circular and outer longitudinal layer of smooth muscles |
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the inner circular layer of anal muscularis externa at the region of pectinate line forms... |
internal anal sphincter muscle |
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skeletal muscles of the floor of the pelvis form... |
external anal sphincter |
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anal examination palpated structures: |
males: bulb of penis, prostate, enlarged seminal vesicles, inferior aspect of bladder enlarged lymph nodes
females: cervix of uterus, pat: ovaries, broad ligament |
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Vermiform appendix: 5-6 cm ---> cecum simple columnar epithelium serosa |
- rich supply of lymphoid elements, contains many more DNES cells in crypts of Lieberkuhn |
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appendicitis- |
- pain in the lower right quadrant - fever, vomiting |
