Setting The Scene Anatomy

Question 1

4 layers of the intestines

Answer 1

Outermost to inner

(Mesentery- double fold peritoneum)

1. Serosa (areolar CT, bv, LV, adipose, epithelium - mostly simple columnar bar anal canal - stratified squamous)
2. Muscularis (circular muscle - myenteric/ Auerbach’s plexus and longitudinal muscle)
3. Submucosa (ct, bv, Lv, glands in submucosa, submucosal plexus/ meissner’s plexus)
4. Mucosa (gland in mucosa, duct of gland outside tract, lymphatic tissue, epithelium- simple columnar enterocytes, lamina propria, muscularis mucosae)

Lumen

Question 2

Mucosa function

Answer 2

Selectively permeable, facilitate transport and digestion if food, absorption, hormones, mucus

Lamina propria- lymphoid nodules and macrophages, produce antibodies (mainly igA resistant to protease)

Muscularis mucosa (crypts or intestinal glands dynamic- keeps epithelium in contact with gut contents

Question 3

Epithelial of the gut

Answer 3

Stratified squamous in oesophagus and distal anus

Everything in between is simple columnar

Question 4

Enterocytes

Answer 4

Simple columnar epithelium with microvilli and villi lining small intestine And colon

Coat contains digestive enzymes

Question 5

Where are goblet cells found in gut

Answer 5

Scattered between enterocytes, increasing from duodenum to colon

Produce mucus - lubricant - acidic environment - physical barrier

Question 6

What are the gastric surface mucous cells called

Answer 6

(Stomach)

Foveolar cells

Line gastric mucosa/ gastric pits

Secrete mucus/ HCO3 forms barrier to stomach acid

Question 7

How does the gut tube increase it’s SA?

Answer 7

Villi with microvilli in small, intestine

SI has permanent folds- plicae circulares (circular folds)

Stomach has rugae - temporary folds

Large bowel has sacculations - Haustra

Question 8

Cells of the crypts

Answer 8

in small intestine and colon

contain stem cells replace epithelium 2-4days,

Paneth cells at base secrete antibacterial proteins , bright red secretory vesicles

enteroendocrine cells deeper in crypts and gastric glands secrete hormones control function of gut (gastric, cholecystokinin, secretin)

Question 9

exocrine Glandular tissue in gut

Answer 9

Organised secretory cells (acini - sac like or tubules) connect to an intercalated duct then these to an interLOBULAR duct which secretes Na+HCO3- then to a main duct to epithelium

E.g. salivary glands, pancreas, Brunners glands (neutralise acidic chyme/ reduce hypertonicity)

Question 10

Abdominal wall layers

Answer 10

Skin

Superficial and deep fascia

3 anterolateral muscles - external oblique, internal oblique and transverse abdominis

Within these muscles is a Rectus sheath (aponeurosis of external oblique contributes to anterior layer and of internal oblique anterior and posterior layers and of transversalis abdominis posterior layer ) surrounding Rectus abdominis which has linea alba through centre and tendinous intersections horizontally

Transversalis fascia

Peritoneum

Question 11

Peritoneal cavity what

Answer 11

Abdominal cavity (where digestive organs are)

Mesothelium lined with flattened simple squamous epithelium - basement membrane and dense irregular Ct

Produces lubricating fluid

Envelopes certain viscera (visceral - from sphlanchnic mesoderm )

Lines cavity wall (parietal - somatic development more pain sensitive-> referred pain in in dermatomes with shared nerve roots)

Non-enveloped viscera that lie posterior to cavity ( retroperitoneal viscera) e.g. pancreas, kidneys, most duodenum, ascending and descending colon, middle rectum, adrenal glands, proximal ureters

Question 12

Mesentery what and function

Answer 12

double Fold of the peritoneum which connects viscera to the abdominal posterior wall, allows for passage of blood vessels, lymphatics and nerves
(abdo aorta and vena cava), contains fat and gives structure by anchoring organs

Attaches: jejenum, ileum, appendix, transverse colon, sigmoid colon, rectum