Anatomy and Physiology Flashcards
Different parts of the alimentary canal (6)
mouth and oropharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus
3 parts of small intestine
duodenum, jejunum, ileum
3 parts of large intestine
caecum, appendix, colon
accessory structures of the GI tract (4)
salivary glands, the pancreas, the liver and gall bladder
4 activities of the digestive tract
motility, secretion, digestion, absorption
4 layers of the digestive tract wall
mucosa, submucosa, muscularis externa, serosa
What is contained within the mucosa?
epithelial cells, exocrine cells, endocrine gland cells, lamina propria, muscularis mucosae
What is contained within the submucosa?
connective tissue, larger blood and lymph vessels, glands, nerve networks
What is contained within the muscularis externa?
circular muscle layer, nerve network (myenteric plexus), longitudinal muscle layer
What is contained within the serosa?
connective tissue
Contraction of the circular muscle causes the lumen to become…
narrower and longer
Contraction of longitudinal muscle contraction causes the lumen to become…
shorter and fatter
Smooth muscle cells are electrically coupled by…
gap junctions
There are two nervous supplies to the GI tract - intrinsic and extrinsic - the intrinsic is…
the enteric nervous system
There are two nervous supplies to the GI tract - intrinsic and extrinsic - the extrinsic is the…
autonomic nervous system
electrical waves (____ _____) pass spontaneously through the stomach, the small intestine and the large intestine
slow waves
Which cells drive the slow wave activity of the gut?
interstitial cells of cajal
where are interstitial cells of cajal?
between the longitudinal and circular muscle layers, also in the submucosa
3 types of stimuli in the GI tract determining basal electrical rhythm
neuronal, hormonal, mechanical
two plexus in the enteric nervous system?
myenteric plexus, submucous plexus
the myenteric plexus mediates
motility and sphincters
the submucosal plexus
epithelia and blood vessels
5major motility patterns within the GI tract
peristalisis, segmentation, colonic mass movement, migrating motor complex, tonic contracions
peristalsis is…
a wave of relaxation, followed by contraction that normally goes in the aboral direction
segmentation is…
mixing and churning movements - rhythmic contractions of the circular muscle layer
colonic mass movement is…
powerful sweeping contraction that forces faeces into the rectum
migrating motor complex is…
powerful sweeping contraction from stomach to terminal ileum
low pressure tonic contractions are within
organs with storage function
high pressure tonic contractions are…
sphincters
The muscles of mastication are supplied by which cranial nerve?
CN V3 - mandibular branch of the trigeminal
Which foramen does CN V3 arise?
the foramen ovale
CN V3 is what type of function i.e. sensory or motor?
sensory and motor
Muscles of mastication (4)
temporalis, masseter, lateral pterygoid, medial pterygoid
Which muscle is required for opening the jaw?
lateral pterygoid
which muscle of mastication is the strongest and has the largest attachment?
masseter - attaches the angle of the mandible and the zygomatic arch
Which bone are the pterygoids attached?
the sphenoid and mandible
the posterior third of the tongue is supplied by which CN?
CN IX - glossopharyngeal, taste and general sensations
The anterior 2/3rds of the tongue is supplied by which nerves?
CN IX and CN V3.CN IX allows for taste.CN V3 allows for general sensation
foramen for CN IX
jugular foramen
Function of CN IX?
sensory and motor - tongue
4 types of papillae on the tongue - which has no taste buds?
Follate, Vallate, Filiform (no taste buds), Fungiform
The superior half of the oral cavity is innervated by which CN?
CN V2 - trigeminal maxillary branch
The foramen for CN V2
foramen rotundum
Function of CN V2 ?
sensory
CNs involved in the gag reflex?
CN IX and X provide motor response, sensory info initially comes from CN IX
The parotid gland is innervated by which CN?
CN IX
The submandibular glands are innervated by which CN?
CN VII
4 muscles of the tongue?
palatoglossus, genioglossus, hyoglossus, styloglossus
Which muscle of the tongue is innervated by the vagus nerve?
palatoglossus
Which CN supply 3 out of 4 muscles of the tongue?
CN XII - hypoglossal
Where is the upper oesophageal sphincter found?
C6 - cricopharyngeus
The pharynx is innervated by CN?
CN X
Where do the muscles of the pharynx insert?
into the midline raphe
Which muscle prevents drooling?
orbicularis oris - CN VII
oesophageal plexus is composed of which nerves?
CN X and sympathetic fibres.
Where does the oesophagus terminate?
the cardia of the stomach
parts of the colon (6)
caecum, appendix, ascending, transverse, descending, sigmoid
Foregut includes which organs?
oesophagus to mid-duodenum, liver, gallbladder, 1/2 pancreas, spleen
The foregut is supplied by nerves from which vertebrae?
T6-9
Mid gut includes which organs?
mid-duodenum to proximal 2/3rds of transverse colon and half the pancreas
The midgut is supplied by nerves from which vertebrae?
T8-T12
The hindgut includes which organs?
distal 1/3rd of transverse colon –> proximal 1/2 of anal canal
The hindgut is supplied by nerves from which vertebrae?
T10 - L2
Intraperitoneal organs
liver, stomach, almost all small intestine, transverse colon, spleen, gallbladder
Retroperitoneal organs
kidneys, adrenal glands, pancreas, ascending and descending colon
The greater omentum has how many layers?
4
the greater omentum attaches to…
the greater curvature of the stomach
Lesser omentum attaches to…
the lesser curvature of the stomach, duodenum and the liver
the lesser omentum has how many layers?
2
The omental foramen contains…
the portal triad, the communication between the greater and lesser omental sacs
Which pouch(es) are formed in the male at the pelvic edge of the peritoneum?
retrovesicle
Which pouch(es) are formed in the female at the pelvic edge of the peritoneum?
vesico-uterine, recto-uterine (pouch of douglas)
What most commonly causes ascites?
cirrhosis and portal hypertension
Sympathetic nerves supplying the GI Tract
Abdominosplanchnic nerves - T5 - L2
Where do the abdominosplanchnic nerves synapse
prevertebral ganglia anterior to the aorta, part of periarterial plexus
sympathetics for the adrenal glands leave where?
T10 - L1
Parasympathetic innervation of the GI Tract?
CN X, pelvic splanchnic nerves S2,3,4
Sphincters of the GI Tract (6)
upper and lower oesophageal, pyloric, ileocaecal, internal and external anal sphincters
Afferent Nerves involved in swallowing
CN X and IX –> Pons and medulla
sEfferent Nerves involved in swallowing
VII, IX, X and XI
structure that prevents aspiration of food
Epiglottis
Swallowing centre of the brain
pons and medulla
3 pairs of salivary glands
parotids, submandibular, sublingual
Dominant salivary gland
submandibular
Salivary glands are Endocrine/exocrine
exocrine
Salivary glands are divided into salivons. What are the parts of a salivon?
secretory acinus, intercalated duct, striated duct, interlobar ducts and excretory ducts
Serous cells of the acinus secrete?
watery saliva rich in a-amylase
Mucous cells of the acinus secrete?
thick, mucus rich secretions
serous demilunes of the acinus secrete?
lysozyme
Functions of saliva (3)
lubrication, protection, digestion
Lactoferrin in saliva provides what function?
chelates iron to limit availability to bacteria
Main electrolytes in saliva
Na, K, HCO3, Cl, Ca, I, PO4
electrolytes in saliva which are higher in concentration than in plasma
K and HCO3
Where does secondary modification of the saliva occur?
the duct cells
What secondary modification occurs to saliva?
Na and Cl out, K and HCO3 down
What about salivary duct cells allows the diluting effect?
impermeable to H20
The submandibular gland is supplied by which cranial nerve?
CN VII
The parotid gland is supplied by which cranial nerve
CN IX
The sublingual gland is supplied by which cranial nerve?
CN VII
Dominant nervous supply in the production of saliva?
parasympathetic
Which receptors are stimulated in the production of saliva by the PS nervous system?
M1 and M3
Sympathetic salivary secretion is stimulated by which receptors?
a and b1-adrenoceptors
Stimulation by sympathetic nervous system produces what sort of saliva?
thick mucousy, small volume
duodenal factors tend to increase/decrease gastric emptying
decrease
Influences which may delay gastric emptying from the duodenum
fat, acid, hypertonicity, distension
Which hormones may delay gastric emptying?
CCK and Secretin
Pyloric gland area secretes which gastric factors?
Somatostatin and Gastrin
Somatostatin is produced by which cells in the pyloric gland area?
D cells
Gastrin is produced by which cells in the pyloric gland area?
G cells
The oxyntic mucosa is found where in the stomach?
fundus and body of the stomach
The chief cells produce which gastric secretion?
pepsinogen
The enterochromaffin cells produce which gastric secretion?
histamine
the parietal cells produce which gastric secretion?
HCl and Intrinsic factor
Function of Gastrin
Stimulates enterochromaffin cells to produce histamine which increases HCl secretion; stimulates CCK2 receptors on parietal cells to produce HCl
Function of somatostatin
to inhibit gastrin
PGE2 receptors cause a(n) increase/decrease in HCl secretion
decrease
HCl is produced by which cells?
parietal
What is intrinsic factor required for?
binds Vit B12 allowing it to be absorbed in the terminal ileum
Cholinergic activation of M3 receptors in the stomach cause?
increases proton pumps at the apical membrane –> HCl
Cholinergic activation of M1 receptors in the stomach cause?
activation of enterochromaffin cells to produce Histamine -> H2 receptors on parietal cells -> HCl secretion
Functions of HCl
Pepsinogen –> Pepsin; breakdown of bacteria and enzyme
Precipitating factor in H.pylori infection
increased salt intake
Proton pumps are stored within tubulovesicles and which are stimulated to go to the membrane by…
PKAs via M3, CCK2, H2 receptors
