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human anatomy > week 8 - gastrointestinal system > Flashcards

week 8 - gastrointestinal system Flashcards

1
Q

gastrointestinal tract components

A

oral cavity
oesophagus
stomach
small intestine
large intestine
anal canal and anus

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2
Q

types of salivary glands

A

parotid - secrete serous saliva
submandibular - secrete serous and mucous saliva
sublingual - secrete mucous saliva

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3
Q

saliva production

A

produced in acini of saliva glands by active filtration of ions from blood
composition is modified by ducts within gland
parasympathetic stimulation produces large volume of watery saliva
sympathetic stimulation produces small amounts of mucous saliva

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4
Q

saliva function

A

Lubrication due to mucin content
Digestion due to presence of α-amylase
Protection of oral mucosa through lubrication, rinsing action and alkaline pH
Antibacterial through actions of antimicrobial thiocyanate
Thirst stimulation
Speech
Absorption in the mouth

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5
Q

muscles of mastication function

A

move the mandible (lower jaw bone) to bring its teeth into contact with the teeth of the maxilla (upper jaw bone)
joint that moves is known as the temporomandibular joint

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6
Q

buccinator muscle

A

muscles of tongue and cheeks aid pulverisation and bolus formation

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7
Q

muscles of mastication

A

Temporalis - elevates jaw
Masseter - elevates and protrudes lower jaw
Lateral pterygoid and medial pterygoid - protrude lower jaw unilaterally

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8
Q

pharyngeal stage of swallowing

A

tongue muscles push bolus posteriorly
oral cavity opens into oropharynx
when food touches back of pharynx, swallow reflex if triggered
soft palate rises to block nasopharynx and elevate larynx (suprahyoid muscles) so the epiglottis moves over trachea

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9
Q

oesophageal stage of swallowing

A

smooth muscle pushed food down oesophagus towards stomach
bands of muscle from diaphragm (lower oesophageal sphincter) increase tension produced by oesophageal wall - prevents reflux of the stomach contents

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10
Q

what is oesophagus lined with

A

stratified squamous epithelium

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11
Q

treatments of reflux

A

eating frequent small meals
reducing caffeine, alcohol and spicy meals
raising upper body slightly when sleeping

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12
Q

parts of the stomach

A

fundus
body
greater curvature
lesser curvature
antrum
pylorus/pyloric part
pyloric sphincter

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13
Q

gastric secretions

A

secretion of stomach mucosa are highly acidic
fundus and body of the stomach secrete acid from parietal cells and pepsin precursor, pepsinogen from peptic cells
antrum produces endocrine secretions which control gastric secretion and gastric mortality
- gastrin
- histamine
- somatostatin

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14
Q

columnar epithelia

A

tight junctions in this layer prevent damage to underlying tissues from acid secretions

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15
Q

duodenum

A

loops round
4 sections
- superior - travels superiorly and posteriorly at side of vertebral column
- descending - travels inferiorly over part of kidney to L3 - receives extra secretions from liver and gallbladder via common bile duct and pancreas via main pancreatic duct
- horizontal - travels medially to left crossing aorta at L3
- ascending part travels superiorly on left of aorta to L2 where become jejunum

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16
Q

jejunum and ileum

A

anchored to posterior body wall by mesentery and primary site of nutrient absorption

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17
Q

large intestine function

A

absorption of ions and water

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18
Q

regions of large intestine

A

caecum
ascending colon
descending colon
sigmoid colon
rectum
anal canal

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19
Q

caecum

A

contains vermiform appendix

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20
Q

colon

A

ascending colon travels superiorly from right lower to right upper quadrant
right colic flexure - 90* bend to transverse colon
transverse colon travels from right upper to left upper quadrant
left colic flexure - 90* bend into descending colon
descending colon travels from left upped to left lower quadrant
becomes sigmoid colon (S shaped)
connects descending colon to rectum

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21
Q

liver functions

A
  • glucose storage
  • protein, lipoprotein and cholesterol synthesis
  • digestion: production of bile and bile salts
  • storage of fat soluble vitamins
  • toxin and drug metabolism and excretion
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22
Q

glucose storage

A

liver stores glucose as glycogen
insulin stimulated conversion of glucose to glycogen

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22
Q

albumin

A

transporter for many molecules and also helps maintain reabsorption of fluid from tissues into the blood
lack of albumin causes oedema

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22
Q

protein, lipoprotein and cholesterol synthesis

A

liver synthesises blood proteins and lipoproteins that act as transporters (albumin)
also synthesises proteins that act as clotting factors in the blood
cholesterol is synthesised by liver - used directly in cell membranes or converted into sex-hormones, excess is excreted in bile

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23
Q

digestion: production of bile and bile salts

A

bile salts are detergents that emulsify fats in the intestines
increases SA and facilitates their absorption

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24
Q

storage of fat soluble vitamins

A

vitamins A,D,E and K are ‘fat soluble’ vitamins
this means they can be stored in fat reserves in liver, around organs or underskin

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25
Q

toxin and drug metabolism and excretion

A

liver enzymes metabolise many drugs, the by-products are excreted in the bile or released into bloodstream to be excreted by the kidneys
the liver also metabolises ammonia (toxic by-product of metabolism) into urea - is released into the blood and excreted by the kidneys.
Bilirubin, released by the spleen from breakdown of red blood cells, is modified by the liver so that it can be excreted in the bile.

26
Q

lobes of the liver

A

right
left
caudate
quadate

27
Q

gall bladder

A

fluid filled sac
stored and concentrates bile
made up from fundus, body, neck
neck leads to cystic duct - transports bile to and from

28
Q

bile functions

A

bicarbonate so alkaline pH - decreases acidity of gastric contents released from stomach - prevents damage to intestine
decreased pH also facilitates emulsion of fats by salts in bile

29
Q

bile production (hepatobiliary system)

A

bile is produced by hepatocytes within liver
hepatocytes are arranged in a 3D lattice
sinusoids run between each layer
products of hepatocyte function are removed via small channels between the cells, called canaliculi. The canaliculi then drain into the bile ducts.

30
Q

hepatic ducts

A

bile drains from liver via R+L hepatic ducts, thewy join to form common hepatic duct
common hepatic duct is joined by cystic duct which drains bile from gall bladder
now called common bile duct

31
Q

common bile duct

A

bile either travels up cystic duct to be stored in the gall bladder or carry on to descending duodenum

presence of food in duodenum stimulates gall bladder to contract and release bile

32
Q

biliary tract

A

all ducts combined (R, L, common hepatic, common bile)

33
Q

hepatopancreatic ampulla

A

where pain pancreatic duct joins common bile duct
opens into the duodenum
controlled by hepatopancreatic sphincter

34
Q

pancreas

A

elongated gland
exocrine (release pancreatic juice) and endocrine functions
5 regions - uncinate process, head, neck, body, tail

35
Q

pancreatic juice

A

transported to duodenum by main pancreatic duct
alkaline secretion
- high bicarb and low enzyme content - neutralises acidity of gastric contents
enzyme rich secretion
- major digestive enzymes - secreted as pre-enzymes which are activated in the gut

36
Q

exocrine glands in pancreas

A

compound acinar
enzymes excreted in acinus and modified in ducts

37
Q

peritoneum

A

layer of connective tissue that covers walls and all of viscera of the abdomen
when it moves off a structure it creates a reflection
reflection of peritoneum that covers abdominal contents is called greater omentum
reflection of peritoneum that surrounds majority of small intestine is called the mesentery

38
Q

classification of epithelium

A

types
simple squamous
simple cuboidal
simple columnar
stratified squamous
stratified cuboidal
stratified columnar
simple = 1 layer, stratified >1 layer
squamous = flat cells, columnar = column like cells

39
Q

mucosa layer

A

epithelium
- selective barrier digested molecules must cross
- may contain mucous secreting goblet cells and endocrine secreting digestive hormones
lamina propria
- loose connective tissue
- first immunological barrier to pathogens in GI system
muscularis mucosa
- thin layer of smooth muscle so localised contractions

40
Q

submucosa layer

A

dense connective tissue containing submucosal plexus

41
Q

submucosal plexus

A

controls secretion and blood flow in submucosa layer
relays info from gut epithelium and stretch receptors in wall
part of enteric nervous system

42
Q

enteric nervous system

A

branch of the autonomic nervous system
can operate independently of the CNS
consists of 2 major plexi in GI wall - myenteric and submucosal plexi

43
Q

muscularis externa layer

A

2 layers of smooth muscle
inner circular and outer longitudinal layer
waves of contraction and relaxation along these layers force food along the digestive tract - peristalsis
myenteric plexus lies between the layers

44
Q

serosa layer

A

forms part of peritoneum

45
Q

mircoanatomy of oesophagus

A

muscularis externa of the upper third of the oesophagus consists of skeletal muscle, the lower two thirds of smooth muscle
mucus secreting glands are present in the lamina propria and the submucosa

46
Q

microanatomy of small intestine

A

the recessions between the villi are known as crypts
epithelial surface is simple columnar
4 specialised cells
- absorptive cells - secrete digestive enzymes and absorb nutrients
- goblet cells - produce mucus that lubricates and protects the epithelium from mechanical damage
- granular cells - secrete enzymes and protect epithelium from bacteria
APUD cells - produce endocrine secretions that regulate secretion and motility of the GI tract and associated glands

47
Q

micro anatomy of large intestine

A

epithelium isn’t villous
simple columnar and contains crypts
goblet and absorptive cells are present, APUD are sparse
outer longitudinal layer of smooth muscle is incomplete - taeniae coli

48
Q

coeliac trunk

A

branches supply foregut structures - stomach, superior duodenum, liver, gall bladder, spleen and pancreas
3 branches - common hepatic, left gastric, splenic arteries

49
Q

stomach arteries

A

L+R gastric arteries, L+R gastroepiploic arteries

50
Q

superior duodenum artery

A

superior pancreaticoduodenal artery

51
Q

liver arteries

A

L+R hepatic arteries

52
Q

gall bladder artery

A

cystic artery

53
Q

spleen artery

A

splenic artery

54
Q

pancreas artery

A

superior pancreaticoduodenal artery and the pancreatic branches of the splenic artery

55
Q

superior mesenteric artery

A

supplies midgut structures (small + large intestine)
branches form large loops (arcades) in mesentery
supply jejunum and ileum

56
Q

inferior pancreaticoduodenal artery

A

arises from the superior mesenteric artery
supplies the inferior part of the duodenum and pancreas and anastomose with its superior counterpart

57
Q

ileocolic artery

A

supplies terminal ileum, caecum, vermiform appendix, and proximal ascending colon

58
Q

right colic artery

A

supplies the distal ascending colon

59
Q

middle colic artery

A

supplies the distal transverse colon

60
Q

inferior mesenteric artery

A

supplies hindgut structures (large intestine from proximal transverse colon to the rectum)

61
Q

left colic artery

A

supplies the descending colon
also anastomoses with the middle colic artery of the superior mesenteric artery

62
Q

sigmoid arteries

A

supplies sigmoid colon

63
Q

superior rectal artery

A

supplies proximal rectum

64
Q

portal vein

A

blood coming out of intestines has lots of amino acids and monosaccharides
filtered by liver before returning to heart and lungs
blood drains from the capillaries of the intestines into the superior and inferior mesenteric veins
join with the splenic vein to form the hepatic portal vein

human anatomy (9 decks)

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