T5: Digestive System Flashcards
5 stages of digestion
ingestion digestion absoprtion compaction defacation
what is digestive tract/alimentary canal
mouth > anus
GI tract
stomach + intestine
what is mechanical digestion p
physical digestion
what is chemical digestion
enzyme breakdown
3 basic layers of gut
mucosa (epithelium , lamina propria, muscular mucosa)
submucosa (loose CT
Muscularis externia (2 smooth muscle layers= inner circular, outer longitudinal)
2 mechanisms that move food
peristalsis - waves of contraction
segmentation- alternate constriction
2 peritoneum layers
- parietal perl (on walls)
2. visceral peri (on organs)
role of mesentaries
allows organ movement
passage for BV, nerve, LV
explain parasympathetic control of digestive
cranio-sacral
- vagus nerve+ sacral spinal cord
- increase secretion and motility
explain sympathetic control of digestive
thoracic-lumbar
- thoracic and upper lumbar spinal cord
- decrease secretion and motility
what does myenteric plexus do
b/w 2 musclurus externa layer
- frequencies and strength of contraction
what does submucosa plexus do
glandular sectrions
what is oral cavity (buccal) lined with
- stratified squamous
- keratoinzed if food abraisens
what does food stimulating oral receptors do
trigger involuntary chewing reflex
what is mastication and what does it allow
chewing= mech digestion
- easy to swallow
- SA for enzymes
determine if herbi or carni
herb= teeth come together at same time
flatter teeth
two types of salivary gland
intrinsic
extrinsic
3 types of intrinsic saliva glands and their function
lingual
labial
buccal
- lingual lipase, saliva
3 types of extrinsic saliva glands and their function
parotid
submandibular
sublingual
PNS response to salivary glands
facial + glosso
= thin, enzyme rich saliva
SNS response to salivary glands
superior cervicle ganglion
= less, thicker, saliva
3 things saliva contains
salivary amylase
linguil lipase
mucus
summarise digestion in oral cavity
mechanical salivary amylase (polysaccharides > oli_|) lingual lipase (fat digestion)
pharyngeal constrictor muscles
force food down when swallowing
2 phases of swallowing
buccal phase (voluntary) pharyngoesphageal phase (invol)
what prevents food from coming back into mouth
tongue against hard palate
pharyngeal constrictor muscles
epiglottis close
what is peristalsis controlled by
myenteric plexus
change in tissue from gastro-oesophageal junction
stratified squamous > simple columnar
rugae
folds outside stomach= flatten when full
whats different about muscular external in stomach
3 layers= inner oblique muscle (mechanical digestion)
what splinter is b/w stomach and duo
pyloric
whys there tight junction b/w simple columnar of stomach
prevents gastric juice from digestion lamina propria
4 types of cell in stomach
mucous: secrete mucos + resist acid
stem= continual new cells
parietal= HCL + intrinsic
chief cells= pepsinogen + gastric lipase
what is a zymogen and example in stomach
digestive enzyme thats a inactive protein
pepsinogen
pepsinogen to pepsin
parietal cells HCL removes amino acid = pepsin
summery digestion in stomach
mechanical (churning)
pepsin (>peptide chains)
gastric + lingual lipase (fat digestion
what happens in duodenum (4)
- stomach acid nutrilsed by bicarbonate form pancreas
- pepsin inactivated with higher pH
- bile acids emulsify fats
- chemical digestion by pancreatic enzymes
ileocecal valve
regulated passage into large intestine
what does liver do
secrete bile = emulsify fats
what artery supplies most of SI and half large
superior mesenteric artery
pancreatic enzymes
panc. lipase
panc. amylase
nuclease
what does plicae circulates do
increase contact wiht mucosa
slow passes\age
mixing
complete digestion of carbohydrates
- salivary amylase (starch olosaccharides)
- pancreatic amylase (starch disaccharides)
- brush border enzymes (monosaccharides)
> cappilaries
complete digestion of protein
pepsin (stomach)
pancreatic protease (polypep > olipep_
brush border (peptides > amino )
> capilaries
complete digestion of fat
lingual + gastric lipase
bile and agitation= emulsification
pancreatic lipase lipase (tryglceride > 2 fatty and mono)
micelles in bile
- transport + diffuse into epithelium
- packaged into secretory vesicles > lacteal)
tissue of large intestine
simple columnar + goblet (librication_
internal vs external anal sphincter
inter= smooth ext= skeletal
neural control of defection
intrinsic defecation reflex (myenteric plexus= stretch receptors para defection reflex (rely of internal spin) voluntary control (extern spin)
