digestive system Flashcards
DIGESTIVE SYSTEM
6 functions
ingestion
mechanical processing
digestion
secretion
absorption
excretion
DIGESTIVE SYSTEM
subdivisions of digestive tract (6)
1) oral cavity, teeth, tongue
2) pharynx
3) oesophagus
4) stomach
5) small intestine
6) large intestine
DIGESTIVE SYSTEM
accessory organs of digestive system (4)
1) salivary glands
2) liver
3) gallbladder
4) pancreas
DIGESTIVE SYSTEM
what is the peritoneum
serous membrane of abdominal cavity
DIGESTIVE SYSTEM
2 components of peritoneum
SEROUS MEMBRANE
visceral layer = organs
parietal layer = cavities
PERITONEAL FLUID
lube for sliding
DIGESTIVE SYSTEM
mesenteries
fold in membrane, attach intestine to stomach lining
expansion/contraction
suspend digestive tract
pass of blood vessels, nerves, lymphatic vessels
DIGESTIVE SYSTEM
what does digestive tract protect against (3)
mechanical stresses
bacteria
digestive acids + enzymes
DIGESTIVE SYSTEM
4 layers of digestive tract
mucosa
submucosa
muscular externa
serosa
DIGESTIVE SYSTEM
digestive tract mucosa
inside
(3)
MUCOSA EPITHELIUM
strat. squam. epithet. in: oral cav, pharynx, oesophagus.
LAMINA PROPRIA
areolar tissue
MUSCULARIS MUCOSAE
inner circle layer/ outer longitudinal layer
DIGESTIVE SYSTEM
digestive tract submucosa
- dense irregular connective tissue
- large blood vessels , lymphatic vessels
- exocrine glands , buffer and enzymes in tract
DIGESTIVE SYSTEM
what is the submucosal plexus
neural network between mucosa + submucosa
DIGESTIVE SYSTEM
digestive tract muscular externa
movements coordinated by _____
smooth muscle cells
ENS enteric nervous system ,
innervated by parasympathetic div of ANS
DIGESTIVE SYSTEM
digestive tract serosa
replaced by? where?
(outside)
serous membrane
replaced by adventitia (dense collagen fibre sheet) :
oral cavity, pharynx, oesophagus, rectum
DIGESTIVE SYSTEM
what cells control movement of food
pacesetter cells
DIGESTIVE SYSTEM
3 stages of moving food
- contract circular muscle behind bolus
- contract longitudinal muscle ahead of bolus
- contract circular muscle layer . force bolus forward
DIGESTIVE SYSTEM
oral cavity functions
(6)
- sensory analysis
- mechanical processing
- lubrication
- limited digestion
- passage for food liquid air
- open to oropharynx
DIGESTIVE SYSTEM
saliva functions (3)
lube mouth + food
dissolve chemicals
initiate digestion of complex carbs
DIGESTIVE SYSTEM
salivary glands (3)
controlled by (2)
parotid
sublingual
submandibular
sympathetic, parasympathetic stimulation
DIGESTIVE SYSTEM
4 phases of swallowing
- buccal phase
- pharyngeal phase
- oesophageal phase
- bolus enter stomach
DIGESTIVE SYSTEM
oesophagus
layers (4)
move food/liquid to stomach
mucosa (inner)
submucosa
muscular externa
adventitia (outer)
DIGESTIVE SYSTEM
stomach functions (4)
store ingested food
mechanical breakdown
chemical breakdown:
- by enzymes (pepsin = break protein)
- by acid (HCL reduce ph)
produce intrinsic factor (absorb b12)
DIGESTIVE SYSTEM
stomach lining layer (5)
simple columnar epithelium (produce mucous)
gastric pits – gastric glands (cells divide at bottom to replace damaged cells by e.g: acids )
submucosa
muscularis externa
serosa
DIGESTIVE SYSTEM
3 components of muscular externa in stomach lining
oblique muscle
circular muscle
longitudinal muscle
DIGESTIVE SYSTEM
where would you find gastric glands?
fundus and body of stomach
DIGESTIVE SYSTEM
3 types of cells in gastric glands
PARIETAL CELLS
secrete intrinsic factor + HCL
CHIEF CELLS
secrete pepsinogen
covert to pepsin by HCL
G CELLS
secrete gastrin
DIGESTIVE SYSTEM
where would you find PYLORIC GLANDS
pylorus, where stomach narrows
DIGESTIVE SYSTEM
pyloric glands
what do they do?
what cells here?
produce mucous
G CELLS = secrete gastrin
D cells = release somatostatin (inhibit gastrin)
DIGESTIVE SYSTEM
how do parietal cells secrete HCL
1)enzyme: carbonic anhydrase convert CO2 + H20 — carbonic acid
dissociate – = H- ions
2) countertransport mechanism:
eject bicarbonate atoms
import chloride ions
3) chloride ions diffuse across cell
exit: chloride channels into gastric gland lumen
4) H ions actively transported — gastric gland lumen
DIGESTIVE SYSTEM
mechanism help protect stomach from acid/protease (6)
mucous lining
rapid cell div
seperate secretion of H+, Cl- in parietal cell
secrete inactive precursor (pepsinogen)
stimulate secretion only when needed
inhibition of secretion
DIGESTIVE SYSTEM
3 inhibitors of secretion
CCK
GIP
secretin
DIGESTIVE SYSTEM
small intestine regions (3)
duodenum
jejunum
ileum
DIGESTIVE SYSTEM
duodenum
proximal
receive pancreas + liver secretion
start digestion
small villi
25 cm
DIGESTIVE SYSTEM
jejunum
large sa
chemical digestion
2.5m long
DIGESTIVE SYSTEM
ileum
immune functions
3.5m long
DIGESTIVE SYSTEM
villi
large sa
capillaries + lymphatic capillaries
Brush border of microvilli
DIGESTIVE SYSTEM
what is the scientific name for lymphatic capillary?
what do they do
lacteal
absorb fats
DIGESTIVE SYSTEM
what happens to cells in the intestinal gland?
divide at bottom, displaced at top of villi
disintegrate when add enzyme to lumen
DIGESTIVE SYSTEM
brush border enzymes role
break materials in contact with brush border
enteropeptidase = activate trypsinogen (pancreatic proenzyme)
DIGESTIVE SYSTEM
enteroendocrine cells
role
2 hormones examples
produce hormone
CCK + secretin: increase enzyme/bile secretion
GIP gastric inhibitory peptide: inhibit gastrin activity, slows stomach
DIGESTIVE SYSTEM
duodenal glands role
produce mucus
increase pH
DIGESTIVE SYSTEM
intestinal juice
moisten chyme
buffer acids
DIGESTIVE SYSTEM
what does pancreatic juice include
what breaks down:
1) cho
2) lipids/fats
3) nucleic acids
4) proteases/ peptidase
pancreatic enzymes:
1) alpha amylase
2) lipase
3) nucleases
4) old protein/peptide molecules
DIGESTIVE SYSTEM - pancreas
endocrine cells secrete =
exocrine cells secrete =
ENDOCRINE = insulin + glucagon into blood
EXOCRINE = pancreatic juice
DIGESTIVE SYSTEM
______ is one of the largest organs of the body, adjacent to stomach
liver
DIGESTIVE SYSTEM
where does the liver get
1/3 of its blood
2/3 of its blood
1/3 = hepatic artery proper
2/3 = hepatic portal vein (came from many locations to here)
DIGESTIVE SYSTEM - liver
what is a corner of a lobule called?
what do they contain?
portal area
branch of:
hepatic portal vein, hepatic artery proper, bile duct
DIGESTIVE SYSTEM
name of liver cells
hepatocytes
DIGESTIVE SYSTEM
what happens in lobules?
blood past hepatocytes = absorb solute, secrete protein — sinusoids
bile — bile ducts
DIGESTIVE SYSTEM
liver metabolic functions (5)
metabolise cho, lipid, aa
remove waste
vitamin storage
mineral storage
drug inactivation
DIGESTIVE SYSTEM
liver haematological regulation (3)
phagocytosis , antigen present
plasma proteins synthesis
remove hormone, antibodies, toxins
DIGESTIVE SYSTEM
3 liver functions
metabolic regulation
haematological regulation
bile production
DIGESTIVE SYSTEM
gallbladder bile transport pathway (5)
1) Liver secrete bile
2) Stored, concentrated in gallblader
3) Duodenal release CCK = hepatopancreatic sphincter relax , gallbladder contract
4) Bile ejected into duodenum
5) Bile salts break lipid droplets (emulsifcation)
DIGESTIVE SYSTEM
where are cells that secrete digestive enzymes located?
pancreatic acini
DIGESTIVE SYSTEM
function of large intestine (4)
ABSORPTION (water +. bile salts)
BACTERIAL VITAMIN PRODUCTION
COMPACT CONTENTS – FAECES
STORE FAECES – DEFAECATION
DIGESTIVE SYSTEM
large intestine structure
no villi = smooth surface
mucous cells
muscular externa + thin strips of taeniae coli
DIGESTIVE SYSTEM - neural control of intestine
1) LOCAL REFLEXES
2) CENTRAL CONTROL (2)
1) local response, stretch, ph change
2) PARASYMPATHETIC: increase motility/secretion
SYMPATHETIC: inhibit
DIGESTIVE SYSTEM - neural control of intestine
name of reflex that:
1) stimulate motility + secretion along small intestine
2) open valve between small + large intestine
1) gastroenteric reflex
2) gastroileal reflex
DIGESTIVE SYSTEM
GASTRIN
1) stimulated by:
2) stimulates … :
1) food in stomach
2) increase acid production
stimulate Smooth muscle contract
DIGESTIVE SYSTEM
GIP
1) stimulated by:
2) stimulates… :
1) chyme in duodenum = stretch
2) inhibit gastrin
stimulate insulin from pancreas
DIGESTIVE SYSTEM
SECRETIN + CCK
1) stimulated by:
2) stimulates… :
1) chyme in duodenum
2) - release pancreatic enzyme + buffers
- bile secretion
DIGESTIVE SYSTEM
VIP
1) stimulated by:
2) stimulates… :
1) chyme in duodenum
2) dilate intestine capillary = blood flow up to absorb food
DIGESTIVE SYSTEM
name the 5 hormones produced by digestive system to increase food absorption
GASTRIN
GIP
CCK
SECRETIN
VIP
DIGESTIVE SYSTEM
summarise how CARBOHYDRATES are broken down
1) salivary amylase, oral cavity
2) stomach: – disaccharide, trisaccharides
3) small intestine: pancreatic alpha amylase
4) enzymes in brush border– simple sugar
5) capillaries, through liver, bloodstream
DIGESTIVE SYSTEM
summarise how LIPIDS are broken down
1) lingual lipase ,tongue
2) bile salt + pancreatic lipase (small intestine) —- FA
3) FA diffuse in small intestine cells
4) packaged into chylomicrons —- lacteals
DIGESTIVE SYSTEM
summarise how PROTEINS are broken down
1) pepsin , stomach
2) pancreatic proteases , proteins – AA
3) brush border enzymes — single AA (absorb into capillaries)
4) filtered in liver
