Bio 224 digestive Flashcards
Digestive system overall meaning
Take nutrients from external environment and get into body
- Includes fluids, electrolyte and acid-base homeostasis producing hormones and excreting metabolic wastes
Ingestion
Getting things into digestive system
Secretion
mucus, enzyme, acid and hormones to aid other digestive processes
( Walls of digestive squirting things out)
Propulsion
Rhythmic contractions of smooth muscle of alimentary canal ALSO KNOWN AS PERISTALSIS
Mechanical digestion
digestive organs physically break food down into smaller pieces
Chemical digestion
break chemicals bonds within food particles until only small molecules remian
Absorption
move nutrients from outside the body to inside of the body ( Lumen to blood)
excretion
pooping
Peritoneal cavity
between 2 peritoneal layers and contains SEROUS FLUID ( where most organs are)
Intreaperitoneal
organs located entirely within peritoneal cavity
RETROPERITONEAL
space that holds organs with seran wrap
Mesenteries
(its own organ)
Visceral peritoneum fold over
Superior mesenteric
supplies small intestine and proximal 2/3 colon
Greater omentum
Unique among mesenteries in that it consisits of four layers of folded viseral peritoneum and extends form base of stomach down into pelvis
Lesser omentum
smaller mesentery that extends from medial surface of stomach to liver
Celiac trunk
Supplies the stomach, accessory organs and spleen
Inferior mesenteric
supplies the distal 1/3 of colon, drain into hepatic portal vein to liver for processing
Enteric nervous system innvertaion
celiac plexus, superior mesenteric pelxus, inferior mesenteric plexus
Motility of alementary canal
swallow, churn, peristalsis, defecation
Skeletal muscle to help
mouth, pharynx, superior 1/3 of esophagus and anus
smooth muscle
everything else
Enteric nervous system
self contained branch of autonomic nervous system
- extends from esophagus to anus and are SHORT REFLEXES
mucosa
contract to secrete mucus and other enzyme ( Lines wall os simple cubodial epithelium)
Alimentary canal layers
Mucosa, submucosa,muscularis externa, serosa
Oral cavity
ingestion, secretion, chem and mech. digestion and propulsion
Tounge
muscular organ
- receptor for taste and moves food around
Salivary glands
Accesory organ
- Acinar cells
- Serous cells
- Mucous cell
Serous cell
secrete water based fluid with amylase to breakdown carbs
-IgA
- Bicarb
Mucous cell
secrete mucus
Salivary glands functions
salivation
- Facial nevre innervates submandibular and sublingual glands
- Glossopharyngeal nerve innervates parotid glands
Palatine tonsils and lingual tonsilis function
preform defensive function and protect alimentary canal from any pathogens
MALT
Mucosal associated lymphatic tissue
Esophagus actions
Propulsion and little secretion
Esophagus superior third
Skeletal muscle a
Esophagus middle third
mixture of skeletal and smooth muscle
Esophagus inferior third
smooth muscle
Upper esophageal sphincter
controls passage of bolus into esophagus
Gastroesopageal sphincter ( cardiac sphincter)
Prevents contents of stomach from re-entering esophagus
Muscularis externa
outer longitudinal
middle circular
inner oblique
Gastric glands ( chem digestion)
at base of gatsic pits and significant protein digestion
mucosa neck cell
secrete acidic muscus and prevents acid produced by parietal cells
Paretal cells
secrete HYDROCLORIC ACID
- activates pesinogen
Intrinsic factor
required for intestinal absoprtion of VITAMIN B12
Chief cells
secrte PEPSINOGEN
- when pepsinogen encounters acidic pH and becomes pepsin
G cells
DNES CELLS
SECRETE GASTRIN
CEPHALIC PHASE
sight, smell, taste
gastric, DNES cells
Higher gastrin, histamine,
Lower somatostatin
AL RELEASE HIGH HYDROGEN
Gastric phase
food entering stomach
gastric, DNES CELLS
high gastrin, histamine —> pos. feedback
lower somatostatin
ALL RELEASE HIGH HYDROGEN
Receptive
RESTING STATE
- Stomach vloume of only 50 ml( 0.2 cups) but can expand to 1500 ml (6 cups)
-Relaxation of smooth muscle
Churning
- Smooth muscle produce waves of peristalsis
- ## peristaltic waves’ constant at about 3 per minute
Stimulates gastric motility
enteroendocrine cells of stomach produce hormo SEROTONIN
emptying
- duodenum must mix incoming chyme before it moves to small intestine
- bicarbonate ions to avoid damaging intestinal musocsa
Cholesystikinin
triggers gallbladder to secrete bile
Chyme is acidic and duodenum must mix with _______ to avoid intestinal mucosa
Bicarbonate ions
Chyme is generally very _____ and must be diluted with water from _______ to prevent chyme from drawing water into internal lumen by osmosis
concentrated; pancreatic juice
small intestine
secretion,chemical digestion, ABSORPTION ( MAIN FUNCTION) and propulsion
( duodenum, jujunum, ileum)
Chruing process
- SM contracts and propels small amount of chyme through pyloric sphincter
- stomach peristaltic waves chrun remaing chyme
- remaining chyme is again propelled towards the pyloric sphincter
how long is the SI
6 meters or 20 ft long ( longest portion of alimentary canal)
Duodenum
Major duodenal papilla:
Shortest of 3
;Where secretions from gallbladder and pancreas enter SI
Duodenal (Brunners) gland
Produce alkaine mucus and protect duodenum from acidic chyme
Jejunum
Middle
about 7.5-8 ft
most acive site for CHEMICAL and ABSORPTION
Ileum
final segment
10.8 ft or 3.6 m
Cecum
terminates at portion of large intestine
Ileocecal valve
prevents backflow
Vili
each villus consisits of layer of enterocyte surroduing central core of blood capillaries and lymph vessel called LACTEAL
Microvilli
increases surface area
intestinal crypts
house glands
vagus nerve regulates both
peristalsis and segmentation
Peristalsis
longitudinal muscle ( moves in and flows down)
segmentation
circular muscle ( moves in and turns)
Stomach hormones
Gastrin ; partially digested protiens stimulation from vagus nerve
Intestinal hormo
Cholecystokinin ) cck)
- digested protiens and lipids in chyme entering the duodenum
Large intestine
5 ft long
- receive material from SI that was not digested and passeway for feces
absorption, secretion, propulsion
There are about __ times more bacteria in large intetsine than cell in human bdy; bacteria make up as much as ___ of dry feces
10; 60%
LI produce vitamins,
LI metabolize undigested materials
Vitamin K ( Blood clotting)
for absorption and deter growth of harmful bacteria
and they stimi immune system
pooping
- receptor transmit sensation of rectal distention to spinal cord
- parasympathetic neurons cause SM and others to relax
- impulses from cortex tigger relaxation of external anal sphincter and allow pooping
pharynx
propulsion
oral function
ingestion
mech digestion
propuslion
secretion
esophagus
propulsion, limited secretion
stomach
propulsion
chem digetsion
mech digestion
secretion
limited absorption
SI
chem digestion,
mech digestion
absorption,
secretion
propuslion
LI
absorption
propulsion
limited secretion
defecation
Liver digestive function
produce bile salt and is amphiphilic
- Helps excrete wastes that kidney cannot excrete
LI convert it to _____ the into ___ and is responsible for the brown color in feces
urobilinogen; stercobilin
Carbohydrates
salivary amylase—> salivary galnds —-> polysaccharides—–> oligosacchardies—-> monosaccharides
Water
9L enter SI every day , 2 L ingeted and 7 L secreted
Water souble vitamin
polar molecules ( c and B)
Fat soluble vitamins
lipid based and mostly nonpolar ( A, D,E and K)
