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Digestive System Isabel Blackwood (General functions and structure of the…
Digestive System Isabel Blackwood
General functions and structure of the digestive system
Digestive System Major functions
Break down food to be absorbed into blood as nutrients
eliminate what can't be broken down
Gastrointestinal Tract
Mouth, esophagus, stomach, small intestine, large intestine, rectum, anal canal, anus
Accessory Digestive Organs
Parotid salivary gland, submandibular salivary gland, sublingual salivary gland, liver, gall bladder, pancreas
Digestion
Mechanical
mouth
teeth
stomach
churning
small intestine
segmentation
Chemical
mouth
saliva - enzymes
stomach
proteins and enzymes
small intestine
chemicals from pancreas
Peristalsis
involuntary wave like muscle contractions that begin when you swallow and push food from esophagus through large intestine
Peritoneum and Mesenteries
Mesentery structure
double layer of peritoneum (simple squamous epithelium)
Mesentery function
holds organs in place
provides place for blood vessels and neurons
stores fat
Mesentery Locations
Mesentery proper
jejunum and ileum
Mesocolon
connected to transverse and sigmoid colon and posterior wall of abdomen
Lesser Omentum
lesser curvature of stomach
Greater Omentum
greater curvature of stomach, drapes over organs and connects to posterior wall; can migrate with body movement
Intraperitoneal
liver, stomach, transverse colon, jejunum, ileum, sigmoid colon
within the peritoneum
Retroperitoneal
duodenum, pancreas, ascending and descending colon, rectum
not within the peritoneum
Functions and Features of Digestive Organs
Stomach
functions
store food
mechanical digestion - churning
chemical digestion
features
Parietal cells
produce hydrochloric acid
produce intrinsic factor
needed to produce vitamin B12
needed to produce erythrocytes
chief cells
secrete pepsinogen
needed for enzyme that aids digestion of protien
cardiac sphincter
prevents reflux of acid into esophagus
pyloric sphincter
regulates amount of chyme moving on to small intestine
rugae
increase storage capacity of stomach
Small Intestine
Functions of small intestine
absorption
chemical digestion
mechanical digestion
features of small intestine
circular folds
increase surface area for villi
slow movement of chyme
duodenal glands
secrete alkaline mucus to neutralize stomach acid
intestinal crypts
secrete watery intestinal juice
lymphatic nodules
collections of lymphocytes
ileocecal valve
prevent backwards movement of chyme
Large Intestine, Rectum, Anal Canal
Functions of Large Intestine
absorption of water and electrolytes
function of rectum
storage
well developed muscle to expel feces
Functions of anal canal
provide mucus for lubrication
internal and external sphincters
teniae coli
3 strips of muscle that contract the large intestine into pouches or sacs
haustra
pouches or sacs of the large intestine
epiploic appendages
fat filled sacs on the large intestine
Functions of Accessory Digestive Organs
Liver functions
making bile
filters toxins from blood
stores glucose as gylcogen
stores vitamins
makes blood proteins
albumin, globulin, fibrinogen
Gall bladder functions
stores and concentrates bile
pancreatic acini function
produce 22 or more enzymes that enter duodenum
pancreatic duct functions
produce bicarbonate alkaline substance
neutralizes stomach acid