digestive system
DESCRIPTION
Digestive System. Function. The mechanical/chemical breakdown of foods and absorption of nutrients by cells A limentary canal (9m from mouth to anus) A ccessory organs- pancreas, liver, gall bladder. Alimentary Canal. - PowerPoint PPT PresentationTRANSCRIPT
Digestive System
The mechanical/chemical breakdown of foods and absorption of nutrients by cells
Alimentary canal (9m from mouth to anus) Accessory organs- pancreas, liver, gall
bladder
Function
mouth, pharynx, esophagus, stomach, sm intestine, lg intestine, anal canal
Movements of Tube:◦ Mixing movements- rhythmic contractions that
mix food with digestive juices◦ Propelling movements- rings of muscles
contract/relax to push food down canal (Peristalsis)
Alimentary Canal
Begins digesting by chewing/mixing food with saliva
Tongue- moves food◦ connect to floor of mouth by frenulum◦ taste buds
Mouth
Palate- forms roof of oral cavity◦ Uvula at back of mouth
Palatine tonsils- back of mouth/throat◦ Organs protect against infection
Teeth- primary vs. secondary◦ Incisors, cuspids, bicuspids, premolars, molars◦ Used for chewing food
Serous cells produce amylase- breakdowns food
Mucous cells produce mucus- lubrication during swallowing◦ Parotid Glands◦ Submandibular Glands◦ Sublingual Glands
Salivary GLands
Pharynx- nasal and oral cavities nasopharynx,oropharynx, laryngopharynx Esophagus- moves to the stomach,
penetrates the diaphragm at the esophageal hiatus
lower esophageal sphincter-prevent food and chemicals from moving up the stomach
Pharynx/Esophagus
*J-shaped, pouch like organs that hangs inferior to the diaphragm
1 liter capacity Four main parts of the stomach1. Cardiac -esophageal opening-cardiac sphincter2. Fundic -temporary storage area, lies above the
cardiac region3. Body -central area of the stomach4. Pyloric -pyloric sphincter, controls emptying of
the stomach into the sm. Intestine
Stomach
Rugae – folds within the stomach, increase surface area
Lining of the stomach is a mucous membrane – with small openings called gastric pits, containing gastric glands
Gastric Juice- pepsin Chyme –broken down food molecules from gastric juices/movement of stomach◦ released from the pyloric sphincter valve into the
first portion of the small intestine – duodenum
secretes pancreatic juicePancreatic juice – digests fats, breaks down nucleic acids into nucleotides
Pancrease
BILIARY SYSTEM – functions to create bile used in digestion; liver, gall bladder and ducts
LIVER- large right lobe and small left lobe Hepatic portal vein – delivers blood to the
liver
Liver
maintains normal concentration of blood glucose
breakdown of lipids and fats protein metabolism (forming urea,
synthesizing plasma proteins such as clotting factors,(converting amino acids);
stores iron and vitamins destroys damaged red blood cells removes toxic substances from the blood secretes bile
Functions
Bile – yellowish-green liquid secreted from hepatic cells
(when bile pigments build up in blood, skin turns green, a condition called jaundice).
Bile empties into the duodenum Bile aids in digestion, bile salts break down
fat globules into smaller droplets – emulsification
Gall Bladder- stores bile
tubular organ that extends from the pyloric sphincter, many loops and coils, fills much of the abdominal cavity
receives secretions from the pancreas and liver, completes digestion of nutrients and chyme, absorbs1. Duodenum - first part of the small intestine2. Jejunum – second part, ~2.2 m3. Ilium – third part, longest ~3.3 m
*jejunum and ilium are continuous
Small Intestine
Intestinal Villi – increase surface area for absorption
Function- secrete chemicals to break down food and carry away these nutrients in the blood (absorption)
1. Cecum – beginning of the large intestine, pouchlike, closed end called the vermiform appendix (ileocecal valve)
2. Colon – ascending / transverse / descending / sigmoid
3. Rectum – stores waste before it is expelled from the body
4. Anal canal - ends in the anus, muscular sphincter which controls the exit of waste
Large Intestine
– secretes mucus to protect the wall against abrasion- reabsorbs water and passes along material that was not digested- contains intestinal flora (bacteria to break down cellulose, also produce intestinal gas)
Mass movements – large portions of the colon contract to move material through it, 2-3 times a day usually after eating
Functions
1. Food 2. Mouth-teeth, tongue, amylase break down3. Moves down Esophagus by Peristalsis4. Enters stomach- chyme5. Enters Sm. Intestine at Deudenum-
liver/gall bladder secret bile – villi absorb nutrients jejunum ileum
6. Enters Lg. Intestine Cecum Colon Rectum Anus
Sum it up