Transcript The Digestive System - Downey Unified School District

Eric Soza, Nick Soto, Andres Padilla
Period 2
2/10/15
Alimentary Canal
 Extends from the mouth to the anus, includes accessory
organs
 Mouth, pharynx, esophagus, stomach, small intestine,
large intestine, and anal canal

Accessory organs- salivary glands, liver, gallbladder, and
pancreas
 About 8 meters long
 4 layers
Mucosa
Submucosa
Muscular layer
Serosa
 Segmentation and Peristalsis




Mouth
 1st portion of alimentary canal
 Receives food, begins digestion
 Mastication
Cheeks and Lips
 Form lateral walls of mouth
 Subcutaneous fat
 Muscles associated with chewing
 Stratified squamous epithelium
 Mobile structure
 Skeletal muscles and sensory receptors
 Red color due to blood vessels
Tongue
 Oral cavity, thick
 Lingual frenulum
 Papillae
 Lingual tonsils
Palate
 Roof of oral cavity
 Hard and Soft
 Uvula
 Palatine tonsils
 Pharyngeal tonsils
Teeth
 Hardest structures in the body
 Types (primary, etc.)
 Crown, enamels, root canals
 Help break down food into pieces
Salivary Glands
 Function:
 Overall saliva begins chemical digestion of
carbohydrates, cleans teeth and mouth, and binds food
 Two types of secretory cells:
 Serous Cells- secrete salivary amylase
 Mucous Cells- secrete thick liquid
Salivary Glands
 Three major glands:
 Parotid Glands- Largest, secretes salivary amylase rich
liquid
 Submandibular Glands- Secretes a fluid that is equally
serous and mucus
 Sublingual Glands- Secretes a thick mucus fluid
Salivary Glands
 Two types of secretion Stimuli:
 Sympathetic- impulses that secrete viscous saliva
 Parasympathetic- secrete watery saliva, activated by
sight, taste, smell, or thought of pleasant food
Swallowing
 3 stages
 Voluntary; food chewed and mixed with saliva; bolus.
 Swallowing reflex at pharyngeal opening
 Peristalsis transports food from esophagus to stomach
Pharynx and Esophagus
 Pharynx connects nasal and oral cavities with larynx
and esophagus
 Nasopharynx
 Oropharynx
 Laryngopharynx
 Swallowing stages
 Peristalsis
Stomach
 Has three regions:
 Cardiac region: small area near esophageal opening
 Funic region: temporary storage area
 Pyloric region: narrows and becomes pyloric canal

Pyloric sphincter is the valve that control gastric emptying
Stomach
 Gastric Glands:
 Mucous cell- alkaline secretion that protects stomach
wall
 Parietal cells- (oxyntic cells) release hydrochloric acid

Also secretes intrinsic factor needed for absorption of vitamin
B12
 Chief cells- (peptic cells) release digestive enzymes
Stomach
 Releases pepsinogen which becomes pepsin from HCl

Digests most dietary proteins
 All three cell secretions together create gastric juice
 Gastric lipase is a weak secretion that breaks down fats
Stomach
 Regulation:
 Cholecystokinn (from intestine), intestinal
somatostatin, urogastrone
 Acetylcholine from nerve endings
 Parasympathetic impulses release gastrin

Both of these release histamine from mucous cells which
stimulates gastric secretion
Stomach
 Gastric secretion occurs in three phases:
 Cephalic- sight, taste, smell, or thought of food releases
gastric secretions
 Gastric- Food in stomach releases gastrin
 Intestinal- small intestine releases intestinal gastrin
which increases gastric juice secretion
Stomach
 Absorption:
 Not very effective at absorbing

water, some salts, lipid-soluble drugs, and alcohol
 Mixing and Emptying:
 Chyme produced from mixing
 Peristalsis pushes it to pyloric sphincter which causes it
to relax
 Length of time in stomach depends:

Liquids very rapid, fats long, proteins quick, carbohydrates
very quick
Liver
 Location/Background
 Angiotensinogen
 Thrombopoietin
 Hepcidin
 Betatrophin
 Structure
 Functions
 Produces
 Metabolic Activities
 Stores
Bile
 Background
 Contains
Gallbladder
 Location/Background
 Structure
 Functions
 Storage
 Bile salts
 Chyme
Pancreas
 Location
 Structure
 Secretions
 Pancreatic Juices


Contains…
 Enzymes
 Nuclei
 Amylase
 Lipase
 Trypsin
 Chymotrypsin
 Carboxytrypsin
They digest…
Small Intestine
 The small intestine is about six meters long and
contributes to digestion, absorption, and
transportation
 Contains three parts:
 Duodenum- shortest part and is responsible for most
chemical digestion

Contains a large amount of mucus secreting cells and receives
digestion aid from pancreas and liver
Small Intestine
 Jejunum- Contains most of the absorption. Villi and
microvilli absorb what the body needs
 Ileum- Primarily absorbs B12 and bile salts. Also absorbs
anything the jejunum missed
Small Intestine
 Secretions:
 Secretin- in duodenum
 Motilin- also in duodenum
 Peptidase- breaks down peptides into amino acids
 Sucrase, maltase, lactase- break down disaccharides into
monosaccharides
 Intestinal lipase- breaks down fatty acids and glycerol
 Enterokinase- Shortens trypsinogen and trypsin
 Regulation:
 Direct contact with chyme stimulates secretions,
parasympathetic reflexes trigger secretions as well
Small Intestine
 Absorption:
 Carbohydrates are absorbed by both facilitated diffusion and active
transportation through villi
 Proteins are broken down into amino acids and are absorbed into
villi by active transportation
Small Intestine
 Fat molecules are absorbed in several steps:





Fatty acid diffuses through villi
Resynthesized into previously digested forms
Encased in proteins
Large molecules of lipoprotein called chylomicrions go to
lacteals of the villi
Molecules are emptied into the lymphatic system
Small Intestine
 Water and electrolytes such as sodium and potassium
are absorbed
 Movement:
 Peristalsis occurs along with segmentation

Segmentation- ring like contractions that cut chyme into
segments and slow its movements
 Parasympathetic impulses enhance movement and
sympathetic impulses inhibit movement
Large Intestine
 Contains several parts:
 Cecum, colon, rectum, and anal canal

Colon divided as well:
 Ascending, transverse, descending, and sigmoid colons
Large Intestine
 Function:
 Very little digestion
 Secrete large amounts of mucus regulated by chyme and
parasympathetic impulses
 Absorption limited to water and certain ions such as
sodium
 Bacteria is prevalent and can aid in digestion of certain
substances
Large Intestine
 Movement:
 Mainly relies on peristalsis but is much slower. Generally
only two to three mass movements per day
 Rectum:
 Feces enters the rectum which causes the defecation
reflex to occur
 Peristalsis movements increase, the glottis closes and
the diaphragm lowers
 The external anal sphincter is signaled to relax and feces
is forced out
Works Cited












www.meritnation.com
www.studyblue.com
www.pray40.com
www.academic.amc.edu
www.entertainment.howstuffworks.com
http://www.dietdoctor.com/restoring-liver-function-lchf
http://hepatitisctreatsment.blogspot.com/2014/11/liver-disease.html
http://galleryhip.com/bile.html
http://www.webmd.com/digestive-disorders/picture-of-the-gallbladder
http://www.merriam-webster.com/dictionary/chyme
http://www.uchospitals.edu/online-library/content=CDR62957
http://upload.wikimedia.org/wikipedia/commons/7/77/Blausen_0817_SmallIntestine_A
natomy.png
 http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/GutHormones.html
 https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiologytextbook/the-digestive-system-23/phases-of-digestion-226/hormones-of-the-digestivesystem-1110-6772/