The mechanical and chemical breakdown of foods into a form that cell membranes can absorb
Breaking large pieces into smaller pieces without changing chemical composition
Changes food chemically
Passage of digestive food from food tube into circulatory system
Elimination of wastes
How long is the alimentary canal?
30 feet or 8 meters long
What are the organs of the alimentary canal?
What are the accessory organs of the digestive system?
What are the 4 layers of the alimentary canal wall?
Mucous membrane (mucosa)
The innermost layer of the alimentary canal wall which has no direct blood supply, made of epithelium, connective tissue, and smooth muscle.
Mucosa (mucous membrane)
This layer of the alimentary canal wall has tiny folds and projections to increase surface area and functions in protection, absorption, and secretion.
Mucosa (mucous membrane)
Made of loose connective tissue, this layer of the alimentary canal wall contains blood and lymph vessels, nerves, and glands. It functions to nourish surrounding tissue, and transport absorbed materials away.
This layer of the alimentary canal wall, made up of circular and longitudinal fibers of visceral smooth muscle, functions in peristalsis.
This outermost layer of the alimentary canal wall has a layer of epithelial and connective tissue that wraps around your organs (visceral peritoneum) and functions to protect and secretes fluid to moisten the outer surface of those organs
This movement of the alimentary canal causes smooth muscle in small segments to contract rhythmically to mix contents
A wavelike motion in the alimentary canal, rings of contraction with relaxation in front
This part of the nervous system inhibits digestive activities
This part of the nervous system increases digestive activities
This part of the digestive system receives food, mastication, small pieces and saliva
The lateral walls which help hold food inside of the mouth
Has sensory receptors for temperature and texture. Blood vessels give color
The narrow space between the teeth, cheeks and lips
The thick, muscular organ in the floor of the mouth
Connects the tongue to the floor of the mouth
Anchored to the hyoid, this mixes food and moves it into the pharynx
Masses of lymphatic tissue to protect the body against infection
The roof of the mouth
The area of the palate with maxillary bones and palatine bones
The area of the palate with an arch extending downward into the uvula
Closes between the nasal cavity and pharynx during swallowing
uvula and soft palate
Closes off the glottis during swallowing
Tonsils associated with the tongue
When these tonsils become inflamed it is called tonsillitis
Lymph tissue on the posterior wall of the pharynx, which may be removed if it blocks the nasal passage
phayngeal tonsils (adenoids)
Chamber between the palate and tongue
Break up food mechanically to increase surface area
Hardest structure in the body but not part of the skeletal system
First set of teeth
How many deciduous teeth?
Second set of teeth
How many permanent teeth?
Teeth used for biting
How many incisors?
Teeth used for grasping and tearing
How many cuspids?
8 teeth used for grinding
12 teeth used for grinding
Last set of teeth to come in
The area beyond the gum, covered by enamel
The hardest substance of the teeth which wears away with age and can't be replaced
The living part of crown, beneath enamel, harder than bone, extends into root, surrounds pulp cavity
This part of the teeth contains pulp, blood vessels and nerves
Anchored in the jaw, has root canals
The functions of saliva
binds food together
begins carbohydrate digestion
makes taste possible
helps cleanse mouth and teeth
Moistens food and binds food together
Begins carbohydrate digestion and regulates pH
Makes taste possible and helps cleanse the mouth and teeth
Found in saliva to help keep pH levels between 6.5 and 7.5
The cells found in salivary glands which secrete the enzyme amylase
The cells found in salivary glands which secrete mucous to bind food
The largest salivary gland, anterior and inferior to the ear, rich in amylase
The salivary gland located in the floor of the mouth, made mostly of serous cells
The salivary gland located under the tongue made mostly of mucous cells
The passageway at the back of the mouth with skeletal muscle in the walls
With no digestive role, this connects the nasal cavity with the larynx and the esophagus with the oral cavity
The passage for air, opens to Eustachian tubes to middle ear (above soft palate)
Passageway for food and air (behind mouth)
Passageway to the esophagus (inferior to oropharynx)
The 3 stages of swallowing
Voluntary, food is chewed, mixed with saliva, rolled into a bolus, and forced into the pharynx by tongue
Involuntary reflexes move food into the esophagus, breathing halts
Food is moved by peristalsis into the stomach
25cm long passageway through the thoracic cavity from pharynx to stomach, located posterior to the trachea
The opening where the esophagus passes through the diaphragm
Condition where the esophageal hiatus tears
Ring of smooth muscle between esophagus and stomach to prevent regurgitation
J-shaped organ under the diaphragm
Receives food and mixes food with gastric juices and starts digestion of proteins
Carries on a small amount of absorption and moves food into the small intestine
The region of the stomach near the esophagus
The region of the stomach which is a temporary storage area which may fill up with air and show up on x-ray
The main part of the stomach
The region of the stomach near the small intestine
The ring of smooth muscle controlling passage into the small intestine
Cells which secrete mucus to protect the stomach
mucous (goblet) cells
Cells which secrete pesinogen
Inactive form of pepsin
Cells which secrete HC1
Changes pH to acid and activates pepsinogen to become pepsin which starts digestion of proteins
Parietal cells secrete this to aid in the absorption of vitamin B12 from the small intestine
The phase of gastric secretion where parasympathetic reflexes are triggered by sight, taste, smell, or thought of food before it enters the stomach
The phase of gastric secretion where gastrin is secreted when food enters the stomach, stimulates gastric juice secretion
The phase of gastric secretion when food first enters the intestine, intestinal gastrin is released and temporarily increases gastric secretions
As food continues to move into the small intestine, what type of reflexes inhibit gastric secretions?
Semifluid mixture of food and gastric juice
What does the rate of chyme leaving the stomach depend upon?
Fluid level and type of food
How long does it take for fats to leave the stomach?
Located behind the stomach and connected to the duodenum by the pancreatic duct
As an exocrine gland it secretes pancreatic juice
The pancreas is connected to the duodenum by what?
As an exocrine gland, the pancreas secretes what?
Contains enzymes and high bicarbonate ion concentration that neutralizes the acidic pH of chyme
Makes the contents of the small intestines basic
What are the 2 hormones from the small intestines which trigger the release of pancreatic juice?
Pancreatic juice rich in bicarbonate
Pancreatic juice rich in enzymes
Enzyme which changes starch into disaccharides
Enzyme which changes fat into fatty acids and glycerol
Enzyme which changes nucleic acids into nucleotides
Enzymes which breakdown proteins into peptides
The inactive form of trypsin
Trypsinogen is changed into trypsin by this enzyme from glands in the small intestine
These two enzymes are inactive in pancreatic juice until trypsin is formed
Largest internal organ
This organ is highly vascularized
What are the 4 lobes of the liver?
The fundamental unit of the liver contained in each lobe
In hepatic lobules, these radiate from a central vein
Where do hepatic cells radiate from in hepatic lobules?
A central vein
The channels between hepatic lobules
Blood from digestion enters hepatic lobules from here
hepatic portal vein
Nutrients mix with oxygenated blood in hepatic lobules from where?
From hepatic lobules, blood flows over ____ and out ____
Functions of the liver
metabolism of carbohydrates, lipids, and proteins
deamination of amino acids and the forming of urea
storage of substances (iron, blood, vitamin A, D, B12)
filtering blood (Kupffer cells in sinusoids remove bacteria by phagocytosis)
destruction of toxic chemicals (alcohol)
secretion of bile
What organ metabolizes carbohydrates, lipids, and proteins?
What organ deaminates amino acids and is involved in the formation of urea?
What organ functions to store substances such as iron, blood, vitamin A, vitamin D, and vitamin B12?
What organ filters blood?
Cells in sinusoids which remove bacteria by phagocytosis
This organ destructs toxic chemicals, such as alcohol
Organ involved in the secretion of bile
Contains what, bile salts, bile pigments (from breakdown of rbc), cholesterol, and electrolytes
The only part of bile with a digestive role
Functions to emulsify fats and aids in absorption of fatty acids, cholesterol, and vitamins
Reabsorbed in the small intestine for re-use
Triggers the release of bile from the small intestine
Located in a depression on the inferior surface of the liver
Stores bile between meals
Pear-shaped sac connected to the cystic duct which joins the hepatic duct
Cystic and hepatic duct which leads to duodenum
common bile duct
Tubular organ between the stomach and large intestine which is 18-20 feet long
What are the 3 parts of the small intestine?
Double-layered fold of peritoneum which suspends jejunum and ileum from posterior abdominal wall
Drapes the stomach, large intestine, and small intestine, and controls the spread of infection
Controls movement from ileum to large intestine
Line small intestine to increase surface area and aid in mixing and absorption of nutrients
Cavity within the small intestine with villi to increase surface area
Made of simple columnar epithelial with microvilli, connective tissue, lacteal (lymph capillaries), blood vessels, and nerve fibers
Secretions of the small intestine
Helps move food into villi in the small intestine
The enzymes released from intestinal glands in the small intestine
sucrase, maltase, lactase
Turns peptides into amino acids
Turns disaccharides into monosaccharides
Turns fat into fatty acids and glycerol
Turns trypsinogen into trypsin
Absorption and digestion in the small intestine is stimulated by what?
Gastric juices and chyme
Monosaccharides, amino acids, fatty acids, glycerol, water, and electrolytes are absorbed where?
Villi in small intestine
How are fats absorbed?
Enter lacteals and go to lymph
Small ring-like contractions in the small intestine
Weak, slow movements (3-10 hours) in the small intestine
Due to overdistension or severe irritation in the small intestine
peristaltic rush (diarrhea)
Reabsorbs water and electrolytes
Forms and stores feces
Contains bacteria that makes vitamins (K, B12, thiamine, riboflavin)
Beginning pouch-like structure of the large intestine with a narrow tube called vermiform (lymphatic)
Four parts of the colon
Part of the large intestine where feces is stored
Swollen rectal veins in the anal columns
Where are hemorrhoids located?
2 sphincter muscles in the anus
internal anal sphincter
external anal sphincter
Which anal sphincter is controllable?
External anal sphincter
Made of 75% water, undigested material, electrolytes, mucus and bacteria
What is the color of feces caused by?
Odor of feces is caused by?
How much gas do most people pass daily?
99% from nitrogen gas and oxygen taken in during the day