Digestive System Flashcards
what is the purpose of the digestive system?
Mechanical and chemical breakdown of food, and the absorption of nutrients
mechanical digestion
Breaks large pieces into smaller pieces WITHOUT changing the chemical composition
chemical digestion
breaks food into simpler chemicals
alimentary canal
digestive system tube: open at both ends, has specialized regions
lumen
In some areas it is folded over to increase surface area.
accessory organs
salivary glands, liver, gallbladder, and pancreas
alimentary canal (what it consists of)
mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus
cheeks and lips (purpose)
Cheeks are outer layers of skin with subcutaneous fat
Help with expressions, chewing, and maintaining a moist inner liner
Lips are highly mobile
Have skeletal and sensory receptors
Used to sense the temperature and texture of foods
tongue
Mostly skeletal tissue used to help mix food particles with saliva during chewing and move food to the pharynx during swallowing
Frenulum
is the fold on the midline of the tongue that connects it to the floor of the mouth
palate
The roof of the oral cavity
Contains a soft (posterior) and hard (anterior) part
Closes off the nasal cavity during swallowing
teeth (anatomy and purpose)
2 sets of teeth throughout development
The first is primary and usually erupts from 6 months to 4 years
The second is secondary - appears at 6 years and is complete between 17 and 25 years
Teeth begin mechanical digestion
Front 4 are incisors
Canine (cuspid)
Premolars (bicuspid)
Molars
parotid glands
Largest of the major salivary glands
Secrete a clear watery fluid that is rich in amylase
Breaks down carbohydrates
Submandibular Glands
Located on the floor of the mouth
Predominantly serous glands
Secrete viscous fluid
sublingual glands
Smallest
Below the tongue
Primarily mucous cells
Secretions are thick and stringy
nasopharynx
Communicates with the nasal cavity and provides a passageway for air during eating
Oropharynx
Posterior to the soft palate
Passageway for food moving downward from the mouth and for air moring to and from the nasal cavity
Laryngopharynx
passageway to the esophagus
3 stages of swallowing
- Food is chewed and mixed with saliva. The tongue rolls the mass of food into a bolus and forces it into the pharynx.
- Swallowing reflex (6 steps)
- Peristalsis transports food from the esophagus to the stomach
swallowing reflex
- Soft palate raises
- Hyoid bone and larynx are elevated, and epiglottis closes off the top of the larynx
- The tongue presses against the soft palate which seals off the oral cavity from the pharynx
- Longitudinal muscles contract which pulls the pharynx toward the food
- Muscles in the lower portion of the pharynx relax and open the esophagus
- Peristaltic waves begin and force food into the esophagus
esophagus
Straight collapsible tube that connects the pharynx to the stomach
Where is the pancreas
Extends horizontally across the abdomen in the C-shape of the duodenum.
pancreas
secretes insulin which breaks down sugars
Pancreatic Juice also breaks down fat
Both Chemicals empty into the duodenum
structure of the liver
Right lobe and a smaller left lobe
Each lobe is separated into hepatic lobules
A lobule contains many hepatic cells that radiate from the central vein
Hepatic sinusoids separate the groups of cells
Kupffer cells remove bacteria or other foreign particles
functions of the liver
- Maintain blood glucose levels
- breakdown of lipids and fats
- protein metabolism
- stores vitamins
- recycles RBCs
- removes toxins
- secretes bile
bile
yellowish-green liquid aids in digestion, breakdown of fat
gallbladder
stores bile
3 sections of the small intestine
Duodenum
jejunum
ileum
small intestine wall
The inner wall appears velvety due to little projections of mucous membrane called intestinal villi
secretions of small intestine
mucus, thick alkaline mucus, Peptidase, sucrase, maltase, lactase
absorption of the small intestine
Most important absorbing organ of the alimentary canal because of villi
Intestinal villi absorb the broken-down materials that the specific enzymes create earlier in the alimentary canal
amylase
breaks down starch and glycogen
pepsin
begin protein digestion
lipase
breaks down fats into fatty acids and glycerol
nucleases
breaks down nucleic acids in nucleotides
peptidase
breaks down peptides into amino acids
sucrase, maltase, lactase
breaks down disaccharides (complex sugars) into monosaccharides (simple sugars)
movement small intestine
Mixing and peristalsis
Small, and periodic movements → takes about 3 to 10 hours to travel the length of the small intestine
The ileocecal sphincter joins the small intestine to the large intestine
anatomy of large intestine
roughly 1.5 meters.
Composed of 4 major sections
Cecum
Colon
Rectum
Anal canal
colon
Ascending, transverse, descending, sigmoid
functions of large intestine
Little digestive function - only secretes mucus
Absorbs water and electrolytes from the chyme in the alimentary canal
Forms and stores feces
break down molecules that pass through the rest of the digestive tract
intestinal flora
bacteria that normally inhabit the large intestine
movement of large intestine
Mixing and peristalsis
Movements are slower and less often (2 or 3 times a day)
feces
undigested materials, water (75%), electrolytes, mucus, ched intestinal cells, and bacteria.
Walls of alimentary canal (4)
Mucosa (inner)
Submucosa
Muscular layer
Serosa layer (outer)
