Digestive System Flashcards
What is the function of leptin?
helps regulate energy balance by inhibiting hunger
Digestion
process of mechanically and chemically breaking down foods so that they could be absorbed.
Mechanical Digestion
teeth, don’t forget to chew
Where does Chemical Digestion begin?
begins in the mouth, from secretions of enzymes
What are the enzymes in the oral cavity?
Amylase
lingual lipase
Amylase
~secreted by salivary glands
~breaks down carbohydrates into disaccharides
Lingual Lipase
~secreted by tongue
~begins fat digestion
What organs make up the alimentary canal?
What are the accessory organs?
Alimentary Organs:
Mouth, Pharynx, Esophagus, Stomach, Small Intestine, Large intestine, Anal Canal
Accessory Organs:
Salivary glands, liver, gallbladder, pancreas
Functions of the digestive system?
ingest food
breaks apart large particles
secretes enzymes and decomposes food molecules
absorbs products and eliminates unused residu
ingestion
consumption of a substance through the mouth
digestion definition
mechanical and chemical breakdown of foods into forms that cell membrane can absorb
secretion
release of substances from a particular cell or gland
excretion
removal of a substance from the body
absorption
intake of materials, usually nutrients through a membrane
mucosa
mucous membrane
epithelium w/ underlying connective tissue and smooth muscle
contain folds called villa to increase surface area
Protects tissues
carries on secretion and absorption
submucosa
loose connective tissue, glands, blood vessels, lymphatic vessels, nerves, organizec plexuses
vessels nourish surrounding tissues
carry away absorbed material
Muscularis externa
circular and longitudinal smooth muscle layer
moves alimentary tube
Serosa
visceral peritoneum,
comprises outer covering of alimentary tube
secretes serous fluid to reduce friction of abdominal organs
Two types of movements of the Alimentary Tube
mixing movements
propelling movements
Functions of the mouth
receives food
begins digestion by mechanically reducing size of particles and mixing them with saliva
Tongue
mixes food particles with saliva during chewing
moves food towards pharynx when swallowing
Papillae on tongue=rough surface-handles food and contains taste buds
Palate
Hard(anterior)
Soft (posterior)
During swallowing, closes the nasal cavity by moving uvula upward
Where are the lingual tonsils located?
At the root of the tongue
Where are the palatine tonsils located?
On either side of tongue in the back of mouth
Functions of the salivary glands
secrete saliva, moistens food particles and binds them,
begins chemical digestion of carbs
Makes Taste possible, cleanse the mouth
Parotid Salivary glands
secrete saliva rich in amylase, clear watery fluid
submandibular
viscous saliva
sublingual
secrete mucous, thick and stringy
Pharynx
nasopharynx-communicates w/ nasal cav, provides passageway for air.
Oropharynx-passageway for food moving downward
laryngopharynx- inferior to oro, passsageway to the esophagus.
swallowing mechanism
- Food mixed with saliva and forced into pharynx
- Involuntary reflex actions move food into esoph.
- Peristalsis transports food to the stomach
Esophagus
straight collapsible tube (25cm) long
food passageway from pharynx to stomach
passes through an opening, (esophageal hiatus) in diaphram
Functions of the stomach
receives food from the esophagus, mixes food with gastric juice,
initiates protein digestion
carries limited amount of absorption, moves food into small intestine
mucous cells(goblet cells)
secretes mucous (provides protective layer for stomach lining
Chief cell
secretes digestive enzymes: pepsinogen, pepsin
begins protein digestion
Parietal cells
secretes hydrochloric acid which can combine with pepsinogen to form pepsin and
secretes intrinsic factor (aids in vitamin b12 absorption)
Gastrin
increases secretory activity of the gastric glands
Cholecystokinin
peptide hormone responsible for stimulating the digestion of proteins and fats in the small intestine
gastric absroption
stomach absorbs only small quantities of water, certain salts, alcohol and some lipid soluble drugs
How is chyme produced
mixing movements help produce chyme
What happens after chyme is produced?
The peristaltic waves push chyme towards the pyloric region of the stomach.
chyme accumulates near the pyloric sphincter and then muscles begin to relax
stomach contractions then push chyme a little at a time into the small intestine.
What factors affect the rate at which the stomach empties?
- fluidity of the chyme
- types of food present
liquids pass through rapidly
solids remain until mixed with gastric juices
Once chyme enters duodenum… what happens
the accesory organs add their secretions.
