Digestive System Lessons 1-2 Flashcards
components to digestion
mechanical and chemical
what is the mouth bound by
cheeks and lips
when does mechanical digestion begin
when the food is chewed(masticated) and shaped into a ball(bolus)
what is the tongue responsible for
moving and tasting food inside the mouth
what is the tongue composed of
skeletal muscles
what is taste? how is it performed?
taste is a type of chemoreception and it is performed by using the taste buds on a tongue
how do taste buds work?
taste buds absorb molecules and send signals to the brain to identify the molecule that was sensed
what are teeth responsible for
the mechanical breakdown of food
what are teeth? how are they used?
teeth are the hardest substances in the human body and are used with jaw muscles to break down food into smaller bits
how many baby teeth do children have
20
how many teeth would we have after losing our baby teeth
32
describe how teeth are stuck to our gums and the components
anchored in the gums by long root extensions, our teeth are layered with enamel, dentin and pulp which house blood vessels in the center
the 3 types of teeth
incisors, canines, molars
what are incisors usually used for
cutting and plucking(usually plant matter)
what are canines usually used for
tearing(usually flesh)
what are molars usually used for
crushing and grinding(usually plant matter)
what is the roof of the mouth called
the palate
what is the function of the palate
it is used to separate two cavities from one another; the nasal cavity and the mouth cavity
what is the palate composed of
hard palate and soft palate
if a child was born without the full formation of the palate, what would they have?
a cleft palate
what are salivary glands
3 paired regions of epithelial tissue that produce saliva
what is saliva used for
to assist chemical digestion
what is the hard palate composed of
bone
what is the soft palate composed of
muscles
what is saliva composed of
98% water, along with epithelial cells, white blood cells, antimicrobial agents, electrolytes, mucus and enzymes
what is the most important enzyme in saliva
salivary amylase
what is the function of salivary amylase
to break down starch into maltose
how does salivary amylase break it down
it uses hydrolysis
what is the pharynx
the region between the mouth and the esophagus where the digestive and respiratory systems intersect
what is the pharynx used for
to act as a gate that allows the appropriate material to pass into the proper tube
how does the pharynx function
uses flaps of tissue to close off one system when the other is in use
what prevents food from entering the nasal cavity
the uvula and soft palate
how do the uvula and soft palate prevent food from entering the nasal cavity
it blocks the nasopharynx
what is the entry to the trachea called
the glottis
what blocks the glottis to prevent food from going into our trachea(and then into our lungs)
the epiglottis
how is food blocked from the glottis?
the trachea rises up to use the epiglottis to block it
what is the esophagus
a long and muscular tube
what is the function of the esophagus
acts as a pathway for food to travel from the pharynx to the stomach
appearance of the esophagus when there is no food
collapsed
what is the function of valves in our body
to prevent the risk of backflow when the tubes in our body are empty
where does the esophagus terminate/stop
at the lower esophageal sphincter
what is a sphincter
a ring-shaped muscle
what is the function of a sphincter
capable of contracting in on itself, it seals the space in the center, allowing the regulation of the passage of materials through it
when would the lower esophageal sphincter be closed and why
it is closed when food is being digested to prevent the acidic components of the stomach from going back up
what is rugae
thick folds in the stomach
what is the function of rugae
increases the surface area in the stomach to allow for expansion
what are the walls in the stomach composed of and what is their function
smooth muscle, used to assist in mechanical digestion
what is in the stomach’s lumen
mucous cells
what are mucous cells in the stomach used for
to secrete mucous that lines the inner walls to protect the lining from stomach acid
how is mechanical digestion performed in the stomach
contraction of the stomach’s muscular portion, churning the food and breaking it into smaller portions
how is chemical digestion performed in the stomach
by using several important molecules that exist in solution
what do the important molecules in the stomach do during chemical digestion
they begin protein digestion
what is the acidic fluid responsible for chemical digestion
gastric juice
what is gastric juice composed of
HCL, electrolytes, and organic molecules
what are the electrolytes present in gastric juice
sodium, potassium, calcium, phosphate, sulfate and bicarbonate
what are the organic molecules present in gastric juice
gastrins, pepsins and others
what is HCL and what is its function
a strong acid(has a low pH nearing 2), it breaks down the connective tissue in food, kills bacteria and enables the absorption of vitamin B
what is pepsinogen and what is its function
a molecule that is converted into pepsin when exposed to HCL and is responsible for converting proteins into smaller polypeptide chains
what is gastrin and what is its function
a hormone that begins digestion in the stomach.
How is the production and secretion of gastric juice enabled
gastrin is absorbed by the stomach, the transported through the bloodstream to cells lining the stomach. it is secreted by the stomach cells upon sensing the stretching of stomach walls
after 2-6 hours in the stomach, describe the food.
it is partially digested with a soupy consistency, and it is called chyme
how will chyme leave the stomach
through the bottom of the stomach called the pyloric sphincter
what is the pyloric sphincter
a ring-shaped muscle that can contract itself to prevent the passage of materials
how does the pyloric sphincter work and why
it opens and closes repeatedly to only allow small amounts of chyme to pass through at a time
