Digestive system
What is bilirubin?
is produced during degradation of hemoglobin. It is the major excretory product in the feces.
Where is chyme converted to feces?
large intestines
List the layers of the alimentary canal from lumen to the outside.
lumen, mucosa, submucosa, muscularis, serosa
Mucosa function
luminal surface of the digestive tract
Muscularis
major smooth muscle coat of the digestive tract
Distinguish between chemical and mechanical digestion.
Mechanical digestion begins in the mouth as the food is chewed. Chemical digestion involves breaking down the food into simpler nutrients that can be used by the cells.
What is the benefit of the bacteria in the large intestine?
absorption of vitamins
What is the purpose of saliva?
amylase begins digestion of carbohydrates moistens and lubricates food for swallowing antibacterial action dissolves molecules that stimulate taste keeps lips and tongue moist during speech
what are vitamins?
an organic compound and a vital nutrient that an organism requires in limited amounts
Why is cellulose considered to be fiber?
because it can't be broken down,
What is bile made up of? What is its function?
bile salts, cholesterol, lecithin and bilirubin; increases the absorption of fat and fat-soluble substances
What is the difference between bolus and chyme?
bolus is a ball of food that was chewed and swallowed, chyme is the bolus with secretions mixed in it
List the functions of the stomach.
break down and digest food in order to extract necessary nutrients from what you have eaten
What are the parts of the large intestine?
cecum, colon, rectum
What is another term for: swallowing?
deglutition
Provide two structures for each and how they act to contribute to this function Secretion
esophagus (esophageal secretion mucus is protective) and pancreas (secretes enzymes and aqueous alkaline solution)
What is the main energy source of the body?
glucose
What happens during the swallowing reflex?
initiated by touch receptors in the pharynx as a bolus of food is pushed to the back of the mouth by the tongue, or by stimulation of the palate
What is the job of the stomach besides storage of food and mechanical break down of food?
initiates protein digestion and denatures proteins
What is peristalsis?
involuntary constriction and relaxation of the muscles
Distinguish between villi and microvilli. Where are they?
Microvilli can be found in many cell membranes while the villi can only be found in the intestinal wall. The villi are larger than microvilli. The villi act to increase the absorption rate of the intestines while the microvilli have more functions besides absorption of cell nutrients
What are the three sections of the small intestine?
duodenum, jejunum, ileum
another term for vomiting
emesis
another terms for chewing
mastication
Provide two structures for each and how they act to contribute to this function Motility
mouth (food enters the digestive system through the mouth where it is chewed and mixed with saliva) and tongue (propels the bolus to the rear of the throat, to initiate swallowing reflex)
define absorption
movement of a substance, such as a liquid or solute, across a cell membrane by means of diffusion or osmosis
What does the esophagus secrete?
mucus
What cells of the stomach secrete HCl?
parietal cells
What determines the rate of gastric emptying?
pressure generated by the antrum against pylorus resistance
What does bile do? What does it do with bilirubin?
provide emulsification to aid fat digestion form water-soluble micelles to aid fat absorption
Describe the function of mucus
provides as a protective coating
parietal cells
secrete HCL which sterilizes the food in the stomach, prevents harmful bacteria from entering the stomach, and triggers the release of enzymes
chief cells
secrete pepsinogen which is a proteolytic enzyme responsible for the digestion of proteins
mucous cells
secretes an alkaline mucus that protects against shear stress and acid
function of pepsin
starts protein digestion in the stomach
What is hydrolysis?
the chemical breakdown of a compound due to reaction with water
Where does digestion actually begin?
the mouth
Define digestion
the process of breaking down food by mechanical and enzymatic action in the alimentary canal into substances that can be used by the body
What are the functions of the large intestine?
to absorb water from the remaining indigestible food matter and transmit the useless waste material from the body
How many teeth does an adult human have?
32 teeth
function of hydrochloric acid
Activates pepsinogen to active enzyme pepsin. Provides acid medium for optimal pepsin activity. Aids in breakdown of connective tissue and muscle fibers. Denatures protein. Kills most of microorganisms ingested with food.
What are the factors in control of food intake?
Adult animals (including humans) tend to maintain a relatively constant weight known as their "set weight"; starvation or force feeding
What are the functions of the pancreas?
Produces important enzymes and hormones that help break down foods.
What are nutrients?
a substance that provides nourishment essential for growth and the maintenance of life
what are minerals?
a solid inorganic substance of natural occurrence
four layers of the wall of the digestive system
mucosa, submucosa, muscular, and serosa
List the structures of the digestive tract as food passes through it.
oral cavity, pharynx, esophagus, stomach, small intestine, liver, gall bladder, pancreas, large intestine, cecum, colon, rectum, anus
Serosa
outer connective tissue covering
What controls the secretion of saliva?
salivary center
G cells
secretes hormone gastrin which stimulates the release of gastric gas
What type of motility is done by the small intestine?
segmentation
Provide two structures for each and how they act to contribute to this function Absorption
small intestine (end products of carbohydrates and proteins are absorbed into the bloodstream) and large intestine (remaining salt and water converts the contents into feces)
Where is chyme created?
stomach
What are rugae?
stomach folds
Submucosa function
thick layer of connective tissue that provides distensibility and elastic