Chapter 1: Nutrition (1) Flashcards
plays an important role in the utilization of ingested nutrients and water
digestive system
digestive system: organs of the alimentary and accessory digestive system organs
also called the gastrointestinal tract (GI) or gut
alimentary canal
digestive system: organs of the alimentary and accessory digestive system organs
is the continuous muscular tube from the mouth to the anus
alimentary canal
digestive system: organs of the alimentary and accessory digestive system organs
it digests food and absorbs the digested fragments through its lining into the blood
alimentary canal
organs of the alimentary canal (6)
-mouth
-pharynx
-esophagus
-stomach
-small intestine
-large intestine
accessory digestive organs (6)
-teeth
-tongue
-gall bladder
large digestive organs
-salivary glands
-liver
-pancreas
digestive system: organs of the alimentary and accessory digestive system organs
location of teeth and tongue in the accessory digestive organs
mouth or oral cavity
digestive system: organs of the alimentary and accessory digestive system organs
location of digestive glands and gall bladder in the accessory digestive organs lie outside the
gi tract
digestive system: organs of the alimentary and accessory digestive system organs
produce a variety of secretions that help break down food
accessory digestive organs
digestive system
process by which food is broken down into absorbable units
digestion
digestive system
it is the body’s ingenious way of breaking down foods into nutrients in preparation for absorption
digestion
digestive tract - anatomy
where digestion begins
mouth
digestive tract - anatomy (mouth)
act of taking food into the body and swallowing it
ingestion
digestive tract - anatomy (mouth)
the process of biting and chewing with teeth and jaw
breaks food into small particles that are then exposed to enzymes
fine particles ease swallowing and passage through the git
mastication
digestive tract - anatomy (mouth)
soft mass of chewed food swallowed at one time
bolus
food in the mouth stimulates the secretion of salivary glands
the mucus-like saliva performs 3 functions:
1. it mixes with food, _____ dry foods and _____ thicker foods
lubricating; diluting
food in the mouth stimulates the secretion of salivary glands
the mucus-like saliva performs 3 functions:
2. it provides _____ (a polysaccharide digestive enzyme)
alpha amylase
food in the mouth stimulates the secretion of salivary glands
the mucus-like saliva performs 3 functions:
2. it provides _____ (a lipid-digestive enzyme)
lipid-digesting enzyme
food in the mouth stimulates the secretion of salivary glands
the mucus-like saliva performs 3 functions:
3. it dissolves some molecules in food, allowing them to interact with chemoreceptors in the mouth, giving rise to _____
taste sensation
digestive tract - anatomy (mouth)
mechanically divides food into smaller particles
this action enables the enzymes to readily act on food because of the resulting larger surface area
chewing or mastication
digestive tract - anatomy
measures about 10 inches long, connects the mouth to the stomach
esophagus
digestive tract - anatomy (esophagus)
food, lubricated with saliva, is rolled into a small ball (_____) by the tongue to the top of the esophagus
bolus
digestive tract - anatomy (esophagus)
food is prevented from entering the respiratory tract and lungs by the _____. a small flap at the top of the trachea
epiglottis
digestive tract - anatomy (esophagus)
the bolus in the esophagus is then propelled to the stomach by _____ (rhythmic contraction and relaxation of the esophageal muscles) and gravity
peristalsis
digestive tract - anatomy (esophagus)
_____ reduces further the size of food particles and mixes them throughly with digestive secretions
peristalsis
digestive tract - anatomy (stomach)
gastric secretions that mix with the bolus to form chyme include (1) _____ (secreted from parietal cells)
hydrochloric acid
digestive tract - anatomy (stomach)
gastric secretions that mix with the bolus to form chyme include (2) _____ (a hormone secreted by G cells)
gastrin
digestive tract - anatomy (stomach)
gastric secretions that mix with the bolus to form chyme include (3) _____ (secreted by the parietal cells), a protein maintained at pH 1.5-1.7
intrinsic factor
3 gastric secretions
hydrochloric acid
gastrin
intrinsic factor
digestive tract - anatomy (stomach)
food in the stomach cause the release of the hormone _____, which in turn stimulates the stomach wall to secrete hydrochloric acid (HCl) and pepsinogen
gastrin
digestive tract - anatomy (stomach)
food in the stomach cause the release of the hormone gastrin, which in turn stimulates the stomach wall to secrete _____ and _____
hydrochloric acid (HCl) and pepsinogen
digestive tract - anatomy (stomach)
is responsible for the strong acidic condition of the stomach
with such an acidic environment, ingested proteins are denatured thus, facilitating their digestion
hydrochloric acid
digestive tract - anatomy (stomach)
the inactive pepsinogen is converted to the active enzyme called _____
pepsin
digestive tract - anatomy (stomach)
breaks down protein into peptides and amino acids
pepsin
digestive tract - anatomy (stomach)
there is only a partial digestion of proteins in the stomach, whereas no digestion of _____ and _____ takes place in the stomach
cho and lipids
digestive tract - anatomy (stomach)
the very acidic conditions in the stomach inactivate the polysaccharide-digesting enzyme _____
alpha amylase
digestive tract - anatomy (stomach)
to protect the stomach wall from a very acidic content, _____ is secreted forming a protective covering
mucus
digestive tract - anatomy (small intestine)
the major digestive and absorptive organ
small intestine
digestive tract - anatomy (small intestine)
measuring about 20 ft in length, it is the body’s longest organ
its 1.5-inch diameter is much smaller than of the large intestine
small intestine
digestive tract - anatomy (small intestine)
small intestine extends from the _____ to the ileocecal valve
pyloric sphincter
digestive tract - anatomy (small intestine)
small intestine has 3 sections, which connects into the large intestine or colon
duodenum, jejunum, ileum
digestive tract - anatomy (small intestine)
circular folds, vili, and microvilli increase the surface area for _____ and ______
digestion and absorption
digestive tract - anatomy (small intestine)
the chyme leaving the stomach bypasses the opening from the _____ that receives secretions from the gall bladder and the pancreas
common bile duct
digestive tract - anatomy (small intestine)
the liquefied chyme travels the 3 sections of the small intestine
-
digestive tract - anatomy (small intestine)
bile, which is made in the _____ and stored in the gallbladder, is emptied into the small intestine to aid lipid digestion
it breaks fat into smaller particles
liver
digestive tract - anatomy (small intestine)
bile, which is made in the liver and stored in the _____, is emptied into the small intestine to aid lipid digestion
it breaks fat into smaller particles
gallbladder
digestive tract - anatomy (small intestine)
bile contains electrolytes, a variety of fatty substances, bile salts, and bile pigments in an aqueous medium
-
digestive tract - anatomy (small intestine)
are emulsifying agents; they disperse fats and form water-soluble micelles, which solubilize the products of fat digestion
bile sats
digestive tract - anatomy (small intestine)
released by the small intestine stimulates the gallbladder to contract and the hepatopancreatic sphincter to relax, allowing bile (and pancreatic juice) to enter the duodenum
cholecystokinin
digestive tract - anatomy (small intestine)
cholecystokinin released by the small intestine stimulates the _____ to contract and the hepatopancreatic sphincter to relax, allowing bile (and pancreatic juice) to enter the duodenum
gallbladder
digestive tract - anatomy (small intestine)
cholecystokinin released by the small intestine stimulates the gallbladder to contract and the _____ to relax, allowing bile (and pancreatic juice) to enter the duodenum
hepatopancreatic sphincter
the presence of chyme in the small intestine stimulates the release of 2 gastrointestinal hormones
secretin and cholecystokinin
these 2 hormones stimulate the pancreas to release its digestive enzymes and sodium bicarbonate, an alkali with neutralizes the acidic chyme
the neutralization of the hydrochloric acid in chyme raises the pH levels (pH 5-8) activates the digestive enzymes in the lumen of the small intestine
secretin and cholecystokinin
these 2 hormones stimulate the gallbladder to contract to release the stored bile
secretin and cholecystokinin
large intestine
from the small intestine, chyme passes through another sphincter, _____, at the start of the large intestine or colon
ileocecal valve
the subdivisions of the large intestine are (4)
cecum (and appendix), colon, rectum, and anal canal
major functions of the large intestine are
-absorption of water, some electrolytes, vitamins made by enteric bacteria, and defecation
when is the defecation reflex triggered
when feces enter the rectum
digestion - muscular action
wavelike muscular contractions of the GIT that push its contents along
peristalsis
digestion - muscular action
has the thickest walls and strongest muscles of all the gi tract organs
small intestine
digestion - muscular action
composed of circular, longitudinal, and diagonal muscles
these 3 sets of muscles work to force the chyme downward, but the pyloric sphincter usually remains tightly closed, preventing the chyme from passing into the duodenum of the small intestine
result: chyme is churned and forced down, this the pyloric sphincter, and remains in the stomach
small intestine
digestion - muscular action
contraction of circular muscles in small intestine, which mixes the chyme, promoting close contact with the digestive juices and the absorbing cells of the intestinal walls before letting the contents move slowly along
segmentation
digestion - muscular action
sphincter muscles periodically open and close, allowing the contents of the GI tract to move along at a controlled pace
these are the upper and lower esophageal sphincters, pyloric sphincter, ileocecal valve, tightness of the rectal muscle, and sphincters of the anus
sphincter contractions
the presence of _____ and _____ structures (finger-like projections) increases the absorptive capacity of the small intestine
villi and microvilli
the process by which digested food material passes through the epithelial cells of the GI tract (mainly the small intestine) into the blood or lymph
absorption
absorption - mechanisms
some nutrients (water and small lipids) are absorbed by simple diffusion
they cross into intestinal cells freely
simple diffusion
absorption - mechanisms
some nutrients (water-soluble vitamins) are absorbed by facilitated diffusion
they need a specific carrier to transport them from one side of the cell membrane to the other
*facilitated diffusion may occur when the carrier changes the cell membrane in such a way that the nutrients can pass thru
facilitated diffusion
absorption - mechanisms
some nutrients (glucose and amino acids) must be absorbed actively
these nutrients move against a concentration gradient, which requires energy
active transport
absorption - mechanisms
process in which the cell membrane engulfs the molecule, forming a sac that separates from the membrane and moves into the cell
endocytosis
absorption - mechanisms
nutrients leaving the digestive system via the blood are routed directly to the _____ before being transported to the body’s cells
liver
absorption - mechanisms
nutrients leaving via the lymphatic system (large fats and fat-soluble vitamins) will enter the _____ but bypass the liver at first
vascular system
supplies oxygen and absorbed nutrients to the lungc
pulmonary circulation
pertains to the sum of reactions and processes involving building up (anabolic) or breaking down (catabolic) of compounds to yield energy and other functional substances
metabolism
is the separation and elimination of waste matter and water from the blood, tissues, or organs
these wastes include urine, feces, and perspiration
excretion
organs of excretion (4)
lungs, skin, kidney, intestines
organs of excretion
excrete carbon dioxide and water
lungs
organs of excretion
secretes mainly water with some salts
skin
organs of excretion
excrete water, salts, and nitrogenous substances like urea
kidneys
organs of excretion
excrete mineral sats, waste productions in bile, food residues, and some water
intestines
excretion - process
a) excretion through the _____
surplus co2 that is continually formed by oxidation of the energy-yielding nutrients in the tissues
lungs
excretion - process
b) excretion through the skin
water lost through perspiration includes
1. small amounts of _____ products like urea, etc
nitrogenous waste
excretion - process
b) excretion through the skin
water lost through perspiration includes
2. small amounts of _____ like sodium chloride, etc.
mineral salts
excretion - process
c) excretion by the kidneys
2 glandular organs situated at the back of the abdominal cavity on either side of the spinal column
these are directly connected by means of a large artery and vein, respectively, with the main arterial and venous trunks of the body
these are perfused by a large amount of blood
kidneys
excretion - process
c) excretion by the kidneys
functional unit of the kidneys
nephron
excretion - process
nephrons are made of:
-network of capillaries
glomerulus
excretion - process
nephrons are made of:
double-walled, funnel-like in shape, surrounds the glomerulus
bowman’s capsule
excretion - process
nephrons are made of:
proximal convoluted tubule, henle’s loop, and distal convoluted tubule
-
excretion - process
mechanism of excretion by the kidney
the semipermeable membrane of the glomerulus allows cleaning of _____ reaching the glomeruli
blood
excretion - process
mechanism of excretion by the kidney
filtrate includes salts, glucose, amino acids, vitamins, and limited amounts of simple proteins
as the filtrate passes thru tubular cells (proximal tubule, distal tubule, and henle’s loop), the useful substances such as glucose, amino acids and most of the water are reabsorbed
-
excretion - process
mechanism of excretion by the kidney
the ureter collects from the urinary bladder 96% water, waste products made up of urea (about half of the total solids), uric acid, creatinine, and ammonium salts
urine
factors affecting excretion though the kidneys
hormones like _____ (ADH) and _____
antidiuretic hormone and aldosterone
factors affecting excretion though the kidneys
_____ (substances that stimulate urine flow)
diuretics
factors affecting excretion though the kidneys
amount of blood supply to the kidneys
-
factors affecting excretion though the kidneys - dietary factors
_____ and _____ intake requires dilution that increases the sensation of thirst and dehydration of the cells
sodium and sugar
factors affecting excretion though the kidneys - dietary factors
excretion of large amounts of urea resulting from a high _____ intake also requires extra water
protein
kidney - functions
filtration
-
kidney - functions
balance of
electrolyte and water
kidney - functions
acid-base balance
-
kidney - functions
secretes erythropoietin, rennin, prostaglandins, and bradykinins
-
excretion thru the large intestine
the undigested and unabsorbed material expelled thru the anus is known as _____
feces
kidney - functions
hormonal breakdown
-
excretion thru the large intestine
feces - composition
indigestible, undigested, and unabsorbed _____ residues
food residues
excretion thru the large intestine
feces - composition
residues from digestive secretions, mucus, and cell debris from the lining of the ______
alimentary tract
excretion thru the large intestine
feces - composition
bacteria and the products of their action, composes about 1/10 of the feces consisting bacteria (both living and dead)
-
excretion thru the large intestine
feces - composition
water that composes 60-70% of ordinary feces
-
excretion thru the large intestine
amount of water ingested
-
excretion thru the large intestine
indigestible substances, chiefly _____ and other complex cho
cellulose
excretion thru the large intestine
growth of intestinal bacteria
-
excretion thru the large intestine
laxatives
-
excretion thru the large intestine
types and amount of food taken
-
excretion thru the large intestine
psychological influences such as hurry and nervous stress
-
excretion process - intestine
the large intestine composed of the ascending, descending, and transverse colon allows the undigested/digested food items to:
- enter the _____ and allows reabsorption of water and electrolytes until feces are formed
ileocecal valve
excretion process - intestine
the large intestine composed of the ascending, descending, and transverse colon allows the undigested/digested food items to:
- defecate thru the _____ and gastrocolic reflex
peristaltic waves
excretion process - intestine
the large intestine composed of the ascending, descending, and transverse colon allows the undigested/digested food items to:
- ferment thru _____ e.g. fibers yiled short chain fatty acids
bacterial action
excretion process - intestine
the large intestine composed of the ascending, descending, and transverse colon allows the undigested/digested food items to:
other waste products are secreted thru
hair and nails
