digestive system Flashcards
describe the digestive system
- aka the gastrointestinal system
- responsible for changing food & nutrients into waste
digestive enzymes
chemicals that break down food and nutrients into smaller forms so they can be absorbed by the body
list the 4 functions of the digestive system
- ingestion
- digestion
- absorption
- elimination
describe ingestion
the process of taking in food, chewing, and dissolving it in the mouth
-process forms a soft ball of food called a bolus in preparation for digestion
describe digestion
mechanical digestion: mechanical breakdown of food by the teeth or stomach muscles
chemical digestion: The brain sends messages to the gastric glands in the stomach wall stimulating them to secrete gastric juices such as Pepsin
describe absorption
glucose & amino acids:
- absorbed by active transport after combining with a carrier molecule
- enter the blood through capillaries in the villi and transported to the liver
fatty acids & monoglycerides:
-absorbed into the epithelial cells of the intestinal lining where they are reassembled into triglycerides & pass into the villi
describe elimination
the removal of indigestible foods and other waste materials through fecal matter from the body
*defecation is stimulated peristalsis
peristalsis
a series of wave-like muscle contractions that allows food to move through the digestive system
name the 4 primary organs of the digestive system
- Mouth
- Stomach
- Small Intestine
- Large Intestine
mouth (mastication and deglution)
Food enters the system at the mouth and is chewed by the teeth to break it up into smaller amounts so that it can be swallowed and digested.
- The salivary glands produce saliva which contains enzymes that start to break down the food.
- The food then is swallowed and moves down into the esophagus (throat).
- The epiglottis is a small flap of tissue that covers the trachea (windpipe) to prevent food from entering and going into the lungs
stomach (gastric digestion)
located in the left upper quadrant of the abdominal cavity.
- Food reservoir and the first major site of digestion.
- Food leaves the esophagus and enters the stomach via the cardioesophagal sphincter
- Digestive glands in the stomach produce pepsin and hydrochloric acid which turn the food into a semi-liquid called chyme.
- Food leaves the stomach and enters into the small intestine via the pyloric sphincter
small intestine
a coiled, 20ft long tube consisting of 3 parts:
- duodenum
- jejunum
- ileum
- Villi, which line the intestines and contain capillaries, absorb the nutrients
- about 90% of absorption of nutrients occurs here
- The walls of the intestine contract and relax to create segmental waves that push the food through the intestines (peristalsis)
accessory organs of digestion
- liver
- gallbladder
- pancreas
liver
- lies in the upper right side of the abdomen just under the diaphragm
- one of the most complex visceral organs in the body
functions of the liver:
• Secretes bile, which is important in the digestion of fat.
• Converts excess glucose to glycogen and stores it; then, when glucose is needed, it releases glucose into the blood.
• Stores iron and certain vitamins.
• Converts excess amino acids to fatty acids and urea.
• Cholesterol is synthesized and stored in the liver.
• Vitamin D is synthesized and stored in the liver.
• Performs many important functions in the metabolism of proteins, fats, and carbohydrates.
• Manufactures many of the plasma proteins found in the blood (clotting factor).
• Detoxifies many drugs and poisons that enter the body.
• Breaks down bacteria and filters worn-out red blood cells.
gallbladder
a pear-shaped organ of the digestive system that is situated under the liver and anterior to the duodenum
-stores and concentrates bile ready for transport to the duodenum via cystic and bile ducts
pancreas
a large elongated gland the lies in the abdomen below the stomach with its head nestled in the curve of the duodenum
exocrine function: secretes pancreatic juices that chemically digest proteins, fats and carbs
*secretion of digestive juices is stimulated by the presence of chyme and by hormones
endocrine function: secretion of hormones insulin and glucagon
trypsin, amylase, lipase
enzymes secreted by the pancreas
trypsin = breaks down protein amylase = breaks down starch/carbs lipase = breaks down fats
anorexia
loss of appetite
nausea
an unpleasant sensation often accompanied by pallor, sweating and rapid heart beat
vomiting
aka emesis, the sudden and forceful oral expulsion of the contents of the stomach
esophageal reflux disease
refers to the backward movement of stomach contents into the esophagus, a condition that causes heartburn
gastritis
inflammation of the mucosa of the stomach
a. Acute gastritis is usually caused by local irritants such as bacteria, alcohol, caffeine and aspirin. It may cause vomiting, and possibly bleeding.
b. Chronic gastritis is an ongoing problem usually resulting from alcohol abuse, cigarette smoking, or chronic use of anti-inflammatory medication (NSAIDS).
ulcers
Peptic ulcer is a term used to describe ulcerative disorders that occur in the upper digestive tract (stomach and small intestine), the area exposed to acid-pepsin secretions
-causes pain and discomfort described as burning, gnawing or cramp-like and often occurs when the stomach is empty, complications include bleeding and perforation
irritable bowel syndrome
a disorder characterized by recurrent intestinal symptoms not explained by structural abnormalities
symptoms: persistent/recurrent abdominal pain, gas, alternating diarrhea and constipation over a period of 3 or more months
inflammatory bowel disease
a. Crohn’s Disease: can affect any area of the digestive tract from the mouth to the anus It consists of granulomatous lesions that are surrounded by normal-appearing tissue.
symptoms: are diarrhea, cramping pain, usually in the lower right quadrant, weight loss, fluid and electrolyte disorders and low-grade fever. The intestine may not be able to absorb nutrients and deficiencies may occur. There are often periods when the symptoms decrease and then flare up.
b. Ulcerative Colitis is inflammation of the colon only. The main symptom is diarrhea, which may occur many times a day. Lack of appetite, weakness and fatigue are common. The symptoms may decrease and flare up.
appendicitis
condition in which the appendix becomes inflamed, swollen and gangrenous and eventually perforates
*if the appendix is not removed complications can occur which can be life-threatening
diarrhea
excessively frequent passage of stools
constipation
infrequent passage of stools
celiac disease
gluten intolerance
symptoms: diarrhea, bloating, flatulence and abdominal pain. If intake of gluten is continued there may be weakness, muscle wasting and fatigue due
to lack of absorption of nutrients
hemorrhoids
swollen, tortuous veins in the rectum or anus, may be internal or external
symptoms: itching and bleeding bright red blood
large intestine
aka the bowels, extends from the small intestine, joining at the ileocecal valve, to the anus
-large intestine starts at the right lower quadrant, runs superiorly as the ascending colon, crosses the
abdominal cavity as the transverse colon and then runs inferiorly down the left side of the
abdominal cavity as the descending colon
-Food is stored in the large intestine until it is expelled by defecation
- defecation is controlled by:
a. internal sphincter (autonomic/involuntary)
b. external sphincter (somatic/voluntary)
