The alimentary or gastrointestinal tract
& the accessory organs
The digestive system is a collection of organs that can be divided into two
parts:
List, in order, the eight parts of the digestive tract.
1. Oral cavity
2. Pharynx
3. Esophagus
4. Stomach
5. Small Intestine
6. Large Intestine
7. Rectum
8. Anus
The functions of the alimentary tract, overall, would be to:
• Take in food.• Break down the food into
simpler components.• Absorb the nutrients.• Discard the waste.
The three accessory organs found in or near the oral cavity are the
TongueTeeth
Salivary glands
The three accessory organs found in the abdominal cavity are the
LiverGall bladder
Pancreas
The functions of the pharynx, with respect to the digestive system, are to:
• receive partially digested food from the oral cavity
• pass the partially digested food on to the esophagus.
Cutting, grinding, lubricating, tasting, manipulating, and moving food are all examples of ____________ digestion.
mechanical
Converting large, complicated food molecules into glucose, amino acids, and
fatty acids so they can be absorbed is ____________ digestion.
chemical
What is the general name given to substances which perform chemical
digestion in the digestive tract?
enzymes
A common tube shared by the respiratory and digestive systems.
pharynx
Subdivision of the pharynx located behind the nasal cavity is the:
nasopharynx
oropharynx
Subdivision of the pharynx located behind the oral cavity is the:
laryngopharynx
Subdivision of the pharynx located behind the larynx is the:
These act as “first line” defenders, screening out microorganisms from the air,
food, and liquids that enter the body:
tonsils
Tonsils found in the nasopharynx are called:
pharyngeal tonsils
Tonsils located in the laryngopharynx, at the base of the tongue, are called:
Lingual tonsils
Tonsils located at the back of the nasal cavity are called the:
pharyngeal tonsils
What is the main purpose of mechanical digestion?
To increase the surface area of the food for enzymes to
act.
A straight, collapsible muscular tube which lies behind (posterior to) the trachea and is
about 1 inch in diameter and 10 inches long.
Esophagus
The functions of the esophagus are to:
• receive partially digested food from the pharynx
• pass the partially digested food on to the stomach.
Rhythmic contractions of the smooth muscle layers which propel food through
the digestive tract are called:
Peristalsis or Peristaltic waves
The smooth muscle valve located at the end of the esophagus which controls the
entrance to the stomach is called:
Gastroesophageal or cardiac sphincter
The uppermost portion of the stomach is called the:
Fundus or fundic region
A small region of the stomach very near the cardiac sphincter where the esophagus
meets the stomach is the
Cardia or cardiac region
The middle and largest portion of the stomach is called the ___________ of the
stomach.
body
This is the “cone-shaped,” terminal portion of the stomach.
Pylorus or pyloric region
The smooth muscle valve that prevents back flow of material from the small intestine to the stomach is called the
pyloric sphincter
The term used to describe the partially digested food once it has been mixed with the digestive secretions of the stomach.
chyme
Five functions of the stomach, as listed in class, are:
1. Receives bolus from the esophagus.2. Mixes bolus with gastric juices, and
mechanically breaks up the food.3. Begins the chemical breakdown of
proteins.4. Begins the process of absorption.5. Passes the chyme on to the small
intestine.
A collapsible, muscular tube that extends from the pyloric sphincter of the stomach to
the large intestine.
Small intestine
The small intestine is the site where the majority of the _________ digestion of food and _________ of nutrients takes
place.
chemical absorption
The first 10 – 12 inches of the small intestine is called the
duodenum
The middle section of the small intestine representing about 40% of its length is
called the
jejunum
The final portion of the small intestine, which represents about 60% of its length is
called the
ileum
_______________ project into the lumen of the small intestine where they are bathed in the intestinal contents. They function to increase _____________ of the intestinal
lining for absorption.
Intestinal villisurface area
A five foot long collapsible tube that is divided into two parts and is located
between the small intestine and the rectum.
Large intestine
The entrance to the large intestine is called the
cecum
A vestigial structure located off the cecum of the large intestine is the
vermiform appendix
The major portion of the large intestine which is divided into 4 parts is the
colon
The four sections of the colon, in order, are the
AscendingTransverseDescending
Sigmoid
Four functions of the large intestine were discussed. These were:
1. Receives nutrient depleted chyme from the small intestine.
2. Reabsorbs the rest of the water and electrolytes from chyme.
3. Forms and stores feces until defecation.
4. Passes feces on to the rectum.
Final storage area for feces.
When the rectum fills with feces it is stimulated to contract. This is called the
rectum
Defecation reflex
The last section of the digestive tract is called the ______________. It is made up of three
_________________ muscles.
anussphincter