Download Digestive - WordPress.com

Parts of the
The Digestive System
http://highered.mcgrawhill.com/sites/0072495855/student_vie
w0/chapter26/animation__organs_of_d
igestion.html
Anatomical Terms
•
•
•
•
•
•
•
•
Medial- towards the midline of the body
Lateral- away from the midline of the body
Anterior (ventral)- front of the body
Posterior (dorsal)- back of the body
Superior (cranial)- toward the head
Inferior (caudal) – away from the head
Proximal- in proximity to or closer to
Distal- distant from or further away from
Pathway of Food:
- A) Mouth (oral cavity)
- Hard palate- bony anterior portion of the roof
of the mouth
- Soft palate- entirely muscular posterior part of
the roof of the mouth
- Tonsils- protection against disease
- Salivary glands- has an enzyme that are
involved in chemical digestion
• B) Teeth
• - used to break down (masticate) food
• C) Pharynx
• - portion of the digestive tract between the
mouth and the esophagus
• Serves as a passageway for food and also air
on its way to the trachea
• D) Esophagus
• -muscular tube passing from the pharynx
through the thoracic cavity into the
abdominal cavity to the stomach
• Usually collapses until it receives bolus
• Peristalsis- rhythmic contraction that pushes
food along the digestive tract
• Sphincter is located between the esophagus
and the stomach to prevent acidic content
from coming up
• Heartburn/indigestions/acid reflux- when
stomach contents enter the esophagus
• Stomach “Gastric”
• Muscular sac that mixes food with digestive
juices to form chyme which enters the small
intestine
• Length- 25 cm
• Rugae- deep folds in the wall of the stomach
• Protein digestion begins
• Mechanical and chemical digestion
•
•
•
•
•
Gastric glands secrete gastric juices:
Enzymes and HCl
Stomach empties in 2-6 hours
Chyme enters small intestine via a sphincter
Mucous- help protect the lining of the
stomach wall
• Ulcer- open sore in the wall of the stomach
caused by the break down of tissue.
•
•
•
•
•
F) Small intestine
Named for its small diameter
Absorb nutrients
6 m in length
Bile (from the liver) and pancreatic juices
(from the pancreas) are emptied into the
small intestine
• Bile emulsifies fats
• Pancreatic juices- aid in digestion and
neutralize acidic content coming from the
stomach
• The small intestine has a huge surface areatennis court
• G) Large intestine
• Function- absorb water, salts and vitamins
• Parts include: cecum, appendix, colon
(ascending, transverse and descending) and
rectum
• When feces are forced into the rectum by
peristalsis a defecation reflex occurs
• Stretching of intestinal wall sends a message
to the spinal cord. Shortly after the rectal
walls contract and the anal sphincter relaxes.
Waste Elimination
• Defecation is a way in which the body
maintains homeostasis
• Feces are ¾ water and ¼ solids- include
bacteria and indigestible remains
• Polyps
• Constipation and diarrhea
• Diarrhea can be caused by nervous
stimulation or infection
• When a person is constipated, the feces are
dry and hard
• Water and fiber will help!
Assignment
• Choose 10 structures/processes that have
been presented about the digestive system
• For each structure write “who/what am I?”
questionsI am a process that helps move food along the
digestive tract by rhythmic contractions....
I am ______________________________