Lab 14: Digestive System Flashcards
(46 cards)
The digestive system can be separated into two main components:
- digestive tract - a continuous tube that begins at the mouth and ends at the anus.
- accessory organs - teeth, tongue, salivary glands, liver, gall bladder, and pancreas
gingiva
gums, a delicate mucosa,
Cranial nerves for taste
facial nerve VII, the glossopharyngeal nerve IX, vagus nerve X
Mastication
• accomplished via teeth
Teeth Used:
- Incisors: cutting and shearing food
- Canines (cuspids): tearing food
- Premolars (bicuspids): crushing and cracking food
- Molars (tricuspids): grinding food into fine pieces
Teeth Evolution
- deciduous (primary or baby) teeth
* permanent (secondary) teeth
Teeth From birth to 6
- Teeth erupt at six months
* By six years old, full set of deciduous teeth (consisting of 20 teeth)
dental formula
• Each half of each jaw contains two incisors, one canine and two molars
Infant Dental Formula: I 2/2 , C 1/1 , P 0/0 , M 2/2
Adult Dental Formula: I 2/2 , C 1/1 , P 2/2 , M 3/3
How do permenat teeth grow in?
- permanent teeth grow in the jaws beneath the deciduous teeth.
- When enlarged sufficiently, they exert pressure on the roots of the deciduous teeth above.
- Roots are resorbed and the deciduous teeth are shed (exfoliated).
- Process begins at 6 years old, completed by 11 - 12.
- At the same time, the permanent teeth start erupting. All of the permanent teeth do not appear until a person is 18 to 20 years of age.
- In the adult, there are 16 teeth in each jaw, 32 teeth altogether. It is not unusual for the third molar (the “wisdom” tooth) never to develop or erupt.
- Extra teeth (supernumerary teeth) occur frequently as well.
primary salivary glands
• Accessory organs • secrete saliva 3 Types: • parotid glands • submandibular glands • sublingual glands
Saliva Functions
- lubricating the mouth
- moistening the food
- dissolving chemicals in food so that they can be tasted. • contains the enzyme – salivary amylase that begins the digestion of carbohydrates.
oropharynx and the laryngopharynx
- common passageways for food, liquids and air.
* nasopharynx is not part of the digestive tract.
esophagus
- muscular tube that functions in the transport of food to the stomach
- enters the abdominal cavity through an opening in the diaphragm
- opening to the larynx is closed off by the epiglottis
stomach
- chemical digestion of proteins begins
* functions as a temporary storage area for food.
small intestine
• primary digestive organ • chemical digestion of food is completed • absorption of nutrients occurs. • 3 Regions: -duodenum -jejunum -ileum
large intestine
- absorption of water from the undigested food material
* cecum–> ascending colon –>transverse colon.–>descending colon –> sigmoid colon –> rectum–> anus
Pathway of food
mouth–>oropharynx –> laryngopharynx–>esophagus–>stomach–>duodenum–>jejunum–>ileum–>cecum –>ascending colon –>transverse colon.–>descending colon –> sigmoid colon (s-shaped) –> rectum–> anus
liver
• function: production + secretion of bile (main function),
- removing nutrients from blood
- storing glucose, liver glycogen, and vitamins
- detoxification of metabolic waste
- synthesis of blood-clotting factors
• divided into two main lobes
• lobes made up of functional units = lobules
gall bladder
- green-coloured muscular sac attached to the ventral surface of the liver
- bile stored and concentrated until needed
- Bile release into duodenum (under nervous and hormonal control)
pancreas
Exocrine glands:
- comprise 98% of the organ.
- produce pancreatic juice
Endocrine tissue
- comprises 2% of the organ
- “ductless glands”
- Islets of Langerhans (release hormones into blood)
lobules
• consisting of plates of liver cells or hepatocytes
- manufacture bile (fat emulsifier)
• portal triad: hepatic artery + hepatic portal vein + bile duct
function of the fluid produced by the peritoneum?
Lubricates parietanel surfaces to reduce fricton, allow organs to slide easily over each other
mesenteries
• membranes, made up of folds of the peritoneum, which hold the digestive organs in place and contain blood vessels, lymphatic vessels and nerves
Omentum – bind organs to each other
Mesentareies – bind organs to abdominal wall
- greater omentum: greater curvature over S.I/L.I
- lesser omentum: lesser curvature to liver
- falciform ligament: suspends liver from diaphragm / abdominal wall
- mesentery proper: connects parts of small intestine to itself
Function. keeps organs from tangling, gives roots for blood vessels and nerves and a way to store fat.
spleen
removal of aged and defective blood cells, but is not involved in digestion
Four layers compose the wall of the digestive tract
- mucosa - inner lining, stratified squamous epithelium
- submucosa - layer of connective tissue, infiltrated with blood vessels and nerves,
- muscularis (externa)- 2 layers of smooth muscle
- serosa - outermost layer (visceral peritoneum)
