Digestive system Flashcards
Label the digestive system
What is the function of the GI system?
- To break down food into a form that can be utilised by the human body
- To absorb water from food and drinks
What is the GI system comprised of?
- The alimentary canal
- The accessory digestive organs (teeth, tongue, salivary glands, liver, gallbladder and pancreas)
What Structures Comprise the Accessory Organs?
- Teeth
- Tongue
- Salivary glands
- Liver
- Gallbladder
- Pancreas
What are the 3 parts of your teeth?
- The crown – visible above the gums
- The neck – connects the crown and the roots
- The roots – teeth have between one and three roots which ‘slot’ into sockets within the mandible (fibrous gomphoses joints)
Label the parts of the mouth (oral cavity)
Label the Longitudinal Section
through a Tooth
Describe the composition of a tooth?
- Composed primarily of dentine (calcified connective tissue)
- Enclosed within the dentine is the pulp cavity which contains connective tissue, blood vessels, nerves and lymph vessels
- The root canal is an opening which runs through the root to open at the base of the tooth and is the means by which vessels and nerves enter and leave the tooth
- The crown is covered with enamel (calcium phosphate and calcium carbonate)
- Enamel is the hardest substance within the human body and protects the tooth from mechanical wear and tear
What is the function of teeth?
•The function of the teeth is to cut, tear and grind food in order to reduce solid material into smaller particles that can be more readily swallowed
When do deciduous teeth start to erupt?
Begin to erupt age 6/12 m
Appear at rate of one pair a month until all 20 are present
How many teeth are in an adults full set?
32
Label the cross section of a tongue
The Tongue
- Skeletal muscle covered with mucous membrane
- Is anchored to the floor of the oral cavity by the lingual frenulum (a fold of mucous membrane on the inferior surface of the tongue)
- The extrinsic muscles of the tongue manoeuvre food around the mouth for mastication
- The intrinsic muscles of the tongue enable swallowing and speech
What are the 3 taste buds?
Fungiform papillae
- Most contain taste buds
Vallate papillae
- All contain taste buds
Filiform papillae
- Do not contain taste buds
- Receptive to touch
- Increase friction
Where are papillae found?
What are papillae?
- The superior and lateral surfaces of the tongue are covered with raised projections called papillae
- These papillae are projections of the lamina propria and are covered with keratinized epithelium
- The majority of the papillae contain taste buds
Fungiform papillae- where are they found?
Found mainly on the sides and tips of the tongue – deep red in colour (most contain taste buds)
Vallate papillae- where are they found and how many are there?
•Found on the posterior surface of the tongue, about 8 – 12 in number (all contain taste buds)
Filiform papillae- where are they found?
•Found in parallel rows on the anterior 2/3 of the dorsum of the tongue (lack taste buds but are receptive to touch and increase friction between the tongue and food enabling the tongue to manoeuvre food)
Label the taste cell
Label the taste senses on the tongue
eg. sweet, sour
Label the types of cell on this tongue
Label the 3 salivary glands
Composition of saliva
- 99.5% water
- 0.5% solutes including salivary amylase, lysozyme (antibacterial enzyme), ions, dissolved gases and organic compounds including urea
- The salivary glands each produce saliva that has a slightly different composition (e.g. with a varying amount of mucous depending on how many mucal cells line the gland)
Salivary glands:
Sublingual gland
Mostly mucous alveoli
Produces a thick saliva with only a small amount of salivary amylase
Salivary glands:
Submandibular gland
Some mucous alveoli
Produces a saliva partially thickened by mucous
Salivary glands:
Parotid gland
Some mucous alveoli
Produces a saliva partially thickened by mucous
Label the salivary glands
Explain the functions of saliva?
- Under basal conditions the saliva is mostly the mucous type, and during sleep very little saliva is secreted. The flow of saliva helps to wash away some of the bacteria on food particles not completely broken down after a meal. Saliva contains thiocyanates and lysozymes that will attack and destroy bacteria in the mouth. Saliva can contain antibodies that destroy oral bacteria.
- The more common functions include the following: moistening and lubricating of mouth and food, aiding in tasting, swallowing, and speaking, and early metabolism of carbohydrate due to -amylase action. Finally, saliva helps to maintain the calcium phosphate matrix of the teeth
Interesting facts about the liver?
- Heaviest organ in body
- 2nd largest organ
- Almost completely covered by the peritoneum
- Completely covered by dense irregular connective tissue
- Divided into two principal lobes (right and left) by the falciform ligament which is an extension of the peritoneum