CTB 3 – Tooth morphology and mastication

Question 1

Why do humans have a higher metabolic rate than replies?

Answer 1

Reptiles just grab their food and swallow

Humans need their energy faster, therefore chew food to reduce size, increase SA and hence a faster digestion

Question 2

How long is the masticatory sequence?

Answer 2

Cycle is 1 second

Question 3

How is the masticatory sequence controlled?

Answer 3

Neural circuitry

Question 4

Describe the masticatory sequence.

Answer 4

• Lower jaw orbits
• Mouth opens and food collected by tongue
• Tongue picks up particles and mixes with saliva by pressing into the hard palate
• Food moves laterally to posterior canine teeth (1 side)
• Food falls laterally during chewing are put back in the mouth by the contraction of the BUCCINATOR
• Relax before closing
• Once tongue and cheek are out of the way there is fast closure of tooth-food contact
• Mandible slows just before contact to allow for perception of food properties to judge the strength of bite

Question 5

What is the function of the tongue in the masticatory sequence?

Answer 5

• Tongue picks up particles and mixes with saliva by pressing into the hard palate
• Food moves laterally to posterior canine teeth (1 side)

Question 6

What is the main component of food chewing dependent on?

Answer 6

Physical properties of foods

Question 7

What is the function of sensory feedback during the masticatory sequence?

Answer 7

Monitors food properties

Question 8

What is the most sensitive part of the oral cavity in the masticatory sequence? What is the discrimination of these?

Answer 8

Tongue and hard palate

1-2mm

Question 9

Where are the most important sensors during mouth closing

Answer 9

TMJ

Question 10

What type of receptors does the PDL have?

Answer 10

Mechanoreceptors

Question 11

What particle size can teeth detect?

Answer 11

8 – 15 microns

Question 12

What force reaches a maximum when food is swallowed?

Answer 12

When cohesive force is max

Question 13

What forces are applied to cause distortion to food?

Answer 13

• Stress
• Strain
• Stiffness
• Yield strength
• Brittle
• Hardness – stress for perm indentation
• Fracture strength - tough foods have slow feeding rates

Question 14

What is yield strength?

Answer 14

Stress at which a solid begins to perm deform

Question 15

What is the function of anterior teeth?

Answer 15

Biting and gripping

Question 16

What is the function of posterior teeth?

Answer 16

Fracturing food

Question 17

What is the function of secondont teeth? Give an animal example.

Answer 17

Slicing function for meat – only peaks in the tooth – e.g. cat

Question 18

What is the function of bunodont teeth? Give an animal example.

Answer 18

For eating meat and plants – flattened occlusal surfaces for crushing and grinding – human

Question 19

What animals have selenodont teeth?

Answer 19

Cow, deer, sheep, goat

Question 20

What animals have lophodont teeth?

Answer 20

Elephant, mouse

Question 21

What animals have selenolophodont teeth?

Answer 21

Horse

Question 22

What is the shape of the selenodont, lophodont and selenolophodont teeth?

Answer 22

Complex infolding for herbivory to eat plants etc

Question 23

What shapes in the posterior teeth are limited during tooth mastication?

Answer 23

Cusps and dips

Question 24

What are the 4 occlusion surfaces of upper and lower teeth to aid different types of mastication?

Answer 24

• Alternation – teeth interdigitate to grip not fracture food
• Opposition – cusps fit into basins for crushing
• Shearing – oblique/parallel movement movements of crest past each other
• Grinding – mortar and pestle motion

Question 25

What are sauguinivore?

Answer 25

Blood feeders

Question 26

What type of teeth do tertiary consumers have?

Answer 26

Very sharp teeth

Question 27

Give examples of omnivores

Answer 27

Hyena and jackal

Question 28

What type of animals have no upper front teeth?

Answer 28

Browsers and grazers