Download Digestive System

Anatomy and Physiology
Digestion and Absorption
Mastication
• Mechanical reduction of the ingested food
particles
• Food is mixed with saliva forming a bolus
• Tongue (muscular organ) moves food around
mouth to form and push bolus down
esophagus
Tongue
• Taste buds – more discriminatory when food is
in a native or unprocessed state (able to
distinguish between harmful and proper
foods)
Taste Buds
• Humans:
– 5-6 types of taste buds: sour, bitter, salty, umami
(meatiness) and sweet (possibly fat)
– sweet receptor made up of two coupled proteins
generated by two separate genes
• Tas1r2 and Tas1r3
Cats Can’t Taste Sweet
• Cats have about 470 taste
buds
• lack 247 base pairs of the
amino acids that make up
the DNA of the Tas1r2
gene
– does not code for the
proper protein
Why do you think it is a
good thing that cats can’t
taste sweet things?
Cats Can’t Taste Sweet
• cats can taste things
humans cannot
– ATP
– signal for meat
• most major pet food
manufacturers use corn
or other grains in their
meals
– Cat food = ~20%
carbohydrates
– Is this causing diabetes in
cats?
Cats Can’t Taste Sweet
• The suggestion that cats may have difficulty
adapting to high-carbohydrate meals appears
to be based on two observations:
– (1) cats lack glucokinase, an enzyme used to
phosphorylate glucose inside cells
– (2) cats lack salivary amylase and, compared with
dogs, may have lower activities of the enzymes
involved in carbohydrate digestion
Cats Can’t Taste Sweet
• For glucose to be used by a cell, it must enter
the cell and be phosphorylated by glucokinase
• Lacking glucokinase activity, cats rely on other
enzymes, including hexokinase
– less efficient than glucokinase when glucose
concentrations are high, cats have considerably
more hexokinase, phosphofructokinase and
pyruvate kinase enzyme activities than dogs
Dogs Can’t Taste Salt
• Dogs have only about
1,700 taste buds that
people (~10,000) do,
and their distinct sense
of taste is actually quite
poor
Diseases of the Oral Cavity
• Oral Tumor: can arise from the bone, teeth or
soft tissue structures of the lower (mandible)
or upper (maxilla) jaw, or the tongue or
pharynx
Oral Tumors
• most are malignant
• malignant melanoma
and squamous cell
carcinoma are the most
common oral tumors in
dogs
• squamous cell carcinoma
is the most common oral
tumor in cats
Oral Tumors
• Diagnosis
–
–
–
–
–
Physical exam
Blood tests
Aspiration
MRI
Chest X-rays
• Treatment
– Surgery
– Radiation
– Chemotherapy
Periodontal Disease
• Preventable
• Shows up at 3-4 years
of age
• Clinical Signs
–
–
–
–
–
Inflamed gums
Tartar build up
Loose teeth
Difficulty eating
Halitosis
Periodontal Disease
• Mainly caused by bacteria: Peptostreptococcus,
Actinomyces, and Porphyromonas
• Treatment:
–
–
–
–
Dental cleaning (vet)
Brush teeth daily (home)
Diet (tartar contro, i.e. T/D)
Tooth extraction
Stomatitis
• Painful, inflammation of the mouth
• Potential to be fatal
Periodontal Disease
• Periodontal disease can lead to heart disease
and kidney disease if left untreated