WARM UP 4/10WHAT DO YOU KNOW? What do you know about the digestive

system?

1. Write down anything you know about it – parts, how it works, purpose, etc.

2. Also write down where food goes after you swallow it – all the way through the body naming the parts

PARTS OF THE DIGESTIVE SYSTEM

On your warm up, label A-F the best you can

THE DIGESTIVE SYSTEM

CHAPTER 21

4/10

WHY DO WE NEED THE DIGESTIVE SYSTEM? Food we eat is not

in a form that can be used by the cells

DIGESTION – process of altering the physical and chemical composition of food so it can be used by our cells

ALIMENTARY CANAL or GASTROINTESTINAL TRACT (GI) – tube from mouth to anus

MOUTH Buccal cavity

Lips – obicularis musclephiltrum

tubercle Oral fissure

CLEFT LIP – philtrum to the nasal cavity

CHEEKS – buccinator muscles

PALATES – top of mouth a. Hard – front (bone under) b. Soft - back

TONSILS – sides of back of mouth; fight infections

UVULA – hangs in the back of the mouth, no known function

TONGUE Skeletal muscle covered by mucous

membrane

Connected to the hyoid bone

(Hypoglossal and glossopharyngeal nerves bring impulses to and from)

Covered with PAPILLAE – bumps

LINGUAL FRENULUM – fold of tissue that helps anchor tongue to the floor of the mouth

PLICA FIMBRIATA – tissue on both undersides of the tongue; contains lingual vein

Vessels very close to surface – soluble drugs absorbed rapidly under the tongue

                                                     

TONGUE FUNCTIONS

- helps in mastication (chewing) - helps in deglutition (swallowing) - helps in speech - sense of taste

SENSE OF TASTE - GUSTATION TASTE BUDS – 50-100 inside the

papillae 4 main tastes: sweet, salty, sour,

bitter Ave person has 10,000 taste buds Decrease with age, so food stronger in younger• Less taste buds in smokers

Sense of taste a. Bitter – back b. Salty – sides c. Sweet – tip d. Sour - middle

How we taste Substance dissolves and fits into a

taste bud receptor. Sends message through facial or

glossopharyngeal nerves to parietal lobe of cerebrum

Brain interprets the taste Can detect about 5,000 diff. tastes

Hot and spicy foods actually stimulate pain receptors

Smells of foods can cause stimulation of saliva

Bitter taste is actually a protection – most spoiled or toxic foods are bitter

Our genes determine the number and types of taste buds we have…that is why some people think certain foods taste good and some don’t

EX: PTC paper

OLFACTION = SMELL

Olfactory cells high in nasal cavity

SENSE OF SMELL influences taste• As you chew, chemicals released up into nose• Trigger receptors in nose• Send message to brain through olfactory nerve• Goes to temporal lobe • Brain interprets• Brain can detect about 10,000 different smells

• NOSE + TASTE BUDS = TRUE FLAVOR

(why stuffy nose = less taste – can’t get to receptors)

If same smell is detected for a period of time, body adapts to smell and no longer notice it

Ex: perfume or cologne you are wearing, chemicals working with (fingernail salons), etc.

Many smells linked to memories - mamillary body