Digestive - PowerPoint Presentation

Slide1

Digestive System: From Mouth to Anus

Digestion: Function is to breakdown food into smaller molecules (nutrients) to be absorbed by the body. All undigested food is removed as solid waste.Two parts: digestive tract and digestive glands.Slide2

Digestive Glandsis a long tube ~27 feet that starts at mouth, where food and drink enter the body, and ends at the anus, where leftover food and waste leaves the body.

Includes: Mouth, pharynx, esophagus, stomach, small intestines, large intestines, rectum, anusProduce chemical secretions needed to breakdown food.Includes: salivary glands, gastric glands, the liver, pancreas, and intestinal glands.

Digestive TractSlide3

Food DigestionIngestion and propulsion of food

Digestion of foodAbsorption of nutrientsElimination of fecal matterMechanical digestion/transformation: physically mixing and breaking down food into smaller partsChemical digestion/transformation: chemically breaking down food from complex molecules into simpler molecules. Occur due to secretions from the digestive glands.Slide4

MouthIngestion: taking substances into body via mouth.

Teeth: rips, cuts, crushes and grind food [mastication: chew food] into a soft pulp that is easy to swallow (mechanical digestion).Incisors: cut and tearCanines: tearPremolars and Molars: chew and grindMasticating mixes food with saliva, from the salivary glands, to make it moist and easy to swallow.

Tongue

: moves the food in your mouth and helps to swallowSlide5

SalivaSecreted by the salivary glands

The glands are found in and around your mouth and throat. Salivary glands produce the saliva used to moisten your mouth and food, initiate digestion, and help protect your teeth from decay.Contains: enzyme called Amylase, which helps breakdown starch into simple sugars (chemical digestion).Enzyme called Lingual

L

ipase

, begins breakdown of lipids.Slide6

Deglutition (Swallowing) Food moves to the back of your mouth to your

pharynx: where there is the opening to both the trachea (windpipe) and esophagus.Swallowing is a voluntary action involving many muscles.When swallowing the epiglottis (flap of cartilage) prevents food from going into the trachea allowing the food to move into the esophagus.Slide7

EsophagusA muscular tube ~25 cm long.

Passage for food and drink between pharynx and stomach. Food moves by rhythmic waves of muscle contractions called peristalsis. (mechanical digestion)Note: peristalsis also occurs in the stomach, small and large intestines.Slide8

StomachFood moves into the stomach from the

esophagus by passing through the cardiac sphincter (muscle at top of stomach).Acts like a blender churning and mixing the food (mechanical digestion).Mixes food with

HCl

(hydrochloric acid) and other gastric juices that

uncoils proteins

(

chemical digestion).Food now known as chyme moves through the pyloric sphincter

(muscle at bottom of stomach) into the small intestines.Slide9

Small IntestinesMajor sight of digestion.

Chymes moves by peristalsis into small intestines at the duodenum (first section).Secretes digestive juices.

Liver

produces

bile

that is stored in the

gallbladder

.

Gallbladder

releases bile into the

small

intestines

.

Bile

aids to break down

fat

into droplets (

chemical

).

Pancreas

secretes pancreatic juices (

enzymes

) into the

small intestines

that helps to neutralize stomach acid. Also, aids in the further digestion of

carbohydrates

glucose

,

fats

fatty acids and glycerol

, and

proteins

amino acids

(

chemical

).

Peristalsis

moves the

chyme

mixing it with digestive enzymes (

mechanical digestion

).

Absorption

: passage of nutrients from digestive tract into blood stream or lymph.

90% of nutrients absorbed through the

villi

: folds in the walls of the small intestines

.Slide10

Large IntestinesLiquid matter with little nutrients move into large intestines by peristalsis.

~4 feet long No villiNo further digestionReabsorbs excess waterContains bacteria that releases vitamin B and K that gets absorbed (symbiotic relationship).Stores and concentrates feces

Peristalsis moves feces to

rectum

for storage.

Signal sent to brain triggers need for bowel movement and feces exits via anus (anal sphincter).Slide11