Digestive System

what are two types of digestive tracts

complete and incomplete

what is an incomplete digestive tract

a gastrovascular cavity

what is a complete digestive tract

an alimentary canal

what is a gastrovascular cavity

single opening where food enters and waste exits

gastrovascular cavity lacks ___ parts

specialized

how many openings does an alimentary canal have

two

alimentary canal=

food enters through mouth waste exits through anus

what type of digestive system do humans have

complete, alimentary canal

humans are a ___ within a ____ body plan

tube within a tube

in humans digestion is entirely ____

extracellular

what digests food in humans

digestive enzymes secreted by lining of digestive tract and nearby glands

digestion begins in the ____

oral cavity

what is the oral cavity

the mouth

what happens to food in the oral cavity

it is masticated (chewed) by teeth and moistened by saliva

what does masticated mean

chewed

salivary glands secrete amylase and lipase which begin to digest ____ and ____

starches and fats

salivary glands secrete ____ and _____ which begin to digest starches and fats

amylase and lipase

what type of muscles is the tongue composed of

striated muscle

what is teh function of the tongue

mixes chewed food with saliva and forms mixture into a bolus

what is the pharynx

where digestive and respiratory passages come together

what closes off the nasopharynx

the soft palate

what covers opening of trachea and keeps food from air passages

epiglottis

what takes food from the mouth to the stomach

the esophagus

what process does the esophagus use to transport food

peristalsis

what is peristalsis

rhythmical contraction to move contents in tubular organs

the stomach is acidic or basic

acidic

where is most of the protein from food digested

the stomach

stomach walls have ____

deep folds

folds disappear as the stomach fills to an approximate volume of _____

one liter

epithelial lining has millions of gastric pits, which drain ____

gastric glands

what is chyme

food mixed with gastric juices

what controls the junction between stomach and small intestine

pyloric sphincter

when the pyloric sphincter relaxes, a small quantity of ____ passes into the ___

chyme, small intestine

what takes place in the small intestine

Further digestion and absorption

what protects the small intestine from stomach acid

mucous membrane

small intestine has _____ that give it a corrugated surface

ridges and furrows

what are ridges on the surface of the small intestine called

villi

vili contain even smaller ridges called

microvilli

villi and microvilli greatly increase

absorptive area

each villus in the small intestine contains

blood capillaries and a lymphatic capillary

what does the large intestine include

cecum, colon, rectum, and anus

large intestine compared to small intestine

larger in diameter but shorter in length

what does the large intestine absorb

water, salts, and some vitamins

constipation=

feces are hardened because of excess water removal in the colon.

diarrhea=

not enough water is removed from the feces

accessory organs of the digestive system include

salivary glands, liver, pancreas, gallbladder

liver produces ___

bile

what is bile

an alkaline digestive juice that is required for the
breakdown of fatty components of the food in the duodenum

The liver also processes ____ and synthesizes many ______

vitamins and fats, plasma proteins

pancreas makes juices that

neutralize the acidic chyme exiting the stomach and contain enzymes needed to digest protein and carbohydrates

gallbladder aids the liver by

storing bile and concentrating bile salts

what is the primary source of energy for animals

carbohydrates (mainly glucose)

digestible carbohydrates get turned into what in the body

glucose

cellular respiration turns glucose and oxygen into

ATP

digestion of carbohydrates is performed by

several enzymes

Starch and glycogen are broken down into glucose by

amylase and maltase

sucrose is broken down by

sucrase

lactose is broken down by

lactase

The enzyme ____ plays an important role in the digestion of proteins by breaking down the intact protein to peptides, short chains of 4-9 amino acids

pepsin

The enzyme pepsin plays an important role in the digestion of proteins by breaking down the intact protein to ____, short chains of 4-9 amino acids.

peptides

The enzyme pepsin plays an important role in the digestion of proteins by breaking down the intact protein to peptides, ______

short chains of 4-9 amino acids.

amino acids synthesized in the stomach are absorbed into the bloodstream where

in the large intestine

where does lipid digestion begin

the mouth

bulk of lipid digestion occurs in the____

small intestine

bulk of lipid digestion occurs in the small intestine due to _____

pancreatic lipase (enzyme)

Bile aids in the digestion of lipids, primarily triglycerides, by _____

emulsification

what are the three phases of digestion

cephalic, gastric, intestinal

the first phase of digestion begins where

in your head

the cephalic phase of digestion is what

neural response to the stimulus provided by food

cephalic phase of digestion triggers _____

triggers salivation and secretion of gastric
juices to prepare the stomach to receive food

when does the gastric phase of digestion begin

when food arrives in the stomach

what stimulates the gastric phase

distension of the stomach, a decrease in the pH of the gastric contents, the presence of undigested material

when does the intestinal phase of digestion begin

when chyme enters the small intestine triggering digestive secretions

what phase of digestion controls gastric emptying

intestinal phase