chapter 34 (digestive system)

Question 1

Digestive system functions

Answer 1

Ingests food
Breaks food down into small molecules that can cross plasma membranes
Absorbs nutrient molecules
Eliminates indigestible remains

Question 2

Digestive System

Answer 2

Includes all the organs, tissues, and cells involved in ingesting food and breaking it down into smaller components
Contributes to homeostasis by providing body with nutrients needed to sustain life of cells

Question 3

incomplete digestive tract

Answer 3

has a single opening used as an entrance for food and exit for wastes

Question 4

complete digestive tract

Answer 4

has two openings

Question 5

Continuous filter feeders

Answer 5

Always have water moving into the mantle cavity via the incurrent siphon
Particles are deposited on gills.
Size of incurrent siphon permits entry of only small particles.
Do not need food storage area

Question 6

Discontinuous feeders

Answer 6

Moves rapidly through water using jet propulsion
Uses tentacles to seize prey
Beaklike jaws pull pieces into the mouth with the radula
Food storage area needed
Stomach, with cecum, retains food until digestion is finished

Question 7

Dentition

Answer 7

differs with mode of nutrition

type, number, arrangement, set of teeth.

Question 8

Herbivores

Answer 8

Eat only plants
Incisors for clipping
Premolars and molars for grinding
Land snails and some insects are herbivores.
Koalas, which are mammals, eat only eucalyptus leaves.
Grazers, like horses, feed on grasses.
Ruminants, like cattle, goats, and sheep, have a four-chambered stomach which allows them to regurgitate solid material for complete digestion.

Question 9

Carnivores

Answer 9

Eat only other animals
Pointed incisors and enlarged canines
Shear off pieces small enough to swallow
Spiders and sea stars are carnivores.
Dogs, lions, and dolphins are carnivores.
The lion’s pointed canine teeth are used for
killing, sharp incisors for scraping bones,
and pointed molars for slicing flesh.

Question 10

Omnivores

Answer 10

Variety of specializations to accommodate both vegetation and meat
Clams and tube worms are invertebrate omnivores.
Humans, pigs, raccoons, and most bears are omnivores.
Dentition of the above is specialized to accommodate vegetable and meat diet.
Better ability to adapt to different food sources

Question 11

Human Digestive System

Answer 11

Human digestive tract is complete. 
Part of a tube-within-a-tube body plan
Begins with a mouth and ends in an anus
Digestion is entirely extracellular.
Is mechanical as well as chemical
Digestive enzymes are secreted by
The wall of the digestive tract
Nearby accessory glands

Question 12

Mouth

Answer 12

Where digestion begins

Question 13

Tongue

Answer 13

Composed of striated muscle and an outer layer of mucous membrane
Mixes chewed food with saliva
Forms mixture into a bolus

Question 14

Pharynx

Answer 14

Digestive and respiratory passages come together in the pharynx, then separate.
Soft palate closes off nasopharynx during swallowing
Epiglottis

Question 15

Epiglottis

Answer 15

Covers the glottis (opening into the trachea)

Keeps food from air passages (most of the time)

Question 16

Esophagus

Answer 16

Moves food to stomach by peristalsis

Peristalsis – Rhythmical contraction to move contents in tubular organs

Question 17

Stomach

Answer 17

Stomach wall has deep folds (rugae)
Folds disappear as the stomach fills to an approximate volume of one liter.
Epithelial lining of the stomach has millions of gastric pits, which lead to gastric glands.

Question 18

Stomach pH

Answer 18

about 2.0, which can kill bacteria in food

Question 19

pepsin

Answer 19

is a hydrolytic enzyme that acts on protein to produce peptides.

Question 20

Gastric glands

Answer 20

secrete hydrochloric acid (HCl) and pepsin

Question 21

what protects the stomach wall from enzymatic action.

Answer 21

A layer of mucus

Question 22

in the stomach When gastric acid leaks upward

Answer 22

the mucosal lining can be irritated.

Question 23

GERD

Answer 23

Gastrointestinal reflux disease can cause heartburn

Question 24

chyme

Answer 24

happens when Food mixes with gastric juices

Question 25

villi

Answer 25

are ridges on the surface, which contain even smaller ridges called microvilli. Contain digestive enzymes called brush-border enzymes Greatly increase the surface area for absorption

Question 26

what is in the wall of the small intestine

Answer 26

villi

Question 27

lacteal (lymphatic capillary)

Answer 27

blood capillaries in the villus

Question 28

large intestine has what pertaining to bacteria?

Answer 28

has a large population of bacteria that break down indigestible material and produce vitamins.

Question 29

Pancreas

Answer 29

Lies deep in the abdominal cavity

Question 30

what is the endocrine function of the pancreas

Answer 30

Secretes insulin and glucagon hormones to regulate blood glucose levels

Question 31

what is the exocrine function of the pancreas

Answer 31

Secretes pancreatic juice and digestive enzymes Sodium bicarbonate in pancreatic juice neutralizes acid chyme from the stomach. Pancreatic amylase digests starch Trypsin digests protein Lipase digests fat

Question 32

functions of the liver

Answer 32

``` Detoxification of the blood Storage of iron and some vitamins Production of plasma proteins Regulation of blood glucose levels Storage of glucose as glycogen Production of urea Removal and storage of iron and vitamins Production of bile Removal of bilirubin Regulation of blood cholesterol levels ```

Question 33

Jaundice

Answer 33

yellowing of skin due to excess bilirubin

Question 34

Hepatitis

Answer 34

inflammation of liver, most commonly caused by a virus

Question 35

Cirrhosis

Answer 35

scarring of liver tissue, leading to reduced function | Common in alcoholics

Question 36

is the liver able to regenerate in some cases?

Answer 36

yes

Question 37

galbladder

Answer 37

Pear-shaped, muscular sac attached to the liver Stores excess bile Gallstones form when the cholesterol in bile crystallizes.

Question 38

Carbohydrates

Answer 38

Carbohydrates are present in food in the form of sugars, starch, and fiber. Fruits, vegetables, milk, and honey are natural sources of sugars

Question 39

Monosaccharides

Answer 39

Glucose | Fructose

Question 40

Disaccharides

Answer 40

Lactose (milk sugar) | Sucrose (table sugar)

Question 41

After being absorbed from the digestive tract, all sugars are converted to

Answer 41

glucose

Question 42

glucose is used for

Answer 42

Much of glucose is used for production of ATP by cellular respiration

Question 43

plants and animals store glucose as:

Answer 43

Plants store glucose as starch. | Animals store glucose as glycogen.

Question 44

glycogen

Answer 44

Starch is digested to glucose in the digestive tract and excess glucose is stored as

Question 45

Fiber

Answer 45

Includes various indigestible carbohydrates derived from plants Food sources rich in fiber include beans, peas, nuts, fruits, and vegetables. Technically, fiber is not a nutrient for humans: Cannot be digested

Question 46

Soluble fiber

Answer 46

combines with bile acids and cholesterol in the small intestine and prevents them from being absorbed.

Question 47

Insoluble fiber

Answer 47

adds bulk to fecal material. | This bulk stimulates movement in the large intestine, preventing constipation.

Question 48

Cholesterol can be synthesized

Answer 48

by the body and is found in animal foods.

Question 49

Lipids

Answer 49

Fat, oils, and cholesterol

Question 50

Saturated fatty acids

Answer 50

(solids at room temperature) usually come from animals. | Butter, meat, whole milk, and cheeses contain saturated fats.

Question 51

unsaturated fatty acids

Answer 51

found in plant oils

Question 52

Proteins

Answer 52

Adequate protein formation requires 20 different types of amino acids. Nine essential amino acids are required in the diet.

Question 53

how does body fat accumulate? what are the risks?

Answer 53

Consumption of an excess amount of calories from any source contributes to body fat. Increases risk of obesity and associated illnesses

Question 54

what health problems are seen in obese people?

Answer 54

Type 2 diabetes and cardiovascular disease are often seen in people who are obese.

Question 55

BMI

Answer 55

(BODY MASS INDEX) can be calculated by dividing weight in kilograms by height in meters squared. Estimates indicate that about 30% of Americans are obese.

Question 56

Diabetes mellitus

Answer 56

occurs when the hormone insulin is not functioning properly. May occur due to insulin deficiency or insulin resistance Excess blood glucose winds up in the urine. High blood glucose can cause tissue damage and even death.

Question 57

Type 1 diabetes can be managed by

Answer 57

insulin injections but type 2 is more resistant.

Question 58

Leading cause of death in the US.

Answer 58

Cardiovascular disease

Question 59

Cardiovascular disease

Answer 59

Arteries become blocked with plaque. | Plaque contains saturated fats and cholesterol.

Question 60

Low-density lipoproteins (LDL) and high-density lipoproteins (HDL)

Answer 60

carry cholesterol in the blood. | HDL is “good” and LDL is “bad.”

Question 61

Vitamins

Answer 61

Organic compounds the body is unable to produce, but are required for metabolic purposes. The absence of a vitamin may be associated with a particular disorder.

Question 62

Minerals

Answer 62

The body needs about 20 elements for various physiological functions. Some individuals don’t get enough iron, calcium, magnesium, or zinc in their diets. Many people consume too much sodium, which can contribute to hypertension.