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Flashcards in chapter 34 (digestive system) Deck (62):
1

Digestive system functions

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

2

Digestive System

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

3

incomplete digestive tract

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

4

complete digestive tract

has two openings

5

Continuous filter feeders

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

6

Discontinuous feeders

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

7

Dentition

differs with mode of nutrition
type, number, arrangement, set of teeth.

8

Herbivores

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.

9

Carnivores

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.

10

Omnivores

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

11

Human Digestive System

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

12

Mouth

Where digestion begins

13

Tongue

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

14

Pharynx

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

15

Epiglottis

Covers the glottis (opening into the trachea)
Keeps food from air passages (most of the time)

16

Esophagus

Moves food to stomach by peristalsis
Peristalsis – Rhythmical contraction to move contents in tubular organs

17

Stomach

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.

18

Stomach pH

about 2.0, which can kill bacteria in food

19

pepsin

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

20

Gastric glands

secrete hydrochloric acid (HCl) and pepsin

21

what protects the stomach wall from enzymatic action.

A layer of mucus

22

in the stomach When gastric acid leaks upward

the mucosal lining can be irritated.

23

GERD

Gastrointestinal reflux disease can cause heartburn

24

chyme

happens when Food mixes with gastric juices

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villi

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

26

what is in the wall of the small intestine

villi

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lacteal (lymphatic capillary)

blood capillaries in the villus

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large intestine has what pertaining to bacteria?

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

29

Pancreas

Lies deep in the abdominal cavity

30

what is the endocrine function of the pancreas

Secretes insulin and glucagon hormones to regulate blood glucose levels

31

what is the exocrine function of the pancreas

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

32

functions of the liver

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

33

Jaundice

yellowing of skin due to excess bilirubin

34

Hepatitis

inflammation of liver, most commonly caused by a virus

35

Cirrhosis

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

36

is the liver able to regenerate in some cases?

yes

37

galbladder

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

38

Carbohydrates

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

39

Monosaccharides

Glucose
Fructose

40

Disaccharides

Lactose (milk sugar)
Sucrose (table sugar)

41

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

glucose

42

glucose is used for

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

43

plants and animals store glucose as:

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

44

glycogen

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

45

Fiber

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

46

Soluble fiber

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

47

Insoluble fiber

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

48

Cholesterol can be synthesized

by the body and is found in animal foods.

49

Lipids

Fat, oils, and cholesterol

50

Saturated fatty acids

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

51

unsaturated fatty acids

found in plant oils

52

Proteins

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

53

how does body fat accumulate? what are the risks?

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

54

what health problems are seen in obese people?

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

55

BMI

(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.

56

Diabetes mellitus

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.

57

Type 1 diabetes can be managed by

insulin injections but type 2 is more resistant.

58

Leading cause of death in the US.

Cardiovascular disease

59

Cardiovascular disease

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

60

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

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

61

Vitamins

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.

62

Minerals

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.