chapter 34 (digestive system) Flashcards Preview

Biology 1201: Organisms and Diversity > chapter 34 (digestive system) > Flashcards

Flashcards in chapter 34 (digestive system) Deck (62)
Loading flashcards...
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

25

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

27

lacteal (lymphatic capillary)

blood capillaries in the villus

28

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