Digestion

Question 1

digestion

Answer 1

consists of the degradation of large molecules into smaller molecules, which can be absorbed into the blood stream and used directly by cells.

Question 2

Intracellular digestion

Answer 2

occurs within the cell usually in membrane bound vesicles

Question 3

extracellular digestion

Answer 3

refers to a digestive process that occurs outside of the cell within a lumen or tract.

Question 4

unicellular organism digestion

Answer 4

food capture is primarily done by phagocytosis. Food vacuoles from immediately following ingestion. lysosomes fuse with the food vacuole and release their digestive enzymes which act upon the nutrients. resulting in molecules that can diffuse in the cytoplasm and unused expelled.

Question 5

physical breakdown

Answer 5

large particles that are ingested begin breakdown by cutting and grinding in the mouth and churning in the digestive tract. molecular composistion is unchanged but surgace area for enzymes is increases

Question 6

chemical breakdown

Answer 6

accomplished by enzymatic hydrolysis. the smaller digested nutrients pass through a semipermiable membrane of the gut cells to further metabolize or transport

Question 7

Cnidarians

Answer 7

hydra uses intracellular and extracellular digestion tentacles bring food to the mouth and release the particles in a cuplike sac. endodermal cells lining this gastrovascular cavity secretes enzymes. thus digestion occurs outside the cell mostly, but smaller fragments are completed within the gastrodermal cells. undigested food is expelled from the mouth

Question 8

annelids

Answer 8

earthworms have a one way digestive tract with both a mouth and an anus. it has specialization of different parts of the digestive tract. soluble nutrients pass by diffusion through the walls of the SI into the blood.

Question 9

earthworm digestive parts

Answer 9

mouth, pharynx, esophagus, crop (to store food), gizzard (to grind food) intestine ( contains large dorsal fold for surface area increase) and anus

Question 10

arthropods

Answer 10

have the digestive system similar to earthworms but include a jaws for chewing and salivary glands that improve food digestion

Question 11

oral cavity of the human

Answer 11

where mechanical and chemical digestion of food begins. Mechanical digestion is the breakdown of large particles by mastication. Chemical refers to enzymatic breakdown of macromolecules into smaller. beings with saliva.

Question 12

saliva

Answer 12

lubricates food to facilitate swallowing and provides a solvent for food particles. it is secreted in response to a nervous reflex triggered by food.

Question 13

salivary amylase

Answer 13

within saliva, hydrolyzes starch to maltose

Question 14

esophagus

Answer 14

the muscular tube leading from the mouth to the stomach. food is moved by peristalsis.

Question 15

peristalsis

Answer 15

rhythmic waves of involuntary smooth muscle contractions

Question 16

stomach

Answer 16

large muscular organ located in the upper abdomen, stores and partially digests food. Lined by thick mucosa which contains glands.

Question 17

Glands in the stomach

Answer 17

secrete mucous that protects the stomach from acidic juices

• secretes pepsin which is a protein hydrolyzing enzyme
• secretes HCl which kills bacteria and dissolves the intracellular glue of food.

Question 18

chyme

Answer 18

the churning of the stomach produces acidic, semi fluid mixture of partially digested food. passes into the small intestine through the pyloric sphincter

Question 19

small intestine

Answer 19

chemical digestion is completed here. divided into three sections. duodenum, jejunum and ileum.

• very long and coiled
• also highly adapted to absorption. numerous villi extend out of the intestinal wall

Question 20

villi

Answer 20

contain capillaries and lacteals. amino acids and monosaccs pass through the villi walls into the capillary system.

Question 21

lacteals

Answer 21

vessels of the lymphatic system. large fatty acids and glycerol pass into the lacteals and are then reconverted into fates.

Question 22

where does most digestion occur in the SI

Answer 22

in the duodenum, where the secretions of the intestinal glands, pancreas, liver and gall bladder mix with the acidic chyme entering from the stomach.

Question 23

intestinal mucosa secretes

Answer 23

lipases (fat digestion), aminopeptidases (for polypeptide digestions), disaccs (for digestion of maltose, lactose and sucrose)

Question 24

lactase

Answer 24

breaks down lactose (milk sugar). enzyme is present in infants but not many adults making them lactose intolerant

Question 25

the liver

Answer 25

produces bile which is stored in the gall bladder prior to release into the small intestine. Bile contains no enzymes it emulsifies fats.

Question 26

elmusification

Answer 26

breaks down large globules into small droplets. this exposes fats to a greater surface area of the fat to the action of pancreatic lipase.

Question 27

the pancreas

Answer 27

produces enzymes such as amylase for carbohydrate digestion, trypsin for protein digestion and lipase for fat digestion. also secretes bicarbonate rich juice that neutralizes acidic chyme.

Question 28

large intestine

Answer 28

approximately 1.5 meters long and functions in the absorption of salts and any water not already absorbed by the SI. rectum provides for transient storage of feces prior to elimination of the anus

Question 29

digestion in plants and fungi

Answer 29

have no digestive system but intracellular digestive processes similar to those of animals do occur.

Question 30

intracellular digestion

Answer 30

plants store insoluble polymers, starches, lipids and proteins in the cells. pricnciple storage is starch. found in large amounts in the roots, stem and seeds. broken down by hydrolysis. then diffused or used locally

Question 31

extracellular digestion

Answer 31

some heterotrophic organisms such as fungi must obtain preformed organic molecules from the environment. enzymes are secreted, hydrolizing complex nutrients into simpler molecules which are then absorbed and used for energy.