D1a2: Digestion

Question 1

Digestion

Answer 1

Process in which food is broke. Down to use as energy

Question 2

Mechanical digestion

Answer 2

Physical change in food (chewing)

Question 3

Chemical digestion

Answer 3

Chemical change in food

Question 4

Peristalsis

Answer 4

Rhythmic muscle contractions in longitudinal muscles (esophagus, stomach, intestines, rectum)

Question 5

Segmentation

Answer 5

Rhythmic muscle contractions in circular muscles (mixed food)

Question 6

1. Oral Cavity

Answer 6

Mechanical digestion makes food easier to swallow and increases surface area

Salivary gland- Begins chemical digestion as saliva contains amylase to break down starch

Tongue- determines which foods need to be processed further, shapes food into bolus and then pushed it to the back of pharynx

Question 7

2. Esophagus

Answer 7

•Flexible tube that leads to stomach
•secretes mucus
•passed through diaphram to connect w stomach at lower esophageal spincter (regulates entry and exit)

Question 8

3. Stomach

Answer 8

•Cross crossed muscle layers create churning motions (ingested food and digestive juice=chyme)
•Site of food storage and initial protein digestion
•Physical and chemical digestion

Question 9

3. Stomach sphincters

Answer 9

Strong circular muscles that move good in and out of stomach

Lower esophageal spincter contractions closes opening to stomach, relaxation allows food in, prevents regurgitation

Pyloric Sphincter- Moves food and stomach acid into small intestines

Question 10

3. Chemicals in Stomach acid

Answer 10

Gastric glands- makes gastric acid (water ,mucus,HCL,pepsin)
•HCL secreted from parietal cell (hormone gastric stimulates release)
•conveys pepsinogen to pepsin

Pepsinogen (inactive)+HCL=pepsin (active)
•hydrolyzes proteins S into smaller polypeptides by breaking peptide bonds

Question 11

4.1 Small intestine (Duodenum)

Answer 11

•Chyme leaves stomach and goes here

Question 12

4.1 S.I (Duodenum) response to amino and fatty acids

Answer 12

amino and fatty acids in chyme release CCK (stimulates pancreas to release enzymes and gallbladder to release bile)

Question 13

4.1 S.I (Duodenum) response to chyme w low pH

Answer 13

•chyme w low ph=hormone secretion (sodium bicarbonate) from pancreas which neutralizes gastric fluid and brings pH to 8

Question 14

4.1. S.I (Duodenum) response to lipids

Answer 14

Enterogastron secreted so that time for fat digestion increases as it inhibits secretion of gastric juices and slows peristalsis)

Question 15

4.1. S.I (Duodenum): Dugesting of macromolecules

Answer 15

Carbs- hydrolyzed into monosaccharides
Proteins- broken down into amino acids
Fats- hydrolyzed by lipases into glycerol and fatty acids
Dna divested by nuclease=nucleotide

Question 16

4.2,Small Intestine (Jejnum and Ileum) and explain the role of lacteal villi, capillaries and the epithelial barrier

Answer 16

Absorbs nutrients and water from circulatory and lymphatic system

Lacteal- absorbs fatty acids and glycerol
Capillaries- absorbs nucleotide, monosaccharides and amino acids
Epithelial- impermeable barrier between digestive juices and tissues

Question 17

4.3 Intestinal Villi

Answer 17

MR LIM

Microvilli- high SA:V ratio
Rich capillary network- transports digestive products
Lacteals- absorbs lipids from lymphatic system
Intestinal glands- exocrine pits release enzymes
Membrane protein- facilitated product transport

Question 18

5. Large intestine (colon)

Answer 18

•Absorbs water
•bacteria decompose leftover organic matter
•makes vitamin B, K and folic acid (needed to make rbc)
• stores and eliminates waste

Question 19

6.Rectum

Answer 19

Where waste leaves

Question 20

Accessory organs

Answer 20

Pancreas- Endocrine cells (hormones): insulin=lower blood sugar and glucagon=raise blood sugar; exocrine cells (gastric juice)

Liver- makes bile, secreted surfactants into bile to break lipid droplets

Gallbladder- Stores and regulates release of bile

Question 21

Methods of absorption from the intestine to epithium

Answer 21

•Secondary active transport- glucose (polar) cannot diffuse simply. Sodium potassium pumps, actively pump sodium ions into the intestine and potassium out creating concentration gradient. Sodium glucose co transporters (proteins) transfer a sodium ion w a glucose into the epithelium (Factiliated)

•Simple and Facilitated- Triglycerides
must be digested before absorbed. So they are broken down into monoglyceride and fatty acids which are absorbed into villus epithelium cells by simple diffusion. Fatty acids can also be transported by fatty acid transporters (proteins) in microvilli=Facilitated. Once inside epithelium cells monoglyceride and fatty acid combine again and CANNOT diffuse into lumen

Question 22

Lipid digestion

Answer 22

Needs proteins to be transported in blood (lipids=water insoluble)
•lipid globules are emulsified by bile salts before being chemically digested by pancreatic lipase
•components +protein=chylomicrons (go to liver and get converted to solvable lipoproteins

Question 23

Carbs digestion

Answer 23

Amylase digests starch
Glucose used in cell resp or stored in liver as glycogen)

Question 24

Tissue layers in SI

Answer 24

Serosa- Outer coat
Muscle layers- longitudinal muscle and inside it is circular
Sub Mucosa- contains blood
Mucosa- lining w epithelium