Lecture 8: Digestive System

Question 1

What is mechanical digestion?

Answer 1

physically breakdown food to increase surface area

Question 2

What is chemical digestion?

Answer 2

breaks of chemical bonds of biomolecules

Question 3

Where does food absorption occur?

Answer 3

small intestine

Question 4

What are the 3 regions of the digestive tract?

Answer 4

• bucal/oral avity
• pharynx -> connects respiratory & digestive tracts (mouth to alimentary)
• alimentary canal -> from pharynx to anus

Question 5

What layer does the digestive tract form from?

Answer 5

endoderm

Question 6

Where is the first site of mechanical digestion?

Answer 6

mouth

Question 7

What is the purpose of a hard & soft palate?

Answer 7

• separates respiration & digestive tracts
• aids in suckling in infants

Question 8

The tongue is formed from what group of muscles?

Answer 8

hypobranchial

Question 9

What is the tongue attached to?

Answer 9

hyoid bone

Question 10

What are the roles of a tongue?

Answer 10

• speech
• chemoreception
• mixing of food & mucus
• swallowing

Question 11

What is mastication?

Answer 11

mechanical breakdown of food in the mouth

Question 12

What are the types of teeth in the mouth?

Answer 12

• 8 incisors -> grasp, pull, break food
• 4 canines -> puncture, tear, shred food
• 8 premolars (bicuspid)-> grind & crush food
• 12 molars (tricuspid)-> grind & crush food

Question 13

What is the crown of a tooth?

Answer 13

• region above gum/gingiva
• made on dentin covered by enamel
• covers pulp (connective tissue, blood)

Question 14

What is the root of a tooth?

Answer 14

• continuous with pulp cavity
• passageway for nerves & blood vessels

Question 15

What hold the tooth in place?

Answer 15

cementum & ligaments

Question 16

What dissolves particles for taste buds?

Answer 16

mucus/saliva

Question 17

What type of enzymes does saliva have?

Answer 17

amylases (breaks down carbs) & lipases (breaksdown lipids)

Question 18

What are the pharyngeal arches?

Answer 18

• 1st arch -> middle ear cavity & auditory tubes
• 2nd arch ->palatine tonsils
• 3rd arch ->thymus
• 3rd & 4th arch-> parathyroid
• 4th & 5th arch -> parafollicular thyroid

Question 19

What is the submucosa in the alimentary canal?

Answer 19

• connective tissue, digetsive glands, & nerves
• houses vessels & lymph lacteals/nodules

Question 20

What is the muscular layer of the alimentary canal?

Answer 20

• contains circular & longitudinal muscle
• promotes mechanical digestion through rhythmic contractions
• drives peristalsis

Question 21

What is peristalsis?

Answer 21

• periodic wavelike contraction of alimentary canal
• longitudinal muscles shorten tube
• circular muscle contrict tube
• propels food forward through rest of system

Question 22

How can smooth muscles be stimulated?

Answer 22

• autonomic hormones
• influx of Ca2+ -> binds to calmodulin -> activates myosin kinase
• self stimulate = pacemaker potential

Question 23

What is the adventitia?

Answer 23

• outermost layer of alimentary canal
• holds canal in place
• can form loose glandular messentery -> serosa

Question 24

What is the esophageal sphincter?

Answer 24

• msucular ring that allows food to pass if relaxed
• prevents regurgitation

Question 25

What macromaolecule does the stomach digestive?

Answer 25

proteins

Question 26

What are the 4 major regions of the stomach?

Answer 26

1. cardiac -> mucus glands to lubricate food 2. fundus -> storage area 3. body -> bulk of stomach; mucus glands produce bicarb rich mucus; parietal cells produce acid to denature proteins; chief cells produce pepsinogen 4. pylorus -> keeps food trapped for some time & exits

Question 27

What is chyme?

Answer 27

when food mixes with chemicals

Question 28

What is the small intestine?

Answer 28

* longer & narrower than large intestine * composed of duodenum, jejunum, & ileum

Question 29

The cells in the intestinal mucosa possess what to increase suface area?

Answer 29

villi & microvilli

Question 30

What is the pancreas?

Answer 30

* froms from buds of liver & intestines * makes enzymes (lipases, nuclease, amylase, protease) * release bicarb to neutralize chyme

Question 31

Everything from the pancreas is secreted into the duodenum through what?

Answer 31

pancreatic duct

Question 32

What are the functions of the liver?

Answer 32

* emulsifies fats * contains pigments, electrolytes, cholesterol, lipids, & salts * processes nutrients from digestive tract through hepatic portal vein

Question 33

Where are the contents of the liver stores?

Answer 33

in the galbladder & released when fat is consumed

Question 34

Where does absorption occur in the small intestine?

Answer 34

in jejunum & ileum

Question 35

What is the large intestine?

Answer 35

* contains cecum that collects waste from ileum * connects to appendix * connects to colon

Question 36

What is the function of the colon?

Answer 36

* adds mucus * absorpbs water, fatty acids, & vitamins

Question 37

What is the colon continuous with?

Answer 37

rectum

Question 38

What prevents feces release?

Answer 38

ext & int anal sphincter

Question 39

What are polysaccharides?

Answer 39

* broken into disaccharides * results from amylases in mouth & duodenum * produces lactose, maltose, & sucros

Question 40

Lipids are stored as what?

Answer 40

adipose tissue -> triglycerides

Question 41

Can humans synthesize unsaturated fats?

Answer 41

NO

Question 42

Which omegas do humans require?

Answer 42

omega 6 & omega 3 for phospholipid production & to regulate inflammation

Question 43

What are the 2 forms of lipoproteins?

Answer 43

* LDL -> low-density lipoproteins with ALOT of cholesterol; carries fat & cholesterol to tissues * HDL -> mostly protein; picks up excess fat & cholesterol

Question 44

What is the difference between plants & humans when it comes to amino acids?

Answer 44

humans are complete & plants are incomplete

Question 45

What are fat soluble vitamins?

Answer 45

Vit A (visual pigments) & Vit D (calcium absorption)

Question 46

What are water soluble vitamins?

Answer 46

Vit B (cell repsiration) & Vit C (collagen production)

Question 47

What is an exmaple of an inorganic & an organic micromolecule?

Answer 47

* inorganic-> minerals * organic -> vitamins