Lecture 8: Digestive System Flashcards
What is mechanical digestion?
physically breakdown food to increase surface area
What is chemical digestion?
breaks of chemical bonds of biomolecules
Where does food absorption occur?
small intestine
What are the 3 regions of the digestive tract?
- bucal/oral avity
- pharynx -> connects respiratory & digestive tracts (mouth to alimentary)
- alimentary canal -> from pharynx to anus
What layer does the digestive tract form from?
endoderm
Where is the first site of mechanical digestion?
mouth
What is the purpose of a hard & soft palate?
- separates respiration & digestive tracts
- aids in suckling in infants
The tongue is formed from what group of muscles?
hypobranchial
What is the tongue attached to?
hyoid bone
What are the roles of a tongue?
- speech
- chemoreception
- mixing of food & mucus
- swallowing
What is mastication?
mechanical breakdown of food in the mouth
What are the types of teeth in the mouth?
- 8 incisors -> grasp, pull, break food
- 4 canines -> puncture, tear, shred food
- 8 premolars (bicuspid)-> grind & crush food
- 12 molars (tricuspid)-> grind & crush food
What is the crown of a tooth?
- region above gum/gingiva
- made on dentin covered by enamel
- covers pulp (connective tissue, blood)
What is the root of a tooth?
- continuous with pulp cavity
- passageway for nerves & blood vessels
What hold the tooth in place?
cementum & ligaments
What dissolves particles for taste buds?
mucus/saliva
What type of enzymes does saliva have?
amylases (breaks down carbs) & lipases (breaksdown lipids)
What are the pharyngeal arches?
- 1st arch -> middle ear cavity & auditory tubes
- 2nd arch ->palatine tonsils
- 3rd arch ->thymus
- 3rd & 4th arch-> parathyroid
- 4th & 5th arch -> parafollicular thyroid
What is the submucosa in the alimentary canal?
- connective tissue, digetsive glands, & nerves
- houses vessels & lymph lacteals/nodules
What is the muscular layer of the alimentary canal?
- contains circular & longitudinal muscle
- promotes mechanical digestion through rhythmic contractions
- drives peristalsis
What is peristalsis?
- periodic wavelike contraction of alimentary canal
- longitudinal muscles shorten tube
- circular muscle contrict tube
- propels food forward through rest of system
How can smooth muscles be stimulated?
- autonomic hormones
- influx of Ca2+ -> binds to calmodulin -> activates myosin kinase
- self stimulate = pacemaker potential
What is the adventitia?
- outermost layer of alimentary canal
- holds canal in place
- can form loose glandular messentery -> serosa
What is the esophageal sphincter?
- msucular ring that allows food to pass if relaxed
- prevents regurgitation
What macromaolecule does the stomach digestive?
proteins
What are the 4 major regions of the stomach?
- cardiac -> mucus glands to lubricate food
- fundus -> storage area
- body -> bulk of stomach; mucus glands produce bicarb rich mucus; parietal cells produce acid to denature proteins; chief cells produce pepsinogen
- pylorus -> keeps food trapped for some time & exits
What is chyme?
when food mixes with chemicals
What is the small intestine?
- longer & narrower than large intestine
- composed of duodenum, jejunum, & ileum
The cells in the intestinal mucosa possess what to increase suface area?
villi & microvilli
What is the pancreas?
- froms from buds of liver & intestines
- makes enzymes (lipases, nuclease, amylase, protease)
- release bicarb to neutralize chyme
Everything from the pancreas is secreted into the duodenum through what?
pancreatic duct
What are the functions of the liver?
- emulsifies fats
- contains pigments, electrolytes, cholesterol, lipids, & salts
- processes nutrients from digestive tract through hepatic portal vein
Where are the contents of the liver stores?
in the galbladder & released when fat is consumed
Where does absorption occur in the small intestine?
in jejunum & ileum
What is the large intestine?
- contains cecum that collects waste from ileum
- connects to appendix
- connects to colon
What is the function of the colon?
- adds mucus
- absorpbs water, fatty acids, & vitamins
What is the colon continuous with?
rectum
What prevents feces release?
ext & int anal sphincter
What are polysaccharides?
- broken into disaccharides
- results from amylases in mouth & duodenum
- produces lactose, maltose, & sucros
Lipids are stored as what?
adipose tissue -> triglycerides
Can humans synthesize unsaturated fats?
NO
Which omegas do humans require?
omega 6 & omega 3 for phospholipid production & to regulate inflammation
What are the 2 forms of lipoproteins?
- LDL -> low-density lipoproteins with ALOT of cholesterol; carries fat & cholesterol to tissues
- HDL -> mostly protein; picks up excess fat & cholesterol
What is the difference between plants & humans when it comes to amino acids?
humans are complete & plants are incomplete
What are fat soluble vitamins?
Vit A (visual pigments) & Vit D (calcium absorption)
What are water soluble vitamins?
Vit B (cell repsiration) & Vit C (collagen production)
What is an exmaple of an inorganic & an organic micromolecule?
- inorganic-> minerals
- organic -> vitamins
