digestion part 2 Flashcards
What are simple lipids and what are compound lipids?
simple: fatty acids, triacylyglycerol, sterols
compound: phospholipids, lipoproteins
Triacylglycerols
characteristics?
most stored body fat is in this form
FFA broken down from glycerol by lipases
fatty acid characteristics?
saturated: no carbon carbon double bond
unsaturated (mono or poly) carbon-carbon double bond
Fatty acids:
animals can make fatty acids from what?
acetyl CoA
Fatty acids:
what can animals not produce enough of?
omega-3 and omega-6 fatty acids
Fatty acid:
omega 6 must be ingested as waht?
gamma-linoleic acid
omega-3 fatty acid must be ingested as what?
alpha-linolenic acid
Phospholipids:
characteristics
dominant biological membranes - two classes in animal cells
what are the two classes of phospholipids?
phosphoglycerides:
- constructed from diacylglycerol
- polar group on third carbon
sphingolipids:
-sphingosine backbone
What are phospholipids broken down by?
phospholipase
what are sphiinggolipids broken down by?
sphingolipase
LIPIDS:
digestion and import of lipids is complicated by what?
hydrophobicity
GI tract secretes what that emusifies lipids into small drolets(micelles)?
bile
dietary fats are broken down into what?
fatty acids and monoglycerides-lipases
lipases is secreted by what?
pancrease
lipids diffuse across cell membrane into what?
enterocyte
Transport of lipids depend on what?
physical properties
Short chains of fatty acids and glycerols are transported in what?
blood
longer chain fatty acids, monoacylglycerides, triglycerides and cholesterol is transported how?
first packaged in the smooth ER and golgi with protein coats- chylomicrons(lipoproteins)
what do chylomicrons do?
released in lymphatic system then in circulatory system- lipoprotein lipase break down triglycerides and used by tissue
lipoproteins in the blood:
how are lipids carried in the blood?
carried as lipoprotein complexes
when carbohydrate and fat intake exceceeds energy demand what happens?
the liver produces and exports it to other tissues for storage in the form of lipoproteins
Gastrointestinal tract:
one way gut- characteristics
one way gut
specialized regions
Gastrointestinal tract:
mechanical breakdown of food occurs where?
mouth, pharynx and esophagus
Gastrointestinal tract:
stomach has what?
acidic compartment
Gastrointestinal tract:
upper or small intestine
digestion and absorption
Gastrointestinal tract:
lower or large intestine
absorption of water
Gastrointestinal tract:
anus
release of indigestible material
Teeth:
whata re the four types?
incisors, canines, premolars, molars
teeth:
shape of teeth relects what?
type of diet
teeth:
incisors and canines are for what?
piercing and tearing flesh
Salivary Glands:
where do the multicellular exocrine glands open to?
into the mouth
what does saliva do? (5)
lubricates food
dissolves food so nutrients can bind to gustatory receptors
cleanses the mouth with antimicrobial properites
contains enzymes that initiate digestion
salivation is controlled by nerve signals
Parasympathetic nerve stimulates what?
ssalivation
sympathetic nerve does what?
inhibits salivation
Gut formation:
what is the gut derived from?
endoderm
What are the threee regions of the gut?
foregut
midgut
hindgut
Characteristics of the Foregut?
esophagus, stomach and the anterior section of the duodenum
forms buds that become the pancreas and liver
characteristics of the midgut
posterior part of duodenum, jejunum, ileum, cecum and 2/3 colon
characteristics of the Hindgut?
final third of colon and rectum
Surface area:
in most animals nutriets and hydrolyzed where?
in the lumen of the GI tract
how is nutrients taken up?
by cells lining the gut
nutrient uptake is improved how?
increasing surface area in two ways:
increasing length of gut
increasing surface undulation (circular folds, villi, microvilli)
Specialized compartments:
what do these do?
increase efficiency of digestion
compartments have functional specializations suce as differences in what?
PH, enzymes, Types of secretory and absorptive cells
muscular vales (sphincters) control what?
passage of food from one compartment to the next
complexity of gut morphology varies across taxa and reflects what?
complexity of the diet and ease of digestion
Ruminants:
this does what?
some mammals possess modifications that improve the digestion of plant materials
Stomach:
surface in composed of waht?
columnar epithelial cells
what do tight junctions do?
prevent leakage across epithelium
Mucous neck cells do what?
secrete mucus
parietal cells do what?q
secrete hydrochloric acid
Chief cells do what?
secrete the protease pepsin
enteroendrocrine cells do what?
secretes hormones into the blood eg. gastrin
Intestines:
most nutrients are absorbed in the intestines four layers, what are they?
mucosa
submucosa (blood and lymphatic vessels, nerves)
circular smooth muscle
longitudinal smooth muscle
Villi of the intestine
Enterocytes do waht?
absorptive cells with microvilli
Villi of the intestine
goblet cells do what?
secrete mucus
Villi of the intestine
enteroendocrine cells do what?
secretes homromes
Villi of the intestine
paneth cells do what?
secretes antimicrobial molecules (lysozyme)
Villi of the intestine
crypt of lieberkuhn
secretes sucrase, maltase, lactase, peptidase
Absorption of peptides:
protein digestion yeilds what?
peptides and AA
Absorption of peptides:
peptides and AA and absorbed into what?
the enterocyte of the small intestine
Peptides are transported across what?
across the apical membrane of the enterocyte by transport systems different than those of AA
