unit 4 study guide Flashcards
describe the main functions of the digestive system
- take in food
- breaking it down into nutrient molecules
- absorbing molecules into the bloodstream
- ridding the body of any indigestible remains
describe the difference between mechanical and chemical digestion
mechanical - chewing, mixing food with saliva, chumming food in stomach, and segmentation
segmentation
local constriction of intestine that mixes food with digestive juices
1st layer of the digestive tract
- mucosa: tunic layer that lines lumen
- secretes mucus, digestive enzymes, and hormones
- absorbs end products of digestion
- protects against infectious disease
2nd layer of the digestive tract
- submucosa
- consists of areolar connective tissue
- contains blood and lymphatic vessels
- has an abundant amount of elastic tissues
3rd layer of the digestive tract
- muscularis externa
- muscle layer responsible for segmentation and peristalsis
- circular, longitudinal muscle
4th layer of the digestive tract
- serosa
- outermost layer
- made up of visceral peritoneum
mesentery
double layer of peritoneum
splanchnic circulation
arteries that branch off aorta to serve digestive organs
hepatic portal circulation
drains nutrient-rich blood from digestive organs
delivers blood to liver for processing
mouth
food is chewed and mixed with enzyme-containing saliva that begins process of digestion, and swallowing process is initiated
-soft and hard palate
tongue
occupies the floor of the mouth
- gripping, repositioning, and mixing of food during chewing
- formation of bolus, mixture of food and saliva
lingual frenulum
attachment to floor of mouth
ankyloglossia
congenital condition in which children are born with an extremely short lingual frenulum (tongue tied)
saliva
-cleanses mouth
- dissolves food chemicals for taste
- begins breakdown of starch with enzyme amylase
salivary glands
parotid
submandibular
sublingual
salivary glands composed of what cells
- serous cells: produce watery secretion, enzymes, ions, bit of mucin
- mucous cells: produce mucus
composition of saliva
- mostly water
- slightly acidic
- electrolytes
- contains enzymes salivary amylase and lingual lipase
- proteins
-metabolic wastes: urea, igA
-lysozyme`
teeth
lie in sockets in gum covered margins
-mastication
pharynx
allows passage of food, fluids, and air
esophagus
flat muscular tube that runs from laryngopharynx to stomach
heartburn
cause by stomach acid regulating into esophagus
deglutition
- buccal phase - voluntary contraction of tongue
- pharyngeal-esophageal phase - involuntary contraction
stomach
temporary storage tank that starts chemical breakdown of protein digestion
chyme
bolus of food to paste
types of gland cells of the stomach
- mucous neck cells
secrete thin, acid mucus - parietal cells
secrete hydrochloric acid (HCL)
- denatures protein, activates pepsin
intrinsic factor
- required for absorption of vitamin B12 - chief cells
secrete pepsinogen , that is activated by pepsin
pepsin
lipase - enteroendocrine cells
paracrine: serotonin & histamine
Hormones: somatostatin & gastrin
gastrin
stimulates HCI secretion in stomach
somatostatin
inhibits GI activity and the secretion of insulin and glucagon
bile
fat emulsifier
galbladder
storage of bile
liver
digestive function is production of bile
- detoxifies blood
- removes and stores nutrients
- stores iron and vitamins A,D,E, and K
- produces urea after breaking down amino acids
hepatic artery
supplies oxygen
hepocytes
increased rough and smooth ER, Golgi apparatus, peroxisomes, and mitochondria
jaundice
can be cause by liver failure
- blockage can cause bile salts and pigments to build up in blood
exocrine
produce pancreatic juice
endocrine
secretion of insulin and glucagon `
amylase
digest starch (carbs)
lipase
digest fat
nucleases
break down nucleic acids
protease enzymes
for protein digestion
secretin
secreted by duodenum
secretin
secreted by duodenum
when secreted by HCI and chyme, the gall bladder is stimulated to release bile and pancreatic juice
cholecystokinin (CCK)
release by the duodenum when proteins and fats are present
stimulates output of pancreatic juice
small intestine
the major organ of digestion and absorption
ileocecal valve
point at which it joins large intestine.
villi
fingerlike projections of mucosa
lymphatic capillary- lacteal for absorption
microvilli
cytoplasmic extensions of mucosal cell that give fuzzy appearance
brush border- final carbohydrate and protein digestion
intestinal crypts
tubular glands scattered between villi
villi
absorbs nutrients and electrolytes
crypts
produce intestinal juice, carrier fluid for chyme
peyers patches
aggregated lymphoid nodules
lamina propria
also contains large numbers of plasma cells that secrete igA
large intestine
- propulsion of feces to anus and defecation
- vitamins, water, and electrolytes are reclaimed
digestion
catabolic process that breaks macromolecules down into monomers small enough for absorption
hydrolysis
water is added to break chemical bonds
absorption
is the process of moving substances from lumen of gut into body
emulsification
triglycerides and their breakdown products are insoluble in water
diffusion
lipid products leave micelles and cross epithelial membrane via diffusion
anabolism
synthesis of large molecules from small ones
catabolism
hydrolysis of complex structures to simpler ones
post absorptive state
- catabolism of fat, glycogen, and proteins exceeds anabolism
insulin
hormone that stimulates glucose uptake
glucacon
hormone that stimulates a rise in blood glucose levels
metabolic role of the liver
- process nearly every class of nutrient
- maintains blood glucose levels
-primary site of fat metabolism - site of plasma protein metabolism
- regulating plasma cholesterol levels
- store vitamins and minerals
- metabolize alcohol, drugs, hormones, and bilirubin
glycolysis
converts glucose to pyruvic acid
glycogenesis
polymerizes glucose to form glycogen
glycogenolysis
hydrolyzes glycogen to glucose monomers
gluconeogenesis
forms glucose from noncarbohydrate precursors
