Digestive System Test

what are the functions of the digestive system

ingestion, mechanical processing, digestion, secretion, absorption, excretion

ingestion

food entering the mouth

mechanical processing

physical manipulation by tongue, teeth, swirling, mixing

digestion

chemical breakdown

secretion

release of water, acid, enzymes, and buffers

absorption

organic molecules, water, electrolytes, and vitamins move into cells

excretion

removal of wastes compacted into feces and gotten rid of by defecation

serous membrane

thin moist sheet of lubricating tissue of the alimentary canal

peritoneum

most extensive serous membrane in the body found in the alimentary canal

visceral peritoneum

covers surfaces of digestive organs (serosa)

peritoneal cavity

the space between the parietal and visceral peritoneum that contains serous fluid to reduce friction

falciform ligament

connects liver to abdominal wall and diaphragm

lesser omentum

between the stomach and liver hangs over stomach and small intestine

mesentery

suspends coils of small intestine from posterior abdominal wall *lacey*

greater omentum

double layered fold of visceral peritoneum of the stomach and small intestine

what are the layers of the alimentary canal

mucosa, submucosa, muscularis, serosa

what are the functions of the mucosa

Protection from microbes Absorption of nutrients
Secretion of mucus +enzymes

what are the functions of the submucosa

Nourishment
Removing absorbed material

what are the two layers of the muscularis

Inner: composed of circular fibers with thickened areas forming sphincters
Outer: made of longitudinal fibers

sphincters

muscular valves to control food or material passage from one organ to another

what are the functions of the muscularis

Mixes materials during mechanical digestion
Propulsion via peristalsis

peristalsis

movement of food through rhythmic contractions

serosa

a.k.a. visceral peritoneum and outer covering of alimentary canal that secretes serous fluid

how much food can the stomach temporarily store

one liter

rugae

deep folds of inner lining of the stomach "wrinkles"

what are the divisions of the stomach

cardia, fundas, body, pyloris

cardia

small area around esophagus entrance

fundas

bulging area above cardiac for temporary storage

pyloris

inferior end of stomach with sphincter and moves chyme

chyme

semi-fluid paste of food and gastric juice

stomach wall

has 4 alimentary canal layers but mucosa/muscularis differ

mucosa of stomach

millions of little pits (gastric pits) that lead to gastric glands which secrete gastric juices

what are the gastric juice cells

zymogenic (chief) cells, parietal cells, mucous cells

zymogenic (chief) cells

secrete digestive enzymes

parietal cells

secrete HCl and intrinsic factor

mucous cells

secrete mucus

what are the functions of the stomach

mechanical digestion, chemical digestion, absorption, propulsion, intrinsic factor

how does chemical digestion happen in the stomach

by gastric juices and pepsin

how are digestive enzymes pepsin secreted

inactive form as pepsinogen so as not to hurt chief cells that made it

when does pepsinogen become pepsin

mixes with HCl

gastric ulcers

holes in stomach

how fast does each macromolecule get out of the stomach

carbohydrates move the fastest, then proteins, then fats take the longest to get out of the stomach

intrinsic factor

secreted by parietal cells of gastric gland to help vitamin B12 to be absorbed by the small intestine

what does B12 help make

red blood cells

what gets gastric glands moving as soon as you see food

hypothalamus

what relays a message back to the stomach wall to secretory cells to produce gastrin

medulla oblongata

gastrin

a hormone that stimulates the continued production of gastric juice and peristalsis

what do the hormones secretin and CCK cause

digestion to slow down in the stomach and secretion of pancreatic enzymes and bile from the lives to enter the small intestine

exocrine glands

has ducts to exit hormones to body surface

endocrine glands

hormones are secreted directly into the blood and are produced in one area but have an affect elsewhere

how is the stomach an exocrine gland

excretes HCl, mucus, intrinsic factor, pepsinogen

how is the stomach an endocrine gland

secretes gastrin, CCK, secretin

how is the pancreas an exocrine gland

excretes pancreatic juice

how is the pancreas an endocrine gland

secretes insulin

what does pancreatic juice act as

pH buffer to combat the acidity from the chyme that goes into the duodenum, released into the blood as secretin, and enters the pancreas

hyperglycemic

increase insulin to absorb simple sugar and tells liver to store glucose as glycogen

hypoglycemic

releases glucagon to tell the liver to release glycogen (a hormone) into sugars

acini

secrete a mix of enzymes collectively called pancreatic juice

common bile duct

tube originally from the liver

islets of langerhans

endocrine gland cells that empty hormones directly into the bloodstream to produce insulin and glucagon

what does pancreatic juice digest

all macromolecules

pancreatic amylase

digests carbohydrates and continues the work begin by salivary amylase

what enzymes digest proteins

trypsin, chymotrypsin, carboxypeptidase

what enzyme digests fats into glycerol and fatty acids

pancreatic lipase

what enzyme digests nucleic acids

nucleases

what is the largest visceral/internal organ

liver

why is the left lobe of the liver smaller

stomach and pancreas are in the way

hepatocytes

liver cells

sinusoids

blood-filled spaces that separate adjacent columns of liver cells

Kupffer cells

liver macrophages that remove bacteria arriving with blood in the sinusoids from the digestive tract

bile canaliculi

small channels carrying bile in the liver

emulsification

breaking fat into tiny droplets which increases surface area to move digestion

what are the functions of the liver

stores iron and B12, stores glucose as glycogen, packages fat. metabolizes proteins and converts toxic chemicals into urea

lipoproteins

packages of fat that are sent to other cells

what are the types of lipoproteins

VLDL, LDL, HDL

VLDLs

very low density lipoproteins that go straight to adipose for fat storage

LDLs

low density lipoproteins that move cholesterol to cells

what can cause atherosclerosis or the hardening of arteries

LDLs

HDLs

high density lipoproteins that transport cholesterol to live to make bile, repair cells, help cells grow

what does the liver do with any chemicals it cannot detoxify

stores them

what are the functions of the gall bladder

store and concentrate bile

where does bile come in from to the gallbladder

cystic duct

when can bile leave the gallbladder through the common bile duct

sphincter of Oddi opens

what are the segments of the small intestine

duodenum, jejunum, ileum

duodenum

receives chyme from the small intestine

jejunum

second part of the small intestine that absorbs the most

ileum

unites with the large intestine at the ileocecal value (sphincter) and regulates the flow of chyme

what is the intestinal wall covered by

intestinal villi with each covered by microvilli that increase surface area

each villus of the small intestine has what

a lacteal or its own blood and lymph vessels

Peyer's patches

lymphatic nodules in the small intestine that protect the body from microorganisms that try to invade the intestinal wall

Brunner's glands

secrete alkaline mucus to help increase the chyme's pH in duodenum

plicae circularus

permanent folds in small intestine

how are carbohydrates digested

mouth\>salivary amylase\>monosaccharide\> complete in small intestine\> diff. of glucose and fructose

how are proteins digested

stomach\>enzymes from pancreas and small intestine mucosa

how are fats digested

bile salts and enzymes in the small intestine\> fatty acids and glycerol\> lacteal\> blood

improper diet and bacteria can cause peristalsis to increase which causes what

diarrhea

what are the segments of the large intestine

cecum, colon, rectum, anal canal

what are the parts of the colon

ascending, transverse, descending, sigmoid

what are the sphincters of the anal canal

internal-involuntary
external-voluntary

large intestine absorbs water so chyme hardens into what

feces