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Bio 224.3 > Digestive system > Flashcards

Digestive system Flashcards

1
Q

what is digestion

A

process of mechanical and chemical breakdown of food into molecular subunits small enough to be absorbed into body fluids and cells (nutrients)

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2
Q

what is chemical and mechanical breakdown of food

A

-mechanical: chewing
-chemical: enzymes and acids being mixed with food

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3
Q

nutrients

A

substances essential for growth and maintaining life

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4
Q

what are the main functions of the digestive system

A

-breakdown food into smaller molecules that can cross plasma membranes
-food storage
-absorption of nutrients
-elimination of undigested food (feces)

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5
Q

macro-nutrients

A

requires in large amounts (carbohydrates, fat, protein, macro elements)

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6
Q

micro-nutrients

A

required in small amounts (vitamins, trace elements)

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7
Q

essential nutrients

A

animals cannot synthesize themselves and must be acquired from food (essential amino acids, essential fatty acids, vitamins, minerals)

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8
Q

essential amino acids in humans

A

-9 (number varies depending on species)
-lysine, histidine, tryptophan, phenylamine, threonine, valine, methionine, leucine, isoleucine

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9
Q

essential fatty acids in humans

A

-2
-linoleic acid (omega-6)
-linolenic acid (omega-3)

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10
Q

how many essential vitamins in humans

A

-13
-humans can synthesize vitiman D from sunlight

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11
Q

what are the fat soluble essential vitamans in humans

A

-A (retional)
-D (dalciferol)
-E (tocopherol)
-K (napthoquinone)

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12
Q

what are the water soluble essential vitamans in humans

A

-B1 (thiamine)
-B2 (riboflavin)
-niacin
-B6 (pyridoxine)
-pantothenic acid
-folic acid
-B12 (cobalamin)
-biotin
-C (ascorbic acid)

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13
Q

what are the macronutrients for humans

A

-calcium
-chlorine
-chromium
-cobalt
-fluorine
-iodine
-iron
-magnesium
-manganese
-mollybdenum
-nitrogen

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14
Q

what are the essential micronutrients for humans

A

copper

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15
Q

some monosaccharides

A

-glucose, fructose, galactose
-a few of which are normally found in most diets
-absorbable units

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16
Q

some disaccharides

A

-sucrose (glucose and one fructose)
-trehalose (two glucose molecs in opposite orentations)
-maltose (two glucose molecs in the some orientation)
-lactose (milk sugar; glucose and one galactose)

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17
Q

some polysaccharides

A

-chains of interconnected monosaccharides
-most common carbohydrate of animal diets
-starch from plants and glycogen form animals
-both have alpha bonds between the glucose units

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18
Q

cellulose

A

-beta bonds
-most abundant organic molec in the biosphere
-major component of plant material, comprising over half of the plant cell wall
-to be usable must be hydrolyzed into monosaccarides
-we cant break this down because our enzyme cant break down beta bonds

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19
Q

how is glycogen made up

A

-formed form glucose units joined in chains by alpha(1-4) linkages
-side branches are linked to the chains by alpha (1-6) linkages

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20
Q

how is cellulose made up

A

-formed form glucose units joined ends by beta (1-4) linkags
-hundreds to thousands of cellulose chains line up side by side in an arrangement reinforced by hydrogen bonds between the chains, to form cellulose microfibrils in plant cells

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21
Q

what are proteins

A

consists of various combinations of amino acids (absorbable units) held together by peptide bonds

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22
Q

what are most dietary lipids

A

bulk of dietary lipid is triglyceride, but also contains phospholipids, cholesterol, fat soluble vitimans

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23
Q

what are triglycerides

A

glycerol+fatty acids (which is the absorbable units)

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24
Q

how do fats pass through the the gut

A

after being broken down they pass through simple diffusion

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25
Q

how are nucleotides broken down

A

-nucleic acid
-nucleotides
-nucleosides
-ribose and nitrogenous base (which are the absorbable units)

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26
Q

what is a calorie

A

a unit of energy difined as the amount of energy needed to raise the temp of one gram of water by one degree Celsius at a pressure of 1 ATM

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27
Q

how many cals are in a gram of fat, protein, carbohydrates

A

carb/pro=4cal/gram
fats=9cal/gram

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28
Q

what is a unit of energy in international system of units

A

the joule
one cal=4.2 joules

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29
Q

how does are bonds broken during chemical break down in the digestive system

A

-bonds are broken by hydrolytic hydrolysis
-addition of H+ and OH- form water

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30
Q

what enzymes is the chemical break down in the digestive system driven by

A

amylase-starch
lipase-fats and other lipids
protase-proteins
-nucleases-nucleic acids

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31
Q

what kind of vitamins (fat or water soluble) can our body not store thus needs daily supply

A

-water
-fat soluble can be stored by the body water cannot it gets urinated out

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32
Q

what are the two ways digestion can occur

A

-intracellularly
-extracellularly

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33
Q

intracellular digestion

A

cells take in food particles by endocytosis

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34
Q

extracellular digestion

A

takes place in a tube enclosed in body but outside body cells (the digestive tract)

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35
Q

how does intracellular digestion happen in a sponge

A

-H2O carrying food particles
-food enters cell phagocytosis
-goes in food vacuoles
-lysosomes with digestive enzymes merge with food vacuoles
-waste products are expelled by exocytosis

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36
Q

where does extracellular digestion occur

A

in compartments that are continuous with the outside of the animals body

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37
Q

what is the gastrovascular cavity

A

a structure found in primitive animal phyla that functions in both digestion and distribution of nutrients

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38
Q

what is the evolutionary significance of the extracellular digestive system

A

-better food storage
-dont need to eat all the time
-you can ingest a lot more food so allows animals to increase body size, ingest more food=grow larger
-expands the food range (what they can eat)

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39
Q

what are the different classifications for ways animals can acquire nutrients

A

-fluid feeders
-suspension feeders
-deposit feeders
-bulk feeders

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40
Q

fluid feeders

A

ingest liquids containing organic molecules (e.g. tapeworms, mosquitos, insects, birds, bats)

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41
Q

suspension feeders

A

eat small particles of organic matter of small organisms in fluids (e.g. mussels, whales)

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42
Q

deposit feeders

A

ingest small organic particles form solid matter that feeders live on (e.g. earthworm, fiddler crab, polychaete worms)

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43
Q

bulk feeders

A

consume large pieces of organisms, or entire large organisms (e.g. most animals)(mostly carnavores)

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44
Q

tapeworm digesive tract

A

-they have none
-there fore they must eat food already digested by another animal
-they are fluid feeders
-they are parasites inside animals intestines, absorb nutrients directly by diffusion across their skin (cuticle)

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45
Q

what is the digestive system like of a earth work (deposit feeder)

A

-it is divided into many regions each with a certain function
-digestive system consists of mouth, esophagus, crop, intestine, gizzard
-gizzard uses stones the worm eats to grind the food

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46
Q

what is the digestive system of a grasshopper like

A

-foregut=mouth, salivary glands, esophagus, crop, gizzard
-midgut=chemical digestion takes place in the stomach and 6 pairs of gastric ceca extending from stomach, digestion aided by bacteria
-hindgut=coiled structure consisting of anterior ileum, middle colon, posterior rectum, anus

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47
Q

what are the parts that make up the digestive system of birds

A

-the canal includes the oral cavity, esophagus (which includes crop in some birds), stomach (proventeuculus, glandular portion of stomach), gizzard, small intestine, large intestine
-also has accessory structures including the beak, salivary glands, liver, pancreas

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48
Q

carnivore

A

digest animal products

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49
Q

herbivore

A

digest plant products

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50
Q

omnivore

A

digest both plant and animal products

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51
Q

what is the digestive tract of a carnivore like

A

-have a greatly enlarged stomach, which secretes powerful digestive enzymes, along with 10 times more HCL then herbivores

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52
Q

what is the digestive tract of the herbivore like

A

they have a long digestive tract because it take a long time to absorb nutrients form the plant material which they eat. they also have large caecu which helps along with enzyme, breakdown the plant material and cellulose

53
Q

how can mammal be classified by the type of stomach

A

-monogastrics
-ruminants

54
Q

monogastrics

A

they have a simple single chambered stomach such as humans, swine, rabbits, and horses

55
Q

ruminants

A

have a four chambered complex stomach

56
Q

what is the stomach of monogastrics like

A

-muscular digestive organ
-glands in the stomach wall secrete gastric juices
-gastric juices have about 0.2 to 0.5 precent HCL
-stomach muscle mix and sqeeze the food, and forces the chyme to go into the small intestine
-occupies 3/4 of abdominal cavity mostly on left side

57
Q

what is a rumen stomach like

A

-4 chambers
-ferments food prior to digestion through microbial actions
-microbes digest cellulose
-uses lots of water

58
Q

what are the five stages of digestion in animals with a GI tract

A

-mechanical processing
-secretion of enzymes and other digestive aids
-enzymatic hydrolysis
-absorption
-elimination

59
Q

what are the main organs in the human GI tract (alimentary canal)

A

-tube form mouth to anus
-mouth
-pharynx
-esophagus
-stomach
-small intestine
-large intestine

60
Q

what are the accessory digestive organs in the human GI tract to

A

-teeth
-tongue
-salivary glands
-liver
-gullbladder
-pancrease

61
Q

what do the accessory organs help with in the human digestive tract

A

mechanical and digestive organs

62
Q

what are the 4 layers of the GI tract

A

-mucosa
-submucosa
-muscularis
-serosa

63
Q

mucosa

A

-the intermost layer of the GI wall that is surrounding the lumen
-responsible for protection, secretion, and absorbtion
-consists of epithelium, lamina propria (connective tissue), and muscularis mucosae (thin layer if smooth muscle)

64
Q

submucosa

A

-areolar connective tissue
-binds mucosa to muscularis
-acts and glue

65
Q

submucosa plexus

A

network of neurons and ganglia

66
Q

muscularis

A

skeletal muscle (volentary swallowing and volentary control of defication) and smooth muscle (breaks down food and mixes it with digestive sectretions)

67
Q

myenteric plexus

A

part of the enteric nervous system that regulates peristalsis

68
Q

serosa

A

serous membrane of areolar connective tissue and simple squamous epithelium

69
Q

enteric nervous system

A

-submucosal plexus + myenteric plexus
-which more or less works as an anomic nervous system
-with out inputs of the CNS

70
Q

what are the 3 muscle layers of the musculais layer

A

-longitudinal muscle
-circular muscle
-oblique muscle

71
Q

mouth

A

where food is taken in an where digestion begins

72
Q

oral cavity

A

chamber contains teeth and tongue, and receives secretions from the salivary glands

73
Q

digestion

A

mechanical and chemical begins in the mouth

74
Q

what happen when food enters the mouth

A

-salivary glands secrete saliva
-salivary amylase digests starch
-saliva (mucus) acts as a softener/lube
-facilitates swallowing of food
-salivary lipases aids in triglyceride digestion

75
Q

where is the parotid salivary gland found

A

infront of the ear

76
Q

where is the salivary duct found

A

opens into the cheek form the parotid salivary gland

77
Q

what does the tongue do

A

moves food during chewing and swallowing

78
Q

where is the sublingual salivary found

A

under the tongue

79
Q

where is the submandibular salivary gland found

A

lies deep in the mouth

80
Q

what happen when bolus is swallowed

A

goes through the pharynx and esophogus to stomach
-epiglottis blocks trachea

81
Q

why is swallowing important

A

it plays a major role in preventing the entrance of food into the respiratory tract

82
Q

is swallowing voluntary or involuntary

A

it involves both voluntary (oral) snd involuntary (pharyngeal and esophageal) phases

83
Q

explain how the esophagus changes through out swallowing (before swallowing)

A

-before swallowing the pheryngoesophageal sphincter muscle is contracted, closing esophogus, the epiglottis is up and the glottis is open to let air in lungs

84
Q

explain how the esophagus changes through out swallowing (during swallowing)

A

-relflex begings when bolus reaches the pharynx
-elevation of soft palate prevents food bolus form entering nasal pasage
-pressure of tongue seals back of mouth and prevent bolus from backing up
-larynx moves up, pushign glottis to prevent bolus form entering airway
-pharyngoesphageal sphincter muscle relaxes, permitting bolus to enter esophagus
-once food is in the esophogus structures of mouth and pharynx reset to non swallow state

85
Q

explain how the esophagus changes through out swallowing (during peristalsis)

A

-circulatory muscle of the espohogus contract behind the food blocking upward movement
-longitudinal muscle of the esophagus contract, opening up the esophagus
-in concert with the constricting circular muscles this pushes the bolus down the esophogus
-series of alter contracts and relaxations of circ and longitudal muscles produces peristaltic waves that move bolus to stomach

86
Q

what is paristalsis

A

involentary contractions and relaxations of the GI tract

87
Q

how are peristalsis waves produced

A

coordinated contractions of circular and longitudal muscles produce peristaltic waves that move digestive contents from mouth to anus

88
Q

what are the functions of the stomach

A

-food is mixed with stomach acid and enzymes to break down the food into smaller prices
-reservoir of food before released to small intestine

89
Q

what is chyme

A

the combination of food and stomach juices

90
Q

what is the function of HCl

A

it doesnt digest food but it does break down the connective tissue of meat and activates pepsin

91
Q

what is the mucus of the stomach for

A

its several mm thisch and it protects the cell wall from the effects if HCl

92
Q

what are the different cells found in the gastric pits of the stomach

A

-surface epithelial cells
-mucous cells (secretes mucus)
-parental cell (secretes H+ and Cl-)
-chief cells (secretes pepsinogen)

93
Q

what happens to the gastric walls when food enters the stomach

A

they stretch which releases HCl

94
Q

what happens when pepsinogen and HCl are secreted into gastric lumen

A

-HCl cleaves pepsinogen to produce pepsin
-pepsin catalyzes conversion of more pepsinogen to pepsin leading to high amounts of pepsin
-digestion of proteins

95
Q

what are the measurements of the small intestine

A

-small diameter (2.5cm)
-6 m long

96
Q

what is the pH of the small intesine like

A

it is slightly basic

97
Q

what is the duodenum, jejunum and iieum length

A

-dou (first 25m)
-jej (2.2-2.4m)
-iileum (3.3-3.6m)

98
Q

what connects the large intestine to small intestine

A

Ileocecal sphincter

99
Q

what is the SA of the small intestine

A

approximately the size of a tennis court

100
Q

what does the inside of the small intestine have to inc SA

A

-projections called villi (sing villus)
-the outer layer of each villus has thousands of microvilli

101
Q

what does the villi contain

A

blood and lymphatic capillaries

102
Q

intentional juices

A

-1-2 L per day
-water and mucus
-slightly alkaline (HCO3-)
-brush-border (microvilli) enzymes

103
Q

what kind of enzymes does the intestinal juice of the intestine have

A

-carbohydrate digesting
-protein digesting

104
Q

what happens in the douodenum

A

digestive juices form the pancreas and liver add enzymes and digestive aids to food mass

105
Q

what are pancreatic juices

A

-digestive enzymes (e.g. amylase, protases, lipases
-HCO3- ions (neutralizes)

106
Q

how does the liver aid in digestion and what does it secrete

A

-secrets bile which emulsifies fats
-bile salts
-cholesterol
-bilirubin
-additional bicarbonate ions

107
Q

what stores bile

A

gullbladder

108
Q

what do the exocrine cells from the pancrease secrete

A

pancreatic enzymes

109
Q

what do the endocrine cells form the pancreas secrete

A

insulin and glucogon into blood stream

110
Q

what is the carbohydrate digestion system

A

-mouth=polysaccharides>smaller polysaccharides, disaccharides (salivary amylase)
-lumen of small intestine=polysaccharides> disaccharides (pancreatic amylase)
-eipthelial cells (brush border) of small intestine=disaccharides(malt, suc, lac) > monosaccharides (glucose) (disaccharidases)

111
Q

what is the protein digestion process

A

-stomach=proteins> peptides (pepsin)
-lumen of sml intest=proteins> peptides (trypsin, chymotrypsin) and large peptides> AAs (carboxypeptidase)
-eipthelial cells (brush border) of small intestine=large peptides> AAs (amino peptidase)
-dipeptides>AAs (dipeptidase)

112
Q

what is the digestive process of fats

A

lumen of small intestine=triglycerides and other lipids>fatty acids, monoglycerides (lipase)

113
Q

what is the digestive process of nucleic acids

A

-lumen of sml int=DNA, RNA>nucleotides (pancreatic nucleuses)
-nucleotides> nitrogen bases, 5C sugars, phosphotates (nucleotidase, nucleosidase, phosphates)

114
Q

how are water soluble nutrients absorbed in GI

A

water soluble molecules are broken into absorbable subunits at brush borders of mucosal cells and transported inside; the subunits are transported on the other side to the extracellular fluids and blood

115
Q

what are the water soluble nutrients

A

-proteins, sugars, nucleotides

116
Q

what are fat soluble nutrients

A

-products of lipid breakdown (FA, monoglycerides)
-fat soluble vitimans and cholesterol

117
Q

how do fat soluble nutrients get absorbed

A

-when a micelle contacts the plasma membrane of a mucosal cell, the hydrophobic molecs within the droplet fuse and penetrate the membrane and enter the cytoplasm

118
Q

what is a micelle

A

fats coated with bile salts

119
Q

what are chylomicrons

A

-in mucosal cells fatty acids and momnoglycerides are re-combined into triglycerides and packages into chylomicrons
-small droplets covered by a protein coat
-hydrophilic surface that keeps the droplets suspended in the cytosol

120
Q

what happens to cholesterol and chylomicrons

A

-cholesterol absorbed in the small intestine is also packed into chylomicrons
-after travelling across the mucosal cells the chylomicrons are secreted into the interstitial fluids of the submucosa
taken up by the lymph vassels and transferred into blood stream

121
Q

what are many nutrients absorbed by the small intestine absorbed by

A

the liver

122
Q

how are nutrients from the small intestine absorbed into the liver

A

-capillaries absorbing nutrient molecules in the small intestine collect into veins that join to form the hepatic portal vein
-a larger blood vessel that leads to capillary networks in the liver small droplets covered by a protein coat
-in the liver some nutrients leave the blood stream and enter the liver cells for chemical processing

123
Q

what makes up the large intestine

A

-cecum, appendix, colon, rectum

124
Q

what does the large intestine do

A

-secretes mucus and HCO3- ions
-absorbs water (1.3-1.5L/day) and other ions (mainly Na+ and Cl-)

125
Q

what happens with matter at the end of the large intestine

A

undigested remnants are expelled form the anus

126
Q

how many bacteria species live in the intestine

A

and many as 500. makes up to 30-50% of the dry matter of feces

127
Q

what is most common bacteria found in the human (and most mammals) digestive tract

A

-escherichia coli
-metabolizes sugars and other nutrients remaining in the digestive residue

128
Q

what do microbe in the intestine do

A

-produce useful fatty acids and vitamins such as: vit K, B group of vitimans (folic acid and biotin) some of which are absorbed in the large intestine
-produces a large quantity of gases: CO2, methane, and hydrogen sulfide

Bio 224.3 (12 decks)

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