D1 A. Digestive System Flashcards
1
Q
Nutrient
A
A substance that provides nourishment essential for growth and the maintenance of life
2
Q
Essential Nutrients
A
- Carbohydrates (sugar)
- Lipids (fats)
- Proteins
- Vitamins
- Minerals
- Nucleic Acids
Water is not a nutrient even though its essential for life
3
Q
True or False
Starch is a type of carbohydrate
A
True
4
Q
True or False
When fats are digested, amino acids are formed
A
False
5
Q
True or False
Enzymes speed up the rate of digestion
A
True
6
Q
True or False
The large intestine is longer than the small intestine
A
False
7
Q
True or False
Proteins are made up of amino acids
A
True
8
Q
True or False
Proteins are our main source of energy
A
False
9
Q
Dehydration Synthesis Reaction
A
- The creation of larger molecules from smaller monomers
- Water is released
- Also known as condensation reaction
10
Q
Hydrolysis Reaction
A
- A chemical reaction where water molecules break larger molecules (polymers) into smaller ones (monomers)
11
Q
Metabolism
A
The totality of chemical reaction that occur in a cell/organism
- Provide energy
- Enable synthesis to make new materials
12
Q
Anabolism
A
Anabolic reactions build up complex molecules from simple ones
- Formation of macromolecules from monomers
- Condensation reactions
13
Q
Catabolism
A
- Breaks complex molecules into simpler ones
- Releases monomers
- Hydrolysis reactions
14
Q
Organic Compounds
A
- Carbon-containing molecules
Exceptions: Carbonate and oxides of carbon such as carbon dixoide
15
Q
Carbohydrates
A
- Fast energy nutrient
- Largest component in most diets
- Get these from plants → cannot produce them ourselves
16
Q
Carbohydrate Structure
A
- Single sugar (monomers) or chain of many sugar units (polymers)
- Classified by the number of sugars they contain
- Chemical Formula: Usually at a ratio of 1C: 2H : 1O
- “ose” suffix
17
Q
Monosaccharides
A
- Simple sugar (single sugar units); one sugar ring
- 3-6 carbons
* Glucose
* Fructose
* Galactose
18
Q
Isomers
A
- Same chemical formula, but different arrangements of atoms
19
Q
Disaccharides
A
- 2 sugar rings / monosaccharides together
- Formed via dehydration synthesis
- Water molecule is formed from 2 monosaccharides
- Glycosidic bond is formed
- Break disaccharide bond via hydrolysis (opposite)
- Water molecule is used to break bond
- Maltose: 2 sugar units
- Sucrose: 1 glucose + 1 fructose
- Lactose: 1 glucose + 1 galactose
20
Q
Polysaccharides
A
- Carbohydrates fromed from many monosaccharide subunits
21
Q
Polysaccharides
Cellulose
A
- Cellulose: Polysaccharide that makes up plant cell walls (glucose)
- Different bonding that starch and glycogen
- Composed of B-glucose subunits (linear arrangement)
22
Q
Polysaccharides
Glycogen
A
- Glycogen: polysaccharides used in animals to store carbs (glucose)
- Energy storage in humans and animals
- Composed of a-glucose subunits (branched orientation)
23
Q
Polysaccharides
Starch
A
- Starch: Energy storage used in plabnts. Exists in form of amylose or amylopectin
- Amylose: 1000 or more glucose subunits; unbranched polymer of glucose
- Composed of a-glucose subunits (linear)
- Amylopectin: 1000-6000 glucose subunits
- Composed of a-glucose subunits (branched)
24
Q
Lipid Function
A
- Storage of energy (triglycerides)
- Hormonal roles (e.g. steroid hormone)
- Insulation (e.g. sphingolipids)
- Protection of internal cavities (e.g. fats and waxes)
- Structral components of cells (e.g. phospholipids)
25
Lipid Structure
* Non-polar
* Composed of 2 structural units; glycerol and fatty acids
* Combined via dehydration synthesis to form an ester bond
26
Triglycerides
* Long-term energy source
* Glycerol + 3 fatty acids
* Removal of water during synthesis
* Oils: Triglycerides that are liquid at room temp
* Unsaturated fat: Some double bonds between carbon atoms
* 1 double bond → monounsaturated
* 2 or more double bonds → polyunsaturated
* Reactive; more easily broken down
27
Fatty Acids
Fats - Usually solid at room temperature
Saturated Fatty Acid - Only single bond between carbon atoms
* Strong bonds; hard to break down
* COOH is a carboxylic acid
* It's linear shape (14-20 carbons) makes the structure of a fatty acid an acid
* Single bonds between carbons, double bonds between carbon and oxygen
28
# Structural Isomers
Cis Isomer
* H atoms are on same side
* Double bond creates kink
* Are loosely packed (liquid)
* Occurs commonly in nature
* Generally good for health
29
# Structural Isomers
Trans Isomer
* H atoms on different sides
* No kink in chain is created
* Are tightly packed (solid)
* Common in processed food
* Generally bad for health
30
Phospholipids
* Phosphate group bonded to glycerol and 2 fatty acids
* Negatively charged P replaces one of the fatty acids
* Head (phosphate + glycerol): Polar end = soluble in water
* Tail (fatty acids): Non-polar = insoluble in water
31
Waxes
* Long-chain fatty acids joined to long-chain alcohols or to carbon rings
* Insoluble in water
* Waterproof coating on plant leaves, animal feather, fur
32
Energy Storage - Lipids vs. Carbohydrates
**S**torage
* Carbohydrate - Short term
* Lipid - Long term
**O**smotic effect
* Carbohydrate - More effect on cell
* Lipid - Less effect on cell
**D**igestion
* Carbohydrate - Readily digested
* Lipid - Less easily digested
**A**TP yield
* Carbohydrate - Lower (rougly half)
* Lipid - Higher (roughly x2)
**S**olubility
* Carbohydrate - Water soluble (monomers)
* Lipids - Not water soluble
33
Body Mass Index
BMI = Mass in kg / (height in m)2
* Value between 18.5 - 24.9 is healthy
34
Protein Functions
1. Defense (antibodies)
2. Movement
3. Catalyst (enzyme)
4. Signalling (hormone)
5. Structure (mechanical support)
6. Transport (carrier/channel proteins, hemoglobin)
35
What are proteins made out of
* Amino acids
* Carbon
* Oxygen
* Hydrogen
* Nitrogen
* Sulfur
36
How many differen amino acids are there
20:
9 ESSENTIAL, 11 NON-ESSENTIAL
37
What determines type of protein
Order and # of proteins
38
Polypeptide
Chain of amino acids
39
# Protein levels of structure
Primary
* Unique sequence of amino acids in the chain
* Determines secondary structure
40
# Protein levels of structure
Secondary
* Formed by hydrogen bonds between peptide chains (between backbone, not R group)
* H bond can pull chain into alpha helix and beta pleated sheets
41
# Types of interactions
Hydrophobic interactions
These amino acids orient themselves towards the center of polypeptide to avoid the water
42
# Types of interactions
Disulphide Bridge
The amino acid cysteine forms a bond with another cysetine through its R group
43
# Types of interaction
Hydrogen Bonds
Polar "R" groups on the amino acids form bonds with other Polar R group
44
# Types of interactions
Hydrophillic Interactions
These amino acids orient themselves outwards to be close to the water
45
# Types of interactions
Ionic Bonds
Positively charged R groups bond together
46
# Types of interactions
Van der Waals
* Weak interactions between hydrophobic side chains
* Increases stability
* Responsible for folding
47
# Types of interactions
Covalent Bonds
* Disulfide bonds
* Form disulfide bridge - Strong links
48
# Protein levels of structure
Teriary
* Depends on 1o and 2o structures
* Additional bending/folding due to interactions between R groups of amino acids
49
Fibrous Protein
* Has a structural role
* Insoluble in water
50
Globular Protein
* Has a functional role
* Soluble in water
51
# Protein levels of structure
Quaternary
* Large, globular proteins
* 2 or more polypeptide chains (same or different)
2: dimer
4: tetramer
* Some polypeptides do not have a quaternary structure
52
Why do proteins fold
To be more stable
53
Denaturation
Uncoil, assume new shape = change in biological property
* When the influencing factor is removed, the protein will assume its original shape
54
2 key coniditons that can denature proteins
1. Temperature - Can disrupt bonds that hold proteins together
2. pH - Can alter charge of protein, and change its solubility/shape
55
Coagulation
Permanent change
* E.g. Boiling an egg = Change in protein shape
56
Genome
All the genes of a cell, tissue, or an organism
57
Proteome
All the proteins produced by a cell, tissue or organism
* Individuals have a unique proteome
* Variable because only some cells produce specific proteins
* Human proteome = 100 000 proteins
* Small differences in DNA = differences in proteome
58
Cholestrol
* Type of lipid found in cell membranes
* Used to synthesize hormones
* Lipoprotein = protein + lipid
* HDL = High Density Lipoprotein (good) (bring LDL to liver to be broken down)
59
Nucleic Acid
* Hereditary material
* Composed of nucleotides
60
Enzymes
* Most reactions are not spontaneous
* Add thermal energy to system = increase kinetic energy = faster, more collision = more likely for reaction to occur
* Enzymes work at low temp.
* 3D proteins that act as catalysts
* Increase reaction probability
* Often end with -ase
61
Catalysts
* A substance that increases the rate of chemical reaction without being changed itself or become part of the product
* Each enzyme usually controls just one reaction
62
Activation Energy
* The energy that must be supplied to cause a reaction
* Enzymes lower the necessary energy of activation
63
4 Steps of Enzyme Action
1. Subrate binds with enzyme
2. Enzyme undergoes confirmational change
3. Substrates converted to products
4. Products are relased
64
Lock & Key Model
* Enzymes act as keys to lock or unlock substrates
* Substrate: Reactants in an enzymatic reaction
* Active Site: Region on enzyme where substrates attach
65
Induced Fit Model
* Replaced lock and key model
* The enzyme (active site) changes shape to fit between site and substrate
* Increases rate of chemical reaction
65
Particle Collision Theory
* The frequency of collisions determines the rate of enzyme activity
* If you increase the probability of collisions occuring, then you increase the frequency of enzyme activity
66
# Factors helping ezyme combine with substrate
Coenzymes
Molecule that assists an enzyme to complete a reaction (organic), synthesized from vitamins
67
# Factors helping enzyme combine with substrate
Cofactors
Inorganic enzyme helpers
68
# Factors affecting enzyme activity
Temperature
* Increase temp. → increase activity, to a point
* Too low of temp. → not enough energy for reaction to occur
* Enzyme is denatured at high temps.
69
# Factors affecting enzyme activity
pH
* Changing pH changes charge/solubility or shape of enzyme
* Decreases ability to bind to the substrate
* Optimal pH = peak enzyme activity and enzyme specificity
70
# Factors affecting enzyme activity
Substrate Concentration
* The greater the number of substrate molecules = the greater the chance of successful collisions
* Plateau because all active sites are occupied
71
# Factors affecting enzyme activity
End Product Concentration
* As enzymes work, they produce an end product
* Some are able to affect another enzymes activity and thus cause feedback inhibition
* Some are poisonous to enzymes in high concentrations
* The substrate can bind to the active site
* Final product attaches to the regulatory site and changes the shape of the enzyme so the substrate cannot bind
72
# Factors affecting enzyme activity
Competitive Inhibitors
* Molecule so close to enzyme's substrate that it competes for the active site
* Inhibitor binds to enzyme and will not allow product to be produced
73
# Factors affecting enzyme activity
Non-competitive inhibitors - allosteric activity
* A chemical binds to a regulatory site causing the active site to change shape
* Enzyme that shapes due to a chemical binding to the regulatory site = allosteric activity
* Sometimes this can cause feedback inhibition (shut off activity)
* Sometimes this can cause a reaction to proceed (precursor activity)
74
# Regulatory of Enzyme Activity - Allosteric Activity
Negative Feedback / Feedback Inhibition
* Occurs when an end product can bind to an enzyme and become a noncompetitive inhibitor slowing the rate of reaction of an enzyme
75
# Regulatory of Enzyme Activity - Allosteric Activity
Precursor Activity
* Substrate molecules accumulate → substrate molecules attach to the regulatory site of an enzyme in a pathway → improves fit between enzyme and substrate → increases reaction rate
76
Digestion
* Process where food is broken down into nutrients your body can use as energy
* Beings in your mouth, finishes at the terminal ileum
77
Mechanical Digestion
Cutting/crushing of food into smaller pieces
78
Chemical Digestion
Breakdown of food using enzymes
79
Peristalsis
Rhythmic muscle contraction of longitudinal muscles
* Occurs in: Esophagus, Stomach, Intestines, Rectum
80
Segmentation
Rhythmic muscle contractions of circular muscles. Moves food back and forth (mixes food)
81
4 Main components of digestive process
* Ingestion (taking in nutrients)
* Digestion (breakdown of complex organic molecules → smaller components by enzymes)
* Absorption (transport of digested nutrients to body cells)
* Egestion (Removal of food waste from body)
82
Roles of saliava
* Contains amylase to breakdown starch
* Lubricates mouth/throat
* Protects teeth from cavity causing bacteria
83
Oral Cavity
* Salivary glands secrete saliava (begins chemical digestion)
* Tongue determines which food needs to be further processed
* Taste buds communicate which food needs to be processed further
* Moves food and helps shape it into a bolus
* When swallowing - pushes bolus to back of oral cavity and pharynx
84
Esophagus
* Flexible tube that leads to stomach
* Secretes mucus
* Passes through the diaphragm to connect with stomach at the lower esophageal sphincter which regulated entry
85
Stomach
* At the left side of the abdodmen
* Secretes gastric juices
* Stores food, continues digestion but does absorb a few compounds
* Has a lining of a layer of mucus which protects it from being digested by pepsin
86
Pyloric Sphincter
Moves food and stomach acid → small intestine
87
Chyme
Ingested food and digestive juice
88
Stomach - Mechanical Digestion
Crisscrossed muscle layers that create chruning and mixing motions
89
Gastrin
A hormone that stimulates release of HCL
90
HCL
* Secreted from parietal cell
* Can convert pepsinogen → pepsin
91
Pepsin
Begings to hydrolyze protein into smaller polypeptides by breaking peptide bonds; works in acidic conditions
92
Stomach - Peptic Ulcer
* Ulcers are open sores that form in stomach/duodenum
* When the mucus layer is reduced, stomach acid can damage the tissue
93
Small Intestine
Responsible for:
* Breaking down food
* Absorbing nutrients
* Solidifying waste
3 Sections:
* Duodenum
* Jejenum
* Ileum
94
# Small Intestine
Duodenum
* Chyme leaves the stomach and enters the duodenum
* Low pH of chyme stimulates hormone secretion
* Secretin causes release of NaHCo3 (sodium bicarbonate) from the pancreas
* NAHCo3 nuetralizes gastric fluid → raising pH to 8
* Amino acids and fatty acids in chyme releases CCK
* CCK stimulates pancreas to release pancreatic enzymes
* CCL stimulates gallbladder to contract and release bile
95
Duodenum response to lipids
* Secretes enterogastrone hormone
* Inhibits secretion of gastric juices by stomach
* Slows down peristalsis; causing food to move slowly
* Thus, increased time for fat digestion
96
Accessory Organs
Food does not pass directly through these organs, but they still contribute to digestion
* Salivary glands
* Pancreas
* Liver
* Gallbladder
97
Pancreas
Endocrine Cells (produces hormones)
* Insulin (decrease blood glucose)
* Glucagon (increase blood glucose)
Exocrine Cells (produce gastric juice) - main digestive enzymes
* Pancreatic amylase
* Proteases
* Pancreatic lipase
98
Liver Functions
* Makes bile
* Cleans toxins out of blood
* Removes old blood cells
* Stores glycogen/vitamins
* Converts glycogen (starch) to sugar
* Breaks down fatty acids
99
Bile
* Stored in gallbladder
* Not an enzyme; it is an emulsifier
* Involved in physical digestion
* Contains bile salts which aid in fat digestion
* When fats are in stomach, signal hormone CCK → blood → gallbladder → trigger gallbladder to release bile salts
100
Small intestine secretions
* Lining of duodenum can also secrete digestive enzymes
* Peristalsis moves mixture of chyme and digestive juices through intestine
* Most digestion complted in duodenum
101
At the end of digestion
* Carbohydrates hydrolyzed to monosaccharides
* Proteins break down into individual amino acids
* Fats hydrolyzed by lipase into glycerol and fatty acids
102
Small intestine secretions
* DNA will also be digested in the enzymes via nucleases
* Will result in nucleotides that cells use to replicate their own DNA
103
Absorption in the small intestine
* Jejenum and ileum main absorption of nutrients and water into circulatory and lymphatic system
* Large folds in lining have fingerlike projections called villi
* Each villi has microvilli
* Increases absorption even more
104
How do the circulatory, lymphatic, and digestive system interact
Each villus has a small lymph vessel and a network of capillaries
105
Lacteal
Absorbs fatty acids and glycerol
106
Capillary
Absorbs nucleotides, amino acids, monosaccharides
107
Epithelial cells are connected by ____ ____
Tight junctions
* Creates impermeable barrier between the body tissues and digestive juices in the lumen
108
Villi Functions
MR SLIM
* **M**icrovilli (increases SA:V)
* **R**ich capillary network (transports digested products)
* **S**ingle-layer epithelium (minimises diffusion distance)
* **L**acteals (absorbs lipids into the lymphatic system)
* **I**ntestinal glands (exocrine pits release enzymes)
* **M**embrane proteins (facilitates transport of products)
109
Methods of membrane transport
* Co-transport (active)
For: Glucose, Amino Acids
* Facilitated Diffusion
For: Monosaccharides
* Osmosis
For: Water
* Simple Diffusion
For: Triglycerides
109
110
# Protein Digestion/Absorption
Secondary Active Transport
Glucose and amino acids are co-transported with sodium ions
111
# Protein Digestion/Absorption
Facilitated Diffusion
Monosaccharides, vitamins and minerals are transported by channel proteins
112
# Protein Digestion/Absorption
Simple Diffusions
Hydrophobic and lipophilic substances (fats) may freely cross the membrane
113
# Protein Digestion/Absorption
Bulk Transport
* Vesicles form around fluid containing dissolved materials
* Pinocytosis takes less time than shuttling materials via membrane proteins
114
Lipid Digestion/Absorption
Lipids are insoluble in water and need to be complexed with proteins in order ot be transported in the blood
* Lipid globules are emulsified by bile salts before being chemically digested by pancreatic lipases
* Components are combined with protein to form chylomicrons which are transported to the liver
* Liver converts chylomicrons into soluble lipoproteins
115
Carbohydrate Digestion/Absorption
* Starch is main polysaccharide in human diets
* Starch is digested via amylase into smaller subunits
* Glucose monomers are used for cell respiration or processed and stored in the liver as glycogen via glycogenesis (liver)
116
# Protein Digestion/Absorption
Protease
* Proteases are secreted in an inactive form so they don't synthesize the cells that digest them
* Activated by specific enzymes or chemical agents (low pH)
117
Large Intestine Function
* Absorb water (mineral and salts)
* Decompose leftover organic material with help of bacteria
* Produce vitamin K and B and folic acid required for red blood cell production
* Stores, eliminates solid waste
118
# Large Intestine
Bowel Movement
* Buildup signal CNS which promts movement
* Stinky because of bacteria
* Removes toxic wastes from body
* Not enough cellulose (fibre) = less movement
119
Large Intestine
* At the end of the small intestine, undigested material pass through the ileocecal sphincter into larger intestine
* Large intestine is wide and short
Three sections:
* Ascending
* Transverse
* Descending
