Circulatory & Digestive System Flashcards
Metabolism
the sum of all chemical reactions that occur in the body
can be divided into catabolic reactions & anabolic reactions
Ingestion
the acquisition & consumption of food & other raw materials
Digestion
the process of converting food into a usable solution form so that it can pas through membranes in the digestive tract & enter the body
Absorption
the passage of nutrient molecules through the lining of the digestive tract into the body proper
Transport
the circulation of essential compounds required to nourish the tissues & the removal of waste products from the tissues
Assimilation
the building of new tissues from the digested food materials
Respiration
the consumption of oxygen by the body
Excretion
the removal of waste products produced during metabolic processes like respiration & assimilation
Regulation
the control of physiological activities homeostasis & irritability
Growth
an increase in size caused by cell division & synthesis of new materials
Reproduction
the generation of additional individuals of species
Respiration
-involves the conversion of the chemical energy in molecular bonds into the usable energy needed to drive the processes of living cells
External Respiration
refers to the entrance of air into the lungs & gas exchange between the alveoli & the blood
Internal Respiration
includes the exchange of gas between the blood & the cells & the intracellular processes of respiration
Dehydrogenation
the process of high-energy hydrogen atoms being removed from organic molecules
Glycolysis
- a series of reactions that leads to the oxidative breakdown of glucose into two molecules of pyruvate, the production of ATP & the reduction of NAD+ into NADH
- occurs in the cytoplasm
- defined as the sequence of reaction that converts glucose into pyruvate with the concomitant production of ATP
Glycolytic Pathway
Glucose (hexokinase) -> Glucose-6-phosphate (phosphoglucose isomerase) -> Fructose-6-phosphate (phosphofructokinase) -> Fructose 1,6 biphosphate (fructose biphosphate aldolase) -> 1,3 diphosphoglycerate -> 3 phosphoglycerate -> 2 phosphoglycerate -> phosphoenolpyruvate -> pyruvate
phosphorylation
from one molecule of glucose 2 molecules of pyruvate are obtained
2 ATP are used and 4 are generated
net of 2 ATP
Anaerobic metabolism
only produces 2 ATP per glucose
Glycolysis
Glucose + 2ADP + 2pi + 2NAD+ -> 2 pyruvate + 2ATP + 2NADH + 2H+ + 2H2O
Anaerobic Conditions
pyruvate can be reduced under fermentation
Aerobic Conditions
pyruvate is oxidized during cellular respiration in the mitochondria
Fermentation
NAD+ must be regenerated for glycolysis to continue in the absence of O2 (reduce pyruvate into ethanol or lactic acid
Alcohol fermentation
occurs in yeast and some bacteria
Lactic Acid fermentation
occurs in certain fungi and bacteria and in human muscle cells during strenuous activity - in the form of lactic acid
Cellular Respiration
- the most efficient catabolic pathway used by organisms to harvest the energy stored in glucose
- can yield 36-38 ATP
- it is an aerobic process
- oxygen acts as the final accept of electrons that are passed from carriers during the final stage of glucose
Pyruvate Decarboxylation
pyruvate is transported from the cytoplasm into the mitochondrial matrix where it is decarboxylated adn the acetyl group is transferred to coenzyme A to form acetyl CoA
Citric Acid Cycle (Krebs Cycle)
- cycle begins when the two-carbon acetyl group from acetyl CoA combines with oxaloacetate, a four-carbon molecule, to form the six-carbon citrate
- for each turn of the citric acid cycle, one ATP is produced by substrate-level phosphorylation via a GTP intermediate
- NAD+ -> NADH FAD -> FADH2
- these coenzymes then transport the electrons to the electron-transport chain, where more ATP is produced via oxidative phosphorylation
2x3 NADH -> 6NADH
2x1 FADH2 -> 2 FADH2
2x1 GTP (ATP) -> 2ATP
net reaction: 2acetyl CoA + 6NAD+ + 2FAD + 2GDP + 2Pi + 4H2O -> 4CO2 + 6NADH + 2 FADH2 + 2GTP +4H+ + 2CoA
Electron Transport Chain
-a complex carrier mechanism located on the inside of the inner mitochondrial membrane
-most molecules of ETC are cytochromes (electron carriers that resemble hemoglobin to the structure of their active site)
2H+ + 2e- + 1/2O2 -> H2O
Total Energy Phosphorylation
-to calculate the net amount of ATP produced per molecule of glucose, we need to tally the number of ATP produced by substrate-level phosphorylation and the number of ATP produced by oxidative phosphorylation
Substrate-level Phosphorylation
-degradation of one glucose molecule yields a net of two ATP from glycolysis and one ATP for each turn of the citric acid cycle (4 total ATP)
Oxidative Phosphorylation
- the process that produces more than 90% of the ATP used by the cells in our body
- major steps involved occur within the ETC or respiratory chain of the mitochondira
Eukaryotic ATP Production
Glycolysis
2 ATP invested (steps 1 and 3) -2ATP
4 ATP generated (steps 6 and 9) +4 ATP (substrate)
2 NADH x 2ATP/NADH (step 5) +4 ATP (oxidative)
Pyruvate Decarboxylation
2 NADH x 3 ATP/NADH +6 ATP (oxidative)
Citric Acid Cycle
6 NADH x 3 ATP/NADH +18 ATP (oxidative)
2 FADH2 x 2 ATP/FADH2 + 4 ATP (oxidative)
2 GTP x 1 ATP/GTP +2 ATP (substrate)
total: 36 ATP
Carbohydrates
disachharides are hydrolyzed into monosaccharides, most of which are converted into glucose or glycolytic intermediates
Fats
- stored in adipose tissue in the form of triglycerides
- when needed, hydrolyzed by lipases to fatty acids & glycerol & are carried by the blood to other tissues for oxidation
- a fatty acid must first be activated in the cytoplasm then transported into the mitochondrion and taken through a series of beta-oxidation cycles that convert it into two-carbon fragments, which are then converted into acetyl CoA
- acetyl CoA then enters the citric acid cycle fats yield the greatest number of ATP per gram
Proteins
- the body degrades proteins only when not enough carbohydrates or fat is available
- most amino acids undergo a transamination reaction in which they lose an amino group to form an alpha keto acid
- oxidative deamination removes an ammonia molecule directly from the amino acid
Enzymes
- regulate metabolism by speeding up certain chemical reactions
- they decrease the activation energy
- they are proteins
- many enzymes are conjugate proteins so they operate with coenzymes meaning both must be present in order to function
- enzymes do no alter the equilibrium constant
- enzymes are not consumed in the reaction
- enzymes are pH & temperature sensitive
- catalyzed reactions are reversible
Organic catalyts
any substance that affects the rate of a chemical reaction w/o itself being changed
Substrate
the molecule upon which an enzyme acts
Active site
the area on each enzyme, which a substrate ends
Lock & Key Theory
the spatial structure of an enzyme’s active site is exactly complementary to the spatial structure of substrate
Induced Fit Theory
- the active site has flexibility of shape
- when the appropriate substrate comes in contact w/ the active site, the confirmation of the active site changes to fit the substrate
Enzyme Specificity
- depend on several environmental factors including temp, pH, & concentration
- as temp rises, the rate of enzyme increases until an optimum temp is reached
- beyond optimal temp, heat alters the shape of the active site of the enzyme & deactivates it leading to a rapid drop in rate of action
- pancreatic enzymes work optimally in alkaline conditions of the small intestines
Pepsin
works best in highly acidic conditions
Competitive Inhibition
- active site of an enzyme is specific for a particular substrate or class of substrates
- if a similar molecule is present to the substrate, it will compete for the site and interfere w/ enzyme activity
Noncompetitive Inhibition
- a substance that forms strong covalent bonds w/ an enzyme, making it unable to bind w/ its substrate
- it is irreversible
- reaction will never reach Vmaz
- when the inhibition takes place at a site other than the active site, it is called allosteric inhibition
Allosteric Inhibition
changes the structure of the enzyme so that the active site is also changed
Hydrolysis
reactions function to digest large molecules into smaller components
Lactase
hydrolyzes lactose to the monosachharides glucose & galactose
Protease
degrade proteins to amino acids
Lipases
break down lipids to fatty acids and glycerol
Synthesis
can be catalyzed by the same enzymes as hydrolysis reactions, but can be reversed
Cofactors
may be required by an enzyme to be activated (Zn2+ or Fe2+)
