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159 Cards in this Set
- Front
- Back
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What are the types of muscle tissue?
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Skeletal, Cardiac, Smooth
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Describe skeletal muscle.
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attaches bone, skin or fascia
striated with light and dark bands voluntary control of contraction and relaxation |
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Describe cardiac muscle.
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striated in appearance
involuntary control autorhythmic uninucleated gap junctions neural and hormonal regulation |
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Describe smooth muscle.
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attached to hair follicles in skin
in walls of hollow organs, bl. vessels and GI nonstriated in appearance involuntary |
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Muscle fibers are filled with threads called _____ separated by _____?
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myofibriils; sarcoplasmic reticulum
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What are the contractile proteins of muscles?
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myofilaments
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Describe the SR and what is stored there?
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System of tubular sacs similar to sooth ER in nonmuscle cells
Stores Ca+2 in relaxed muscles Release of Ca+2 triggers muscle contraction |
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What are the supporting proteins in myofilaments?
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M line, titin, Z disc
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Thick filaments are composed of what?
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myosin
each molecule resembles 2 golf clubs twisted together myosin heads (cross bridges) extend towards the thin filaments |
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Myosin is held in place by what?
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M line proteins
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Thin filaments are made of what?
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Actin, troponin, tropomyosin
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In a relaxed muscle the myosin-binding site on each actin molecule is covered by what?
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tropomyosin
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Thin filaments are held in place by what?
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Z line
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What are all the steps in the contraction cycle?
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Myosin heads are activated by ATP
Activated heads attach to actin & pull (power stroke) ADP is released. (ATP binding & hydrolysis release of Pi & ADP & energy Thin filaments slide past the thick filaments ATP binds to myosin head & detaches it from actin All of these steps repeat over and over if ATP is available & Ca+2 levels near the troponin-tropomyosin complex is high |
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Does cardiac or skeletal muscle have a longer contraction period?
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cardiac
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What are the 2 types of cardiac muscle?
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single-unit visceral smooth muscle tissue
multiunit smooth muscle tissue |
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Describe unitary (single unit) SmM.
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many fibers contract as a single unit
fibers are aggregated in sheets or bundles cell membranes are adheared (no insulation) Gap junctions - syncytial non-nervous control can stimulate syncytium Ex. visceral organs |
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Describe multi-unit SmM.
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Each fiber is dicrete unit
Fibers are covered (insulated) Neural control - no autorhythmicity Ex. ciliary and iris muscles in the eye, piloerectors |
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Does SmM have T tubules?
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no
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What type of SR does SmM have?
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rudimentary SR
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Where does the majority of Ca+2 come from for SmM?
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extracellular fluid
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Myosin filaments form ____ cross-bridges.
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sidepolar
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Sidepolar cross-bridges allow SmM to contract as much as ___% compared to SkM ____%
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80%; 30%
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What does Ca+2 bind to in smooth muscle? This means what is missing?
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calmodulin; troponin
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SmM has no NMJ, but has what?
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diffuse junctions
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What type of innervation does SmM have?
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autonomic
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What type of response does Ach or norepinephrine?
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they can be excitatory or inhibitory
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The contraction of SmM starts ____ and lasts _____.
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Slow; longer
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What replaces troponin in SmM?
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calmodulin
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A single contraction cycle of SmM is shorter or longer than SkM and how much shorter or longer?
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Longer; 10-30x
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How much energy is used in the contraction of SmM?
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1-300x less than SkM
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How strong is the contraction of SmM compared to SkM?
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the force is 1-2x greater
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What feature of SmM allows it to maintain prolonged tonic contraction with very little energy expenditure?
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Latch Mechanism
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In SmM the depolarization leading to a AP is mostly due to what?
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Ca+2 influx
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Regulation of contraction of SmM is due to what?
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nerve signals, local conditions, hormones
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Can SmM regenerate?
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Yes
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What are the functions of food?
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source of energy
essential nutrients stored for future use |
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What is metabolism?
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All the chemical reactions of the body.
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Define a catabolic reaction.
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A reaction that breaksdown complex organic compounds. It provides energy (exergonic)
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What are some catabolic reactions?
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glycolysis, Krebs Cycle, electron transport
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Define a anabolic reaction.
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Reactions that synthesize complex molecules from small molecules. They require energy (endergonic)
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Each cell has about _____ ATP molecules that last for less than ____.
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1 billion; one minute
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How much of the energy released from ATP is converted to heat?
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%60
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Where is energy found?
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Between the bonds of atoms
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What is oxidation?
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A decrease in the energy content of a molecule.
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What is reduction?
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An increase in the energy content of a molecule.
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What type of reactions are almost always coupled within the human body?
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oxidation-reduction
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Biologically what is oxidation?
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The loss of electrons often in the form of hydrogen atoms.
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Biologically what is reduction?
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The gain or addition of electrons (hydrogen atoms) to a molecule.
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What are common coenzymes of living cells that carry H reactions?
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NAD+/NADH
NADP/NADPH FAD/FADH2 |
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What is phosphorylation?
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ADP + P = ATP
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Where does substrate level phosphorylation take place?
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the cytosol and mitochondria
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Where does oxidation phosphorylation take place?
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in the mitochondria
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In carbohydrate metabolism what takes place in the GI tract?
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Polysaccharides are broken down into simple sugars
Absorption of simple sugars (glucose, fructose & galactose) |
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In carbohydrate metabolism what takes place in the liver?
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fructose and galactose are transformed into glucose
storage of glycogen |
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In carbohydrate metabolism what are the functions of glucose in body cells?
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oxidized to produce energy
conversion into something else storage energy as triglyceride in fat |
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What are the fates of glucose?
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ATP production
Converted to amino acids glycogenesis lipogenesis |
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In the GI tract and kidney tubules how does glucose move into the cells?
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Na+/glucose symporters
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In most other cells besides the GI tract and kidney tubules how does glucose move into cells?
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GluT = facilitated diffusion
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What increases the number of GluT transporters in the membrane of most cells?
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insulin
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Does the brain and liver have a few or a lot of GluT transporters?
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lots
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As soon as glucose enters a cell it immediately becomes what?
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Glucose 6 phosphate
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What are the 4 steps involved in cellular respiration?
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glycolysis
acetyl CoA formation Krebs cycle electron transport |
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What are the end products of cellular respiration?
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H2O + energy + CO2
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What parts of cellular respiration is anaerobic?
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glycolysis
formation of acetyl CoA |
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What parts of cellular respiration is aerobic?
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Krebs cycle and electron transport chain
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What molecule is made from the breakdown of a glucose molecule?
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2 molecules of pyruvic acid
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How many molecules of ATP are produced by substrate level phosphorylation after 2 ATP are introduced to the system?
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4 ATP
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If there is a shortage of O2 in a cell pyruvic acid is reduced to what?
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lactic acid so NAD+ will be available for futher glycolysis
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Anaerobic respiration is what?
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The break down of glucose in the absence of oxygen.
It produces 2 molecules of lactic acid and 2 molecules of ATP |
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What are the phases of anaerobic respiration?
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glycolysis and lactic acid formation
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What is the Cori cycle?
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process of converting lactic acid to glucose.
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During the formation of acetyl CoA pyruvic acid enters the _____ with the help of a transporter protein.
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mitochondria
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What are some other names for the Krebs cycle?
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Citric acid cycle
TCA |
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What is the Krebs cycle?
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A series of oxidation-reduction & decarboxylation reactions that occur in the matrix of the mitochondria
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For each molecule of acetyl CoA that enters the Krebs cycle what is produced?
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(each molecule of glucose produces 2 acetyl CoA molecules)
2 molecules of CO2 3molecules of NADH + H+ 1 molecule of ATP 1 molecule of FADH2 |
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What is the electron transport chain?
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series of integral membrane proteins in the inner mitochondrial membrane capable of oxidation/reduction
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How is energy used to form ATP in the electron transport chain?
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chemiosmosis
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What is chemiosmosis?
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Chemical energy used to pump H+ ions from the matrix into space between inner and outer membrane
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What is FMN?
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flavin mononucleotide, it is derived from riboflavin (B12)
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What are cytochromes?
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Proteins with heme group (iron) existing either in reduced form (Fe+2) or oxidized form (Fe+3)
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What contains 2 or 4 iron atoms bound to sulfur within a protein?
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Iron-sulfur (Fe-S) centers
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What is coenzyme Q?
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A nonprotein carrier mobile in the lipid bilayer of the inner membrane
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What are the steps in electron transport?
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Carriers of electron transport chain are clustered into 3 complexes each acting as a proton pump(expel H+)
Mobile shuttles pass electrons between complexes Last complex passes its electrons (2H+) to a 1/2O2 molecule to form a water molecule |
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What is the proton motive force?
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Electrochemical gradient potential energy
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How many ATP are formed during glycolysis?
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2
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How many ATP are formed by phosphorylation during the Krebs cycle?
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2
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How many ATP are formed during the electron transport chain?
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32-34
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What is glycogenesis?
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glucose storage as glycogen
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Where is glycogen stored?
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25% in liver, 75% in skeletal muscle
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What is glycogenesis stimulated by?
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insulin
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What is glycogenolysis?
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glucose is released from glycogen
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Where is phosphorylase found?
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Only in hepatocytes, so muscle cannot release glucose
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What stimulates glycogenolysis?
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glucagon (pancreas), epinephrine (adrenal)
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What is gluconeogenesis?
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formation of glucose from other substances
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When does gluconeogenesis occur?
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during times of fasting and starvation or not eating carbs
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What substances can be used in gluconeogenesis to form glucose?
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lactic acid, triglycerides, certain amino acids
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What is gluconeogenesis stimulated by?
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cortisol (adrenal), glucagon (pancreas), thyroid hormones
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What does cortisol do?
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stimulates the breakdown of proteins freeing amino acids
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What do thyroid hormones do?
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mobilizes triglycerides from adipose tissue
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Where does gluconeogenesis occur?
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liver and kidney cortex
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How are lipoproteins categorized?
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by function and density
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What are the 4 major classes of lipoproteins?
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chylomicrons, very low density lipoproteins, low-density lipoproteins, high density lipoproteins
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Chylomicrons form where?
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intestinal epithelial cells
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What is the role of a chylomicron?
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transport dietary fat from the GI to adipose and muscle tissues
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What activates enzymes that releases the fatty acids from the chylomicron to be absorbed?
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apo C-2
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What do VLDLs do?
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transport triglycerides formed in the liver to fat cells
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LDLs are known as what type of cholesterol?
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bad
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How much of the cholesterol found in the blood is carried to body cells by LDLs?
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75%
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What is a blocking protein for receptor mediated endocytosis of LDLs into the cell?
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apo B100
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What are HDLs known as what type of cholesterol?
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good
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What do HDLs do?
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carry cholesterol from cells to the liver for elimination
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What are the desired reading for adults cholesterol?
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total under 180 mg/dL
triglycerides 10-190 mg/dL LDL under 130 mg/dL; HDL over 40 mg/dL |
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What is the desirable cholesterol/HDL ratio?
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below 4
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What is the fate of lipids?
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oxidized to produce ATP
excess stored in adipose tissueor liver synthesize structural or important molecules |
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What are some of the important structures that are made from lipids?
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plasma membranes
lipoproteines thromboplastin for blood clotting myelin sheaths bile salts and steroid hormones |
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Why are triglycerides perfered over glycogen for storing energy?
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they do not exert osmotic pressure on cell membranes
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What splits triglycerides?
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lipase
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What are triglycerides split into?
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fatty acids and glycerol
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If ATP levels are high glycerol is converted into what?
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glucose
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If ATP levels are low glycerol is converted into what?
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pyruvic acid
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Where does Beta oxidation occur and what does it do?
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in the mitochondria, 2 carbon units are removed from fatty acid to formsacetyl coenzyme A
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What is lipogenesis?
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synthesis of lipids by the liver cells
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In lipogenesis what is formed from amino acids?
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amino acids are converted to acetyl CoA and to triglycerides
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In lipogenesis what is formed from glucose?
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glucose to glyceraldehyde 3 phoshate to triglycerides
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What stimulates lipogenesis?
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insulin
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What happens in lipid metabolism?
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adipose triglycerides are roken down and released as free fatty acids, which are taken up by cells and broken down by Beta oxidation into acetyl CoA which can either enter the citric acid cycle or can be converted to ketone bodies
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What happens in protein metabolism?
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new amino acids are formed by transamination. Amino acids are used to synthesis proteins
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What are the usages of proteins?
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oxidized to produce ATP
used to synthesize new proteins excess is converted into glucose or trigllycerides |
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What stimulates the absorption of proteins into body cells?
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insulin like growth factors and insulin
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What is protein catabolism?
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the breakdown of proteins into amino acids which are converted by liver cells into substances that can enter the Krebs cycle to produce ATP
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What is protein anabolism?
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the production of new proteins by formation of peptide bonds between amino acids
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What stimulates protein anabolism?
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IGFs, growth factor, thyroid hormone, insulin, estrogen and testosterone
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What is phenylketonuria (PKU)?
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genetic error of protein metabolism that produces elevated blood levels of amino acid phenylalanine
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What are key molecules at the metabolic crossroads?
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G-6P, pyruvic acid, acetyl coenzyme A
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What is the metabolic absorptive state?
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period immediately after eating when nutrients absorbed through intestinal wall into circulation and lymphatic system (4 hours after each mena
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What is the metabolic postabsorptive state?
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occurs late in morning, afternoon, night after absorptive state concluded
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What are insulin's functions in the regulation of metabolism?
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Increases anabolism
decreases catabolism promotes entry of glucose and amino acids into cells stimulates phosphorylation of glucose enhances synthesis of triglycerides stimulates protein synthesis |
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What are the 3 major sources of glucose during the postabsorptive state?
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glycogen
glycerol gluconeogenesis |
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What hormones regulate metabolism during postabsorptive state?
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glucagon
norepinephrine epinephrine |
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What is the difference between fasting and starving?
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fasting = w/o food for hours/days
starving = weeks or months |
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What is the metabolic rate?
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rate at which metabolic reactions ise energy
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What is the basal metabolic rate (BMR)
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minimum energy expenditure for the body to exist
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What are some factors that increase metabolic rate?
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Thyroid hormone, male sex hormone, growth hormone, fever
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What are some factors that decrease the metabolic rate?
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lack of thyroid hormone, sleep, malnutrition
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What is the respiratory quotient (RQ)?
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the ration of volume of CO2 produced to the volume of O2 utilized
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Where are the feeding (hunger) center and satiety centers located?
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hypothalamus (arcuate nucleus
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What stimuli decrease appetite?
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glucagon, CCK, epinephrine, glucose, leptin, and stretching of the stuomach and duodenum
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What signals increase appetite?
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growth-hormone-releasing hormone, opioids, ghrelin, glucocorticoids, insulin, progesterone, and somatostatin
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What controls short term regulation of appetite?
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ghrelin, PYY, CCK
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What controls long term regulation of appetite?
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leptin, insulin
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What are the mechanisms of heat transfer?
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radiation, conduction, convection, evaporation
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The body temperature set point is set where?
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hypothalamus
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What is the greatest heat exchange mechanism?
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radiation
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What type of peripheral temperature receptors do humans have?
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few warm, 10x more cold
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What type of deep visceral temperature receptors do humans have?
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they are concerned mainly with keeping the body from hypothermia
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Where is the thermostat for the body?
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peroptic area and anterior nuclei of the hypothalamus
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What is done to decrease core temp?
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vasodilation, sweating, decrease in heat production
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What is done to increase core temp?
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vasoconstriction, piloerection, increase heat production
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