Last minute finals revision Flashcards
Where does the conversion of G-6-P to Glc occur in gluconeogenesis?
In the lumen of the ER using G-6-phosphatase
What does the pentose phosphate pathway produce?
NADPH
3C-7C sugars
What enzyme is used in step 6 of glycolysis?
Glyceraldehyde-3-Phosphate Dehydrogenase
What does the parasympathetic system do in the eye?
Muscarinic Receptors
- > ciliary muscle contracts
- > Eye focuses close up
What do B2 receptors do in the eye?
B-2 receptors
- > Cililary muscle relaxes
- > lens focusses far away
What do alpha-2 receptors do in the eye?
Alpha-2 receptor
- > radial muscle contracts
- > Pupil is dilated
What is the function of B1 receptors in the heart?
B1 receptor on pacemaker cells
-> Increases heart rate
B1 receptors on myocytes
-> increases contraction strength
What do B2 receptors do in the lungs?
B2 receptors
- > relax smooth muslce
- > aiways dilate
How can we use B1 receptors to slow the heart rate?
A beta-1 blocker (antagonist) such as atenolol would slow heart rate
How do we use B2 receptors to relieve ashtma ?
Beta2 agonist like salbutamol will dilate the airways
How does the sympathetic system affect the pancreas?
alpha receptors inhibit secreiton of pancreatic enzymes
Hwo does the sympathetic system affect the Gut?
Both alpha & BEta receptors decrease gut motility
How does the sympathetic system affect the bladder?
B2 receptors relax smooth muscle around the bladder to reduce the need to urinate
Alpha1 receptors contract the sphincter muscle also preventin urination.
How does the sympathetic system affect energy stored?
Beta 2 receptors stimulate glycogenolysis for Glc
Beta 1 recetpros stimulate lipolysis
Alpha 2 receptors inhibit lipolysis
How does the ANS affect your salivary glands?
Parasympathetic
- > Muscairnic receptors
- > thin watery secretion
Sympathetic
- > Beta receptors
- > Thick enzyme rich secretion
What do each sympathetic receptor generally do?
Alpha 1 = gluconeogenesis/vasoconstriction/sphincter constriction
Alpha 2 = Constricts muscle/inhibits energy
Beta 1 = Excitatory/ produces energy
Beta 2 = Smooth muscle relaxant/stimulate glycogenolysis
What do alpha 1 receptors do?
Constrict sphincter of urethra
Gluconeogensis/glycogenolysis
Vasoconstriction
What do alpha 2 receptors do?
Inhibits Lipolysis
What do beta 1 receptors do?
Increase heart rate/contraction strength
Increases lipolysis
What do beta 2 receptors do?
Relax smooth muscle
Stimulates glycogenolysis
Whats the use of blocking isocitrate dehydrogenase?
Blocking isocitrate dehydrogenase causes citrate build up
Citrate is then shuttled into the cytoplasm and inhibits phosphofructokinase
This stops excess glycolysis
Why block alpha-ketoglutarate dehydrogenase?
α-ketoglutarate builds up
Its then used instead to produce amino acids
What is citrte used to produce?
Fatty Acids
Sterols
What is Oxaloacetate used for?
CAC
GLuconeogenesis
Making amino acids & pyrimidines
What is an anaplerotic reaction?
The act of replacing intermediates that have been removed for biosynthesis. (which is cataplerotic)
I.e. When oxaloacetate is removed from CAC for making amino acids, pyruvate carboxylase kicks in & replaces it direct from pyruvate
What are the steps of fatty acid synthesis?
Condensation
Reduction
Dehydration
Reduction
What are the steps of B-0xidation?
Oxidation
Hydration
Oxidation
Thiolysis
Where does the NADPH for FA syntehsis come from?
Some from Pentose phosphate pathway
Some from Citrate shuttle
What is the glucose uniporter called?
GLUT2
How does glycogen form?
1) Glycogenin binds UDP glucose into 8 unit primers
2) glycogen synthase extends the Glc chains
3) glycogen branching enzyme breaks the chain & makes branches
How is glycogen broken down?
1) glycogen phosphorylase removes single monomers as G-1-P
2) De-branching enzyme acts as a transferase moving 3 Glc from branch to chain
3) de-branching enzyme acts as a glucosidase breaking the alpha1-6 bond in branch.
What is hurlers syndrome?
Mucopolysaccharidoses.
I.e. a deficiency in the enzymes needed for GAG breakdown
What is Von Gierkes disease?
Liver G-6-Pase deficiency
What are the symptoms of vongierkes diases?
- High liver gylcogen
- Hypoglycaemia
- lacticacidaemia
How do we treat von gierkes?
Regular carb feeding
What is mcardles disease?
Skeletal muscle glycogen phosphorylase deficiency
Symptoms & treatment for mcardles disease?
- High muscle glycogen
- Weakness/cramp & no glc increase after exercise
Avoid streneous activity & use second wind
What is poduced when Pyruvate is converted to Acetyl-CoA?
NADH & CO2
Pyruvate dehydrogenase
Which muscle filament is thick & which is thin?
Myosin is thick
Actin is thin
What coenzyme accepts electrons in complex 1 & 2 of the electron transport chain?
Coenzyme 10 or Ubiquinone
What carries electrons from complex 1&2 to complex 3?
Ubiquinol
What binds nucleotides together?
Phosphodiester bonds
What do pacemaker potentials do?
Trigger spontaneoulsy to provide breathing & cardiac ryhtyms
What directly generates the resting membrane potential?
The membranes permeability to K+ ions
What does ingesting alcohol use up (especially at teh liver)?
NAD+
Does the eukaryotic plasma membrane contain ribosomes or cholesterol?
It contains cholesterol but no ribosomes
What does Tetrodoxin do?
Blocks soidum channels preventing an AP at the NMJ
What does Joro spider toxin do?
Blocks calcium channels stopping transmitter relase at the NMJ
What does botulinum toxin do?
Disrupts transmitter release
What does curare do?
Blocks Ach receptors preventing an endplate potential
What does hemicholium do?
Blocks Choline reuptake preventing Ach production at the NMJ
What does Neostigmine do?
Its an acetylcholinesterase inhibitor which prevents breakdown of Ach and thus incerases transmission at the NMJ
What is a sarcomere & a Z band?
Sarcomere is the reapeating unit of striated muscle
A Z band is an area of dense proteins connecting the sarcomeres
What are the steps of the cross bridge cycle in skeletal msucle?
- Ca2+ binds to troponin
- Troponin moves tropomysosin exposing Actin binding site
- Cross bridge binds
- ADP +Pi released & cross bridge contracts
- ATP binds to myosin & cross bridge detaches
- ATP hydrolysed ready for next contraction
What receptors are involved in contraction at the muscle?
+ DHP receptors in the T tubules detect depolarisation
They activate ryanodine recptors which activate Ca2+ channels in the SR
What is the optimal length of a muscle?
The length that gives the grearest iosmetric tension
What is the MM equation?
Vo = Vmax[S] / Km + [S]
What is the lineweaver-burke equation?
1 / Vo = (Km / Vmax) (1 / [S]) + (1 / Vmax)
Whats a coenzyme?
Complex organic molecule usualy derived from vitamins. Such as NAD+/FAD+/Ubiquinone