Last minute finals revision Flashcards
Where does the conversion of G-6-P to Glc occur in gluconeogenesis?
In the lumen of the ER usin 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 funciton 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 FA 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
Symptims & 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 think & 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
Whats a prosthetic group?
Cofactor bound or tightly associated to an enzyme
How can we see the direction of mechanical forces on bone?
In the direction of the bony trabeculae
What bones grow by intramembranous ossification?
Flat Bones
Mandibles
Maxilla
Clavicle
Whats the pocess of intramembranous ossification?
Mesenchymal cells develop into osteoprogenitor cells
Osteoprogenitor cells mature to osteoblasts
Osteoblasts lay down bone
what hapens to residual mesenchymal stemm cells in intramembranous ossification?
They become blood vessels & marow
What makes up the Bone ECM?
45% hydroxyapatite crystals for strength under compression
35% ctype 1 collagen for tension strength
20% water
What connects lancunae?
Caniculi
What are osteoclasts dervied from?
monocytes.macrophages
What is pagets disease?
Where both bone formation & resorption increases
results in fragile misshapen bone
How does menopause affect bone mass?
Oestrogen has an inhibitory affect on bone reabsoroption
So after menpause the bone mass decerases as oestrogen is no longer produced
How much blood is in a new born babay?
350ml
What do alpha & beta globulins do?
Transport vitamins
What is the result of colloid oncotic pressure?
The volume of the plasma/ISF changes to generate equal concs of plasma proteins.
What is fluid movement between ISF & plasma dependant on?
Capillary & interstitial hydrostatic pressures (CHP & IHP))
And intersitial/plasma protein concs
What does hypoproteinemia cause?
Oedema due to a lack of oncotic pressure
What are myeloid cells?
All blood cells bar lymphocytes
What are the stem cells that produce myeloid cells?
Pluripotent hematopoietic stem cells
- > Committed progenitor cells
- > myeloid cell
What is the steps in erythrocytes productiosn?
Pluripotent stem cell
- > uncommitted progenitor cell
- > committed progenitor cell
- > Eryhtroblast
- > Reticulocyte (blood)
- > Erythrocyte (blood)
How do neutrohils combat bacteria?
Phaocytosis
Neutrophil extracellula traps (NETS)
Whena re eosinophils most abundant?
During allergic reaction
What is a cytokine?
A protein or peptide thats released from one cell type & acts on another
What 2 types o cytokines are involved in leukopoiesis?
Colony stimulating factors
Interleukins
What is leukocytosis>
Increase in WBC number in blood
What governs platelet formation?>
Thrombopoietin
How does the haematocrit affet blood viscosity?
A 50% haematocrit increase doubles viscosity
How does temp affect viscosity?
A 1C increases in temp decreases viscosity by 2% and vice versa
How does cholesterol get into the membrane?
Inserts itself into the lipid layer
Where are carbs in the membrane & what do they do?
Glycoprotein & glycolipid on extracellular surface
Self-vs-nonself recognition
Why does myelin have a tiny pritein content & inner mt membrane a lot?
In myelin protein is replaced by lipid for insulation of APs
In mt inner membrane protein is required for energy transduction
Name some peripheral proteins & functions
G proteinsperform intracellular signalling functions
Collagen anchors cells to the ECM
Others join membrane & cytoskeleton
What are the main determinants of tonicicty in the ECF & ICF
ECF =Na+ & Cl-
ICF = K+
In what cases does positive feedback occur as part of normal physiology?
- Ovulation
- Sexual behaviour
- Nerve AP
How is water distrivuted in a normal 70Kg young man?
28L in ICF
11L in ISF (~80% of ECF)
3L in plasma (~20% of ECF)
What compartments can be measured for fluid volume?
Only those of which plasma is a component: Plasma ISF ECF TBW
What are the criteria for a test substance when measuring fluid volvumes?
Non-toxic Unchanged by body Musnt affect distribution of water Evenly distributed in measured compartment Easy to measure
What do we use to measure plasma volume (PV)?
Dyes or radioactive labels attachedto plasma proteins
E.g. Evans blue or I25 albumin
What can be used to measure ECF?
Needs to freely corss capilalry wall but not cell membrane:
Na+ or Cl- that are actively excluded from cells
How do we measure TBW?
A loading dose of radioactive water
E.g. Deuterium oxide or ehavy water
How do we determine the volume of ISF or ICF?
ISF = ECF - PV ICF = TBW - ECF
How does determinin the volume of a compatement work?
- Inject the test substance
- Sample the fluid for test substance conc.
- calculate Vd by:
(amount injected - any excreted or metabolised) / conc.
[V=n/c]
What are the 3 types of fibrous joint?
- Suture
- Syndesmosis
- Gomphosis
What are the features of a synovial joint?
Always:
- Fibrous capsule
- Synovial membrane
- Articular cartilage
- Synovial Cavity
Sometimes:
- Bursae
- Ligaments
- Articular Discs
What is an anastomoses?
Where blood vessels branch alot then reconnect allowing multiple paths for blood to flow.
Where are anastomoses commonly found?
Around joint as during movement some of the vessels will be compressed so the blood needs multiple paths to flow
What is hiltons law?
A nerve supplying muscle that cross a joint will innervate the joint as well
What is craniosynostosis?
Premature closure of sutures in the skull resulting in abnormal skull growth.
What are hte outcomes of craniosynostosis?
Can be aesthetic
Can also affect brain development
Can incerase intercranial pressure leading to nerve damage and blindness etc
What are occludin junctions?
Includes tight junctions that seal gaps between epithelial cells preventing backflow of ions
What are the two cell-cell anchoring junctions?
Adherens connects actin filament bundles of adjacent cells
Desmosomes connect intermediate-filament bundles of adjacent clels
What do desmosomes conenct?
Intermediate filaments such as keratin
What do adherens connecT?
Actin filaments (type of microfilament)
What do gap junctions allow?
Passage of small water soluble molecuels
How are cells linked to the matrix?
Using the intermediate filaments by hemidesmosomes
Using actin filaments by actin linked adherenes
What do lysosomes do?
Seperate enzymes from the rest of the cell.
Autophagy
What are ciia & flagella made of?
Microtubules from the cytoskeleton
Configuration vs conformation?
Configuration = fixed Conformation = specific and convertable without breaking bonds
Difference between pyrimidine & purine?
Pyrimidine has a single ring
Purine has a double ring
Exergonic/endergonic?
- Exergonic pathways are catabolic
- Endergonic pathways are anabolic
What is an important buffer systemin cells?
The phosphate buffer system
What is an important buffer in plasma?
The bicarbonate buffer:
H2CO3 dissociates to HCO3-.
It absorbs pH changes caused by cellular products like lactic acid & ketone bodies.
What are the levels of muscle fibre?
Fibril
Fibre
Muscle
When does troponin move tropomyosin off the myosin binding site?
When bound to ca2+
Name the types of contraction
Isotonic - shortening
Lengthening - DUh
Isometric - No lenth change
Tension vs load?
Tension is force exerted by muscle
Load is tension exerted on muscle
What is latent period>
Time between signal & start of contraction
Isometric has the shortest
What is contration time?
Time between start of tension & peak tensoin
What changes with increased load?
The contraction velocity & distance
Whats the difference betwween fused & unfused tetanus?
Fused tetanus is a high & completely constatn contraction
Unfused is varying tension level within a certain range
What causes tetanus contraction?
Repeated stimulus maintiaing a high level of calcium
Why is fatigue useful?
It prevents us using up all our ATP & experiecning Rigor
What causes fatigue i high intensity exercise?
- Acidified proteins by lactic acid
- ADP + Pi inhibiting myosin detachment
- High [K] leads to depolaristion which causes conduction failure
Waht causes fatigue in low intensity xerceise?
Low glycogen
Low blood Glc
Dehydration
Other fatigue?
Central command Fatigue
Cerebral cortex cant excite motor neurones
What causes atrophy?
Disuse atrophy Denervation atrophy (nerve/NMJ damage)
How are filametns arranged differently in smooth msucle?
Diagonally across cells and anchored to membranes & cell structures
Smooth muscle cross bridge cycle:
- Ca2+ binds to calmodulin
- Ca2+/Calmodulin complex binds to Myosin light chain kinase
- Phosphorylates x-bridges with aTP
- Phosphorylated X bridges bind to actin &
- Myosin light chain phosphatase dephosphorylates X-bridges
How do we maintain smooth muscle tension for a long time with relatively little ATP use?
You can slow the cycle by phosphorylating x-bridges while still bound to actin
What is basal tone?
Basal level os smooth muscle contration graded by number of APs
What do pacinian corpuscles repsond to?
Vibration/stretch
Merkel receptors?
Texture/steady pressure
Meissners corpuscle?
Flutter & stroking movement
What is acuity?
The ability to locate a stimulus on the skin & differnetiate from others nearby.
Affected by convergence
Lateral inhibitio?
Pathway close to centre of a stimulus inihbits its neighbours allowing more precise localisation of the stimulus
How is the cortical body map distorted?
The most sensitive areas occupy the biggest space?
Langerhans cells?
Immune surveillance
How do hair follicles form?
Downgrowth of epithelial cells
Invasion of blood vessels
Hair growth
How does the arrector pili muscle work?
Attached to follicle root & base epidermis
Contracts t straigten follicle
What does a sebacseosu gland do?
Releases sebum onto hair follicles for no apparent reason
What causes Body odour?
Protein rich secretion from apocrine sweat glands
What do eccrine sweat glands secrete?
a watery secreiton
