Topic 7 Humphries Flashcards
Synovial membrane
secretes synovial fluid
Fibrous Capsule
encloses joints
Pad of Cartilage
gives additional protection
Cartilage
- strong, flexible supporting tissue
- absorbs synovial fluid
- acts as shock absorber at the ends of bones in joints
Synovial fluid
- viscous fluid, secreted by the synovial membrane
- acts as lubricant (to the joint)
Ligaments
- joins bone to bone
- control and restrict the amount of movement in the joint
- strong and slightly elastic
Tendons
- join muscle to bone
- enable the transmission of forces
- inelastic but flexible
Joint
where 2 bones meet (some moveable - cartileginous or synovial or immoveable - fixed in the skull)
Bones
are made of bone cells and bone matrix (collagen and calcium phosphate) and make up our skeleton
Muscles
Bring about movement at a joint by contracting and relaxing to flex (shorten) and extend (lengthen). Work in antagonistic pairs across joints for movement; extensors - extend, flexors - flex
Muscles can only…
…pull - they shorten (contract) which pulls on the bone and moves the joint
Extensor
a muscle that contracts to cause extension
Flexor
a muscle that contracts to shorten the joint/ reverse the movement
For a joint to move back and forth…
…2 muscles are needed - a pair of muscles that work in this way are antagonistic muscles
Muscle fibre
is a muscle cell
Muscle cell
is a muscle fibre - long, thin, multi-nucleated cell containing myofibrils
Myofibrils
within the muscle fibre, made of a collection of proteins and organised into sarcomeres
Sarcomere
repeating contractile unit in a myofibril
Sarcoplasm
cytoplasm in the muscle fibre/ cell
Sarcolemma
cell membrane in the muscle fibre/ cell
Tropanin
protein attached to actin that binds to Ca2+
Tropomyosin
protein wrapped around actin, shields myosin binding site on actin
Actin
thin filaments
Myosin
thick filaments
Z line
the ends of each sarcomere
Neuromuscular junction
where neurone and muscle meet
Sarcoplasmic reticulum
membrane bounds sacs surrounding the myofibrils - release/ secrete Ca2+
Cross-bridges
when the myosin head attaches to the actin binding site
Ca2+ (muscle)
causes the shape change of troponin and tropomyosin
ATP (muscle)
binds to myosin head, causes it to detach from actin
Role of Ca2+ in muscle contraction
- changes shape of actin by binding to troponin
- this makes tropomyosin change shape to reveal the myosin head binding sites
- this allows actin-myosin cross-bridges to form
Role of ATP in muscle contraction
- permits detachment of myosin head from actin
- hydrolysis of ATP (by ADPase on myosin) causes the shape change of the myosin head
- the shape change of the myosin head allows it to bind to actin again
- ATP also pumps the Ca2+ back into the Sarcoplasmic reticulum
What happens to the thin and thick filaments during muscle contraction?
they slide over each other - they DO NOT SHORTEN
What happens to the sarcomere during muscle contraction?
the length of each sarcomere shortens - z lines get closer together
Uses of ATP
- active transport
- muscle contraction
- photosynthesis
- action potential
- protein synthesis
- spindle action
- glycolysis
- activation of chemicals
- making proteins/ polysaccharides
- secretion - to make vesicles
Aerobic respiration equation
Oxygen and Glucose –> Carbon Dioxide and Water (+ ATP)
The input of energy into respiration…
…is not as great as the energy released when bonds are formed
Substrate level phosphorylation
a phosphate group is transferred from a substrate molecule to ADP (e.g. in glycolysis)
Oxidative phosphorylation
ATP is made from Pi and ADP. Energy comes from a series of oxidation reactions in the electron transport chain in the mitochondria
Photophosphorylation
ATP is made from Pi + ADP (and AMP). Light energy drives the process
What enzyme catalyses both the hydrolysis and phosphorylation of ATP?
ATPase
Hydrolysis of ATP
ATP is broken down into ADP + Pi + energy
Phosphorylation
ATP is made from ADP + Pi (different types of phosphorylation)
Features of a mitochondrion
- DNA loop
- cristae
- matrix
- double membrane (outer and inner)
Glycolysis yields
2 molecules of pyruvate, 2 molecules of NADH (reduced NAD) and a net gain of 2 ATP molecules
Where does glycolysis occur?
in the cytoplasm (or sarcoplasm)
What phosphorylation is used in glycolysis?
substrate level phosphorylation - phosphate’s from intermediate 3C compound used to make ATP
Process of glycolysis
glycogen store or food –> glucose (6C) –> 2x intermediate 3C compounds (phosphorylated) –> 2x pyruvate
2ATP put in and converted to 2ADP
2 hydrogen’s released which go to reduce NAD
4ADP + 2Pi converted to 4ATP
What is NAD? What is its purpose?
a co-enzyme (along with FAD)
to transport hydrogen
Which stage of respiration is anaerobic?
glycolysis - no oxygen is used
For every 1 glucose molecule…
…the link reaction and Krebs cycle happens twice
Link Reaction
pyruvate from glycolysis –> carbon dioxide + 2 hydrogens + acetyl CoA
Krebs cycle
- Acetyl CoA combines with 4C compound to make a 6C compound
- 6C compound undergoes decarboxylation and dehydrogenation to form a 5C compound
- 5C compound undergoes decarboxylation and 1 ATP molecule is formed from substrate level phosphorylation and 6 hydrogens are released in total to reduce the co-enzymes
- This reforms the 4C compound
What has happened to glucose following link and Krebs cycle? Carbon? Oxygen? Hydrogen?
- it has been completely broken down
- carbon and oxygen has been released as CO2
- Hydrogens have been used to reduce co-enzymes NAD and FAD (these transport them to the ETC)
What is an electrochemical gradient?
a really positive to really negative environment
Chemiosmosis
is a method of storing energy by creating a proton gradient across a membrane
What is oxygen’s role in the ETC?
it’s the final electron acceptor
Electron Transport Chain
- reduced NAD and FAD carries proton and electron to ETC
- electrons pass from one electron carrier to the next in a series of redox reactions
- This releases energy, pumping protons across the inner membrane into the inter-membrane space
- There is now a high proton concentration in the inter-membrane space as H+ accumulate there
- Protons diffuse back into the matrix down electrochemical gradient (through stalked particle)
- The movement of the proton diffusion allows ATP synthase to catalyse ATP synthesis
- Protons are collected by 1/2O2 along with electrons forming hydrogen, then water - this is a waste product
What happens if oxygen supply stops?
- no electrons or hydrogen ions accepted so no ATP synthesis from ETC and NADH and FADH can’t deposit electrons at ETC so Krebs cycle and link reaction stops - ATP synthesis stops and ETC stops
- no electrons moving along electron carriers by redox reactions, no protons pumped across membrane
- stop cellular processes so no energy source so no muscle contraction
If there’s no O2…
…no electron transport chain, reduced NAD can’t be oxidised, most respiration reactions (link, Krebs, ETC) stop in the absence of oxidised NAD
Difference between aerobic and anaerobic glycolysis
In aerobic complete oxidation of glucose to produce waste products. In anaerobic incomplete oxidation of glucose to produce lactate –> lactic acid
Anaerobic glycolysis
glucose turns into pyruvate after ADP + Pi is phosphorylated to make ATP and 2 hydrogens are released however the ETC has stopped so no NAD and FAD are there to accept hydrogens so pyruvate comes along to accept hydrogens and is reduced making lactate
What happens to lactate?
- Transported to the liver from the muscles in the blood plasma
- Pyruvate then is completely oxidised via the Krebs cycle (aerobic). This creates an oxygen debt (extra oxygen needed during ‘recovery period’ to ensure complete oxidation of extra pyruvate)
- Some lactate may be converted into glycogen and stored in the muscle or liver
What happens to lactate if it builds up?
can be broken down in the liver or broken down to CO2 and H2O in aerobic respiration
What happens if lactate builds up?
The pH of the cell will fall inhibiting enzymes that catalyse glycolysis reactions - can’t continue. Many amino acids that make up an enzyme have negatively or positively charged groups so if hydrogen ions from lactic acid accumulate in the cytoplasm they neutralise negative groups in the active site of the enzyme which means attractive forces between enzyme and substrate will be affected so substrate may no longer bind to active site
Aerobic respiration facts
- glucose broken down completely into water and carbon dioxide
- up to 38 molecules of ATP produced for each molecule of glucose
- oxygen required (final electron acceptor)
- ATP made via oxidative and substrate level phosphorylation
- glycolysis, Krebs and ETC all working correctly
- Happens in cytoplasm and mitochondria
Anaerobic respiration facts
- glucose not completely broken down to produce lactate
- 2ATP molecules produced for each molecule of glucose
- oxygen not required (only after to break down)
- substrate level phosphorylation ONLY
- only glycolysis occurs
- happens in cytoplasm only
How do we supply energy instantly?
-with creatine phosphate
Creatine phosphate
- stored in muscles
- can be hydrolysed to release energy
- breakdown begins as soon as exercise begins
- can be used to regenerate ATP
- triggered by formation of ATP
- doesn’t need oxygen
- can supply energy for about 6-10 seconds
When is creatine phosphate relied upon?/
for regeneration of ATP during short bursts of intense energy - at rest creatine phosphate will be regenerated
Creatine phosphate equation
Creatine phosphate + ADP –> Creatine + ATP
What is a respirometer used for?
measure the rate of respiration
What should a control tube contain when using a respirometer?
equal volume of non-respiring material
How does a respirometer work?
Small organisms respire; take in O2, CO2 given off, CO2 taken in by soda-lime so pressure in the test tube drops. Due to higher pressure outside, the coloured liquid moves to the left as air is forced in. You can work out the distance moved in a time to get the rate of O2 uptake. Find area to get volume and divide by mass of organisms to get per gram of organism
What is the syringe used for on a respirometer?
to reset the experiment and pressure
What should be controlled? How?
temperature - place in a water bath or use a U tube respirometer which has a built in control so any external changes affect the pressure in both tubes so effects cancel out
Aerobic capacity
the ability to take in, transport and use oxygen
VO2
volume (litres) per minute of oxygen consumed
VO2 max
maximal aerobic exercise –> volume (litres) of oxygen consumed during maximal aerobic exercise
Factors affecting VO2 max
- Exercise type - depends on individual and type of exercise
- Gender - men have higher haemoglobin concentration and women have more body fat
- Heredity - variation attributable to genes
- Level of training - with training can increase
- Age - once reached mid twenties, steadily declines
Cardiac output
volume of blood pumped by the left ventricle per minute
Stroke volume
volume of blood pumped out of left ventricle by each contraction