15 Control and Coordination Flashcards
Explain the sliding filament model of muscle contraction
1 opens (voltage-gated) Ca2+ channels in sarcoplasmic reticulum or
calcium ions leave sarcoplasmic reticulum ;
2 calcium ions bind to troponin;
3 troponin changes shape / tropomyosin moves ;
4 exposes binding site on actin;
5 myosin head, binds to (binding) site / forms cross bridge;
plus
6 myosin head, tilts / AW;
7 pulls actin / power stroke (so sarcomere shortens) ;
Explain the role of the myelin sheath in the transmission of an action potential
1 Schwann cells, wrap around the axon / form the myelin sheath;
2 insulates (axon) / prevents movement of ions ;
3 depolarisation / action potentials, can only occur at nodes (of Ranvier) ;
4 ref. to long(er) local circuits / (nodes are) 1-3 mm apart ;
5 action potentials, move by saltatory conduction / jump from node to node ;
6 speed of transmission is, fast(er) / 100 m s-1 ;
Explain the role of calcium ions in the cholinergic response
1 Са2+ enters / diffuses into, synaptic knob ;
2 through (voltage-gated) calcium (ion) channels;
3 vesicles containing acetylcholine ;
4 move to / fuse with, presynaptic membrane ;
5 exocytosis of acetylcholine ;
Explain how a cholinergic synapse functions
1 vesicles of neurotransmitter are stimulated to move;
2 vesicles fuse with, cell surface membrane / presynaptic membrane ;
3 exocytosis (described) / secretion, of (named) neurotransmitter ;
4 neurotransmitter (ACh) diffuses across, synapse / (synaptic) cleft
5 neurotransmitter binds to receptors ;
6 on, cell surface / postsynaptic / (sensory) neurone / B, membrane;
7 Na+ / sodium, channels open;
8 Na+ enter, (sensory) neurone;
9 postsynaptic membrane / (sensory) neurone membrane, depolarised ;
Describe the structure and function of motor neurone
1 transmits impulses from CNS to effector
2 cell body at end of, neurone / axon
3 cell body in, CNS / brain / spinal cord
4 long axon OR only axon (no dendron)
5 dendrites attached to cell body
Describe the structure and function of sensory neurone
1 transmits impulses from, receptors / (named) sense organs, to CNS
2 cell body, in middle of / part-way along, neurone OR cell body not at end of, neurone / axon
3 cell body in (dorsal root) ganglion
4 short axon OR axon and dendron
5 dendrites attached to dendron
Explain the difference between dendron and dendrites
dendrons branch into dendrites, much like arteries and arterioles
Describe the transmission of an action potential in a myelinated neurone
1 Na+ / sodium ion, channels open ;
2 Na+ / sodium ions, enter, neurone / axon / (nerve) cell;
3 membrane (potential) becomes, positive / +40 mV / depolarised ;
4 (repolarisation / after peak) Nat / sodium ion, channels close ;
5 K+ / potassium ion, channels open ;
6 K+/ potassium ions, leave / move out (of cell) ;
7 membrane (potential) becomes, negative / -90 mV / repolarised ;
Explain the role of ATP in muscle contraction
Breakage of cross-bridges/myosin head not released
Explain role of gibberellin in germination of barley
1 DELLA proteins inhibit, transcription factor / PIF;
2 gibberellin binds to receptor ;
3 in aleurone layer;
4 ref. to enzyme involved ;
5 DELLA proteins broken down ;
6 TF/PIF, binds to promoter region (of DNA) ;
7 transcription of gene coding for amylase / AW ;
8 ref. to translation (leading to amylase production) ;
Describe the rapid response of Venus fly trap to stimulation of hairs on the lobes of modified leaves and explain how the closure of the trap is achieved
1 action potential / depolarisation, reaches lobe (of leaf) ;
2 ref. to hinge / midrib, cells ;
3 H+, pumped out of cells / pumped into cell walls;
4 cell wall, loosens / cross-links broken / AW ;
5 calcium pectate, dissolves / breaks down (in middle lamella);
6 Ca?+ (ions) enter cells ;
7 water enters, by osmosis / down water potential gradient ;
8 (hinge / midrib) cells, expand / become turgid ;
9 leaves / lobes, become concave;
Describe the roles of neuromuscular junctions, the T-tubule system and sarcoplasmic reticulum in stimulating contraction in striated muscle
1 action potential / depolarisation / impulse, at pre-synaptic membrane ;
2 (voltage-gated) calcium ion channels open / calcium ions enter (cell / cytoplasm / (motor) neurone / pre-synaptic knob)
3 vesicles fuse with pre-synaptic membrane ;
4 acetylcholine / ACh, released, by exocytosis / into synaptic cleft ;
5 (ACh) binds to receptors on, muscle cell membrane / sarcolemma / motor end plate ;
6 sodium ion channels open / sodium ions enter (muscle cell / sarcoplasm) ;
7 depolarisation of, (muscle) cell surface membrane / sarcolemma;
8 (depolarisation) spreads / transmitted, to / down / via, T-tubules ;
9 depolarisation of (adjacent) sarcoplasmic reticulum (membrane) ;
10 (voltage-gated) calcium ion channels open ;
11 calcium ions diffuse out of SR
12 calcium ions, move into sarcoplasm
13 calcium ions, start contraction / bind to troponin;
Explain the importance of the refractory period in determining the frequency of impulses
1 limits / controls, (maximum) frequency of action potentials; 2 (action potentials / impulses) travel in one direction;
Outline the role of sensory receptor cells in detecting stimuli
1 detect / respond to, (change in) stimulus / stimuli ;
2 two examples from - light / heat / sound / touch / pressure / pain / chemicals / taste / smell / tension ;;
3 (act as) transducers / convert stimulus energy to electrical energy ;
4 produce, generator / receptor / action, potential;
5 passes impulse, to / along, sensory neurone ;
Explain the role of auxin in elongation growth by stimulating proton pumping to acidify cell walls
1 acid-growth (hypothesis) ;
2 auxin stimulates proton pumps ;
3 (in) cell surface membrane ;
4 H+ pumped into cell wall ;
5 using energy / by active transport ;
6 pH of cell wall decreases / cell wall becomes (more) acidic ;
7 pH-dependent enzymes activated ;
8 ref. to expansins ;
9 bonds between cellulose microfibrils broken ;
10 idea that cell wall, ‘loosens’ /becomes more elastic /able to stretch ;
11 (more) water enters cell/ turgor pressure increases ;
12 (so) cell (wall) expands ;
