Coordination Flashcards
definition of stimulus
change in environment that is detected by a receptor causing a response
definition of response
action resulting from perception of stimulus
three types of neurones
sensory/relay/motor
describe the structure of sensory neurone (6)
long myelinated axon cell body in the middle one side is myelin sheath other side is dendrone many mitochondria in cytoplasm of axon many vesicles for neurotransmission
describe purpose of sensory neurone
receptor to CNS
describe purpose of relay neurone
intermediate neurone
pass action potentials
describe structure of relay neurone (4)
long axon
pre synaptic terminal
cell body
dendrites
describe structure of motor neurone (8)
dendrites lead to cell body nucleus in cell body many mitochondria much RER long axon synaptic knobs schwann cells node of ranvier
describe the myelin sheath (5)
Schwann cells wrap around axon
to form myelin sheath;
insulate axon;
depolarisation occur at nodes of ranvier;
long local circuits;
action potentials move by saltatory conduction;
describe the reflex arc
Stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector
describe the purpose of reflex arc (4)
fast for protection
automatic
same specific response
doesn’t pass CNS
describe the transmission of action potentials (10)
Na+ channels open; Na+ enters axon; depolarisation; Na+ channels close; K+ channels open; K+ move out of cell; repolarisation; local circuits; one way transmission; happens at nodes of ranvier;
what is the resting potential of axon
-60mV
how is the resting potential maintained (3)
active transport
sodium and potassium pump
sodium ions out and potassium ions in
against electrochemical gradient
what gradient causes the flow of Na+/K+
electrochemical gradient
how is the speed of conduction quick
jump from one node to the next (saltatory conduction)
faster in thin axons with less resistance
describe action potential in taste buds (6)
Na+ diffuse through microvilli
membrane depolarised
stimulates voltage gated calcium ions to open
calcium ions flood in cytoplasm
stimulate vesicles of neurotransmitter to perform exocytosis
stimulation above threshold = action potential passed
describe the synaptic transmission (7)
nerve impulse reach presynaptic membrane
voltage gated channels for calcium ions to diffuse in cytoplasm
calcium ions cause vesicles with acetylcholine to move to presynaptic membrane and fuse with membrane → exocytosis
acetylcholine released and diffused across synaptic cleft
acetylcholine molecules bind with receptors on post synaptic membrane, Na+ channels open
depolarisation
describe recycling acetylcholine
acetylcholinesterase hydrolyses Ach → acetate + choline
choline reabsorbed into presynaptic neurone
Choline + Acetyl CoA → Acetylcholine
packed into vesicles to be released again
what is the purpose of acetylcholinesterase (5)
breaks down acetylcholine; acetylcholine leaves binding site; depolarisation stops in post synaptic membrane; stops continuous action potentials; recycle Ach;
purpose of synapses (4)
one way transmission
interconnection between pathways
depolarisation of membrane
memory and learning
describe muscle fibres (12)
fibres are multinucleate; cell surface membrane is sarcolemma; sarcoplasm has many mitochondria; sarcoplasmic resticulum membranes have protein pumps; T system; myofibrils; myosin attached to M line; actin attached to Z line; sarcomere is distance between M line; myosin is fibrous protein with globular head; actin is chain of globular protein molecules; tropomyosin attached to actin;
what is present in sarcolemma
T tubules/deep infolds
what is present in sarcoplasm
many mitochondria
what is present in sarcoplasmic reticulum
many protein pumps
describe the structure of myofibril
A band H band I band M line Z line
events in neuromuscular junction
same as synaptic transmission but
sarcolemma
sarcoplasm
process of muscle contraction (9)
in muscle fibres
sarcolemma is depolarised;
T tubules depolarised due to spread;
calcium ions diffuse out of sarcoplasmic reticulum through channel proteins;
calcium ions bind to troponin;
troponin changes shape and tropomyosin moves;
binding site of actin exposed;
myosin heads tilt through sliding filament model;
sarcomere shortens and muscle contracts;
ATP hydrolysis releases myosin from actin to repeat;
what happens when ATP is unavailable in muscle contraction (5)
no detachment of myosin head; no hydrolysis; no power stroke; no recovery stroke; no pumping of calcium ions in sarcoplasmic reticulum;
definition of voltage gated channels
IONS
ion transport
open/close when voltage changes
specific protein
describe threshold for action potential to occur
all-or-nothing law (as long as its above threshold);
action potential same size no matter how strong stimulus;
where is FSH and LH secreted
anterior pituitary gland
where is oestrogen and progesterone secreted
ovaries
describe the menstrual cycle (14)
FSH secreted by anterior pituitary;
stimulates growth of follicle;
dominant follicle secretes oestrogen;
oestrogen stimulates repar of endometrium;
oestrogen inhibits further release of FSH;
increase in oestrogen day 14;
stimulates secretion of PH from anterior pituitary;
LH stimulates ovulation;
LH stimulates development of corpus luteum;
corpus luteum secretes progesterone;
progesterone maintains endometrium/buildup;
progesterone inhibits LH/FSH;
corpus luterum degenerature - conc. of progesterone falls;
endometrium breaks down;
describe birth control pills
synthetic long lasting hormone of progrestone/oestrogen
purpose of birth control pills (4)
suppress secretion of FSH;
thick mucus shielding sperm;
no ovum matured;
inhibit LH;
describe electrical communication of venus fly trap (13)
Mechanical energy converted to electrical; Sensory hair cell; Cell membrane depolarises; Two hairs touched; Action potential occurs; Action potential spreads over leaf; H+ pumped out of cells; Cell wall cross linked broken; Ca2+ enters cells; Water enters by osmosis; Cells become turgid; Change from convex to concave; Trap shuts quickly in 0.3s;
describe chemical communication in plants (auxin) (11)
Acid growth; Proton pumps; On cell surface membrane; H+ pump into cell wall By active transport pH of cell wall decreases; Activates expansins; To break bonds between cellulose microfibrils; Cell wall loosens; Turgor pressure increases; Cell expands;
describe effect on cell wall with many hydrogen ions moving into cell wall (5)
cell wall becomes acidic activates expansins to loosen bonds between cellulose microfibrils allow cell wall to expand turgor pressure
purpose of gibberellins
stem elongation - activates cell division and cell elongation in stem
how does giberellins cause these effects
regulating genes involved in synthesis of amylase
what is germination
development of plant from seed after dormancy
what is dormancy
very little water
metabolically inactive
how does germination take place (6)
water uptake initiates; embryo synthesises giberellins; aleurone layer synthesises amylase; amylase breaks down starch into maltose; maltose turned into glucose; endosperm tissue contains starch reserves
