[OLD] Nervous Communication - Exam Questions Flashcards
Explain what causes depolarisation. (3)
Sodium voltage-gated channels open.
Sodium ions diffuse into the axon along the electrochemical gradient.
Being positively charged, they trigger a reversal in the potential difference across the membrane.
Explain what causes repolarisation. (5)
Sodium ion channels close.
Potassium ion channels open.
Potassium ion channels diffuse out of the axon.
It’s more positively charged outside the axon.
Sodium ions are actively transported outside the axon.
Explain what causes an action potential. (5)
Sodium ion channels open.
Sodium ions diffuse into the axon along the electrochemical gradient.
Potassium ion channels proteins close.
Inside of the axon becomes positively charged.
Outside of the axon becomes less positively charged.
When a neurone transmits a series of impulses, it’s rate of oxygen consumption increases. Explain why. (3)
The sodium potassium pump is an active protein.
Therefore it requires ATP.
Therefore it requires more oxygen for respiration to generate ATP.
Explain what causes a resting potential. (6)
Sodium potassium pump transports 3 sodium ions out of the axon and 2 potassium ions into the axon.
Active transport - against a concentration gradient.
Concentration of sodium ions outside the cell increases.
Potassium ions diffuse out of the axon.
The sodium ion gate is closed. The sodium ions cannot diffuse into the axon.
Positive charge on the outside of the axon.
Explain what happens in a panini an corpuscle. (5)
Increase in pressure deforms stretch mediated sodium ion channels. Sodium channels open. Sodium ions flow in. Depolarisation. Leads to a generator potential.
Explain how rod cells work. (4)
Rhodopsin breaks down when light shines on it.
Results in a series of reactions.
Generator potential being produced.
ATP is needed to re-synthesise rhodopsin.
Describe how a synapse works. (13)
Action potential reaches end of sensory neurone. Na+ enters axon.
Calcium channels in presynaptic membrane open allowing calcium ions to diffuse into presynaptic knob.
Ca2+ ions cause vesicles containing acetylcholine with presynaptic membrane.
Neurotransmitter released into synapse.
Acetylcholine diffuses across synapse.
Binds to the receptor proteins on post synaptic membrane.
Causes sodium ion channels to open on post synaptic membrane.
Sodium ions enter relay neurone.
Action potential generated at next node of Ranvier.
Acetylcholinesterase breaks down acetylcholine and leaves the receptor protein.
Acetyl and choline diffuse across synapse.
Acetyl and choline reabsorbed into presynaptic knob.
Condense to form acetylcholine.
Explain how muscles contract. (14)
Action potential arrives in the muscle cell membrane.
Action potential travels down a T tubule.
Action potential causes calcium ions to be released from the ER in the muscle cell.
Calcium ions bind to troponin.
Tropomyosin moves and reveals myosin binding sites.
Myosin head binds to actin to form an actinmyosin bridge.
Myosin moves in power stroke.
Myosin pulls the actin.
ADP released from myosin head.
Attachment of ATP to myosin head causes actinmyosin bridge to break.
ATP is hydrolysed.
Energy released used to recock myosin head.
Calcium ions reabsorbed into ER of muscle cell by active transport.
Myosin binding sites are hidden preventing myosin binding to actin.
Explain what causes a resting potential. (6)
Sodium potassium pump transports 3 sodium ions out of the axon and 2 potassium ions into the axon.
Active transport - against a concentration gradient.
Concentration of sodium ions outside the cell increases.
Potassium ions diffuse out of the axon.
The sodium ion gate is closed. The sodium ions cannot diffuse into the axon.
Positive charge on the outside of the axon.
Explain what happens in a pacinian corpuscle. (5)
Increase in pressure deforms stretch mediated sodium ion channels. Sodium channels open. Sodium ions flow in. Depolarisation. Leads to a generator potential.
Explain how rod cells work. (4)
Rhodopsin breaks down when light shines on it.
Results in a series of reactions.
Generator potential being produced.
ATP is needed to re-synthesise rhodopsin.
Describe how a synapse works. (13)
Action potential reaches end of sensory neurone. Na+ enters axon.
Calcium channels in presynaptic membrane open allowing calcium ions to diffuse into presynaptic knob.
Ca2+ ions cause vesicles containing acetylcholine with presynaptic membrane.
Neurotransmitter released into synapse.
Acetylcholine diffuses across synapse.
Binds to the receptor proteins on post synaptic membrane.
Causes sodium ion channels to open on post synaptic membrane.
Sodium ions enter relay neurone.
Action potential generated at next node of Ranvier.
Acetylcholinesterase breaks down acetylcholine and leaves the receptor protein.
Acetyl and choline diffuse across synapse.
Acetyl and choline reabsorbed into presynaptic knob.
Condense to form acetylcholine.
Explain how muscles contract. (14)
Action potential arrives in the muscle cell membrane.
Action potential travels down a T tubule.
Action potential causes calcium ions to be released from the ER in the muscle cell.
Calcium ions bind to troponin.
Tropomyosin moves and reveals myosin binding sites.
Myosin head binds to actin to form an actinmyosin bridge.
Myosin moves in power stroke.
Myosin pulls the actin.
ADP released from myosin head.
Attachment of ATP to myosin head causes actinmyosin bridge to break.
ATP is hydrolysed.
Energy released used to recock myosin head.
Calcium ions reabsorbed into ER of muscle cell by active transport.
Myosin binding sites are hidden preventing myosin binding to actin.
Explain how a lower temperature leads to slower nerve impulse conduction. (2)
Slower diffusion
of ions.
