Amino acids are the monomers that are used to produce proteins in organisms. Amino acids also have other, non-protein, roles in the body. The amino acid glycine can act as a neurotransmitter. A glycinergic synapse is shown in Fig. 7.2. Neurones need to maintain a resting potential before an action potential can occur. Describe how a neurone maintains a resting potential.
Exam No：9700_s23_qp_41 Year：2023 Question No：7(b)(iii)
Answer:
any four from:
1 sodium-potassium pump / active transport ;
2 \( \mathrm{Na}^{+}\), out/leaves and \(\mathrm{K}^{+}\), in / enters ;
3 three \(\mathrm{Na}^{+}\)for two \(\mathrm{K}^{+}\);
4 some \(\mathrm{K}^{+}\)can diffuse out of neurone OR
\((\times 20)\) more \(\mathrm{K}^{+}\)diffuses out than \(\mathrm{Na}^{+}\)diffuses in OR membrane is \((\times 20)\) more permeable to \(\mathrm{K}^{+}\left(\right.\)than \(\left.\mathrm{Na}^{+}\right)\);
5 inside of, axon / neurone, is more negative (than outside) OR outside of, axon / neurone, is more positive (than inside);
1 sodium-potassium pump / active transport ;
2 \( \mathrm{Na}^{+}\), out/leaves and \(\mathrm{K}^{+}\), in / enters ;
3 three \(\mathrm{Na}^{+}\)for two \(\mathrm{K}^{+}\);
4 some \(\mathrm{K}^{+}\)can diffuse out of neurone OR
\((\times 20)\) more \(\mathrm{K}^{+}\)diffuses out than \(\mathrm{Na}^{+}\)diffuses in OR membrane is \((\times 20)\) more permeable to \(\mathrm{K}^{+}\left(\right.\)than \(\left.\mathrm{Na}^{+}\right)\);
5 inside of, axon / neurone, is more negative (than outside) OR outside of, axon / neurone, is more positive (than inside);
Knowledge points:
15.1.1 describe the features of the endocrine system with reference to the hormones ADH, glucagon and insulin (see 14.1.8, 14.1.9 and 14.1.10)
15.1.10 describe the roles of neuromuscular junctions, the T-tubule system and sarcoplasmic reticulum in stimulating contraction in striated muscle
15.1.11 describe the ultrastructure of striated muscle with reference to sarcomere structure using electron micrographs and diagrams
15.1.12 explain the sliding filament model of muscular contraction including the roles of troponin, tropomyosin, calcium ions and ATP
15.1.2 compare the features of the nervous system and the endocrine system
15.1.3 describe the structure and function of a sensory neurone and a motor neurone and state that intermediate neurones connect sensory neurones and motor neurones
15.1.4 outline the role of sensory receptor cells in detecting stimuli and stimulating the transmission of impulses in sensory neurones
15.1.5 describe the sequence of events that results in an action potential in a sensory neurone, using a chemoreceptor cell in a human taste bud as an example
15.1.6 describe and explain changes to the membrane potential of neurones, including:
15.1.7 how the resting potential is maintained
15.1.8.1 how the resting potential is restored during the refractory period
15.1.8.2 describe and explain the rapid transmission of an impulse in a myelinated neurone with reference to saltatory conduction
15.1.8.3 explain the importance of the refractory period in determining the frequency of impulses
15.1.9 describe the structure of a cholinergic synapse and explain how it functions, including the role of calcium ions
Solution:
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