Descending tracts are the pathways by which motor
signals are pass through from the brain to lower motor neurones. Thus, all
the neurones within the descending motor system are classed as upper motor
neurones. The lower motor neurones then directly innervate muscles to produce
movement. Their cell bodies are found in the cerebral cortex or the brain stem,
with their axons remaining within the CNS.
Answer:
b) opening calcium pores in the membrane
Explanation:
The opening of calcium ions channels facilitates the migration of vesicles containing neurotransmitters in the pre-synaptic neurons to the tip of the post-synaptic membrane. at the <u>neuromuscular junction </u>These neurotransmitters can either be <u>cholinergic or non-chorlinergic.</u> <u>At the tip of the pre-synaptic membranes the vesicles empty their neurotransmitter contents into the synapse.</u>
The neurotransmitters, diffuse through the neuromuscular junction to bind with the receptors on the <u>post-synaptic membrane on the post-synaptic neuron.</u> This stimulates opening of<u> ligand gated sodium ions,</u> and sodium ions diffuse into the post-synaptic neuronal membrane, to cause <u>depolarization</u>. if the stimulus is up to the threshold levels it generate action potential.
Therefore , more calcium ions channels opening produces; more diffusion of neurotransmitters;leading to opening of more sodium channels for depolarization; and IPSP or EPSP generation.
Answer: The elastic connective tissue
Explanation: Allow stretched tissues to recoil as pressure is reduced
Any pair of chromosomes other than that of sex pair of chromosomes are referred to as autosomes or autosomal chromosomes.
I don't think the water cycle has a beginning or ending because all the water in the world is always in various stages of the cycle. It's kind of like asking if a circle has a beginning or ending.
At the very least, I can't think of a specific 'beginning' or 'ending', although I suppose there is an argument to be made that percipitation is the ending and evaporation is the beginning.
