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· The myelin sheath means that action potentials can occur only at the gaps between the Schwann cells that make up the myelin sheath.· Effectively the action potential jumps from one node of Ranvier to th...

·   Myelin sheath is an insulating layer of fatty material, composed of Schwann cells wrapped tightly around the neurone.·   Sodium and potassium ions cannot diffuse through this fatty layer.·   In betwee...

Firstly, think of what you already know about the structure of the lungs and how that makes them so effective at their job. (Elasticity, large surface area for gas exchange, high gradient and short diffus...

Baroreceptors detect the rise in blood pressure in the aorta, they send impulses to the cardiovascular centre. Then, impulses are sent via parasympathetic nerves to the SAN. This triggers the release of A...

Anti-diuretic hormone (ADH) is produced by the hypothalamus and stored in the posterior pituitary gland. When the hypothalamus identifies the bloods osmotic pressure as being outside the homeostatic range...