Neuronal Communication

Neuronal Communication

(a)    The roles of mammalian sensory receptors in converting different types of stimuli into nerve impulses

·         Sensory receptors convert the energy of the stimulus into electrical energy, they act as transducers:  convert energy from one form into another.

·         Pacinian corpuscle detects mechanical stimuli (eg pressure) they’re found in the skin and contain the end of a sensory neurone. When it’s stimulated the membranes are deformed causing sodium channels to open creating the generator potential, if this reaches the threshold the action potential is triggered.

(b)   The structure and functions of sensory, relay and motor neurones

·         Sensory neurones carry impulse from receptor cells to cell body via the dendron and then from the cell body to CNS via the axon.

·         Motor neurones have short dendrites that carry impulses from the CNS to the cell body then the impulse is carries from the cell body to effector cells via the axon.

·         Relay neurones have short dendrites that carry impulses from sensory neurones to cell body and short axons that carry impulses from cell body to motor neurones.

·         Myelin sheath speeds up transmission of impulse and non-myelinated neurones are slower. Myelin sheath can be found on motor neurones.

(c)    The generation and transmission of nerve impulses in mammals

·         Resting potential: the sodium potassium pump uses ATP to move 3 sodium ions out of the cell and 2 potassium ions into the cell. All voltage gated channels…