Nervous system Flashcards
The nervous system consists of neurons that receive and transmit impulses. What is characteristic of the nerve cells in the nervous system?
The sensory nervous system sends impulses from somatic and visceral receptors.
What are the 3 main functions of the nervous system?
sensory input- uses sensory receptors to monitor changes inside and outside the body
integration - processes and interpret sensory input and decides what should be done
motor- produces a response by activating effector muscle
When a neuron is at rest, its membrane potential is termed the resting membrane potential. What can distinguish a resting potential from an action potential?
It is -70mV and it is not conducted along the axon
The axons of some neurons in the PNS are protected by glial cells that form a myelin sheath around the axon. Which of the following is the name of these glial cells?
Schwan’s cell
What are the 2 types of organizations of the nervous system? Distinguish between them.
CNS-
Brain + spinal cord
interprets sensory input and dictates the motor response
PNS-
nerves extending from the brain and spinal cord
What are the 2 types of organizations of the nervous system? Distinguish between them.
CNS-
Brain + spinal cord
interprets sensory input and dictates the motor response
PNS-
nerves extending from the brain and spinal cord
What is the difference between the sensory (afferent) division and the motor (efferent) division?
The sensory impulse to the CNS
Motor: impulse from the CNS to the effector organs such as muscles and glands
The part of the nerve cell that consisted of many short branching extensions and plays a role in the function of receiving impulses was damaged. What part of the nerve cell was damaged?
dendrites
You burn your finger. What type of neuron is activated first as a result?
sensory neuron
Why does a myelinated axon conduct action potentials faster than an unmyelinated axon?
unmyelinated axon signals are sent slowly causing a continuous conduction.
Myelinated axon has an increased rate of Ap propagations by acting as an insulator the current passes at the node of Ranvier where an axon is bare and Na channels are concentrated.
How does the axon diameter conduct impulses?
The larger the diameter of the axon the faster it will conduct an impulse the smaller the diameter the slower it will conduct an impulse.
Give an account of the steps involved from the initial depolarisation on the presynaptic membrane to the binding of neurotransmitters on the postsynaptic cell membrane.
Depolarization opens voltage-gated channels, which triggers an inflow of Ca2+.
The increased Ca2+ levels cause synaptic vesicles to fuse with presynaptic membrane, releasing neurotransmitter into the synaptic cleft.
Neurotransmitters usually diffuse across the synaptic cleft and bind to specific receptors on ligand-gated ion channels on the post synaptic membrane.
Distinguish between Hyperpolarisation and depolarisation.
Hyper-
Inc. in MP -70 — -75
the inside of the membrane is more negative
results of outflow of potassium K / inflow of +ve ions
Deploraisation-
Dec in MP -70 — (-55)
the inside of the membrane becomes less -ve
results of the inflow of +ions Na
When is action potential conducted?
When it reaches a threshold of -55mV
