Alberta Biology 30: Nervous System

What are the two divisions of the nervous system?

central & peripheral

What are the two components of the central nervous system?

brain & spinal cord

What two pathways can the peripheral nervous system be further divided into?

sensory & motor

What is the difference between the somatic nervous system and the autonomic nervous system? Which division is it a part of? Which pathway?

somatic = voluntary control

autonomic = involuntary control

peripheral; motor pathways

What is the difference between the sympathetic and the parasympathetic nervous system? Is it a part of the somatic or autonomic?

sympathetic = dominates in times of high activity/stress = FIGHT OR FLIGHT

parasympathetic = dominates during rest = REST & DIGEST

both a part of the autonomic nervous system

Choose sympathetic or parasympathetic: pupils dilate

sympathetic

Choose sympathetic or parasympathetic: heart rate decreases

parasympathetic

Choose sympathetic or parasympathetic: sphincter for bladder relaxes

parasympathetic

Choose sympathetic or parasympathetic: increased blood flow to skin

parasympathetic

Choose sympathetic or parasympathetic: conversion of glycogen to glucose in the liver

sympathetic

What is a nerve?

a bundle of neurons

What is the function of a dendrite?

recieving information

What is the function of an axon?

conducts nerve impulses away from cell body to target cells.

What is the function of the myelin sheath?

insulates axon; speeds up transmission of impulse

What is the difference between white matter and grey matter?

white matter = myelinated nerves

grey matter = unmyelinated nerves

What is the myelin sheath in the PNS composed of? What do they form? What is it's purpose?

composed of schwann cells; form the neruilemma; promotes regeneration of damaged axons

What are Nodes of Ranvier? What are their purpose?

gaps between the myelin sheath; speeds up transmission

What are the function of terminal branches?

end of neuron with axon bulbs; contain vesicles of neurotransmitters needed to bridge the synapse

What is the name of the connection between a neuron and a muscle?

neuromuscular junction

Describe the neural pathway.

receptors - sensory neurons - interneurons - motor neurons - effectors

What are effectors?

muscles/glands/organs that help the organism respond to stimulus

What is a reflex?

motor neurons activated by an involuntary response

What is a reflex arc?

a reflex that bypasses the brain; allows body to quickly respond to stimuli

What is an action potential?

nerve pulse that results from movement of ions across neuron's membrane

What kind of response is an action potential?

all or none

What is the threshold level?

minimal stimulus required to open sodium channels

Describe what is occurring at the axon membrane during resting potential.

sodium/potassium channels closed; leakage corrected by active transport pumps.

POSITIVE OUTSIDE & NEGATIVE INSIDE (more sodium outside neuron)

Describe what is occurring at the axon membrane during depolarization.

sodium channels open; sodium rushes in

POSITIVE INSIDE & NEGATIVE OUTSIDE

Describe what is occurring at the axon membrane during repolarization.

sodium channels close; potassium channels open; potassium rushes out

POSITIVE OUTSIDE & NEGATIVE INSIDE

Describe what is occurring at the axon membrane during hyperpolarization.

membranes become more permeable to potassium than usual and inside becomes more negative than resting potential

What is the refractory period?

recovery time required before a neuron can respond to another impulse

Explain what occurs at the synapse.

membrane depolarizes - synaptic vesicles fuse to membrane - neurotransmitters released via exocytosis - diffuse across synapse - bind to receptors on post synaptic membrane - causes depolarization of next neuron

What is acetylcholine?

neurotransmitter; excitatory/inhibitory; makes postsynaptic membrane more permeable to sodium

What is cholinesterase?

enzyme; breaks down acetylcholine; prevents continuous stimulation