Chapter 42: Nervous system Flashcards
T/F: All animals even sponges have a nervous system
False - All animals except sponges have a nervous system
What 2 structures does the nervous system link together?
It links sensory receptors that detect stimulus with the motor effectors that respond to the stimuli
What are the 3 types of neurons in vertebrates? Explain
1) Sensory neurons (afferent) => carry impulses to the central nervous system.
2) Motor neurons (efferent) => Carry impulses from CNS to effectors.
3) Interneurons => provide more complex reflexes and associative functions.
What are the 2 parts of CNS ?
1) Brain
2) Spinal cord
What is the PNS comprised of?
Sensory and motor neurons
Define the somatic nervous system
Motor neurons that stimulate skeletal muscles to contract (Voluntary movement)
Define the autonomic nervous system
Regulate the activity of the smooth muscles, cardiac muscle, and glands (Involuntary movement)
What are the 2 parts of the autonomic nervous system?
1) Sympathetic (Fight or flight)
2) Parasympathetic (rest and digest)
Counterbalance each other
What are the 3 components of a neuron?
1) Cell body => containing nucleus
2) Dendrites => receive stimuli
3) Axon => conduct impulses
Name 4 glial cell types:
1) Neuroglia
2) Astrocytes
3) Ependymal
3) Microglia
What are the 2 most important kinds of neuroglia? What are their functions?
1) Schwann cells: produce myelin in the PNS
2) Oligodendrocytes: produce myelin in the CNS
They support neurons both structurally and functionally.
What is the main function of astrocytes?
Formation of the blood-brain barrier which selectively restricts the movements of compounds from the blood into the CNS
What is the main function of ependymal cells?
Ciliated cells, lining the cavities of the brain and the central canal of the spinal cord, PRODUCE THE CEREBROSPINAL
Define Cerebrospinal:
Fluid that provides nutrients and the elimination of waste for the CNS.
What is the main function of microglia?
Aid with immune responses and serve as macrophages.
T/F: A potential difference exists across every cell’s plasma membrane.
Negative pole - Cytoplasmic side
Positive pole - extracellular fluid side
True
T/F: When a neuron is not being stimulated, it maintains a resting potential that ranges from -40 to -120 mv, and averages about - 50 mv.
False - from -40 and -90 mV and averages about -70 mV
What are the 3 factors for making the inside of the cell more negatively charged?
1) The sodium-potassium pump (2K+ in 3Na+ out)
2) More K+ channels than Na+ (K+ diffuse out of the cell)
3) Negatively charged molecules that accumulates inside the cell
What creates the diffusional forces?
The build-up of positive charge up outside the membrane and negative charge inside the membrane results in an electrical potential which is an attractive force pulling K+ ions back inside the cell.
What’s the result of the balance between the diffusional forces and electrical force?
Production of the equilibrium potential
T/F: The uniqueness of neurons compared with other cells is the production and maintenance of the resting membrane potential.
False - Rather the sudden temporary disruptions to the resting membrane potential that occur in response to stimuli.
(Graded or Action potential)
Define: Graded potentials:
The summation of subthreshold potentials produced by the opening of different chemically gated ion channels.
Define Action potentials:
o Transient disruptions triggered by a threshold change in potential (voltage-gated channels).
o The actual signals that move along an axon.
Define ligands:
Ligands are chemical signals - hormones or neurotransmitters
What is the main function of ligand-gated channels
Induce opening and cause changes in cell membrane permeability.
Match each number with a letter:
1) Depolarization
2) Hyperpolarization
a) Makes the membrane more negative.
b) Makes the membrane more positive.
1 - b
2 - a
T/F: Depolarization and hyperpolarization result in graded potwntials.
True
T/F: Size depends on the strength of the stimulus only.
False - Size depends either on the strength of the stimulus or the amount of ligand available to bind with their receptors
Define the concept of Summation:
The ability of graded potentials to combine
