Nervous A & P Flashcards
Principle divisions of the nervous system
CNS
PNS
What does the CNS consist of?
Brain and Spinal Cord
What does the PNS consist of?
PNS=12 pairs of cranial nerves and 31 pairs of spinal nerves
What are the 3 PNS sub-devision.
Somatic nervous system (voluntary) i.e. impulses to skeletal muscle.
Autonomic nervous system (involuntary) i.e. impulses to smooth muscle, cardiac muscle and glands.
Enteric nervous system (involuntary) i.e. gastro-intestinal tract.
What are sensory nerves know as?
AFFERENT NERVES (AS) they carry information towards the spinal cord and brain.
What are Motor Nerves know as?
EFFERENT NERVES (ME) carry information from brain and spinal cord, travel down the spinal cord via descending tracts.
What are the 2 types of nervous tissue?
Neuroglia
Neurones
Describe Neuroglia
Supports and protects neurones,capable of multiplying and dividing.
Can not generate electrical impulses.
6 types to be found CNS=4(oligondendrocyctes produce myelin), PNS=2(neurolemnocytes) also know as (Schwann cells) produce myelin.
What is Myelin?
Myelin a multi layered protein covering sheath, cover Axons only.
Axons covered are called MYELINATED, increase nerve impulse conduction.
What rate breaks in myelin sheath along an axon is called?
NODES OF RANVIER
Describe neurones.
Responsible for the transmission of impulses, neurones consist of 3 parts.
Dendrite, cell body (contains nucleus and organelles) Axons.
What do axons do?
They propagate impulses towards additional neurones, effector i.e. muscles or glands. Axons are long thin cylindrical projection.
Name the Nerves impulse conduction
Resting membrane potential. Polarised. Action potential. The absolute refractory period. Relative refractory period. All or nothing principal.
What is resting membrane potential?
An electrical voltage difference across the membrane in excitable cells.
What is it meant by polarised?
Any cell that exhibits a membrane potential.
What is an action potential?
Is also known as an impulse, is the decrease and eventual reversal of the membrane potential (depolarisation) and then restoring it to its original state (repolarisation).
What is it meant by the absolute refractory period?
When another impulse cannot be generated.
What is it meant by the Relative refractory period?
When another impulse can be initiated the stimulus has to be larger than the pervious one.
What is it meant by the all or nothing principle?
Where the stimulus is larger enough to change the membrane potential, therefore producing an action potential I.E the domino falls or it doesn’t.
What are 5 requires for the Reflex arc?
Sensory receptor i.e. skin
Sensory neurones i.e. nerve transmitting impulses towards the spinal cord and brain.
Integrating centre i.e. control centre (brain).
Motor neurone i.e. nerve transmitting impulses out of CNS to the part of the body that will respond.
Effector i.e. the part of the body that responds to motor nerve impulses (finger).
