Nervous system Flashcards
What are the organs of the nervous system
Brain, spinal cord, peripheral nerves, sense organs
What are the 2 divisions of the nervous system
CNS: brain and spinal cord
PNS: nerves and sense organs
What are 3 functions of the CNS
To process and coordinate:
Sensory data (input):
from inside and outside the body
Motor commands (output):
to control activities of peripheral organs (e.g., skeletal muscles)
Higher functions of the brain:
intelligence, memory, learning, emotion
What are 3 functions of the PNS
Connect the nervous system with other systems
Deliver sensory information to the CNS (from the sensory organs)
Carry motor commands to peripheral tissues and effectors (muscles, glands etc)
What 2 types of cells make up neural tissue
Neurones and Neuroglia (glial cells)
What two types of matter make up neural tissue
Grey matter: mainly cell bodies and unmyelinated neurones
White matter: mainly axons of myelinated neurones
Describe the structure of a neurone
Cell body containing a nucleus and perikaryon
Dendrites coming off cell body
Schwann cells form myelin sheath around the axon
Gaps between internode are nodes of ranvier
Describe the structure of a synapse
Axon
synaptic vesicles
Synapse - gap
Neurotransmitter
Receptor
Dendrites
What is an anaxonic neuron
Anaxonic neurons have more than two processes- all dendrites.
brain and special sense organs
What are bipolar neurones
Bipolar neurons have two processes separated by the
cell body.
rare – special sense organs
What are unipolar neurones
Unipolar neurons have a single elongated process, with the cell body located off to the side.
common sensory type
What are multipolar neurones
Multipolar neurons have more than two processes; there is a single axon and multiple dendrites.
somatic motor and autonomic nerves
What is the direction of impulse for sensory neurones
from receptors to CNS
from lower to higher CNS levels
What is the direction of impulse for association (inter) neurones
from sensory to motor neurones
What is the direction of impulse for motor neurones
from CNS to muscles
from higher to lower CNS levels
Efferent autonomic nerve pathways
have a 2-neurone arrangement comprising a pre- and a post-ganglionic nerve
Efferent somatic pathways
have a single neurone from CNS to effector
Types of neuroglia in the CNS
Ependymal cells
Astrocytes
Oligodendrocytes
Microglia
Types of neurolgia in the PNS
Schwann Cells
Satellite Cells
What is the resting membrane potential of a nerve cell
-70mV
Why is there are resting membrane potential
Due to the uneven distribution of charged particles on either side of the cell membrane and selective membrane permeability to ions
Why does the resting membrane potential develop
Organic Anions
Na+/K+ pump
Uneven stoichiometry
Electrogenic
Membrane permeability
More permeable to K+ than to Na+
Ionic Gradients and Equilibrium potentials
ionic concentration in IntraCF and ExtraCF and electrical charge
Where is resting membrane potential
Periphery of the cell
What two types of force influence the movement of ions across the plasma membrane
Chemical gradients and electrical gradients
What is the chemical gradient
Ions want to pass from areas of high concentration to low concentration
Na+ wants to pass into the cell
K+ wants to pass out the cell
What is the electrical gradient
Ions want to pass to areas of opposite charge
Both Na+ and K+ want to pass into the cell
What is the electrochemical gradient
the balance of forces acting upon an ionic species
Na+ both electrical and chemical gradients attract Na+ into the cell
K+ the chemical (out) and electrical (in) oppose one another
What is the equilibrium potential of an ion
The voltage that is achieved when the plasma membrane is exclusively permeable to that ion
When does equilibrium potential occur
When the chemical gradient force is equal and opposite to the electrical gradient force
What is the equation at body temp for equilibrium potential
Ex= 61/n x log ([X]0/[X]i)
61 = constant derived from temp
n = valency of the ion X
log… = ionic concentration gradient across the membrane
