Nervous system Flashcards
what is the nervous system divided into?
Central nervous system - brain & spinal cord
Peripheral nervous system - somatic (motor), and autonomic (sympathetic and parasympathetic)
what are the 3 regions of the brain?
fore brain
mid brain
hind brain
what are the 3 membranes in the brain?
arachnoid
pia mater
dura mater
Role of the cerebrospinal fluid
lies between the membranes - is a cushion, protective 7 homeostatic layer - prevents brain from knocking against the skull and provides nutrients to it e.g glucose & oxygen
what is the spinal cord?
delicate with a central grey area (2 dorsal & 2 ventral horns), and surrounding white matter (nerve fibres connecting spinal cord to brain).
- Afferent nerve fibres enter via dorsal root e.g sensory pain info via DRG cells
- Efferent nerve fibres leave through the ventral root e.g to skeletal muscle or glands
what is the functional unit of the nervous system
neurone
what are the 2 main types of cell in NS
non neuronal cells & neurons
name 4 non neuronal cells
- astrocytes
- oligodendrocytes
- microglial
- ependymal cells
what are astrocytes?
supportive function for CNS neurons. Contribute to the protective blood brain barrier
what are oligodendrocytes?
form the myelin sheath around axons in the CNS
what are microglial?
phagocytic action in Cns
what are ependymal cells?
epithelial cells in the fluid filled spaces brain and central canal of spinal cord - have microvilli which help circulate CSF around CNS
what are the 2 primary functions of neurons?
1- rapid transmission of information from specific sources to selected targets
- integration (summation) of information from many sources
what is role of dendrites?
receive information from other neurons - “convergence”
role of the axon
transmit information to other neurons, or non neuronal cells
role of axon collaterals
increase the transmission speed of information - divergence 10^3 - 10^4 contacts
what happens at the axon hillock?
action potential generated
what do nodes of ranvier contain
high in Na+ channels
how do nerves signal?
using action potentials
what is the equilibrium potential?
the potential at which the tendency of an ion to move down its concentration gradient is balanced by the resting membrane potential
what is the generation of an AP dependent on?
the pre existence of a resting membrane potential
what 2 major currents determine the action of the nerve AP?
1- Na+ current - inward, depolarising current
2- K+ current - outward, hyperpolarising current
where are Na+ channels activated and inactivated?
activated at M-gate
Inactivated at h-gate
where are K+ channels activated?
n-gate