NS- organisation and brain anatomy Flashcards
What is grey matter, where is it found
all unmyelinated parts of neuron (unmyelinated axons, cell bodies, dendrites, axon terminals) and neuroglia
only found
- at periphery of brain
- A few clusters deep within brain
- innermost layer of spinal cord
- called nuclei in CNS and ganglia in PNS (with exception of basal ganglia which is situated in cerebrum)
what is white matter
composed of myelinated axons and dendrites
- CNS- majority of brain tissue and periphery of spinal cord
- PNS- most neuron axons
What are sensory / afferant nerves
carry info from body to spinal cord
impulses may then pass to the brain, or to connector neurones of reflx arcs in the spinal cord
what are sensory receptors
specialised endings of sensory neurones
respond to different stimuli inside / outside the body
what are somatic, cutaneous or common senses
sense that originate from the skin
pain, touch, heat and cold
sensory nerve endings in the skin transmit action potential to the brain where sensation is perceived
what are proprioceptor senses?
senses originating in muscles / joints
send info to the brain about the position of the body and its parts in space
enables maintenance of posture and balance
what are autonomic afferent nerves
originate in internal organs, glands and tissues
what are motor / efferent nerves?
motor nerves originate in the brain, spinal cord and autonomic ganglia
motor nerves transmit impulses to the effector organs (muscles and glands)
2 types
- somatic nerves (voluntary and reflex skeletal muscle contraction)
- autonomic nerves (involuntary)- involved in cardiac + smooth muscle contraction and glandular secretion
- sympathetic
- parasympathetic
describe the nerve pathway for somatic nerves
“lower motor meurone”- only one neurone that leaves spinal cord and travels directly to the skeletal muscle
Synapse is called Neuromuscular junction, NT is always acethycholine
describe nerve pathway for autonomic nerve pathways
involve two nerves
- preganglionic neurone leaves spinal cord and synapses with a second nerve (postganglionic neuron)
- postganglionic neurone synapses with the effector tissue (cardiac muscle / smooth muscle / glands)
main NT’s are noradrenaline (norepinephrine) and acetycholine
- postganglionic neurone synapses with the effector tissue (cardiac muscle / smooth muscle / glands)
what are mixed nerves
nerves found outside the spinal cord
the sensory and motor nerves are enclosed within same sheath of connective tissue (rather than being arranged in separate groups (Tracts) as they are in hte spinal cord
what are the 4 types of neuroglia
astrocytes-
- most abundant
- allow nutrient exchange between neurons and blood vessels
- form part of the blood-brain barrier (selective barrier that protects brain from potentially toxic substances and chemical variations in the blood)
oligodendrocytes
- produce myelin (in CNS)
- Myelin insulates neurons and increases conduction speed
ependymal cells
- line cavities in the brain and spinal cord
- produce adn circulate CSF
microglia
- monitor health of neurons
- remove dead / injured neurons
what are properties of neurones
cell body + axon + dendrites
cannot divide
need continuous supply of oxygen + glucose for survival
can normally synthesize ATP from glucose only (unlike many other cells)
Differentiate betwen function of neurons and neuroglia
neurons - transmit electrical impulses
neuroglia- protect, nurture neurons (e.g. produce myelin to increase conduction speed, remove dead + injured cells, allow nutrient exchange between neurons and blood vessels whilst maintaining blood brain barrier), produce CSF
name the lobes and principal suci of the brain
frontal cortex
parietal lobe
occipital lobe
temporal lobe