9.4 - TNS Structure Flashcards
what is the basic structure of the mammalian nervous system?
the central + peripheral nervous systems
what is the CNS composed of?
the brain (where info is processed + instructions can be issued, coordinate response) & spinal cord (carries nerve fibres into + out of brain and coordinates many unconscious reactions)
what is PNS?
this is rest of NS - divided into somatic (voluntary) and autonomic (involuntary)
it is made up of sensory neurones (carry AP from receptors -> CNS) & motor neurones (carry AP from CNS -> effectors)
what is the somatic nervous system
part that communicates with sense organs + voluntary muscles; it includes all sensory + motor neurones taking info to skeletal/voluntary muscles
what is the autonomic nervous system? its divided into?
communicates with internal organs + glands/neurones supplying internal organs; sympathetic division + parasympathetic division;
what two types of cells is TNS made up of?
sensory/motor/relay neurones - carry ELECTRICAL IMPULSES in form of APs through body
(DNTK) glial cells - many functions -> help nutrients from blood pass to neurones + maintain correct balance of ions in tissue fluid surrounding} the Schwann cells forming myelination around axons of some neurones = glial cells!
describe structure of motor neurones?
cell bodies situated just out spinal cord in dorsal root ganglia; long cytoplasmic processes (dendron) that pick up info at receptors/sense organs and transmit APs towards cell bodies; APS then travel along their axon (long) to CNS
describe structure of sensory neurones?
short axon, long dendron
what do you need to know about nerves?
- axons + dendrons of neutrons generally lie in bundles -> NERVES
- As+Ds leave and enter spinal cord in spinal nerves - occurs bw each pair of vertebrate
- each spinal nerve has DORSAL ROOT - carries impulses from receptors -> spinal cord
- also has VENTRAL ROOT -> carries impulses outwards to effectors
- cranial nerves = brain
what is the function of the autonomic NS?
- resp for controlling majority of homeostatic mechanisms
- carries APs to all internal organs
- controls activity of smooth muscle in body
- controls rate of beating of cardiac muscle in heart + activities of exocrine glans
sympathetic NS?
- fight to flight response
- eg increased HR/BR; inactive digestion
parasympathetic NS?
- rest and digest
- lowered HR/BR, active digestion
what are the structural difs bw sympathetic + parasympathetic systems
- so in both myelinated preganglionic fibres leave CNS + synapse in a ganglion (collection of cell bodies) w myelinated post-ganglionic fibres BUT in sympa -> the ganglia r v close to CNS so preganglionic fibres short and post = long OPP in para - ganglia v close to effector organ
what are the functional difs bw sympathetic + parasympathetic systems
symp - produces noradrenaline at synapses + usually produces rapid response in target organ system = fight/flight system} SNS dominates
para - slower, damping down/inhibitory effect on organ systems - acetylcholine (neurotransmitter) produced at synapses} PSNS maintains normal functioning of body + restores calm
what is the function of the hypothalamus
PLAYING KEY ROLE IN HOMEOSTATIC MECHANISMS - releasing/stimulating release of hormones
- temperature regulation and osmoregulation.
- regulating digestive activity
- controlling endocrinic functions
what is the function of the cerebrum
- carries out loads of conscious activities: vision, hearing, speech, thinking, memory
initiates movement
what is the function of the cerebellum
controls balance and coordination of movement
what is the function of the medulla oblongata
controls breathing (respiratory centre) and heart rate (cardiac centre)
structure of the brain:
cerebrum on outside, cerebellum under, medulla oblongata part sticking out in middle under, hypothalamus = tiny + above medulla
what is the structure of the cerebrum?
- divided into 2 halves (Cerebral hemispheres) - joined by band of nerve fibres (corpus callosum)
- right hemisphere controls left side of body vice versa
- cerebrum has thin outer layer = cerebral cortex (grey matter) -> consists of cell bodies of neurones -> highly folded - large SA - more neurones - more connections - more complex behaviours
- under grey matter is white matter - myelinated axon soft neurones
structure of spinal cord
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