Week 2 - Neurophysiology & nervous system Flashcards
ANS control
- in absence of stimuli, autonomic motor neurons maintain continuous activity →autonomic tone
- DUAL INNERVATION: organs receive signals from both divisions.
→ most effects are atagonistic eg HR
→ cooperative effects are rarer eg. erection - single innervation only occurs for some tissues and is under sympathetic control → role in BP & flow
motor neurons
LOWER: has cell body in ventral horn of spinal cord and an axon that innervates skeletal muscle
UPPER: cell bodies in forebrain/brainstem & send axons to activate lower motor neurons
Afferent
input signals that APPROACH the CNS
Efferent
input signals that EVADE the CNS
Ganglion
collection of cell bodies located in PNS
visceral division
(autonomic)
VISCERAL SENSORY: sensory neurons carry signals from viscera
VISCERAL MOTOR: sympathetic & parasympathetic neurons carry signals to viscera
somatic division
SOMATIC SENSORY : eye, skin, skeletal muscle
- carry signals from muscles, bones, joints & skin, as well as special sensory signals
SOMATIC MOTOR: motor neurons carry signals to skeletal muscles
diencephalon - thalamus
GATEWAY TO CORTEX: filters sensorimotor info from CNS (except smell)
diencephalon - hypothalamus
COMMANDER OF ANS
- controls homeostasis
- endocrine functions via pituitary gland
- connected to limbic system
cerebellum
- monitors & coordinates movement
- 3 lobes for balance & posture, locomotion, skilled motor tasks
diencephalon
- processes, integrates, relays info
- maintains homeostasis
- regulate biological rhythms
cerebrum
- performs higher mental functions
- interprets sensory stimuli
- plans and initiates movement
white matter- functions
- relay impulses to & from brain via ascending & decending tract ie. communication
ASCENDING:
- discriminative touvh
- balance (spacial awareness)
- pain and temperateure
DESCENDING (MOTOR)
- voluntary movement
- involuntary movement (ANS CONT. & posture
grey matter - function
DORSAL HORN: neurons process afferent input from somatic & visceral tissue
- specify stimulus MODALITY & location
- integrating centre for spinal reflexes
LATERAL HORN: present at thoracic and sacral levels
- autonomic NS : visceral motor input
VENTRAL HORN: motor(efferent) output to skeletal tissue
brain stem - midbrain
conciousness, visual & auditory reflexes
brain stem - pons
balance, hearing, facemovement
brainstem - medulla
life support systems eg. breathing & blood pressure
reflex arc - somatic
- receptor
- sensory neuron
- integration centre
- motor neuron
- effector
ANS
- visceral motor system. para*sympathetic div
- NOT under concious control of brain
- regulated by HYPOTHALAMUS & BRAINSTEM
- function: HOMEOSTASIS
→ target: visceral organs of anterior cavities: blood vessels, hairs, sweat glands
cranial nerves
- olfactory S
- optic S
- occulomotor M
- Trochlear M
- Trigminal B
- Abducent M
- Facial B
- Vestibulocochlear S
- glossopharangeal B
- vagus B
- accessory M
- hypoglossal M
Autonomic neuro transmission
POSTGANGLIONIC SYMPATHETIC NEURONS: release noradrenaline as neurotransmitter
POSTGANGLIONIC PARASYMPATHETIC NEURONS: release acetylcholine as neurotransmitter
both systems use acetylcholine (ACH) as their preganglionic neuro transmitter - differ in post
sympathetic div - alarm system
- efferents originate in T1-L2 cord
- use grey & white to allow preganglionic axons access to different body regions
- preganglionic neurons make a SINGLE SYNAPSE at one of these sites
- same level
- above/below
- in collateral ganglia
monosynaptic reflex
- homeostatic response to muscle fatigue/ stretch which lengthen muscle causing to contract back to original
- reflexed give info about health of body
→ PNS damage dec. reflex size
→ CNS damage inc. reflex size
Cholinergic receptors - ANS
NICTONIC: fast excitatory ionotropic channels that evoke AP →hound in post ganglionic neurons, adrenal gland cells & skeletal muscle membranes
MUSCARINIC: parasympathetic NS target tissues & sweat gland
- diff channel type
- evoke slow excitatory graded potentials → dont produce AP unless theres repetitive simulation
