CNS & PNS Flashcards
what are human co-ordinating systems for?
- co ordinating bodily movements
- reacting to stimuli ( changes in external and internal environment)
Endocrine system vs Nervous system
Endocrine= blood with hormones=slower
nerves= faster through impulses
both to maintain constant internal environment
What is CNS made of?
brain and spinal cord
Function of brain and what is it made of?
control all body functions
un repairable nervous tissue
How is brain protected?
bony cranium- prevent mechanical damage
meninges- membranes that protect/ cover the brain and spinal cord.
cerebrospinal fluid- cushioning and fluid to protect/ cover brain and spinal cord
Brain diagram and functions (7)
cerebrum-largest portion= conc. of nerves
control voluntary actions
interpret senses
higher order thinking and memory
cerebellum-second largest part of brain
coordinate skeletal muscles
maintain posture/ balance
muscle tone
medulla Oblongata- located on brain stem above spinal cord
transmit impulse from brain to spinal cord and vice versa
controls breathing/ perastalsis
other reflexes (cough/ sneeze)
hypothalamus- area above pituatry gland
control hunger/ thirst/ emotions and Temperature (ADH-water)
pituatry gland
pons- arousal (sympathetic and parasympathetic)
corpus callosum- connect both hemisphers of brain
allows for communication between hemispheres
spinal cord
brain stem
White matter and grey matter functions and locations?
centre of brain= white (cerebellum)
centre of spinal cord= grey
White= part of brain and spinal cord containing myelenated axons
grey= part of brain and spinal cords containing dendrites and cell bodies
what is spinal cord?
rod of nervous tissue in the vertebral canal
What is spinal cord protected by?
meninges, cerebrospinal fluid
vertebral dics and cartilage (shock absorber)
Functions of Spinal cord?
- transmit impulse from brain to effectors and receptors to brain
- contain reflec centres to automatically protect body
Spinal cord diagram (10)
dorsal root
sensory nueron
interneuron
motornueron
ventral root
central cavity
grey matter
white matter
ganglion
spinal nerves
How many pairs of spinal nerves?
31
Define nuerons?
specialized nerve cells that transmit nervous impulse
Define impulses
electrical signal created by receptor organs in response to stimuli
Define receptor
structure that reacts to stimuli by creating and impulse
Define effector
gland or organ that brings about the response to the stimulus recieved
Motor, sensory vs internueron functions?
sensory neuron transfers impulse from receptor to interneuron/ CNS ( Unipolar)
interneuron transmits impulse from sensory neuron to motor neuron (bipolar)
motor neuron transmits impulse from interneuron/CNS to the effector (Multipolar)
Motor nueron diagram (9)
Dendrite- fibres that transmit impulse toward cell body
axon- transmit nervous impulse from cell body to the terminal branches
myelin sheath- insulate and protect the neuron (faster)
shwann cells- regenerate myelin sheath
nissl granules- protein manufacture
node of ranvier- faster transmission
cytoplasm
cell body- cell metabolism
nucleus- cell metabolism
terminal branches (motor end plates)
Define synapse
gap (functional connection) between the axon of one nueron and the dendrite of another nueron
Why are synapses imortant?
to allow nervous impulse to be transmitted in one direction (sensory to motor)
to prevent over-stimulation of neuron (continuous)
Synapse diagram (5)
neurotransmitter
motor end plates
axon
dendrite
synaptic cleft
define nuerotransmitters?
chemicals within the synaptic cleft which transmit the nervous impulse
Define Reflex arc
pathway along which a nervous impulse is transitted to react to stimuli during reflex action
define reflex action
the quick automatic response of the nervous system in response to a stimuli to prevent danger and pain from body
Why does the reflex action not include the brain?
impulse for pain only sent after for quick reaction
Reflex explanation (6)
- receptor cell detects stimulus and converts to nervous impulse
- sensory neuron transmits impulse to dorsal root of spinal cord
- impulse transmitted from sensory to inter neuron across synapse
- impulse transmitted across synapse from inter to motor nueron
- impulse transmitted through ventral neuron along axon of motor neuron to effector
- effector organ recieves impulse and relevant physical reaction takes place to react to stimuli
What is the peripheral nervous system?
nerves that extend out of central nervous system
What does PNS consist of?
31 pairs of spinal nerves
12 pairs of cranial nervous
Functions of PNS?
transmit impulse from receptors to cns
transmit impulses from cns to effectors
Somatic vs Autonomic nervous system?
Somatic consists of all voluntary movements- change skeletal muscles
autonomic consists of involuntary movements of bodily functions
Sympathetic vs parasympathetic nervous system (8 examples)
sympathetic is the nervous system trigered in emergency situations (fight or flight)
parasympathetic is to restore the body to the normal state (maintain homeostasis- antagonistic)
increase heart rate/ blood pressure
widen bronchioles
sweat
vasoconstriction
relax bladder
decrease perastalsis
dialated pupils
stimulated adrenalin secretion
describe Alzheimers? and symptoms/ causes
neurodegeneretive disease- nerve defects in older people result in memory loss and confusion - no causes or cures
describe Multiple sclerosis? and symptoms/ causes
damage to myelin sheaths of neurons resulting in fatigue- not able to walk and loss of speech/vision- no cause or cures
what are sensory organs
organs with high concentrations of receptor cells
