NERVOUS SYSTEM Flashcards
what does the dorsal root ganglion contain
cell bodies of sensory neurons
what does the dorsal root contain
axons of sensory neurons taking information from the body to the spinal cord
what does the central root contain
contains the axons of motor neuron’s taking information from the brain to the body
what 3 structures protect the central nervous system
bone
meninges
cerebrospinal fluid
list the 3 meninges in order from outer to inner
DURA MATER - tough and fibrous
ARACHNOID MATER - loose mesh fibres
PIA MATER - delicate
list the 3 functions of Cerebrospinal fluid
protection - acting as a shock absorber and cushions the CNS
support - keeps brain suspended in cranium
nutrients - circulates through the central nervous system carrying nutrients to the brain and spinal cord
what does grey matter contain (3)
nerve cell bodies
myelinated fibres
central canal
what does white matter contain (2)
myelinated fibres
bundles of fibres arranged in ascending and descending tracts
what is the function of the spinal cord
carrying impulses to and from the body via the ascending (sensory info to brain) and descending (motor info to body) tracts of white matter
what is the function of the hypothalamus
maintaining homeostasis
controlling hormone secretion
what is the function of the medulla oblongata
automatically adjusts body functions
cardiac centre - regulating heart beat
respiratory centre - regulating breathing rate
vasomotor centre - regulating the diameter of blood vessels
what is the function of the cerebellum
conscious level
coordinates fine / controlled motor movement
muscle tone control (balance)
storing memory
what is the function of the corpus callosum
nerve fibres connecting both hemispheres, allowing both sides to communicate with eachother
what is the function of the cerebrum (3x tracts)
tracts connecting areas within same hemisphere
tracts carrying impulses between hemispheres
tracts connecting cortex to other parts of brain and spinal cord
what does the left hemisphere control
right side of body
verbal function
speaking, reading, writing, analysis, logic
what does the right hemisphere control
left side of body
non-verbal functions
emotion, intuition, music, art, belief, picture
what is the role of the frontal lobe
movement and intelligence
thinking, problem solving, emotion, personality
what is the role of the parietal lobe
processing sensory information such as temperature, touch, taste and pain
what is the role of the temporal lobe
receives auditory information
processes memories through linking sense
what is the role of the occipital lobe
receiving visual information from eyes
what is the function of a neuron
generating electrochemical signals/impulses carried from one body part to another
what is the function of the neurolemma
outer of shwann cells, repairing injury
what is the function of shwann cells
firing myelin sheathe by wrapping around the axon depositing layers of myelin around each coil as they wrap
what are the 3 functions of myelin sheathe
insulator - preventing electrical current from leaving cell
protection - protection of axon
Speed - speeds up electrical conduction along axon
what is the electrical conduction called along a myelinated axon
saltatory conduction
what are unipolar neurons usually?
sensory neurons
what are multipolar neurons usually?
motor neurons
interneurons
what are 2 characteristics of unipolar neurons
1x extension
connecting to a continuous axon
what are 3 characteristics of bipolar neurons
2x extensions
1x axon
1x dendrite
what are 3 characteristics of multipolar neurons
multiple extensions
1x axon
lots of dendrites
what are 4 distinct differences between motor and sensory neurons
MOTOR - impulses from CNS -> body
SENSORY - impulses from body -> CNS
MOTOR - multipolar
SENSORY - Unipolar
MOTOR - cell body in grey matter of spinal cord
SENSORY - cell body is dorsal root ganglion
MOTOR - pass through ventral root
SENSORY - pass through dorsal root
define synapse
junction between branches of adjacent neurons
how is a nerve impulse transferred rapidly across a nerve fibre (2)
- change in electrical voltage
- change in concentration of positive and negative ions inside/outside of cell membrane of a neuron
what is the resting membrane potential of unstimulated nerve cells ?
-70mV
where is extracellular fluid and what ions does it contain
fluid outside of cell
containing Sodium ions
where is intracellular fluid and what ions does it contain
inside of cell
containing potassium ions (K+) and large organic ions (-)
what occurs at resting membrane potential if a stimulus occurs?
if sodium or potassium leaves cell, pumped back by sodium potassium pump
stimulus occurs, sodium gated channels open for sodium to flow into cell
what occurs at threshold?
-55mV is reached
enough sodium enters the cell to reach -55mV (threshold)
what occurs during depolarisation?
sodium enters inside of cell causing the inside of the cell to become more positive and the outside becomes more negative
what occurs at the peak of the membrane potential arc?
everything is inside of the neuron cell
sodium channels close
potassium voltage-gated channels open
what occurs during repolatisation?
potassium leaves the cell via potassium voltage-gated channels
what occurs during hyperpolarisation
sodium and potassium pump swaps the sodium and potassium by pumping sodium out of the cell and potassium back into the cell
what is a refractory period?
during membrane potential/ for a beige time afterward, part of the nerve cannot be stimulated to respond again
ends when resting membrane potential is regained
what is meant by the all or none response ?
depolarisation only occurs if initial stimulus is strong enough (exceeds threshold) to open sodium gated channels
how is resting membrane potential maintained ? (3)
- highly permeable to potassium and chlorine ions
- only slightly permeable to sodium ions
- impermeable to negative organic ions
what is the difference between stimulus gated and voltage gated channels?
stimulus gated - open relative to stimulus and are always open depending on size of stimulus
voltage gated - open/close according to voltage of membrane = never always open, only open OR closed
where are transmitters released into from the axon terminal ?
into the synaptic cleft
what is the role of excitatory neurotransmitters
cause action potential in the receiving neuron
what is the role of inhibitory neurotransmitters
causing hyperpolarisation in receiving neuron making it hard to generate action potential
what happens if excitatory neurotransmitters bind to the receptors of the post synaptic cell?
ion channels open, influx of sodium into cell, causing threshold to be reached and action potential to be triggered
what happens to the neurotransmitter after it has binded to the receptor and passed in its action potential?
recycled back into the pre-synaptic cell
what type of neurotransmitter is adrenaline?
excitatory
what type of neurotransmitter is acetylcholine
both excitatory and inhibitory
define receptor
structure able to detect a change in the bodies internal/external environment
specialised to respond by producing an electrical/chemical discharge (AP)
define the role of thermoreceptors and their location
respond to heat and cold in the skin and hypothalamus
warm - fire fast if warmed
cold - fire fast if cold
define the role of osmoreceptors and where they are located
detect the changes in osmotic pressure within the body
located in the hypothalamus which stimulate the hypothalamus to maintain water content in the body
define the role of chemoreceptors and their location
stimulated by specific chemicals
chemicals bind to channels - ligand
located in the nose - sensitive to odour
located in aortic and carotid bodies detecting blood gas levels
define the role of mechanoreceptors
sensitive to touch
light touch receptors that are able to adapt rapidly
located on skin surface and base of hair follicles
define the role of nociceptors
sensitive to pain
stimulated by tissue damage
important for making body aware to take action and seek medical advice
located on skin surface and mucous membranes
define reflex
rapid, automatic response in external/internal environment
what are the 4 characteristics of a reflex
S - stimulus is required to trigger a reflex
I - involuntary (without conscious control)
R - Rapid occurring quickly
S - Stereotyped (happens the same @ every occurrence)
what occurs during a spinal reflex ?
message is not sent to the brain first
the message is passed to motor neurons at another level on the spinal cord
impulse is sent to brain after reflex to become consciously aware
RECEPTOR —> EFFECTOR = SPINAL REFLEX
what does the central nervous system involve
brain and spinal cord
what does the peripheral nervous system involve
12x cranial nerves
31x spinal nerves
what branches come off the peripheral nervous system ?
Afferent (sensory)
Efferent (motor)
what branches off the efferent division of the nervous system ?
somatic (voluntary)
autonomic (involuntary)
what is the effector in the somatic nervous system
voluntary skeletal muscles
what is the function of the somatic nervous system
respond to the external environment
which of the somatic and autonomic contains a ganglion ?
autonomic nervous system
what is the effector of the autonomic nervous system ?
involuntary muscles and glands such as the heart
what is the function of the autonomic nervous system?
to maintain the bodies internal homeostasis levels
what does the autonomic nervous system branch into
sympathetic (fight/flight) division
parasympathetic (rest and digest) division
what regions of the spinal cord arise during a fight or flight response?
lumbar and thoracic region
what region of the spinal cord arises during a rest and digest response?
the cranial and spinal regions (upper and lower)
what neurotransmitters are released during a fight and flight response ?
acetylcholine released to the first ganglion
noradrenaline released to the effector
what neurotransmitters are released in a rest and digest response?
acetylcholine both to the ganglion and effector
which has a longer pre-ganglionic axon
parasympathetic nervous system
what causes parkinson’s disease and what part of the nervous system is affected?
basal ganglion region in the substantial nigra (dopaminergic neurons)
dopaminergic cells stop making dopamine
what are 3 symptoms of Parkinson’s disease?
shakiness/tremours
cognitive improvement
sleep disorders
mental health disorders
what are 2 treatments for parkinson’s disease?
cell replacement therapy - replacing damaged dopaminergic cells
levodopa/dopamine drugs
physiotherapy, deep brain stimulation
what causes alzheimers disease?
slow plaque growth covering cerebrum which degenerates neuron’s
what part of the brain is affected by alzheimers disease?
cerebrum
what are 3 symptoms of alzheimers?
memory loss
aggression/irratic behaviour
difficulty thinking/understanding
inability to control muscles
what are 2 treatments for alzheimers
physical exercise
cognition enhancing medication
is cell replacement therapy possible for alzheimers disease? why?
not possible
too many cells affected in different areas
