5.Nervous system Flashcards
what’s the nervous system
complex highly organised network of specialised cells that enables the brain to receive internal and external stimuli
Outline 3 functions of Nervous system
-maintain homeostasis
-detect, interpret and respond to internal AND external stimuli
-control and coordinate voluntary and involuntary activities of the body
what’s the CNS consist of
brain
spinal chord
what’s the PNS consist of
Peripheral nerves
-cranial and spinal nerves
Outline how the body coordinates a response
- Sensory receptors eg photoreceptors detect sensory information and carry it to the CNS via the afferent pathway
- Interneurons of the CNS coordinate a response
3.Motor neurones carry the motor command from the CNS to an effector (down the efferent pathway) and the effector carries out a response
Major division of NS
CNS and PNS
division of PNS
Sensory and motor divison
division of motor and sensory NS
Autonomic and Somatic NS
Division of somatic NS
-transmits sensory info
-carry out voluntary muscle movements
Division of Autonomic NS
Sympathetic and Parasympathetic NS
AND ENTERIC NS
Function of CNS
process information received from body internal and external environments
What is the brain
-mass of soft nerve tissue
-1.4 kg
Brain function
receive and interpret sensory information
-responsible for memory, curiosity,thinking, learning…
Function of spinal chord
-connects brain to rest of body
-receives sensory information and transfers it from body to brain
-receives motor information and transfers it from brain to body
Four lobes of brain
Frontal
Parietal
Occipital
Temporal
Whats concussion
mild traumatic brain injury caused by direct or indirect blow to head
symptoms of concussion
-headache, dizziness, blurred vison, nausea, confusion
Whats the peripheral NS
all nerves outside brain and spinal chord
Function of PNS
carries sensory information from body to CNS and motor information from CNS to body
types of sensory information
Visceral-signals from internal organs
Somatic- position, touch, pain ,temp and pressure
Special senses- smell, taste, vision, balance and hearing
Function of autonomic NS
controls INVOLUNTARY systems
-heartbeat
-peristalsis
-breathing rate
-glands
-hormones
Function of Somatic NS
Controls voluntary skeletal muscle movements
Function of Sympathetic NS
-prepares the body for a fight or flight response
Function of Parasympathetic NS
-Prepares body for rest and repair
4 Physiological changes for sympathetic NS
reduce digestion, decreased bladder control, dilate pulse, increase HR , diversion of blood towards muscles
4 Physiological changes for Parasympathetic NS
Decreased HR, pupils constrict, increased bladder control, stop sweating, increased digestion
identify parts of neuron
dendritic spines, dendrite, nucleus, cell body/soma, axon, myelin sheath, node of ranvier, Schwann cell, axon terminals, terminal buttons/synaptic knobs, synapse
What are glial cells
supportive/connective cells of the NS that do not transmit an action potential
Identify CNS glial cells
Astrocyte, microglia, oligodendroglia
Identify PNS glial cells
Schwann and satellite cells
Astrocyte function
-star shaped that provide physical and nutritional support eg.clean neural debris, digest dead neurons, transport nutrients to nucleus
Microglia function
digest part of dead neurons
Oligodendroglia function
produce myelin sheath for CNS neurons (insulate + protect)
Schwann cell function
produce myelin sheath for PNS neurons (insulate+protect)
Satellite cell function
physical support to PNS neurons
function of nerve cells
transmit electrical signals
Dendrite function
branch like extensions which receives input from other neurons
Cell body/soma function
includes a nucleus which controls the neuron
Axon function
carries electrical information from the cell body to the axon terminals
Synapse function
-space between neurons where transmission occurs
-allows for transmission between neurons via chemical communication
Axon terminals function
branch like extensions from axon that carries messages to terminal buttons
Terminal buttons function
sends signals from a neuron to adjacent cells (release neurotransmitters)
Myelin sheath function
white fatty substance that covers and insulates the axon, hence speeding up the rate of transmission and prevents stimuli interfering with transmission
Function of node of ranvier
gaps in myelin sheath, allow for rapid depolarisation of nerve impulse
Identify stages of neural communication
Resting Potential
Threshold
Depolarisation
Repolarisation
Describe resting potential
=-70m/v
-Sodium outside the cell and potassium inside, positive outside and negative inside the cell
-Sodium and Potassium channels closed
-Neuron at rest
Describe Threshold
-Stimulus (neurotransmitters bind to receptor sites on dendrites intern increasing the charge inside the cell
=-55m/v is the threshold
-once -55m/v reached sodium channels open and the action potential fires in an all or nothing event
Describe Depolarisation
-Positively charged sodium ions rush onto the cell and cell becomes more positively charged
=+40m/v
-the cell is now positive inside and negative inside and hence opposite of polarised
Describe Repolarisation
-after action potential the cell returns to its resting state
-K+ channels open, potassium rushes out of cell reversing the depolarisation and cell becomes polarised once again (back to -70m/v)
-
Reflex definition
involuntary and nearly instantaneous movement in response to a stimulus
Reflex arc is
the path taken by nerve impulse in reflex
RECPETOR–> Sensory neuron –> interneuron–>motor neuron–> effector
Identify two types of reflex
monosynaptic and polysynaptic
contrast a mono and polysynaptic reflex
Monosynaptic only contains one synapse and a sensory+motor neuron whereas polysynaptic contains multiple synapses and more than 2 neurons.
Outline the patella knee jerk reflex
Monosynaptic reflex (patella nerves are directly attached/connected to spinal chord) and the hamstrings lengthen / quads contract
Outline withdrawal reflex
-sensory stimulus detected by sensory receptors
-sensory neurons carry information via sensory neurons (afferent pathway) to spinal chord
-interneurons in spinal chord initiate an involuntary movement
-relayed to motor neurons that carry the motor command down the (efferent pathway) to the muscle
-muscle (somatic NS) carries out reflex without brain input
Purpose of reflexes
largely protective- aid survival
-allow one to adapt to changing environments
-rapid response to hazard eg hot pan
What are primitive reflexes
reflex actions originating in CNS
-normal in infants and abnormal in adults (these reflexes usually suppress with frontal lobe development)
Examples of. primitive reflexes
moro (startle)
grasp
suck
babinski
Name 4 adult reflexes
Jaw jerk
ankle jerk
corneal reflex
distal finger flexors
Wha are upper motor neuron lesions
lesions anywhere from Cortex to descending tracts
Identify 6 common neurotransmitters
Acetylcholine
dopamine
endorphin
GABA
epinephrine
serotonin
glutamate
other name for epinephrine
adrenaline
Function of acetylcholine
-muscle contraction
-heartbeat
-memory
-excitatory neurotransmitter
Function of dopamine
-memory/learning
-behaviour
-movement coordination
function of endorphin
-pain signals
-euphoric feelings
Function of epinephrine
-hormone and neurotransmitter
-fight or flight
function of GABA
-mood regulation
-inhibitory neurotransmitter
function of serotonin
-mood,apetite and sleep
Briefly describe Myasthenia gravis
-autoimmune disease in which antibodies produced block Ach receptors on the post synaptic neurone and messages are unable to pass to the muscle effector and initiate muscle contraction
Where does myasthenia gravis occur
the neuromuscular joint
symptoms of myasthenia gravis
-diplopia, ptosis, dysphasia and difficulty walking
Distinguish between white and grey matter
white matter is found deeper in the brain whereas grey matter is more superficial
white matter are generally made of bundles of axons whereas grey matter is comprised of cell bodies, axon terminals and dendrites
List three ways brain is protected
Cranium/skull
meninges
CSF
What is the meninges
membrane that surrounds the brain and contains 3 layers
Outline 3 layers of meninges
-Dura mater= outermost layer/2 layers of dense tissue (inner surface of skull and outer surface of brain)
-Arachnoid mater=fibrous tissue in between dura and Pia mater/seperates the dura mater and subdural space
-Pia mater= fragile layer of connective tissue with many minute blood vessels/completely covers brain and spinal chord
Where is Cerebrospinal fluid
-surrounds brain and spinal chord
-fills ventricles of brain
What is Cerebrospinal fluid
-clear colourless fluid
-made of water, salts, minerals, protein, leukocytes, urea…
Function of Cerebrospinal fluid
-provides cushioning for brain and signal chord to protect/ decreases friction in the cranial cavity
-maintains pressure
-circulates nutrients and chemicals from blood
-removes wastes from brain
Overall 3 sections of brain
cerebrum
cerebellum
brainstem
what connects two hemispheres of cerebrum
corpus callosum
describe structure of cerebrum
-4 lobes
-2 hemispheres
-cerebral fissure divides cerebrum
-superficial is made of grey matter and deep layers are made of white matter
Identify 5 functions of cerebrum
Initiate / coordinate movement
learning
touch
problem solving
emotions
Identify 4 lobes of brain
frontal
parietal
occipital
temporal
Location of frontal lobe
most anterior lobe
5 functions of frontal lobe
executive functions
language- Broca
Voluntary skeletal movements
personality
memory
Location of parietal lobe
-between frontal and occipital lobes
-superior to temporal lobe
4 Functions of parietal lobe
-receive and process sensory informant from the SKIN
-perception (spatial awareness)
-arithmetic
-spelling
Describe motor cortex
in frontal lobe and coordinates motor output
Describe somatosensory cortex
in parietal lobe and receives sensory output from SKIN
Location of temporal lobe
-side of head/near ears and temples
4 functions of temporal lobe
-memory consolidation
-language
-hearing
-understanding
Location of occipital lobe
posterior in skull
Function of occipital lobe
-process visual information regering shape, perspective and colour
Where is diencephalon
-posterior part of forebrain
-above brainstem between cerebral hemispheres
Function and structure of diencephalon
-relays and processes sensory information for autonomic control
-epithalamus, thalamus, hypothalamus, ventral thalamus
Function of hypothalamus
MAINTAINS HOMEOSTASIS
-satiety and appetite
-water and thirst balance
-sleep wake cycles
Function of thalamus
-sleep, wakefulness and alertness
-relay motor and sensory signals to cerebral cortex
Limbic system structures
-hypothalamus
-amygdala
-thalamus
-hippocampus
Functions of limbic system
memory and emotions
Cerebellum functions
-voluntary muscle movement
-balace
-posture
-equilibrium
-eye movement
Functions of brain stem
-conducts all signals from spinal chord to brain and vice versa
-regulates reflex centres for vital functions
-contains nuclei of cranial nerves
-other autonomic functions
location of cerebellum
back of brain behind pons and posterior to cerebrum
Midbrain function
reflexes re: hearing and vision
Pons function
relay station for cranial nerves
Medulla function
controls autonomic reflexes eg swallow, breath, sneeze
how many cranial nerves
12 pairs
what are cranial nerves
nerves part of PNS that connect your brain to different parts of head, neck and trunk
Functions of cranial nerves (5)
smell
sight
hearing
balance
sensation in face
Ischaemic stroke
blood vessels suppling blood to brain become blocked due to blood clot (thrombocyte) that has migrated from elsewhere in body
Heamorrhagic stroke
blood vessel supplying blood to brain lyses/bursts due to high BP and causes internal bleeding in brain
Describe spinal chord
-long thin tubular structure of nervous tissue
-from medulla to lumbar region
Function of spinal chord
carries sensory and motor information from body to brain and vice versa
reflex arcs
protection
What are spinal nerves
-emerge from spinal chord between vertebrae
-run from spinal chord to specific body area
-31 pairs
Two roots of spinal nerves
-The front (motor/anterior root) of spinal chord
-the back (sensory/posterior root) of spinal chord
