CNS + brain Flashcards
3 structures that protect the CNS
bone
meninges
cerebrospinal fluid
how does bone protect the CNS?
cranium protects brain
vertebral canal protects spinal cord
what are the meninges and their function?
- 3 layers of connective tissue which serve as a protective barrier that safeguard CNS organs against trauma
- connects brain and spinal cord to skull and spinal canal
- contain blood vessels that deliver blood to CNS tissue
- produces CFS
3 layers of meninges
- dura mater
- arachnoid mater
- pia mater
what is the dura mater?
- outer meningeal layer
- tough and fibrous > provides a layer of protection
- sticks closely to bones of the skull
on inside of vertebral canal - not so close-fitting
what is the arachnoid mater?
- middle meningeal layer
- loose mesh of fibres
what is the pia mater?
- the inner meningeal layer
- far more delicate
- contains many blood vessels and sticks closely to surface of the brain and spinal cord
what is cerebrospinal fluid and where is it produced?
- found between inner and middle layer of meninges
- clear, watery fluid which circulates nutrients absorbed by blood and collects waste
what are the functions of the cerebrospinal fluid?
- protection > acts as a shock absorber, cushioning shocks CNS will sustain
- support >brain is suspended inside the cranium and floats in the fluid surrounding
- transport > formed from blood, and circulates around through the CNS before reentering the blood
takes nutrients to cells and removes wastes
4 structural features of the cerebrum
- largest part of the brain
- surface is folded into convolutions to increase SA
- outer surface of thick grey matter - cerebral cortex
- white matter below the cortex
what is the longitudinal fissure
- deepest fissure
- separates cerebrum into 2 halves
what are the 5 lobes
- frontal lobe
- parietal lobe
- temporal lobe
- occipital lobe
- insula
what are the 6 functions of the frontal lobe
- thinking
- problem-solving
- emotions
- personality
- language
- control of movement
what are the 5 functions of the parietal lobe?
- processing temperature
- touch
- taste
- pain
- movement
what are the two functions of the temporal lobe?
- processing memories and liking them with senses
- receives auditory info
what is the function of the occipital lobe?
vision
what are the 2 functions of the insula?
- deep inside the brain
- recognition of different senses and emotions, addiction and psychiatric disorders
what are the 3 functional areas of the cortex?
sensory areas
motor areas
association areas
what is the basal ganglia?
- additional grey matter deep inside cerebrum
- consist of groups of nerve cells bodies associated with control of skeletal muscles = initiate desired movements and inhibit unwanted movements
what is white matter?
made up of myelinated axons
what are tracts?
bundles of nerve fibers
what are the 3 types of tracts?
- tracts that connect various areas of the cortex within the same hemisphere
- tracts that carry impulses between left and right hemispheres
- tracts that connect the cortex to other parts of brain or spinal cord
what is the corpus callosum?
- wide band of nerve fibres that lies underneath cerebrum
- nerve fibres cross from one hemisphere to other to allow 2 sides to communicate
what are the 4 structural features of cerebellum?
- lies under rear part of cerebrum
- surface folded into parallel ridges
- outer folds is grey matter
- inside is white matter
what are the functions of cerebellum and where it receives info from?
- controls posture, balance and fine coordination of voluntary muscle movement
- receives info from inner ear about posture and balance and stretch receptors in skeletal muscles for info about length of muscle
- allows smooth, coordinated movements
what is the hypothalamus?
- lies in the middle of brain
- controls many bodily activities and maintains homeostasis
what are the 6 functions of the hypothalamus?
- regulation of HR, BP, secretion of digestive juices, movements of the alimentary canal
- body temp
- food and water intake
- patterns of waking and sleeping
- contraction of bladder
- emotional responses
what is the structure of the medulla oblongata?
- continuation of the spinal cord
- extends just above point where spinal cord enters skull
what are the 3 centres of the medulla oblongata and their functions?
- cardiac centre = regulates rate and force of heart beat
- respiratory centre = control rate and depth of breathing
- vasomotor centre = regulates diameter of blood vessels
what is the structure of spinal cord?
- cylindrical structure
- extends from foramen magnum to second lumbar vertebra
- space containing fat, connective tissue, and blood vessels serves as padding and allows cord to bend
- grey matter of spinal cors is at centre surrounded by white matter
what is grey matter?
- composed of nerve cell bodies and unmyelinated nerve fibres
what are ascending tracts?
sensory axons that carry impulses upwards, toward brain
what are descending tracts?
contain motor axons that conduct impulses downwards, away from brain
functions of spinal cord
- carry sensory impulses up to brain and motor impulses down from brain
- integrates certain fast, automatic responses called reflexes
what is the peripheral nervous system?
- takes messages from receptors to CNS and from CNS to muscles + glands
- consists of nerve fibres that carry info to and from CNS + ganglia
what are spinal nerves?
- 31 pairs of spinal nerves
- pass between vertebrae and divide into dorsal and ventral branch
what are cranial nerves?
- 12 pairs of cranial nerves
- connect directly with brain
- may be motor, sensory or mixed
what is the afferent division of the nervous system?
- known as sensory division
- fibres that carry impulses into CNS by sensory neurons from receptors in skin and around muscles and joints
what are somatic sensory neurons?
bring impulses from skin and muscles
what are visceral sensory neurons?
bring impulses from internal organs
what is the efferent division?
- known as motor division
- has nerve fibres that carry impulses away from CNS
divided into somatic and autonomic
what is the autonomic nervous system?
- controls body’s internal environment and involved in many mechanisms that keep it constant
- involuntary
how does a nerve impulse travel in the autonomic nervous system?
- impulses travels along 2 neurons from CNS to organ with a synapse as ganglion
- first neuron is myelinated
- second neuron is unmyelinated
what is the parasympathetic nervous system?
produce responses that maintain homeostasis
rest and digest
what is the sympathetic nervous system?
produce responses that disrupt homeostasis and prepare the body for strenuous physical activity
fight or flight
what happens during the flight or fight response?
- balance between sympathetic and parasympathetic stimulation is upset and sympathetic becomes dominant
- prep body for activity and rely on skeletal muscles to produce movement and increase alertness
what happens to: heart rate blood pressure blood vessels in working organs blood vessels in nonworking organs rate and depth of breathing blood glucose levels secretion of sweat glands
during the fight or flight response (sympathetic NS)?
- increase HR and force of contraction = increase BP
- blood vessels dilate in working organs
- blood vessels constrict in non working organs
- rate and depth of breathing increase
- blood glucose levels increase
- secretion from sweat glands increase
what is the functional role of the CNS?
integrative role - interprets sensory info and determines motor response
what is the functional role (sensory and motor) of the PNS?
- sensory role - reception of internal and external stimuli and sends message to CNS
- motor role - receives messages from CNS and initiates response from a particular effector
nerve length in the parasympathetic division
ganglia are near effectors
preganglionic nerves are long
postganglionic nerves are short
more specific, slower as these jobs aren’t as urgent
nerve length in the sympathetic division
ganglia are close to spinal cord
preganglionic nerves are short
postganglionic nerves are long
gets to effector quicker as they’re more urgent
short first 1st neuron gives greater range for effectors
AUTOMATIC DIVISION
- effectors
- general function
- efferent pathways
- neurotransmitter at effector
- control
- nerves to the target organ
- effectors = heart muscle, involuntary muscles, glands
- general function = =adjustment of the internal environment
- efferent pathways = two motor neurons from the CNS to the effector with a synapse in a ganglion
- neurotransmitter at effector = acetylcholine or noradrenaline
- control = involuntary
- nerves to the target organ = excitation or inhibition
SOMATIC DIVISION
- effectors
- general function
- efferent pathways
- neurotransmitter at effector
- control
- nerves to the target organ
- effectors = skeletal (voluntary) muscles
- general function = response to external environment
- efferent pathways = one motor neuron from the CNS to the effector; no synapse and no ganglion
- neurotransmitter at effector = acetylcholine
- control = voluntary
- nerves to the target organ = excitation
what happens to: heart rate blood pressure blood vessels in working organs blood vessels in nonworking organs rate and depth of breathing blood glucose levels secretion of sweat glands
during the rest and digest response (parasympathetic NS)?
- decrease HR and force of contraction
- blood vessels constrict in working organs
- blood vessels dilate in non-working organs
- rate and depth of breathing decrease
- blood glucose levels decrease
- secretion from sweat glands = no effect
