BIOL2051 “Principles Of Neuroscience” Flashcards
What is the PNS made up of? (general)
Cranial nerves
Spinal nerves
Ganglia (dorsal root ganglia and autonomic ganglia)
What is the CNS? (general)
Brain
Spinal cord
Control centre for info processing, responding to sensory info
Neurones (general)
Receive stimuli
Transmit nerve impulses or action potentials
activate muscles
Define a neurone
The functional units of the nervous system, organised into a functional network capable of:
- Response to stimuli
- Information processing
- Communication (?)
Function of dendrites
Collect electrical signals and carry input to cell body
Function of cell body/soma of a neurone
Integrates signals and generates action potential
Function of axons
Transmit signals over long distances from the cell body to the axon terminals
List 4 ways in which neurones are organised
Nerve nets
Cephalisation
CNS
PNS
What are invertebrate nervous systems specialised for?
Stimulus/response, receptor/effector
Reflexes, conditioned responses
What are nerve nets?
Definition (kind of): simplest form of nervous system found in some invertebrates (such as hydras, jellyfish, etc.)
Individual nerve cells exist in a net-like formation scattered in layers of body wall. Neurones exist in a ‘loose network’ to allow for contraction and expansion of the body cavity
Nerve nets lack distinct central or peripheral regions, and anything that resembles a brain
What can/can’t nerve nets do?
Nerve nets have no associative activity, only reflexes (with action potentials)
However, neurones can carry:
- Info from sensory organs that detect touch, light, or other changes in the environment
- These neurones in turn contact neurones that control movement of the organism, such as swimming
Describe the structure of the nervous system found in species such as sea stars (echinoderms)
Display some centralisation of the nervous system
A ring of neurones is located in the centre with simple bundles of neurones (radial nerves) extending from the ring to the tip of each arm
Radial nerves form nerve nets, permitting coordinated movement of each arm and the tube feet located on the surface of the arm
Cephalisation and formation of the primitive brain
In animals with bilateral symmetry, there is a clustering of neurones into ‘ganglia’ near head of animal to form more complex systems to integrate incoming/outgoing signals (sight, hearing, taste, etc.)
Nerve cords and trunks:
- With bilateral symmetry (flatworms, etc.), 2 nerve cords run down the length of the body
- This system allows more complex control of muscles for movement
Distinct PNS and CNS regions:
- Connections required between PNS and CNS, but PNS can act autonomously in some cases
- Invertebrates lack myelin but AP propagation overcome by increasing diameter of axons (giant squid axons)
Summarise the different nervous systems (/list them)
Giant neurones and axons - no myelin
Nerve nets - APs, reflexes
Ganglia chains (in molluscs, worms, arthropods)
- Head ganglia are fused/cephalisation
- Specialisation of cells (receptors - eyes, etc.)
Brain (& spinal cord) - organisation of CNS (vertebrates)
What do all vertebrate nervous systems contain? (general)
Sophisticated sensory mechanisms
Clear differentiation of CNS and PNS as well as sensory and motor nerves
Elaboration of brain structure, etc.
3 general regions of the brain, and which specific brain regions make them
Forebrain:
- Cerebrum
- Optic structures
- Olfactory lobe
Midbrain
Hindbrain: coordination of motor reflexes in vertebrates; regulation of autonomic processes
- Brainstem - pons
- Medulla
- Cerebellum
What are sulci?
Infoldings of the cerebral hemispheres that form ‘valleys’ between the gyri
Singular = sulcus
What are gyri?
Ridges of the infolded cerebral cortex
Singular = gyrus
Brain areas based on development
Forebrain:
Prosencephalon
- Telecephalon (cerebrum)
- Diencephalon (thalamus, & hypothalamus)
Midbrain:
Mesencephalon
Hindbrain:
Rhombencephalon
- Myelencephalon (medulla)
- Metencephalon (pons & cerebellum)
Name the four lobes of the cerebrum
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
Functional areas of the cerebrum
Motor: primary motor and premotor in FRONTAL LOBE
Sensory: primary somatosensory and somatosensory association areas in PARIETAL LOBE
Vision: primary viual and visual association areas in OCCIPITAL LOBE
Auditory: primary auditory & auditory association areas in TEMPORAL LOBE
What are the 7 major parts of the human CNS?
Cerebrum
Diencephalon
Brain stem
- Midbrain
- Pons
- Medulla
Spinal cord
What is grey matter?
Cell bodies of neurones reside in the grey matter
Has a pinkish/grey colour in the brain, and is a major component of the CNS
What is white matter?
Myelinated axons reside in white matter
These axons connect different parts of the grey matter to each other
What are the 3 brain planes?
Coronal (slice vertically from ear to ear)
Sagittal (slice vertically from front to back of head)
Horizontal/axial (what it says on the tin)
If you look at someone from their left side (they are facing the left), what are each of the directions in the head?
North = superior
East = posterior
South = inferior
West = anterior
If you look at someone from their left side (they are facing the left), what are the directions in the brain?
Dorsal = back of brain
Caudal = south/brain stem
Ventral = towards the mouth
Rostral = forehead
Which 3 things protect the CNS?
Bone (skull & vertebral column)
Meninges
CSF (cerebrospinal fluid)
Meninges & each of the layers
Meninges: encloses the brain and spinal cord, and their blood vessels
3 protective tissue layers:
Dura - superficial most and strongest, usually in contact with bone
Arachnoid - adhered closely to dura, web-like in appearance
Pia - deepest layer, in direct contact with CNS tissue
CSF (cerebrospinal fluid)
Clear, cell-free fluid produced by the choroid plexus (ependymal cells) that circulates in the subarachnoid space
What is the subarachnoid space?
The space between the arachnoid and pia matter
Which areas does afferent input to the (neo)cortex come from?
Ascending info from the thalmus
Ascending info from the brainstem and other parts of the forebrain, also the hypothalamus
Axons travelling between hemispheres (commisural fibres)
Info from the ipsilateral cortex
Output from the neocortex
Is excitatory from pyramidal cells (uses excitatory neurotransmitters such as glutamate, etc.)
- All parts of cortex project to thalamus
- Axons from motor & somatosensory cortices project to basal ganglia
- Axons project to brainstem (nuclei) & spinal cord
- Axons project to contralateral hemisphere; axons project to ipsilateral hemisphere
Functions of the brain
Serves as aconduit for ascending & descending tracts connecting the spinal cord to higher centres (cerebrum, cerebellum)
Contains important relex centres associated with control of respiration, heart rate & blood pressure, & consciousness
Contains cranial nerve nuclei
Functions of the cerebellum
Integrates ascending (proprioceptive information, feeds back to cerebral cortex to refine movement
Modifies movement (compares sensory info with pre-motor inifo)
Maintenance of upright posture
Maintenance of the tension or firmness (i.e., tone) of the muscle
Aids the cerebral cortex in planning sequential mmovements to make smooth progressions from one movement to the next
Synergy of movement - motor coordination
Balance
Cerebellar input
Spinal cord
Cerebellar cortex
Vestibular system
Motor systems in neocortex
Cerebellar output
Vestibular systems
Brain stem
Muscle spindles
Motor & pre-motor cortices
Spinal cord (general)
2 way impulse conduction pathway and reflex centre
31 pairs of spinal nerves in total
Name the sections of spine
Cervical (C1 - C8)
Thoracic (T1 - T12)
Lumbar (L1 - L5)
Sacral (S1 - S5)
Coccygeal (Co)
Dorsal root
Posterior
Through which afferent fibres enter (sensory)
Contains dorsal root ganglion (DRG) with the cell bodies of the afferent fibres
Ventral root
Anterior
Through which the efferent fibres leave
Their cell bodies are within the spinal cord
Reflexes
Survival mechanism
Inherited (‘hard-wired’), pre-set behaviour that does not require learning, practice, or experience
Simplest type of animal behaviour
Performed without conscious thought; usually rapid, automatic/involuntary responses to stimuli
Usually follow specific pattern
Reflex arc
Receptor (site of stimulus) –> sensory neurone (transmits stimulus) –> integration centre (can be mono or polysynaptic) –> motor neurone (conducts impulse to effector) –> effector (muscle or gland)
Spinal reflex
Somatic spinal reflexes provide info on integrity of the reflex pathway and degree of excitability of the spinal cord
Polysynaptic reflexes
Involves multiple synapses between sensory axons, interneurones, and motor neurones
- Interneurones control more than 1 muscle group
- Produce either EPSPs or IPSPs
Autonomic nervous system (ANS) (general)
2 divisions responsible for maintenance of homeostasis (sympathetic and parasympathetic divisions)
Both systems are continuously active under normal conditions, with each having discreet and independent functions (antagonistic functions)
ANS together with endocrine system controls body’s interal organs, thus controlling the circulation of blood, activity of the GI tract, & body temp’
Innervates smooth msucle, cardiac muscle, & glands of internal organs (involuntary)
