Nervous System Flashcards
Homeostasis
- maintaining constant internal environment despite changes in the external environment
- eg: we get cold so we shiver, we get hot so we sweat
Different types of receptors (5)
Chemoreceptors –> chemicals (eg: taste buds on tongue)
Mechanoreceptors –> pressure, vibrations and touch (pressure receptors in skin)
thermoreceptors –> temperature (hot and cold receptors in skin)
photoreceptors –> light (rods and cones in retina)
pain receptors, nocireceptors –> cell damage/excess heat
Nervous System breakdown
CNS (body master control unit)
1. brain and spinal cord
PNS (body link to the outside world)
1. autonomic NS (internal stimuli, involuntary process)
- sympathetic NS (fight or flight)
- parasympathetic NS (rest + digest)
- somatic NS (external stimuli, voluntary movements, sensory info from organs to CNS and then to muscles)
- sensory input (Afferent)
- motor output (Efferent)
3 functions of the nervous system
1) Sensory input from sensory receptors (PNS) is transfered to CNS.
2) integration and intepretation in the CNS
3) Conduction of signal from CNS to effector cells, muscles + glands which carry out the bodys responses (PNS)
SENSORY INPUT PNS –> INTEGRATION/INTREPRATION CNS –> MOTOR OUTPUT PNS
Dendrites
- INPUT zone where cell recieved neural information
- recieve info from environment/other neurons
- conduct nerve impulses AWAY from cell body
Cell bodies
- contains the nucleus
- recieve, sort, priritize neural information
Axon Hillock
- act like a switch
- trigger electrical impulses to move to the axon
Axon
- OUTPUT zone
- conducts nerve impulses toward axon terminal
- long cord like extension of cytoplasm, conducts nerve impulses away from cell body
- larger diameter of the axon the faster the speed of nerve impulse
Nodes of ranvier
Allow diffusion of ion
Axon terminal
- At hthe end
- forms junctions with other cells
- store NT chemicals which control transfer of neural info btwn neurons
Myelin sheath
- insulation for neurons
- made up of schwann cells
- nerve impulses move faster along myelinated nerve fibres than unmyelinated
Neurilemma
- surrounds the axon, on top of myelin
- formed by schwann cells and promotes regeneration of damaged azons
White/Gray matter and neurilemma etc
- Just because there is a myelin sheath doesn’t mean there is a neurilemma
White matter in brain have myelin
Gray matter dont have myelin (in spinal cord)
White and gray matter both odnt have neurilemma which means damage to CNS is permnant
Order of axon, myelin etc
Innermost –> outermost
Axon > myelin > neurilemma > Schwann
Schwann Cell
Produces the myelin sheath
3 groups of neurons
Sensory neurons (afferent neurons)
- relay info/stimuli thats received by sensory receptors about external/internal environment
- cell bodies of sensory neurons are located in clusters called ganglia (outside the spinal cord)
2) interneurons (association neurons)
- link neurons to other neurons
- integrate + interpret sensory info + connect sensory neurons to outgoing motor neurons
- only in brain + spinal cord
3) motor neurons (efferent neurons)
- relay information to the effectors (cell/organ that responds to stimulus)
Glial cells
non conducting cells that are Support cells
- support neurons structurally
- deliver nutrients + remove waste
- repair neurons in PNS
- insulate neurons
Glial cells in the PNS
Schwann cells
- axon > myelin > neurilemma
- has a nucleus that directs growth of myelin
- gaps btwn schwan cells are nodes of ranvier
Glial cells in the CNS
1) oligiodendrocytes
- wrap around neurons making insulating sheaths
- made up of myelin (white matter)
- astrocytes
- provide structure + metabolic support
Reflex Arc
- reflexes involuntary + unconscious
- neural circuit that travels through spinal cord and provides a framework for reflex action
sensory receptor –> sensory neuron –> interneuron in spinal cord –> motor neuron –> effector
action potential
change in electrical potential associated with passage of an impulse
voltage gated channels, ligand gated channels and mechanically gated channels
voltage gated: open at certain membrane potential and close at others (eg: NA channels open around -55mV)
ligand gated channels: open when a specific NT latches
mechanically gated channels: open in response to physically stretching the membrane
If action potentials are all the same how do we know the strength of a stimulus?
1) More sensory receptors fiting, mean more action potentials = stronger stimulus
2) higher frequency of firing = stronger stimulus
Salatory conduction
node to node conduction. conduction that happens myelinated axons.
1) saves energy by decreasing use of sodium potassium pump
2) its faster which allows organism to react faster
Synapse
region btwn neurons or btwn neurons and effectors
- junction/cross roads
Presynaptic and Postsynaptic neuron
presynaptic: (cell that sends the signal) neuron that carries impulse towards synapse
postsynaptic: (recieving cell) neuron that carried impulse away from synapse
Excitatory vs inhinitory neurotransmitters
Excitatory: Makes the inside more positive (depolarized), closer to action potential threshold and more likely to cause an action potential
Inhibitroy: hyper polarizes by making the inisde more negative and driving it away from the threshold.
Summation
effect produced by accumlation of NTs from 2+ neurons
Aceyylcholine and Cholinesterase
Acetylcholine: An excitatory NT that causes NA+ channels to open and causes depolarization.
Cholinsterase: Presynaptic membrane releases this and it destroys acetylcholine. Once acetylcholine is destroyed the sodium channels close.
Preganglionic nerve and postganglionic nerve
Preganglionic nerve: Connect from CNS to a ganglion where they connect to a second group.
Postganglionic nerve: Connect the ganglion to the effector organ.
Effects of the autonomic nervous system: HEART
Sympathetic NS: increase heart rate
Parasympathetic NS: decrease heart rate
Effects of the autonomic nervous system: DIGESTIVE TRACT
Sympathetic NS: Decrease peristalsis (contraction + relaxtion of muscles)
Parasympathetic NS: increase perstalsis
Effects of the autonomic nervous system: LIVER
Sympathetic NS: increase release of glucose
Parasympathetic NS: store glucose
Effects of the autonomic nervous system: EYES
Sympathetic NS: dilate pupil
Parasympathetic NS: constrict pupil
Effects of the autonomic nervous system: BLADDER
Sympathetic NS: contract sphincter
Parasympathetic: relax sphincter
Effects of the autonomic nervous system: SKIN
Sympathetic: decrease blood flow
Parasympathetic: increase blood flow
Effects of the autonomic nervous system: ADRENAL GLAND
Sympathetic: causes release of epinephrine
Parasympathetic: No effect
Meninges
protective membranes that surround the brain + spinal cord
Outermembrane: dura mater
Middle membrane: arachnoid mater
Inner: pia mater
Cerbrospinal fluid
- circulates btwn pia + arachnoid matter & in central canal of spinal cord
- shock absorber
- deliver nutrient
- remove waste
3 things that protect our brain
- bone (skull + spinal cord)
- meninges (blood/brain barrier)
- cerebrospinal fluid
Encephalization
evolutionary increase in complexity and size of brain.
Spinal cord definition
carries sensory nerve messages from receptor to the brain and relay motor nerve messages from brain to effectors
2 types of nerve tissue in spinal cord
1) gray matter: consists of nonmyelinated interneurons
2) white matter: myelinated nerve fibres from the sensory + motor neurons
Dorsal & Ventral root
Dorsal root: brings sensory info into spinal cord (to the back).
- made up of sensory neurons.
Ventral root: carries motor info from spinal cord to the effectors (to the front)
- made up of motor neurons leaving the CNS and carrying signal to your tissues
3 parts of the brain
1) HINDBRAIN: most primal part. basic control systems, similar to all species with a brain.
2) MIDBRAIN: more advanced, next part to develop. control + communication
3) FOREBRAIN: most advanced area & last to develop. highly advanced functions (senses, consciousness, thinking, speec emotions)
Parts of the forebrain: (2)
Cerebrum: largest + most highly developed part of brain. Stores sensory info + initiate motor activity.
Cerebral cortex: outer layer of cerebrum. made of gray matter. has fissures to increase SA.
Fissure
deep folds.
used as landmarks in so we can locate specific areas od brain.
central & lateral, longtidinal fissure.
Association cortex is ____ and what are the parts?
Associate cortex is the lobes of the brain.
FRONTAL: voluntary movement. walking and talking. personality, motivation, [ ], social behaviour.
TEMPORAL: sensory info from ears/eyes, memory + interpretation of sensory info
PARITIAL: touch, temp, pain, memory + interpretation of emotion and speech
OCCIPITAL: sensory info associated w/ vision. interpret visual info
Motor cortex
region of cerebral cortex involved in planning, control + execution of voluntary movement
sensory cortex
section of cerebral cortex which is responsible for receiving + interpreting sensory info from diff parts of body
3 cortex (CNS)
1) association cortex (tempora, partial, occipital, frontal)
2) motor cortex
3) sensory cortex
Corpus Callosum
Nerve tract that joins 2 cerebral hemispheres
- allows communication btwn 2 hemispheres
Right brain vs Left Brain
right brain: visual patterns + spatial awareness
left brain: verbal skills
Thalamus
relay station
- directs incoming sensory info to appropriate parts of cerebrum for interpretation
Hypothalamus
- helps maintain homesostatis
- direct connection btwn hypothalamus and pituitary gland
- control system 3.0, sythesize + secrete hormones that stimulate or inhibit hormones released from the pituitary gland
- controls body temp, hunger, aggression, fatigue etc
Olfactory bulbs
receive and interpret info about smell
one bulb in each hemisphere
3 parts of the hindbrain? What do they do?
cerebellum, pons, medulla oblongota
cerebellum: largest section of hindbrain. control lumb movement, balance, muscle tone.
pons: the bridge. relay station, passes info from cerebellum to medulla
medulla oblongota: postereior region of hindbrain. the connection btwn PNS and CNS. control involuntary muscle action (breathing, heart rate). Coordinating centre for ANS
