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Anatomy + Physiology (606) > Nervous System > Flashcards

Nervous System Flashcards

1
Q

roles

A

monitors internal and external environments
integrates sensory information
coordinates voluntary and involuntary responses of many other organ systems
performed by neurons which are protected by neurologia

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2
Q

receptors

A

mechanoreceptors- respond to mechanical pressure or distortion
chemoreceptors- respond to chemical changes
photorecpetors- respond to light
thermoreceptors- sense changes in temperature

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3
Q

structure

A

CNS- brain and spinal cord
integrates and coodrinates the processing of sensory data and transmission of motor commands

PNS- includes all neural tissue outside CNS
delivers sensory info to cns

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4
Q

divisions

A

afferent - sensory commands, coming back to CNS
efferent - motor commands, moving away from CNS (includes somatic and autonomic- parasymp and symp)

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5
Q

anaxonic neurons

A

found in brain and special sense organ- pass info between other neurons
very small
no anatomic features that distinguish dendrites from axon
functions poorly understood

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6
Q

structure of neuron

A

cell body- nucleus, mitochondria, golgi
dendrites extending from cell body
axon hillock- origin of action potential
myelin sheath- surrounds axon
nodes of ranvier- gaps between sheath
axon- action potential travels down
axon terminals synapse with dendrites of next neuron

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7
Q

bipolar neuron

A

have 2 processes- 1 dendrite and 1 axon with cell body between them
rare
occur in special sense organ eg sight, hearing etc

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8
Q

unipolar

A

dendrites and axon are continuous, cell body lies off to one side
most sensory neurons of PNS are unipolar

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9
Q

multipolar

A

has 2 or more dendrites and a single axon
most common neurons in CNS
all motor neurons that control skeletal muscle are multipolar

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10
Q

spinal cord

A

major passageway of sensory and motor impulses to/from the brain
integrated info on its own and controls spinal reflexes and automatic motor responses
white matter- motor neurons (myelinated)
grey matter-interneurons (unmyelinated)

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11
Q

spinal cord structure

A

consists of 31 segments- each containing a pair of dorsal root ganglia containing cell bodies of sensory neurons
dorsal roots bring sensory information to spinal cord

pair of ventral roots contains axons of motor neurons
d + v roots are bound together into a single spinal nerve

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12
Q

sectional anatomy of spinal cord

A

gray matter contains cell bodies and neuroglia cells
white matter contains myelinated and unmyelinated axons

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13
Q

spinal nerves

A

31 pairs of spinal nerves are grouped according to the region of vertebral column from which they originate
each pair of spinal nerves monitors a specific region of the body surface known as a dermotome
damage of the spinal nerve or of dorsal root ganglia produces a characteristic loss of sensation in the corresponding region of the skin

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14
Q

reflex arc

A

arrival of stimulus and activation of receptor
activation of a sensory neuron
information processing in CNS
activation of a motor neuron
response by a peripheral effector

withdrawal reflex- may involve other parts of the body too

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15
Q

parts of brain

A

reptilian brain- brain stem
mamallian brain- limbic system (feelings, social interactions)
higher brain- decision making, ethics etc, separating us from other species
20% of energy expenditure only 3% of body mass

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16
Q

6 regions of brain

A

cerebrum
cerebellum
diencephalon
mesencephalon
pons
medulla oblangata

17
Q

lobes - cerebrum

A

frontal- voluntary motor activity, speech, elaboration of thoughts
somatic motor association
temporal- initial reception of auditory info
auditory association
occipital- initial processing of visual info
visual association
parietal- receiving and processing sensory info
somotic sensory association

18
Q

cerebellum

A

cortex and nuclei- involuntary coordination and control of ongoing body movements
cerbelllar peduncles- link regions of the brain, integration and communication
affected by alcohol which affects balance

19
Q

diencephalon

A

contains thalamus, epithalamus, hypothalamus, pituitary gland, pineal gland
hypothalamus- controls emotion

20
Q

mesenchephalon (midbrain)

A

processes audio and visual data- links to temporal and occipital lobe
maintenance of consciousness

21
Q

pons

A

links cerebellum with mesencephalon, diencephalon, cerebrum and spinal cord
involved in control of respiration- pace and depth of breathing

22
Q

medulla oblangata

A

link between brain stem and spinal cord
relaying sensory info to brain stem and soinal cord
autonomic regulation of visceral functions- organs eg control of heart

23
Q

brain protection and support

A

physical protection- bones of the cranium, cranial meninges, cerebrospinal fluid

biochemical isolation- blood brain barrier- isolation of circulation through variation in permeability of CNS capillaries

24
Q

cranial meninges

A

layers of membrane
3 layers- dura mater, arachnoid mater (web like structure) , pia mater
protects brain from cranial trauma

25
Q

cerebrospinal fluid

A

surrounds exposed surfaces of CNS
interchanges with interstitial fluid of brain

functions- cushion, support, transport of nutrients and chemical messengers and waste products

26
Q

cell membrane potential

A

uneven distribution of charges known as potential difference
PD across cell membrane called membrane potential
resting potential -70mV (very small)-(-ve =polarised)

27
Q

ions in membrane

A

outside cell= high conc of Na+ and Cl-
inside cell= high conc of K+ and negatively charged proteins Pr-
membrane has selective permeability which maintains intra vs extracellular fluid differences
ions can enter or leave the cell with help from channel and carrier proteins

28
Q

resting potential

A

membrane contains different types of channels- leak and gated
leak= always open
gated= open/close depending on circumstances

29
Q

passive movement

A

chemical conc gradient-
K+ moved out of the cell and Na+ into cell
K+ moves out of cell faster than Na+ can move into cell

electrical gradient- +ve charged outer membrane surface repels +ve K+ ions
-ve charge inner membrane attracts +ve Na+
chemical gradient is stronger than electric repelling force

30
Q

sodium potassium pump

A

maintains resting potential at -70mV
NaK+ pump- 3 intra Na+ ions exchanged for 2 extra K+ ions
Na+ out and K+ in
rate of Na+ entry to K+ loss is precisely balanced

31
Q

depolarisation

A

opening of gated Na+ channels increases Na+ entry into cell
as +ive ions increase on the inner surface of the cell, the membrane potential shifts to 0mV
this shift is called depolarisation
when stimulus is removed, repolarisation occurs

32
Q

graded potentials

A

local potentials
only affect a limited portion of cell membrane- cannot spread far from site of stimulation
affect a small area
produced by any stimulus that opens a gated channel

33
Q

graded potential

A

1- resting membrane exposed to chemical, Na+ channels open and enter, depol occurs

2- movement of Na+ produces local current, depolarises nearby cell membrane (graded- lower further away), change in potential proportional to stimulus

3-inactivation of sodium channels and activation of K+ channels

4-when stimulus is removed, membrane potential returns to normal (repol)

graded potentials can influence operations in distant portions if they lead to action potentail

34
Q

action potential

A

electrical signal that affects entire membrane surface
change of permeability of cell membrane
skeletal muscle fibres and axons have excitable membranes that will conduct action potential
begins near axon hillock
generated by opening and closing of Na+ and K+
must depolarise to threshold
all or none principle

35
Q

continuous propagation

A

occurs in unmylelinated axon
1- action potential in first segment depolarises membrane
2-local currents form and Na+ spread away from channel, depolarises next segment
3- second segment develops action potential and first segment enters refractory period
4- local current depol next segment and cycle repeats, action pot travels in 1 direction (1m/sec)

36
Q

saltatory propagation

A

occurs in myelinated axons- axon is wrapped in layers of myelin
depolarisation only occurs at the nodes, action potential jumps from node to node
faster than continuous propagation (18-140m/sec)

1-action potential at segment
2-local current produces graded depol
3-action potential develops at node
4-local current produces graded depol that brings axolemma at next node to threshold

37
Q

chemical synapse

A

synapse- site of communication between a nerve cell and other cell
information transfer occurs through the release of neurotransmitters from synaptic terminal
may occur on a dendrite/ cell body
opposing cell membranes are separated by a space called the synaptic cleft

38
Q

neurotransmitters

A

excitatory- cause depol of PSM
promote action potentials

inhibitory- cause hyperpol of PSM
suppress action potentials

39
Q

acetylcholine and cholinergic

A

ACh is released at cholinergic synapses

Anatomy + Physiology (606) (15 decks)

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