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Phys > Week 1 - Overview of nervous system > Flashcards

Week 1 - Overview of nervous system Flashcards

1
Q

Feedback - negative

A
  1. blood pressure drops
  2. brain detects change, signals heart to inc HR + constrict blood vessels
  3. pressure restored
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2
Q

Feedback - positive

A
  1. blood pressure drops
  2. blood flow to heart dec
  3. heart unable to pump enough blood to maintain pressure
  4. blood flow to cardiac muscles decrease
  5. pressure decreases further
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3
Q

neurons

A
  • have axons
  • receives, generates & transmits electrical signals (impulses)
  • Function: cellular communication eg. thinking, controlling, muscle activity
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4
Q

grey matter

A

40%

contains:
- neuronal cell bodies
- dendrites
- gigal cells

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5
Q

White matter

A

60%

contain MYELIN that surround nerve axons

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6
Q

gila

A
  • no axons
  • Function: homeostasis & neuronal supp.
  • outnumber neurons by 25:1
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7
Q

neuron - structure

A
  • cell body: contain nucleus
  • dendrites: receive info
  • axons: conduct ELECTRICAL IMPULSES, away from cell body, often wrapped in a MYELIN SHEATH
  • axon terminals: release neurotransmitters (chemical signals)
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8
Q

neuron - classification

A

sensory (input;PNS) motor (output; CNS)

  • interneurons: MODIFY COMMUNICATION → excitatory, inhibitory, local circuit
  • PROJECTION NEURONS: connect diff regions of CNS
  • distal axon terminals are often specialised
  • communication signal propogates from distal to proximal
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9
Q

astrocytes

A
  • provide STRUCTURAL & NUTRIENT SUPPORT to neuron
  • homeostasis role: regulate pH
  • connects blood vessels to neurons to form BLOOD BRAIN BARRIER → REGULATE movement from blood to brain (toxins/drugs)
  • PREVENTS CNS REGENERATION - from scar tissue when CNs is damaged
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10
Q

neurogila

A

Functions: homeostasis, structural support, protein for neurons
$ cell types in CNS, 2 in PNS

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11
Q

oligodendrocytes

A
  • found in WHITE MATTER
  • SUPPORT & ELECTRICALLY INSULATE CNS axons →forming myelin sheaths
  • damage produces de-myelination → alters axonal transmission
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12
Q

microgila

A
  • 1st response of immune system
  • become movile & phagocytic: eat cellular debris: rapidly multiplying & changing shape
  • found in grey and white matter
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13
Q

Schwann cells

A
  • found in PNS
  • enshcath single PNS axon
  • each cell produces part of axon myelin sheath
  • gaps between adjacent cells: NODES OF RANVIER
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14
Q

satellite cells

A
  • Surround neuronal cell bodies in peripheral sensory & autonomic ganglia
  • flattened cells
  • provide STRUCTURAL & NUTRIENT SUPPORT to neuron
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15
Q

ependymal cells

A
  • line brain fluid cavities ( ventricles) & central canal in spinal cord
  • PRODUCE & CIRCULATE CSF
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16
Q

Action potentials - cell membrane

A
  • made of phospholipids and proteins → barrier due to HYDROPHOBICITY
  • proteins allow cells to communicate → provide pathway across lipid boundary as transporters or ION CHANNELS
  • chemical/electrical signals received must CROSS MEMBRANE to generate an electrical potential
17
Q

neuron - communication

A
  1. STIMULUS on dentrites
  2. PRODUCTION of potential in cell body
  3. ACTION POTENTIAL PROPAGATION
  4. SYNAPTIC ACTIVITY (chemical transmitter) released to synaptic cleft
18
Q

ion channels

A
  • ‘leak pores’ : always open, contributes to RMP

Gated channels: closed at rest

  • ligand gated: open in response to chemical stimuli acting on receptors on channel
  • voltage gated: open to changes in RMP
  • stimulus transducing: open to phys. stimulus
19
Q

action potentials - stage 1

A
  • resting membrane potential (RMP)
  • ions cannot diffuse through plasma membrane; rely on protein channels

exterior: high extracellular Na+, Cl-, low K+
interior: high intracellular K+, low Cl-, Na+
RMP ~ 70mV

20
Q

refractory period - absolute

A
  • ONLY when Na+ gates open
  • no new stimulus can trigger AP
  • sets upper limit on firing frequency
21
Q

ion pumps

A
  • contributes to maintenance of RMP
  • requires energy to transport ions against conc. gradient
  • without it, eventually Na+ influx through leak channels will destroy RMP
  • no neurotransmissions
22
Q

action potentials - stage 2

A
  1. hyperpolarisation (inhibitory)
    - RMP becomes more -ve
    - no AP possible
  2. depolarisation (excitatory)
    - RMP becomes more +ve
    - Ap possible is depolarisation is large enough
23
Q

AP propagation - myelinated axons

A
  • more energy sufficient - reliable
  • SALATORY CONDUCTION: insilating prop. of myelin sheath inc. efficiency & speed
  • AP propagates from 1 node of ranvier to next by generating currents that open ion channels
24
Q

AP propagation - unmyelinated axons

A
  • passive, slow & unreliable
  • ionic current flows across each adgacent segment of membrane
  • step by step depolarisation & repolarisation of each voltage gated ion channel in membrane
25
Q

refractory period - relative

A
  • ONLY when K+ gates open
  • only supramaximal stimuli will trigger a new AP
  • prevent back propagation
26
Q

electical signalling - gap junctions

A
  • less common: bidirectional & fast
  • found between adjacent gigal cells, smooth muscle myocytes, gila & some CNS neurons
  • alows for synchronising of interconnected neyrons
  • can allow small chemical through
27
Q

chemical signalling

A
  • unidirectional pre-to-post synapse
  • to complete the signal transfer, a chemical neurotransmitter is released @ synapse to signal next neuron
  • post synaptic receptors receive chem. messages ex/in
  • slower
28
Q

synapse

A
  • junction between 2 communicating neurons

- synaptic transmission is a core process

29
Q

summation

A

TEMPORAL: graded potentials generated by one synapse firing in rapid succession
SPATIAL: graded potentials generated by synaptic transmission of TWO- OR MORE SYNAPSES acting on same neurons

30
Q

neurotransmitters

A

Glutamate (+)
Gaba/ Glycine (-)
Acetylcholine (+)

31
Q

physiology

A
  • study of functions in living organisms : cellular, systems/organs, pathophysiology
  • exercise physiology: study of acute responses + chronic adaptations to a range of physical conditions
  • comparative physiology: study across species

Phys (14 decks)

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