Module 9 - Nervous Intro

Question 1

Functions

Answer 1

Functions of Nervous System
Sensory – sense changes in internal and external environment – sensory receptors
Integrative – analyze information – decisions for appropriate behaviours – association neurons
Motor – respond to stimuli by initiating action – motor neurons

Question 2

Components

Answer 2

Nerve
Brain
Cranial Nerves
Spinal cord
Spinal nerve
Ganglia
Enteric Plexus
Sensory receptors

Question 3

Nerve

Answer 3

Nerve – bundle of axons – goes along a defined path to serve a specific region of the body

Question 4

Cranial Nerves

Answer 4

Cranial Nerves – 12 pairs – base of brain through foramina

Question 5

Spinal cord

Answer 5

Spinal cord – connected to brain at foramen magnum – surrounded by vertebra

Question 6

Spinal nerves

Answer 6

Spinal nerves – 31 pairs – contact specific region

Question 7

Ganglia

Answer 7

Ganglia – outside brain and cord – nervous tissue – contain the cell bodies of neurons

Question 8

Sensory receptors

Answer 8

Sensory receptors – parts of neurons or specialized cells monitoring changes inside and ou

Question 9

CNS

Answer 9

CNS – central – brain and spinal cord

Question 10

PNS

Answer 10

PNS – peripheral – cranial and spinal nerves – sensory = afferent – motor = efferent – ganglia and sensory receptors – subdivided into SNS and ANS

Question 11

SNS

Answer 11

SNS – Somatic – voluntary – neurons conduct impulses from cutaneous (skin) and special sense receptors to CNS – motor neurons conduct from CNS to skeletal muscle tissue

Question 12

ANS

Answer 12

ANS – Autonomic – involuntary – smooth and cardiac muscle – sensory neurons from visceral organs – motor neurons convey impulses from CNS to smooth, cardiac muscle tissues and glands – subdivided
Sympathetic & Parasympathetic

Question 13

Sympathetic

Answer 13

Sympathetic – fight or flight

Question 14

Parasympathetic

Answer 14

Parasympathetic – rest

Question 15

ENS

Answer 15

ENS – Enteric – neurons in enteric plexuses extending length of GI tract – many neurons function independently from ANS and CNS – sensory = monitor chemical changes of GI and stretching of walls – motor neurons = contractions and control endocrine cells

Question 16

Neurons

Answer 16

Neurons
Electrical excitability
Parts:
Cell body (Soma)
Dendrites
Axon
Synapse

Question 17

Cell body (Soma)

Answer 17

Cell body (Soma) – nucleus, lysosomes, mitochondria, golgi complex, and rough endoplasmic reticulum – RER = NISSL BODIES – Neurofibrils = cytoskeleton

Question 18

Dendrites

Answer 18

Dendrites – many – conduct impulses from receptor or neurons to cell body

Question 19

Axon

Answer 19

Axon – single – conduct impulses from neuron to dendrites, or to cell body of other neurons, or to effector organ – muscle or gland

Question 20

Synapse

Answer 20

Synapse – functional contact b/w two neurons or neuron and effector

Question 21

Neuroglia

Answer 21

Neuroglia - Specialized cells to support neurons

Question 22

Myelin

Answer 22

Myelin – electrically insulate axon and increase conduction – lipid and protein covering – surround axon of neurons – gaps = nodes of Ranvier

Question 23

CNS Neuroglia

Answer 23

CNS Neuroglia
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells

Question 24

Astrocytes

Answer 24

Astrocytes – filter – build and regulation blood-brain barrier – maintain the balance of extracellular ions – control the production of neurotransmitters – modify synapse – maintains chemical environment - CNS

Question 25

Oligodendrocytes

Answer 25

Oligodendrocytes – support – myelin production - CNS

Question 26

Microglia

Answer 26

Microglia – phagocytotic = cell eating – immune responses – take out bad cells - CNS

Question 27

Ependymal cells

Answer 27

Ependymal cells – line fluid-filled spaces in brain – barrier b/w cerebrospinal fluid and brain tissue – control production and flow CSF, brain metabolism, and waste clearance - CNS

Question 28

PNS Neuroglia

Answer 28

PNS Neuroglia Schwann cells Satellite cells

Question 29

Schwann cells

Answer 29

Schwann cells – myelin (neurolemma) production – maintain and regenerate axons - PNS

Question 30

Satellite cells

Answer 30

Satellite cells – support – nutrients to neurons – protective and cushioning cells - PNS

Question 31

White Matter

Answer 31

White Matter – Communicator – pale tissue Long axons with myelin sheaths and unmyelinated Cortex of brain – 60% of brain Surface of spinal cord – outside of “H” – surrounds grey Transmits sensory and motor impulses b/w PNS and grey matter Controls involuntary functions Blood pressure Heart rate Temperature

Question 32

Grey Matter

Answer 32

Grey Matter – Processor – darker tissue Surface of brain – forms cortex – 40% Inside spinal cord Cell bodies, axon terminals, & dendrites Capillary blood vessels Unmyelinated axons Neuroglia Processes white matter info, sends instructions to effectors through white matter Controls senses and muscle control Hearing Feeling Seeing Speech Memory

Question 33

Resting membrane potential

Answer 33

Resting membrane potential Existence of transmembrane polarity Determined by unequal distribution of ions on plasma membrane Na+ - pumps compensate for slow leak into cell – pumps it out K+ Voltage measured across a membrane – usually -70 millivolts = polarized Positive outside Negative inside Ion channels allow ion movement across membrane to change potential Leakage – non-gated – always open Gate – open and closed Voltage changes Specific ligands (chemical) Mechanical vibration or pressure

Question 34

Synaptic Events

Answer 34

Synaptic Events 1) Impulse at bulb of axon 2) Ca+ channels open, Ca+ flows in 3) Neurotransmitters release into synaptic gap/cleft 4) Bind to receptors, open ion channels on dendrites 5) More ions enter and can trigger impulse

Question 35

Uptake of Neurotransmitters

Answer 35

Diffusion Enzymatic degradation Uptake into cells

Question 36

Action Potentials

Answer 36

Action Potentials – communication over short and long distances Rapid Conducts/propagates point to point across membrane = nerve impulse Voltage gates for Na+ and K+ open All or nothing – stronger stim doesn’t = stronger action

Question 37

Depolarization

Answer 37

Depolarization Decrease and reverse membrane potential Activation gate – Na+ gates open – send rush of + ions into cell – throws off the charge of the cell Must pass threshold to full excite membrane = -55mv or reversed Rises to +30mv Nerve impulse is fired

Question 38

Continuous conduction

Answer 38

Continuous conduction – unmyelinated – slower – travels down axon

Question 39

Saltatory conduction

Answer 39

Saltatory conduction – myelinated – fast – jumping node to node

Question 40

Repolarization

Answer 40

Repolarization Restoration of resting membrane potential Even out chargers within membrane K+ gate opens – delayed reaction Inactivation gate – Na+ closes Refractory period – Absolute – Impulse cant be generated

Question 41

Hyperpolarization

Answer 41

Hyperpolarization K+ channel is late – pumps too much back in Overextends – too negative Refractory period – relative Must send back to resting membrane potential = -70mv - suprathreshold stim

Question 42

Rules of Propagation

Answer 42

Rules of Propagation Larger fibres = faster impulse – more flow Myelinated = faster – less energy needed Warm = faster conduction

Question 43

Grade Potentials

Answer 43

Grade Potentials – communication over short distances Waves in pond Dendrites – Starting = high membrane potential Soma – Waves get smaller and smaller as they travel Doesn’t always have a strong enough charge to make it to the axon hillock where it would be propagated Over time charge will add up and hit the threshold Gates open over time

Question 44

Neurotransmitter

Answer 44

Neurotransmitter Excitatory or inhibitory Body's chemical messengers Transmit messages between neurons, or from neurons to muscles

Question 45

Classes of Neurotransmitters

Answer 45

2 classes of Neurotransmitters Small molecule – acetylcholine, amino acids, biogenic amines, ATP, purines, and gases Neuropeptides – amino acids linked by peptide bone

Question 46

Types of Neurotransmitters

Answer 46

Types of Neurotransmitters Acetylcholine – ANS – Contracts smooth muscles, dilates blood vessels, increases bodily secretions, and slows heart rat Glutamate – CNS – memory, cognition, and mood regulation Aspartate GABA – CNS – gamma-aminobutyric acid – chemical messenger in, slows down by blocking specific signals in CNS – calming effect. Glycine Norepinephrine - neurotransmitter and hormone - “fight-or-flight” – mobilizer Epinephrine – neurotransmitter and hormone - “fight-or-flight” – mobilizer Dopamine – emotions, behavior, and movement