Nervous System I

Question 1

Sensory input is information gathered by

Answer 1

By sensory receptors about internal and external change

Question 2

Integration

Answer 2

Interpretation of sensory output

Question 3

Motor output (hint: think efferent pathway)

Answer 3

Activation of effector organs (muscles and glands) produces a response

Question 4

CNS- central nervous system

Answer 4

Brain and spinal cord- integration and command centre

Question 5

PNS- Peripheral nervous system

Answer 5

Paired spinal and cranial nerves carry messages to and from CNS

Question 6

ANS Autonomic Nervous System

Answer 6

Sympathetic and parasympathetic- involuntary nervous system eg heart and gastrointestinal

Question 7

Neurons transmit

Answer 7

Electrical and chemical signals, can live longer than 100 years

Question 8

Dendrites

Answer 8

Synapse with other neurons and are receptive input region

Question 9

Axon hillock

Answer 9

Site of electrical impulse (action potential) generation in response to stimulus from dendrites

Question 10

Axon is the…

Answer 10

Outgoing tail, generates and transmits nerve impulses away from cell body

Question 11

Neuroglia are glial cells

Answer 11

Groups of supporting cells in CNS and PNS eg Schwann cells

Question 12

Myelin sheath role

Answer 12

Protects and electrically insulated the axon to prevent charge leaks, increases conduction velocity of nerve impulse transmission.

Question 13

Myelin sheath Schwann cells

Answer 13

Wrap around axon many times

Question 14

Myelin sheath Nodes of Ranvier

Answer 14

The gaps between Schwann cells

Question 15

Electrical current is

Answer 15

The imbalance of ions across cell membrane and subsequent movement of these ions

Question 16

Polarisation

Answer 16

Membrane is at rest neurons ~70 mV

Question 17

Depolarisation

Answer 17

Membrane potential less negative ~ -70 to ~ +30 mV

Question 18

Hyperpolarisation

Answer 18

Membrane potential more negative than testing polarised potential -70 - -90 mV

Question 19

Membrane ion channels- Leakage

Answer 19

Non-gated ion channels always open

Question 20

Voltage gated ion channels

Answer 20

Ion channels open in response to changes in membrane potential

Question 21

Mechanically gated channels

Answer 21

Open and close in response to physical deformation of receptors eg hair cells of inner ear

Question 22

Ions during polarised

Answer 22

Inside membrane more K+ ions than Na+

Channels closed

Question 23

Ions during Depolarisation phase

Answer 23

Na+ channels open and Na+ flows down concentration gradients in cell. More positive near inside of cell membrane

Question 24

Ions during depolarisation phase

Answer 24

Na+ channels close and K+ channels open so K+ flows out of cell. More negative bear inside of cell membrane

Question 25

Ions during hyperpolarisation phase

Answer 25

Some K+ channels open to allow excessive efflux. Some Na+ channels open allowing membrane potential to return to polarisation

Question 26

Threshold refers to

Answer 26

Membrane potential required to stimulate an action potential. Na+ permeability increases triggering action potential event

Question 27

Subthreshold stimulus refers to

Answer 27

Weak local depolarisation that does not reach threshold. No action potential event

Question 28

Absolute refractory period

Answer 28

Resistant to stimulus where neuron cannot respond to another stimulus. Enforces one way transmission of nerve impulses

Question 29

Relative refractory period

Answer 29

Follows absolute refractory when depolarisation is occurring. Threshold for AP generation is elevated during hyperpolarisation

Question 30

Conduction velocity

Answer 30

Myelinstion can speed conduction velocities. At node of ranvier, voltage gated Na+ ion channels open and ions flow to next node of ranvier.

Question 31

Synapse is

Answer 31

The gap between axon of one neuron and dendrites of another neuron

Question 32

Presynaptic neuron

Answer 32

conducts impulses towards the synapse

Question 33

Postsynaptic neuron

Answer 33

Transmits impulses away from synapse

Question 34

Chemical synapses

Answer 34

Release and receive neurotransmitters | Composed of axon terminal and receptor region

Question 35

Synaptic cleft

Answer 35

Fluid filled space separating pre and post synaptic neurons prevents nerve impulses from directly passing from one neuron to the next. Chemical event

Question 36

Information transfer step 1

Answer 36

AP arrived at axon terminal and opens voltage gated Ca+ channels.

Question 37

Information transfer step 2

Answer 37

Influx of Ca+ promotes fusion of synaptic vescicles with axon membrane and executor is of neurotransmitter occurs

Question 38

Information transfer step 3

Answer 38

Neurotransmitter diffuses and binds to receptors (can be chemically gated ion channels) on postsynaptic neuron

Question 39

Termination of neurotransmitter effects

Answer 39

Can be degraded by enzymes Re-uptaken by axon terminal in presynaptuc neuron and recycled Diffusion away from synaptic cleft