Nervous System

Question 1

Stimuli:-

Answer 1

Internal/external changes in the environment (s/ stimulus).

Question 2

Sensitivity:-

Answer 2

The ability to respond appropriately to stimuli.

Question 3

Sense organs:-

Answer 3

Detect stimuli.

Question 4

Effectors:-

Answer 4

Organs that respond to stimuli.

Question 5

Cell signalling:-

Answer 5

Used to pass information in the nervous system (and the endocrine system).

Question 6

Neurones:-

Answer 6

Nerve cells, convey info as nerve impulses (electrochemical cell signals).

Question 7

Neurone cell body:-

Answer 7

Contains nucleus

Question 8

Neurone nerve fibres:-

Answer 8

Long extensions that transmit nerve impulses rapidly from one part of the body to another.

Question 9

Axon:-

Answer 9

Nerve fibre carrying away from cell body.

Question 10

Dendron:-

Answer 10

Nerve fibre carrying towards cell body. May also be small dendrons (dendrites) extending from the cell body.

Question 11

Sensory neurones:-

Answer 11

Carry messages from peripheral sense organs to CNS.

Question 12

Motor neurones:-

Answer 12

Convey instructions from CNS to effector organs (mainly muscles + glands). V. fast.

Question 13

Myelin sheath:-

Answer 13

Enclosed motor neurones along most of their length. Produced by Schwann cells. Essentially a series of cell membranes wrapped several times around the axon.

Question 14

Nodes of Ranvier:-

Answer 14

Gaps between parts of myrlin sheath membrane, key to fast nerve impulse transmission.

Question 15

CNS organisation:-

Answer 15

Consists of a prominent brain enclosed in a skull and a spinal cord (cylinder of tissue running from brain down the back). Brain integrates info from many internal + external sense organs. Stores info in memory centres.

Question 16

Peripheral nervous system:-

Answer 16

Consists of all nerves + associated nervous tissue outside CNS. Nerve = thread-like structure containing a bundle of neurone fibres. Made up of somatic and autonomic NS.
Forms a vast comms network of sensory + motor pathways.

Question 17

Ganglia:-

Answer 17

(S/ ganglion)- contained in PNS, contains many cell bods + synapses enclosed in a connective tissue sheath.

Question 18

Somatic NS:-

Answer 18

Voluntary. Sensory neurones transmit info from peripheral receptors to CNS. Motor carry nerve impulses to skeletal muscles.

Question 19

Autonomic nervous system:-

Answer 19

Involuntary. 2 divisions- parasympathetic NS and sympathetic NS which generally have opposing actions.

Question 20

Parasympathetic NS:-

Answer 20

Maintains normal functioning of body on non-theatening conditions- e.g reduces heart rate, constricts pupils + bronchioles but dilutes blood vessels leading to guy. Usually use acetylcholine as neurotransmitter.

Question 21

Reflex actions faster:-

Answer 21

Faster as they use relay neurones rather than transmitting back to the brain = shorter.

Question 22

Reflex actions stereotyped:-

Answer 22

A particular stimulus always evokes the same response.

Question 23

Reflex actions innate:-

Answer 23

Unlearned, genetically determined responses that use inherited nervous pathways.

Question 24

Reflex arc:-

Answer 24

Simple nervous pw that rapidly transmits info receptor to effector.

Question 25

Monosynaptic reflex arc:-

Answer 25

Single synaptic between sensory and motor neurone e.g knee jerk reflex.

Question 26

Interneurone:-

Answer 26

Sometimes between sensory and motor in spinal cord AKA relay/association neurone. Makes synaptic connections w/ nerves that pass upwards into association areas of brain. Enable brain to modify reflex actions.

Question 27

Reciprocal inhibition:-

Answer 27

E.g knee jerk:- when quadricep stretch receptors stimulated, bring about stretch reflex but also send info to antagonistic muscles ensuring they’re relaxed.

Question 28

Response to stimuli order:-

Answer 28

Stimulus -> receptor (sensory cells) -> CNS (sensory neurone ->(relay) -> motor) -> effector (muscle/gland) -> response.

Question 29

Spinal cord TS image on phone.

Answer 29

.

Question 30

Hydra (cnidarian) simple nervous system:- (5)

Answer 30

• ns characterised by a nerve net.
• simple nerve cells with short extensions branching in all directions.
• comms between neurones can be in both directions at the synapse within a nerve net.
• sense receptors respond to limited stimuli number = small effector no.
• allows to sense touch, pain and detect food and other chemicals.

Question 31

Mammalian NS vs cnidarian nerve net speed:-

Answer 31

Fast impulse transmission vs slow

Question 32

Mammalian NS vs cnidarian nerve net neurone types:-

Answer 32

Sensory, relay and motor vs 1 type of simple neurone.

Question 33

Mammalian NS vs cnidarian nerve net neurone length:-

Answer 33

Long vs short

Question 34

Mammalian NS vs cnidarian nerve net myelin:-

Answer 34

Myelinated vs non-myelinated

Question 35

Mammalian NS vs cnidarian nerve net branching:-

Answer 35

Non-branched vs branched

Question 36

Action potential and cathode ray oscilloscope:-

Answer 36

-70= start, resting potential. Goes up to +40 (depolarisation) and goes back down (repolarisation) slightly lower for a moment (hyper polarisation -refractory period). -55 threshold.

Question 37

Inside axon:-

Answer 37

Phospholipid bilayer with axonplasm inside.