How nerves work 1-5

Question 1

Nervous system (2 areas)

Answer 1

CNS and PNS

Question 2

CNS

Answer 2

Brain and spinal cord encased in bone

Question 3

PNS

Answer 3

Somatic and autonomic

Question 4

Autonomic

Answer 4

Sympathetic and parasympathetic

Question 5

Meninges

Answer 5

3 membranes that envelop brain and spinal cord and protect the spinal cord

Question 6

Gyrus

Answer 6

Ridge on cerebral cortex - high

Question 7

Sulcus

Answer 7

Ridge on cerebral cortex - low

Question 8

Where is the cerebellum?

Answer 8

Back of the brain for balance

Question 9

4 cerebral cortexes

Answer 9

Frontal, parietal, temporal and occipital

Question 10

Diencephalon

Answer 10

In forebrain below cerebrum

Thalmus and hypothalamus

Question 11

Thalmus

Answer 11

Last relay of information from spinal cord q

Question 12

Hypothalmus

Answer 12

Hormones and endocrine gland

Question 13

3 parts of brainstem

Answer 13

Pons, midbrain and medulla

Question 14

How many spinal nerves are there?

Answer 14

31

Question 15

Name how many nerves there are at each vertebrate level

Answer 15

7 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal

Question 16

Axon hillock/initial segment

Answer 16

Make action potential

Question 17

Axon terminal

Answer 17

Release neurotransmitter

Question 18

Astrocytes

Answer 18

Maintain external environment and make blood brain barrier and surround blood vessels

Question 19

Oligodendrocytes

Answer 19

Wrap feet around axon to form myelin sheath in CNS

Question 20

Microglia

Answer 20

Little cells in immune system and mop up infection

Question 21

What is the function of the resting membrane potential?

Answer 21

Keep cell ready to respond

Question 22

Is the inside of the cell negative or positive to the outside of the cell

Answer 22

Negative = -70mV

Question 23

Why is the inside of the cell negative in comparison?

Answer 23

Leaky potassium membrane moves out of cell down concentration gradient

Question 24

Equilibrium potential

Answer 24

Membrane potential at which the electrical gradient is equal and opposite to the concentration gradient

Question 25

Why is more K+ in ECF bad?

Answer 25

Less concentration gradient Smaller electrical gradient RMP reduced so fire at random time due to less -ve Capillaries in blood brain barrier prevent this but heart ==>ventricular fibrillation

Question 26

Why is normal RMP -70mV

Answer 26

- leaky channels - Electrogenic nature of the pumps - large intracellular proteins

Question 27

When RMP is an action potential fired at?

Answer 27

-55mV

Question 28

Name the 4 graded potentials

Answer 28

- Generator => sensory - endplate => neuromuscular - pacemaker => heart - Post synaptic => at synapses

Question 29

Name some properties of graded potentials

Answer 29

- Decremental - current leaks out - non propagated - graded - more channels= bigger potential - electrotonic potentials

Question 30

In graded potentials where is the intensity encoded?

Answer 30

Amplitude

Question 31

Are graded potentials hyperpolarising or depolarising?

Answer 31

Both

Question 32

Hyperpolarising

Answer 32

- inhibitory IPSP - fast - CL- in - slow - g protein coupled K+ out eg GABA and glycine

Question 33

Depolarising

Answer 33

``` fast = ATPase slow = gprotein coupled stop K+ leaving ```

Question 34

Ligand gated ion channel

Answer 34

Neurotransmitter

Question 35

Voltage gated ion channel

Answer 35

Depolarisation of membrane potential

Question 36

Temporal summation

Answer 36

2 EPSP added together

Question 37

Spatial summation

Answer 37

2 different stimulations added together

Question 38

Postsynaptic inhibition

Answer 38

Straight on to dendrite

Question 39

Synaptic integration

Answer 39

the process of summing all those inputs in space and time, to determine whether or not the initial segment reaches threshold.

Question 40

Action potentials

Answer 40

- Have a threshold = fired once depolarised - all or none - all the same size - Encodes stimulus intensity in frequency, fire more - Self propagate - Can't travel back as all neurons in the refractory period

Question 41

Gaps in myelin

Answer 41

Nodes of ranvier

Question 42

Big axons

Answer 42

Lower axial resistance | Depolarisation travel further and spread out sodium channels

Question 43

Myelination

Answer 43

Increase resistance - AP spreads | less leaky and saltatory reduction

Question 44

Demyelination

Answer 44

MS - resistance so low so will decay and not big enough to fire AP

Question 45

Compound action potential

Answer 45

Axons variable size and myelination with different conduction velocities A alpha big and myelinated and C opposite

Question 46

Endplate

Answer 46

Where sarcolemma invaginates

Question 47

Neurotransmitter released in vesicles to fuse with presynaptic membrane due to what?

Answer 47

Exocytosis triggered by calcium concentration changes

Question 48

Brief steps

Answer 48

AP-Calcium channels open- vesicles of acetylcholine released, NA/K, graded potential, depolarise, Na and acetylcholinesterase

Question 49

CNS receptors

Answer 49

Acetylcholine, NO, serotonin, dopamine, GABA

Question 50

axo somatic synapse

Answer 50

Synapse on cell body

Question 51

axo dendritic synapse

Answer 51

Synapse on dendrite

Question 52

axo axonial

Answer 52

Synapse on axo dendritic

Question 53

Feedback inhibition

Answer 53

Inhibitory interneuron close to axon hillock

Question 54

Why is CNS more complex than neuromuscular?

Answer 54

- Bigger range of receptors - Range of postsynaptic potentials - small potentials - integration - variations on connectivity and anatomical arrangement