neuronal communication

Question 1

outl ine ways in which mtoor neuroens and sensory neuroens are similar ?

Answer 1

both have dendrites ,axon, cell body w nucleus, mylein sheathand volatge gated channels

Question 2

effect that sweating has on the body ? (2)

Answer 2

reduced body temperature + heat is taken from skin / supplied from body

Question 3

what does shivering do (1)

Answer 3

idea that to increase body temperature as it is lower than the ‘new’ set-point (even though body is hot) ;

Question 4

why it aint a good idea to have vasodilation if you ahve hypothermia (2)

Answer 4

vasodilation results in more blood nearer to the skin surface (1) idea that will lose (even) more heat / further heat loss (from body) / body temperature decreases further ;

extra makr (named organ would not be able to function further )

Question 5

what does pacinian corpuscle do ?

Answer 5

converts mechanical energy to electrical energy

Question 6

all or nothing rule (1)

Answer 6

if the , stimulus is not strong enough / threshold (value) is not reached / depolarisation (of membrane) is insufficient , then , it / an action potential , is not , generated

Question 7

Suggest an explanation for the fact that action potentials are not generated constantly whilst wearing clothes. (1)

Answer 7

sodium (ion) channels (remain) open / resting potential not re-established ;

idea of ions being in the wrong place for correct ion movement (across membrane)

Question 8

the roles of synapses :?

Answer 8

1 allows , neurones to communicate / cell signalling ;

2 ensure transmission (between neurones) in one direction (only) ; 3

allows , convergence / impulses from more than one neurone to be passed to a single neurone ; 4

allows , divergence / impulses from a single neurone to be passed to more than one neurone ;

5 idea that filters (out) , ‘background’ / low level , stimuli or ensures that only stimulation that is strong enough will be passed on ;

6 prevents fatigue / prevents over-stimulation ;

7 allows many low level stimuli to be amplified ;

8 idea that presence of inhibitory and stimulatory synapses allows impulses to follow specific path

; 9 permits , memory / learning / decision making ;

Question 9

post-synaptic membrane ; (TRPA1) prevents attachment of (named) neurotransmitter to its receptor ;

Answer 9

post-synaptic membrane ; (TRPA1) prevents attachment of (named) neurotransmitter to its receptor ;

Question 10

Answer 10

A sinusoid ;

B (branch of) bile duct ;

C (branch of) hepatic portal vein ;

D (branch of) hepatic artery / arteriole ;

E (branch of) hepatic / central , vein ;

note: hepatic artery is the smaller one !

Question 12

Name the liver cells that can lead to this regeneration and the type of cell division that they carry out.

Answer 12

hepatocytes

mitosis

Question 13

Answer 13

A cytoplasm ;

B cell surface (plasma) membrane / neurone / neurilemma / axon / dendron ;

C nucleus (of Schwann cell) ;

Question 14

why do myelinated neurones transmit impulses at a faster speed that non myelinated? (4)

Answer 14

link to the textbook

conduction of electrical impulses is faster in the myelinated neurone than non myelinated neurone (1 )

depolarisation of axon can only occur at the nodes of ranvier where no myelin is present (1)

longer localised circuits arise between the nodes (1)

thus action potential jumps from one node to another (1)

the reason why its so fast is because there are fewer places where sodium ion channels open etc

Question 17

Botulinum toxin is a protease that is produced by the bacterium, Clostridium botulinum. If this toxin is present in the body, for example as a result of eating contaminated food, the toxin enters neurones. With reference to Fig. 1.2, suggest, with reasons, the effects that botulinum toxin may have once it has entered a neurone.

( note botox does something to the SNARE protein (receptor) that allows exocytosis to happen )

Answer 17

vesicle cannot fuse with cell membrane and acetylcholine not secreted ( 1) because the toxin hydrolyses the SNARE protein (1) thus VAMP protein ( on vesicle which allows binding) cant bind to snare protein (1)

Question 18

what do you call a gland which release hormone into bloodstream ?

Answer 18

endocrine gland

AKA

pancreas

Question 19

how do nervous systems cause relaxation ?

Answer 19

through the parasympathetic nervous system

its part of the autonomic nervous system which is under subconscious control and releases impulses to smooth muscles etc..

works off of the neurotrnasmitter acetly choline

Question 20

label

why is B the dendron

why is A the axon ?

Answer 20

A dendrite(s)

; B dendron (membrane) #

; C cell body (of neurone) ;

D axon (membrane) ;

B is the dendron because it carries cell signals TO the cell body

A is the axon because it carries cell signals AWAY from the cell body!

Question 21

explain how the resting potential is maintained in a neuroen (4)

Answer 21

there is an active part of maintenance

sodium/pottasium ion pumps pump 3 sodium ions out and 2 pottasium ions in (1) BY ACTIVE TRANSPORT (1)

there is passive part of maintenance

K+ , diffuse ,(freely) back out (of cell) ; (1)

membrane less permeable to Na+ / fewer Na+ channels open , so fewer Na+ , diffuse / move / flow / leak , back in ; (1)

voltage-gated (Na+) , channels closed ; (1)

Question 22

comment on the frequency of action potential

Answer 22

‘strong stimulus increases frequency but not magnitude of action potential’ = 2 marks