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Flashcards in grey matter Deck (30)
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1
Q

What is the bipolar membrane responsible for?

A

Connects photoreceptors to the optic nerve.

2
Q

Where are rods found?

A

Retina

3
Q

Where are cones found?

A

The fovea

4
Q

What is the light sensitive pigment that is found in rods?

A

Rhodopsin

5
Q

What is rhodopsin made from?

A

Retinal and opsin

6
Q

What prevents information reaching the brain when the rods are unstimulated?

A
  • open sodium channels causes depolarisation
  • neurotransmitters released
  • these inhibit the bipolar neurone
7
Q

What is bleaching?

A

When light energy causes rhodopsin to break into retinal and opsin

8
Q

What phase is the membrane in when rod cells are stimulated?
Why does this allow information to reach the brain?

A

Hyperpolarisation

-it prevents the release of more neurotransmitters, uninhibiting the bipolar neurone

9
Q

What happens to the impulses when there is a bigger stimulus?

A

Action potentials fire more frequently, not more often

10
Q

Outline the course of events which cause the action potential to move down the neurone

A
  • some of the Na+ ions diffuse sideways
  • this causes sodium channels in the next region of the neurone to open, and Na+ ions to diffuse into it
  • this causes a wave of depolarisation to spread down the neurone
11
Q

Why are impulses discrete?

A
  • during the refractory period, ion channels can’t be opened
  • this prevents action potentials from overlapping.
12
Q

Why do impulses move down myelinated neurones faster?

A
  • myelin is an electrical insulator
  • depolarisation can only occur at the nodes of ranvier
  • the cytoplasm conducts enough charge to depolarise the next node, the impulse jumps
13
Q

What is it called when the impulse jumps down the nodes of ranvier?

A

Salutatory conduction

14
Q

what do the sodium potassium pump and potassium ion channels regulate?

A

-resting potential

15
Q

what does ‘resting potential’ refer to?

A

the polarisation of the membrane, there are more positive ions outside the cell than inside

16
Q

how do the sodium potassium pump + potassium channels work?

A
  • Na/K pumps sodium ions out of the cell via active transport, they cant diffuse back into the cell
  • this creates an electrochemical gradient because there are more Na ions outside the cell
  • K ions are moved back in, but the membrane is permeable to K, so they diffuse back out
  • this makes the outside of the cell positively charged
17
Q

why does the membrane become depolarised when a stimulus arrives?

A

Na+ channels open, Na+ ions diffuse into the neurone making the inside less negative

18
Q

why does repolarisation occur?

A

Na+ channels close and K+ channels open, K+ diffuses out of the neurone

19
Q

why does hyperpolarisation occur?

A

K+ channels are slow to close, too many leave

20
Q

what is meant by ‘refractory period’?

A

ion channels are recovering and cannot be forced to open

21
Q

what affect does habituation have on the amount of calcium ions in the pre-synaptic membrane?

A

decreases the number of Ca2+ ions which enter the pre-synaptic membrane, causing less neurotransmitter to be released from vesicles into the pre-synaptic cleft

22
Q

what does the visual cortex do?

A

recieves and processes visual information

23
Q

what happens when a stimulus is provided during the critical period?

A

synapses that receive visual stimulation and pass nerve impulses to the visual cortex are retained

24
Q

what is a dopamine agonist?

A

something that mimics dopamine, binding to dopamine receptors in the brain and triggering an action potential

25
Q

how does fMRI work?

A

oxyhaemoglobin produces a weaker response to magnetic fields.
this means that more active parts of the brain produce a weaker signal due to increased oxygen uptake

26
Q

what are the roles of glycolysis?

A
  • phosphorylation of hexoses

- production of ATP, reduced coenzyme, pyruvate and lactate

27
Q

how are drugs made using genetically modified microorganisms?

A
  • gene is isolated using restriction endonucleases
  • gene copied using PCR
  • copies inserted into plasmids
  • microorganisms grown and produce protein which can be purified
28
Q

what does the sarcoplasmic reticulum do?

A

stores and releases Ca2+

29
Q

name two benefits of habituation

A
  • dont waste energy

- more energy can be used for food

30
Q

how does the level of activity of the enzymes in a metabolic pathway ensure that optimum level of product is produced?

A
  • compound cant be broken down faster than it is made
  • activity of enzyme that makes the product must be similar to the activity of the enzyme that breaks it down
  • one enzyme is rate limiting