Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology: Alex > Topic 8 > Flashcards

Topic 8 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Describe a neurone at rest

A
  1. outside has a more positive ions so higher charge than inside (polarised)
  2. Resting potential is about -70mv
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How is resting potential created and maintained

A
  1. Na/K pumps use active transport to move 3 sodium ions out for every 2 K moved in (ATP)
  2. K ion channels allow facilitated diffusion out of membrane down conc gradient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe permeability at resting

A
  1. Not permeable to sodium ions so cannot diffuse back in

2. More positively charged Na ions outside so cerastes electrochemical gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 5 steps of an action potential

A
  1. Stimulus
  2. Depolarisation
  3. repolarsiation
  4. Hyperpolarisation
  5. Resting potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe step 1 of action potential (stimulus)

A
  1. Excited neurone membrane causing voltage sensitive sodium ion gates to open
  2. Makes membrane more permeable to sodium so they diffuse in
  3. Makes inside less negative
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe Depolarisation (step 2)

A
  1. If potential difference reaches threshold of -55mv it causes more sodium ions gates to open
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe repolarisation

A
  1. When potential difference if around +30mv the Na channels close and K channels open causing lots of K ions to diffuse out
  2. This restores resting potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe Hyperpolarsion

A
  1. K ions channels are slow to close so slight overshoot where too much K diffuses out of
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe step 5 (resting potential)

A
  1. Ion channels at rest

2. Sodium-potassium pumps return membrane to resting potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the period where ion channels are recovering called

A

Refractory period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does an action potential move along a neurone

A
  1. Some Na ions diffuse sideways
  2. Causes sodium ion channels in next region to open
  3. Wave of depolarising
  4. Moves in right direction because can’t fire in refractory period
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is good about refractory periods

A
  1. Action potentials don’t overlap so are discrete

2. Unsure unidirectional

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is a bugger stimulus revived

A
  1. Action potential always same voltage

2. So will trigger more frequency impulses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does a local anaesthetic work

A
  1. Bind to sodium ion channels
  2. Prevents Na ions moving in so membrane not depolarised
  3. No action potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the Myelin

A
  1. Schwann cell
  2. Insulates axon
  3. Patches of bare membrane where Na ion channels are concentrated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What’s the gaps between Myelin called

A

nodes of Ranvier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe saltatory conduction

A
  1. Depolarisation only happens at noses as that’s where Na ions can get through
  2. Cytoplasm conducts enough charge to depolarise next node
  3. Speed called condition velocity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define a stimulus

A

A change in internal or external environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why can we detect stimulus

A
  1. Increases chance of survival

2. By avoiding harmful situations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What detects a stimuli

A

Receptor cell (or protein on CSM)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What effectors

A

Cells that bring about a response to stimulus

  1. Muscle cells
  2. Glands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How do receptors communicate with effectors

A
  1. Nervous or hormonal system

2. Or both

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

State the 4 steps of a reflex

A
  1. Stimulus detected by receptor cells which send electrical impulse down sensory neurone
  2. Synaptic transmission
  3. Relay neurone
  4. CNS processes then sends impulse down motor neurone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe the 5 step process of your eye in Bright light

A

Stimulus: bright light
Receptors: photoreceptors detect bright light
CNS: processes information
Effectors: circular muscles in Iris stimulated by motor neurone
Response: circular muscles contract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What muscles contract in bright/ dim light

A

Bright: circular
Dim: radial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Define a gland and a hormone

A

Gland: group of cells specialised to secrete a hormone
Hormone: chemical messengers ( either protein or lipid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How is a gland stimulated

A
  1. By a change in conc of a specific substance

2. Electrical impulse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How do hormones work?

A
  1. Diffuse directly into blood from glands
  2. Transported in circulatory system
  3. Diffuse out of blood all over body by will on bind to cells with specific receptors found on membrane of target cells
  4. Triggers response form target cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe how light enters the eye

A
  1. Through pupil
  2. Amount of light controlled by iris
  3. Focused by Lens into retina (contains photoreceptors)
  4. Transmits to optic nerve
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the light-sensitive pigment in Rod cells

A

Made of retinal and opsin (protein)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Describe Rod cells when unsitumulated (in dark)

A
  1. Na+ pumped out of inner segment via a action channel (active)
  2. Na+ diffuse back into putter segment via cation channels
  3. Ion movement creates electric current making membrane depolarised
  4. Triggers the release of neurotransmitters
  5. Is inhibitory so stops bipolar neurone depolarising to trigger ganglia cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Describe rod cells in light (stimulated)

A
  1. Light energy bleaches rhodopsin into retinal and opsin
  2. Opsin binds to outter segment membrane which blocks Na+ ions diffusing in
  3. Na+ still pumped out so inside very negative, hyperpolarising membrane
  4. Stops releasing neurotransmitters so no inhibition of bipolar neurone
  5. No longer inhibited so depolarises bipolar cell, triggering an action potential to brain via optic nerve
33
Q

What do dendrons and axons do?

A

Dendrons: carry toward cell body
Axons: away from cell body

34
Q

Describe habituation

A
  1. Repeated stimulus decreases permeability of pre-synaptic neurone
  2. So fewer Ca+ ions move into neurone
  3. Fee vsicles fuse with membrane
  4. Less neurotransmitter released
  5. AP less likely to occur in post synaptic neurone
35
Q

Define synapse

A

Junction between neurone and neurone or neurone and effector cell

36
Q

Synaptic knob

A

Swelling on presynaptic neurone containing vesicles contains neurotransmitters

37
Q

Describe how an action potential triggers the release of neurotransmitters up

A
  1. Action potential stimulated voltage-gated calcium ion channels to open
  2. Calcium ions diffuse in
  3. Influx of Ca+ causes vesicles to move towards presynaptic membrane and fuse with it
  4. Vesicles release neurotransmitters into cleft via exocytosis
38
Q

How do neurotransmitters cause an action potential

A
  1. Diffuse across cleft and bind to specific receptors on PS membrane
  2. Causes Na+ ion channels to open on post synaptic neurone
  3. If influx reaches threshold level and action potential is triggered
  4. Neurotransmitters removed from cleft to stop response
39
Q

What ions are involved in synaptic transmission

A

Pre synaptic membrane: calcium ions (and channels)

Post synaptic neurone: sodium ions (and channels)

40
Q

Describe synaptic divergence

A
  1. One neurone connects to many, allowing information to be dispersed to different parts of body
41
Q

Describe synaptic convergence

A

Many neurones connecting to one to amplify an impulse

42
Q

Describe spatial summation and temporal

A

Spatial: action potential reached as a result of accumulated neurotransmitter from multiple neurones

Temporal: reached as a result of repressed stimulation from one neurone to another in a short period of time

43
Q

Define tropism

A

Positive: towards stimulus
Negative: away from a stimulus

44
Q

How are responses in plants brought about

A

No nervous or circulatory system so use growth factors at speed up/ slow down growth

45
Q

What are Auxins

A

Growth factors

46
Q

Describe the role of IAA

A

Enters nucleus and controls transition genes responsible for cell elongation

47
Q

Where would IAA go if the left side was shaded

A

The left side to bend towards the light

48
Q

How do plants detect light

A

Photoreceptors called phytochromes

49
Q

What are the two states of phytochromes

A

Pr: absorbs red light at wavelength 660nm

Pfr: far-red light at 730nm

50
Q

What happens to phytochromes in darkness

A

Pfr is slowly converted into Pr

51
Q

How does levels of Phytochrome control responses

A
  1. Regulate transcription of genes such as flowering or germination
52
Q

Location and function of hypothalamus

A
  1. Just below middle part
  2. Thermoregulation
  3. Produces hormones to control pituitary gland
53
Q

Function and location of medulla oblongata

A
  1. Top of spinal cord, at base of brain

2. Automatically controls breathing and heart rate

54
Q

Location and function of cerebellum

A
  1. Has a folded cortex (it’s that weird bit at back of head)

2. Coordinating movement and balance

55
Q

Describe the cerebrum

A
  1. Largest part of brain
  2. Divided into two hemispheres
  3. Outer layer called Cerberul cortex
  4. Cortex is folded for a large SA
  5. Recabelum is involved in vision, learning, processing and emotions
56
Q

Why is it useful to be able to scan the brain

A
  1. Investigate structure and function

2. Diagnose medical conditions

57
Q

What are the 4 types of brain scanner

A
  1. Computer Tomography (CT): X rays
  2. Magnetic Resonance Imaging (MRI): uses magnetic fields
  3. fMRI: blood oxygenation level
  4. Positron emission tomography (PET) use radioactive tracers
58
Q

Describe how CT works

A
  1. Use X as to produce a cross-section image

2. Dense structures absorb more radiation so show up as lighter colours

59
Q

How is CT useful in diagnosis

A
  1. Damaged areas will have different density
  2. Blood has a different density
  3. Not really good for function
60
Q

What’s a disadvantage to CT

A
  1. Ionising radiation used in X rays
  2. Can mutate DNA leading to cancer
  3. Can only use so many times in a row
61
Q

Describe how MRI works

A
  1. Electromagnets and radio waves

2. Produces cross section

62
Q

What’s the 2 advantages to MRI

A
  1. Very high resolution to detect normal and abnormal brain tissue
  2. Non ironising so can be used lots of times
63
Q

How is MRI good for diagnosis

A
  1. Tumour cells respond differently to magnetic field so show up a lighter colour
  2. Can tell you exact size and location
64
Q

Who cannot use MRI

A

People with metal implants as is very magnetic

65
Q

How does fMRI work

A
  1. Tracks oxyhemoglobin, this does not absorb radio waves whereas deoxyhaemoglobin does
  2. Active parts of brain have higher demand for oxygen
66
Q

How can fMRI be useful for brain function

A
  1. More active areas have a higher demand for oxygen

2. Patient can carry out a certain function and specific area that shows up can be observed

67
Q

How does PET work

A
  1. Measures photons
  2. Glucose with radioactive tracer
  3. Body breaks down tracer into positrons which collide with electrons to release photons
  4. Places with high glucose metabolism show up
68
Q

How can PET be used to look at structure and in diagnosis

A
  1. Very detailed structure and function observed in real time
  2. Can be compared to a healthily brain picture
69
Q

Define habituation

A

Reduced response to an unimportant stimulus after repeated stimulation

70
Q

What is the advantage of habituation

A
  1. Animal can ignore unimportant stimuli meaning they can continue carrying out survival function
71
Q

Describe the process of habituation

A
  1. Repeated exposure to stimuli decreases sensitivity of calcium ion gates so less Ca+ ions enter presynaptic neurone
  2. Less Ca+ less neurotransmitter released so fewer bind to PSM
  3. Fewer Na+ ion channels open on PSN so less likely threshold reached
  4. So fewer signals sent to effector to carry out response
72
Q

What is the location and function of the visual cortex

A

Area of cerebral cortex used to revive and process visual information from the eyes

73
Q

What are visual neurones grouped together in

A
  1. Columns called ocular dominance columns

2. Right eye are called right ocular dominance columns

74
Q

Describe the arrangement of the columns

A
  1. All same size

2. Arranged left right left right across visual cortex

75
Q

Describe the procedure into kittens visual cortex development

A
  1. Stitches an eye shut
  2. Unstitched 3 months later
  3. Blind in that eye
  4. Visual columns for closed eye small and for unclosed eye much bigger
  5. Had expanded and taken over unstimulated columns
76
Q

What were the findings of the experiment on adult cats

A

Fully recovers vision and same size ocular dominance columns

77
Q

What did Hubel and Wiesels experiment show

A

Visual context development only occurs if both eyes are visually stimulated in the critical period

78
Q

Describe the critical period

A
  1. Period early in life were visual stimuli is needed for ocular dominance columns to develop properly

Biology: Alex (44 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions