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Biology > 13 Neuronal Communication > Flashcards

13 Neuronal Communication Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

1 internal factor that cause a response in a plant and animal

A

Plant- water potential

Animal- blood glucose concentration

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2
Q

What responses do animals react through?

A

Electrical (via neurones)

Chemical (via hormones)

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3
Q

Why is coordination needed?

A

Coordinate functions of different cells and systems to operate in response to internal and external changes

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4
Q

Example of coordination ?

A

Muscle cells need to respire in order to contract. Thus need oxygen thus need red blood cells

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5
Q

What is homeostasis?

A

Constant internal environment.

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6
Q

What is cell signalling?

A

Communication at cellular level. Cells can transfer signals locally between neurones or synapses using a neurotransmitter or across large distances using hormones

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7
Q

Role of neurones?

A

Transmit electrical impulses rapidly around body so organism can respond to changes in internal and external environment

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8
Q

Structure of neurone?

A

Cell body (contains nucleus surrounded by cytoplasm. Cytoplasm contains many ER and mitochondria involved in production of neurotransmitters)

Dendrons (transmit e impulses towards cell body)

Axons (transmit e impulses away from cell body)

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9
Q

Types of neurone

A

Sensory
Relay
Motor

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10
Q

Function and makeup of sensory neurone

A

Transmit impulses from sensory reception to relay or motor or brain. One dendron one axon.

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11
Q

Function and makeup of relay neuron

A

Transmit impulses between neurones I.e sensory and motor. Many short axons and dendrons

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12
Q

Function and makeup of motor neurone

A

Transmit impulses from relay or sensory to an effector (muscle or gland). One long axon and many short dendrites

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13
Q

What are some axons of neurones covered in?

A

Myelin sheath made of layers of plasma membrane. Schwann cells produce these layers creating a double layer of phospholipid bilayer each time.

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14
Q

What does a myelin sheath do?

A

Acts as an insulating later and allows neurones to conduct electrical impulses at a faster rate of 100m per second

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15
Q

What is between each adjacent Schwann cell?

A

Node of ranvier (electrical impulse jumps from one node to the other)

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16
Q

Features of sensory receptors?

A

Specific to one type of stimulus

Act as a transducer converting stimulus into a nerve impulse (generator potential)

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17
Q

What is a pacinian corpuscle?

A

Mechanoreceptor. Detects mechanical pressure, located in skin

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18
Q

How does pacinian corpuscle convert mechanical pressure into a nervous impulse?

A
  1. ) in resting state the stretch-mediated sodium iron channels in membrane are too narrow to allow sodium to pass through them.
  2. ) when pressure applied= corpuscle changes shape which stretches membrane.
  3. ) membrane stretches, sodium iron channels widen and allow sodium ions to enter neurone
  4. ) influx of positive sodium ions causes membrane to become depolarised. Resulting in a generator potential
  5. ) generator potential causes action potential along sensory neurone to CNS
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19
Q

Explain how your body detects your finger has touched a pin!

A
  1. ) in resting state the stretch-mediated sodium iron channels in membrane are too narrow to allow sodium to pass through them.
  2. ) when pressure applied= corpuscle changes shape which stretches membrane.
  3. ) membrane stretches, sodium iron channels widen and allow sodium ions to enter neurone
  4. ) influx of positive sodium ions causes membrane to become depolarised. Resulting in a generator potential
  5. ) generator potential causes action potential along sensory neurone to CNS
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20
Q

Events creating a resting potential in axon

A
  1. ) 3 Na+ ions out and 2 K+ ions in axon by active transport
  2. ) thus Na+ ions diffuse back into axon down electrochemical gradient. k+ ions diffuse out.
  3. ) most gated sodium ion channels closed. Many potassium ion channels open so more K+ diffuses out. Thus more positively charged ions outside axon than inside- created resting potential of -70mV
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21
Q

Action potential of axon

A

1.) energy of stimulus opens sodium voltage-gated ion channels, allowing Na+ ions to diffuse into axon down electrochemical gradient
2.) change in charge causes more Na+ ions to open (positive feedback)
When potential reaches +40mV then the voyage gated sodium ion channels close and potassium open open. Na+ ions can no longer enter axon.
3.) K+ diffuses out down electrochemical gradient so the inside becomes more negative
4.) too negative = hyperpolarisation
5.) so K+ ion channels close and sodium- potassium pump cause Na+ ions to move out and K+ ions to move in. Axon returns to resting potential- repolarised

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22
Q

In an axon how is depolarisation continued along all regions? And what is this called?

A

Action potential in sensory receptor causes first region to be depolarised. This acts as a stimulus for depolarisation of next region. Process continues along length forming a wave of depolarisation

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23
Q

Why is a refractory period important in axon?

A

Makes sure all action potentials are unidirectional

And ensures action potential do not overlap

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24
Q

What is saltatory conduction?

A

Action potential jumps from one node to another on myelinated axons. Faster than wave of depolarisation. Long term s conduction is also more energy efficient as it reduces amount of repolarisstion (using ATP) needed

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25
Q

What three factors affect the speed at which an action potential travels?

A

1- myelinated neurone
2- axon diameter (bigger/ faster. Bc less resistance to flow of ions in cytoplasm)
3- temp (higher/faster. But obvs only up to 40•c

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26
Q

What is the all-or-nothing principle of nerve impulses?

A

Threshold value triggers a response. If threshold is reached there’s always an action potential. Strong stimulus creates same size action potential but occurs more frequently

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27
Q

What is the junction between two neurones called?

A

Synapse

28
Q

How are impulses transmitted across synapse ?

A

Using neurotransmitters

29
Q

The 6 features of a synapse ?

A 
Synaptic cleft
Presynaptic neurone
Postsynaptic neurone
Synaptic knob
Synaptic vesicles
Neurotransmitter receptors
30
Q

What is a presynaptic neurone?

A

Neurone along which the impulse has arrived

31
Q

What is a postsynaptic neurone

A

Neurone that receives neurotransmitter

32
Q

What is a synaptic knob?

A

Swollen ;) end of presynaptic neurone. Contains many mitochondria and ER to make neurotransmitters

33
Q

What is a synaptic vesicles

A

Vesicles containing neurotransmitters. They fuse w presynaptic membrane and release contents into synaptic cleft

34
Q

What is a synaptic cleft

A

Gap which separates axon of one neurone from the dendrite of another

35
Q

What are neurotrnsmitter receptors ?

A

Receptor molecules which the neurotransmitter binds to in the postsynaptic membrane

36
Q

2 types of neurotransmitter?

A

1- excitatory (result in depolarisation of postsynaptic neurone. If threshold is reached in postsynaptic membrane then an action potential is triggered)

2- inhibitory (results in hyperpolarisation of postsynaptic membrane. Prevents action potential being triggered )

37
Q

Example of a excitatory neurotransmitter?

A

Acetylcholine

38
Q

Example of inhibitory neurotransmitter?

A

GAMA

39
Q

Explain transmission of impulses across synapse

A

1.) action potential reaches end of presynaptic neurone
2.) depolarisation of presynaptic membrane causes calcium ion channels to open
3.) calcium ions diffuse into presynaptic knob
This causes presynaptic vesicles containing neurotransmitter to fuse w presynaptic membrane. Neurotransmitter released into synaptic cleft by exocytosis
4.) neurotransmitter diffuses across synaptic cleft and binds w it’s specific receptor molecule on postsynaptic neurone
5.) action potential triggered. Impulse is propagated along the postsynaptic neurone

40
Q

Any neurotransmitter left in the synaptic cleft is removed. Why?

A

Prevents the response from happening again and allows the neurotransmitter to be recycled

41
Q

What is the role of synapses? X3

A

Ensure impulses are unidirectional

Allow an impulse from one neurone to be transmitted to a number of neurones at multiple synapses. Results in a single stimulus creating a number of simultaneous responses

A number of neurones may feed into the same synapse with a single postsynaptic neurone. Results in a stimuli from different receptors providing a single result

42
Q

What is spatial summation?

A

Occurs when a number of presynaptic neurones connect to one postsynaptic neurone. Each releases neurotransmitter which builds up to a high level in the synapse to trigger an action potential.

43
Q

What is temporal summation?

A

Occurs when a single presynaptic neurone releases neurotransmitter as a result of an action potential several times over a short period. This builds up in the synapse until the quantity is enough to trigger an action potential

44
Q

How do drugs work on synapses ?

A

Mimick shape of neurotransmitter (I.e nicotine has same shape as acetylcholine

Stimulates release of more neurotransmitter

Inhibiting the enzyme responsible for breaking down the neurotransmitter in synapse can result in loss of muscle control.

45
Q

Explain how synapses ensure impulses are only transmitted in one direction?

A

Neurotransmitter receptors are only present on the postsynaptic membrane so can only cause depolarisation of this membrane resulting in action potential

46
Q

Mammalian nervous system is organised structurally into two systems. What r they?

A

Central nervous system (brain and spinal cord)

Peripheral nervous system (consists of all neurones that connect CNS to rest of body)

47
Q

Nervous system is functionally organised into two systems. What r they?

A

Somatic nervous system (under conscious control I.e move a muscle in arm)

Autonomic nervous system (works constantly. Under subconscious control. I.e heart beat or digesting food)

48
Q

The autonomic nervous system further divided into what ?

A

Sympathetic (if outcome inc activity)- inc in ❤️ rate

Parasympathetic (if outcome Dec activity)- Dec in breathing or ❤️ rate after excersize

ONLY EXCEPTION IS PROCESSES TO DO W DIGESTION

49
Q

State and explain one reason why many autonomic functions can also be controlled by the somatic nervous system?

A

Breathing can be controlled by holding breath when swimming as we can’t breath under water

50
Q

5 main areas of the brain

A

Cerebrum- controls voluntary actions - conscious thought

Cerebellum- controls unconscious functions- posture, balance. If damaged causes jerky movements

Medulla oblongata- used in autonomic control - ❤️ rate and breathing rate.

Hypothalamus - regulatory centre for temp and water balance and produces hormones I.e ADH

Pituitary gland - stores and releases hormones (and releases hormones produced by hypothalamus). Divided into 2 sections- anterior pituitary (front section produces 6 hormones). Posterior pituitary (stores and releases hormones produced by Hypothalamus)

51
Q

State the pathway followed by a nervous impulse produced by a sound wave?

A

Sound receptor in left ear
Sensory neurone
Temporal lobe in cerebral hemisphere

52
Q

What is a reflex arc?

A

An involuntary response to a sensory stimulus

53
Q

Pathway of reflex arc between stimulus and response

A

Stimulus

Receptor (detects stimulus and creates an action potential)

Sensory neurone (carries impulse to spinal cord)

Relay neurone (connects sensory n to motor n)

Motor neurone (carries impulse to effector to carry out response )

54
Q

What type of reflex is a knee-jerk reflex ?

A

Spinal reflex

55
Q

Why are reflexes essential to survival?

A

Avoid body being harmed/ less damage I.e iris contracts in pupil in bright light to prevent damage to the retina

56
Q

How do reflexes increase survival? (Basically what features)

A

Being involuntary responses

Not having to be learnt

Extremely fast

Many reflexes are everyday actions I.e those keeping us upright

57
Q

State the reflex arc which occurs when a doctor tests the knee -jerk reflex

A

Pressure receptor in skin

Sensory neurone

Relay neurone

Motor neurone

Muscle

58
Q

3 types of muscle?

A

Skeletal (responsible for movement)

Cardiac muscle (in ❤️- these cells are myogenic meaning they contract without need for a nervous stimulus )

Smooth muscle (found in walls of stomach and blood vessels )

59
Q

What is the structure of skeletal muscle?

A

Made of bundles of fibres enclosed in a plasma membrane called sarcolemma. Muscle fibres have lots of mitochondria to provide ATP for contraction. Also have modified version of ER called sarcoplasmic reticulum- contains calcium for contraction
Each fibre contains many myofibrils.

60
Q

Myofribils are made up of two types of protein filaments

A

Actin- thinner, consists of 2 strands twisted round each other

Myosin- thicker, consists of rod shaped fibres

61
Q

Structure of a myofibril

A

Light bands (I bands)- actin and myosin filaments don’t overlap

Dark bands(A bands)- myosin overlapped w actin

Z lines- at centre of each light band. Distance between adjacent z lines is called sarcomere l. Muscle contracts makes the sarcomere shorten

H zone- lighter coloured region found in centre of each dark and. Only myosin filaments present. When muscle contracts h zone decreases

62
Q

Properties of slow twitch fibres

A

((Found in Calf muscles ))

Contract slowly

Less powerful contractions but over longer period

Gain Energy from Aerobic respiration

Rich in myogloblin (red) stores oxygen

Rich supply of blood vessels

63
Q

Properties of fast twitch fibres

A

((Found in biceps and eyes))
Contract quickly

Powerful contractions but shorter time period

Gain energy from anaerobic respiration

Pale coloured- low levels of myogloblin and blood vessels

Contain more myosin filaments

64
Q

How does skeletal muscle contract ?

A

Actin and myosin filaments within myofibrils slide past each other (sliding filament model)

65
Q

During contraction myosin filaments pull the actin filaments inwards towards the centre of the sarcomere. What does this result in?

A

Light band becoming narrower

Z lines moving closer together, shortening sarcomere

H zone becoming narrower

Dark bands remain same width

Biology (10 decks)

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