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Uni prep- nerves > Nerves > Flashcards

Nerves Flashcards

1
Q

Why is a nervous system necessary?

A

It’s important that organisms respond to changes in the environment, the nervous system coordinates these responses. They respond to stimuli

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2
Q

What constitutes a neurone?

A

Cell Body, Dendrons and Axon

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3
Q

Describe a cell body

A

Nucleus surrounded by a cytoplasm, plenty of RER to make neurotransmitters.

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4
Q

What are dendrons?

A

Short extensions that transmit electrical impules towards the cell body.

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5
Q

What are axons?

A

Transmit electrical impulses away from the cell body

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6
Q

Describe the structure of an axon

A

Narrow region of cytoplasm surrounded by a plasma membrane

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7
Q

Role of a sensory neurone

A

Transmit electrical impulses from sensory receptor cell to a relay neurone, motor neurone or brain

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8
Q

Description of sensory neurone

A

One axon, one dendron

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9
Q

Role of relay neurone

A

Transmit impulses between neurones

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10
Q

Description of relay neurone

A

many short axons and dendrites

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11
Q

Role of motor neurone

A

Transmit electrical impulses to an effector from a relay or sensory neurone

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12
Q

Description of motor neurone

A

one long axon and many dendrites

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13
Q

What is myelination

A

many layers of plasma membrane wrapped around axon- for each wrap a double layer of phospholipid bilayer is laid down

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14
Q

Which cells produces the myelin sheath

A

Schwann cells

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15
Q

Why is myelination important

A

faster transmission of electrical impulses

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16
Q

How does the myelin sheath speed up nervous transmission

A

Electrical impulse has to travel from one node of ranvier to the next- saltatory conduction

17
Q

Where are sensory receptors located

A

The sense organs- ears, eyes, nose…

18
Q

What is the role of sensory receptors

A

To detect changes in the environment (stimulus)

19
Q

How do sensory receptors perform their role

A

they convert the stimulus into an action potential which is then transmitted to the CNS

20
Q

What does the CNS do with this information

A

Sends an impulse to an effector, via a motor neurone, to coordinate the appropriate response

21
Q

Characteristics of sensory receptors

A

They are specific to the stimulus. They act as transducers.

22
Q

What is a transducer

A

Converts stimulus to an electrical impulse- converts energy from X- electrical

23
Q

Mechanoreceptors

A

Stimulus: Pressure and Movement
Example: Pacinian Corpuscle
Location: Skin and joints

24
Q

Chemoreceptors

A

Stimulus: Chemicals
Example: Olfactory receptor
Location; Nose

25
Q

Thermoreceptor

A

Stimulus; Heat
Example: End-bulbs of Krause
Location; Tounge

26
Q

Photoreceptor

A

Stimulus: Wavelengths of light
Example: Cone cell
Location: eye

27
Q

The Pacinian corpuscle

A

abundant in fingers and soles in feet, located deep within skin and in joints- to allow awareness of changes in direction

28
Q

Structure of Pacinian corpuscle

A

Ending of sensory neurone in centre. Surrounded by layers of connective tissue with viscous gel between, contained in a capsule

29
Q

Basics of nervous transmission

A

Transmission of impulse temporarily changes the p.d of the axon’s membrane- switching it between an action potential and resting potential

30
Q

What is the resting potential

A

-70mV, inside of axon membrane more negative than outside, membrane is polarised

31
Q

How is the resting potential maintained

A

Na+/K+ pump- 3Na+ actively transported out, 2K+ actively transported in.

32
Q

Why the Na+/K+ maintains resting potential

A

More Na+ outside, more K+ ions inside.
Na+ diffuses in, K+ diffuses out down their electrochemical gradients.
More gated K+ channels, hence more K+ diffuses out than Na+ diffuses in inside is more negative.

Uni prep- nerves (3 decks)

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