Brainscape's Knowledge GenomeTM

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


See full index

Chem 20 > Chapter 11.1 > Flashcards

Chapter 11.1 Flashcards

nervous system

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

Nervous and endocrine systems work together to maintain what?

A

homeostasis

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

homeostasis

A

maintaining internal balance

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

general functions of nervous system

A

a. reception of stimuli and conduction of impulses (message) to the central nervous system (CNS)
b. interpretation of impulse - followed by decisions
c.sorting of impulses and setting priorities for actions upon them (insignificant info is ignored while urgent info is given priority)
d. transmission- impulses to effectors - carry out appropriate activities

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

nervous system composed to two main types of cells

A

1) neurons
2) glial cells

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

1) neurons

A

basic structural, functional unit of nervous system
- specialized to respond to both physical and chemical stimuli
- conduct electrochemical signals (impulses)
-release chemicals that regulate various body processes
individual neurons (nerve fibres) are organized into tissues called nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

2) Glial cells (aka glia)

A
  • non conducting cells
  • outnumber neurons by 50:1
  • nourish neurons, remove their waste and defend against infection
  • also provide supporting framework for the nervous system tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Sensory neurons

A
  • relay information about the environment to the CNS for processing (e.g) eyes- light, skin-pressure and temp)
  • cell body found midway through the axon
  • myelinated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

interneurons

A
  • link neurons within body
  • found mainly in brain and spinal cord
  • integrate and interpret sensory info & connect to outgoing motor neurons
  • unmyelinated and shorter in length
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

motor neurons

A
  • relay info from cns to effectors (muscles, glands)
  • myelinated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

four common features of neurons

A

dendrites, cell body, axon, axon terminals

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

Dendrites

A
  • numerous and highly branched to increase surface area to receive incoming signals from specialized receptors or other neurons
  • conduct nerve impulses toward to the cell body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

cell body (soma)

A
  • receives impulse from dendrites- then spreads over the cell body and through to the axon (acts as a bridge)
  • contains all major cellular organelles (nucleus, ER, ribosomes, etc)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Axon

A
  • conducts nerve impulses away from cell body
  • range in length from 1mm to 1m depending on neurons location in body
  • carries nerve impulses towards other neurons or to effectors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

myelin sheath

A

In many vertebrates, axons that convey signals rapidly are enclosed, along most of their length, with a thick insulating material.
- resembles a chain of oblong beads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

schwann cell

A

type of glial cell that wraps many times around the axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

spaces between schwann cells

A

nodes of ranvier

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

nerves within the brain contain:

A

myelinated fibres and neurilemma - called white matter
myelin- white fatty protein
- unmyelinated- grey matter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

neurilemma

A

all nerve fibers within the PNS contain a thin membrane, called neurilemma
- surrounds the axon and promotes regeneration of damaged axons

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

Axon terminal

A

at the end of the axon- branches off to form axon terminals
- axon terminals store neurotransmitters- chemicals that will be released to carry the message across the synapse (space between neurons) to a dendrite of another neuron or an effector

20
Q

Reflex arc

A
  1. receptor
    2.sensory neuron
    3.interneuron in the spinal cord
    4.motor neuron
    5.effector
21
Q

the nerve impulse

A

neurons establish a voltage difference between the inside and the outside of the cell membrane. This difference is used to generate a neural impulse

22
Q

The electrical nature of nerves

A

Nerve conduction depends on the movement of ions across the cell membrane of an axon. The charge separation across the membrane is a form of potential energy or membrane potential

23
Q

Non-Voltage Gated Ion Channels

A

-some are open all the time
-some are stimulated by chemicals to open/close
-ions move via diffusion

24
Q

Voltage gated Ion Channels

A
  • Stimulated by specific charge to open/close.
  • ions move via diffusion
25
Q

Na+/K+ pump

A
  • always active
  • utilizes ATP to actively transport ions across the membrane
26
Q

Resting membrane potential

A

the potential difference across the membrane in a resting neuron
- in most neurons = -70mV
- Negative on INSIDE relative to outside

27
Q

Polarization

A

process of generating a resting membrane potential. The resting membrane is said to be charged or polarized with the potential to do work.

28
Q

How is polarization achieved? Small contributor:

A

Intercellular fluid exists inside the neuron. The fluid contains large negatively charged protein molecules (cannot escape cell due to size) and small negatively charged ions (Cl-) (cannot escape due to selectively permeable membrane)

29
Q

How is polarization achieved? Most Important contributor:

A

The sodium-potassium exchange pump in the axon membrane
- uses ATP to pump 3 Na+ OUT of the axon and 2K+ ions INTO the axon
- An excess of positive charge accumulated outside of the cell.

30
Q

Excitation of the neuron definition:

A

The action potentials
(nerve impulses) occur in the axons of neurons and in the dendrites of certain sensory cells.
A nerve impulse is established once the resting potential voltage is altered or depolarized, creating an electrical current that travels across the neural membrane

31
Q

Excitation of a neuron steps

A
  1. The graph starts at the membrane’s resting potential (-70mV)
    - the inside of the axon is negatively charged compared to the outside
    - both voltage gated sodium and potassium gates remain closed
  2. The stimulus is applied
    - It triggers the opening of a few non voltage gated sodium gates
    - If it is strong enough, the voltage rises to what is called the threshold (-55mV)
    - the difference between the threshold and the resting potential is the minimum change in the membrane’s voltage that must occur to generate the action potential
  3. Once the threshold is reached, the action potential is triggered
    - voltage gated sodium channels open, allowing even more sodium to diffuse into the cell
    - the membrane polarity is reversed abruptly ( = depolarized)
    - as more Na+ moves into the axon, the voltage reaches it’s peak ( approx. +35mV)
  4. The peak voltage triggers closing and inactivation of the voltage gated sodium channels
    - meanwhile the voltage gated potassium channels open, allowing potassium to diffuse out rapidly
    -these changes produce the downswing int he graph = membrane rapidly repolarizes as the voltage drops back down
    - na+/k+ pump will also assist in the repolarization process by actively pumping 3 sodium out and 2 potassium into the axon
  5. a very brief undershoot of the resting potential (= hyperpolarization) results because the K+ channels close slowly ( @-80mV)
  6. The membrane then returns to its resting potential
32
Q

refractory period

A

repolarization takes approx 0.001s or 1ms. this time frame is known as the refractory period. (impulse cannot be activated during this time

33
Q

Impulse propagation

A
  1. an action potential continues to travel down the neuron in a wavelike motion
  2. The depolarization associated with an action potential in one region stimulated an action potential in the adjacent region that is at rest. Therefore, action potentials are propagated in only one direction along the axon.
34
Q

saltadory conduction

A

Action potentials are generated by the movement of ions into and out of the axon. Therefore they can only occur where the axon membrane is exposed

35
Q

continuous conduction

A

Unmyelinated neurons: Action potentials occur at every location along the membrane.
as a result, the impulse transmission along an unmyelinated axon is much slower (5m/s) than the saltadory conduction along a myelinated neuron (150m/s)

36
Q

Saltadory conduction in what type of neurons?

A

Myelinated neurons: Action potentials “JUMP” from one node of Ranvier to the next
(action potentials only occur where axon membrane is exposed)

37
Q

Threshold levels

A

In experiments with nerve and muscle- electrical stimulus has to be at a certain value before a neuron will fire and the muscle will contract
- if below value- no response, if at or above value - response. (known as threshold level)
- each neuron has a different threshold level ( MOST are close to -55mV)
- once the threshold level is reached - nerve impulse is total

38
Q

Stimulus can be:

A

changes in pH, pressure, or specific chemicals

39
Q

All or none response

A

Increasing intensity of stimuli above threshold value will not produce an increased response - nerve impulse and speed of transmission remain the same

40
Q

How can we detect intensity? (ie. warm vs hot)

A
  1. Increase stimulus- more neurons are stimulated (due to their different threshold levels) the brain interprets a high number of neurons firing as an increased intensity
  2. Increase stimulus - increased frequency of action potentials
41
Q

The synapse

A

known as synaptic cleft
- small spaces between neurons or between neurons and effectors. Neuromuscular junction is the specific synapse between a motor neuron and muscle

42
Q

neurotransmitter process

A
  1. nerve impulse (action potential) moves along the axon to the end plate (axon terminal/presynaptic knob) which has small vesicles containing chemicals called neurotransmitters.
  2. The neurotransmitters (example- acetylcholine) are released from the presynaptic neuron and travel to the post- synaptic neurons via diffusion
  3. neurotransmitters binds to receptors on the post synaptic dendrite
  4. An excitatory neurotransmitter, OPENS chemically gated sodium chennels- causing depolarization
  5. Action potential
  6. The neurotransmitter is eventually deactivated by an enzyme (example : cholinesterase), resulting in the closure of chemically gated sodium channels
  7. post synaptic neuron begins repolarization. components of neurotransmitter get reabsorbed by presynaptic knob and repackaged in vesicles
43
Q

Excitatory neurotransmitters

A

neurotransmitters that stimulate an action potential on post synaptic neuron

44
Q

Inhibitory neurotransmitters

A

neurotransmitters that prevent an action potential on post synaptic neuron

45
Q

Summation

A

A single neuron may be influenced by many different neurons. Summation is the final outcome of the simultaneous released of excitatory and inhibitory neurotransmitters in a synapse

Chem 20 (9 decks)

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