Brainscape's Knowledge GenomeTM

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


See full index

HUMB1000 > Compendium 8 > Flashcards

Compendium 8 Flashcards

1
Q

List functions of the nervous system

A 
Maintaining homeostasis
Receive sensory input
Integrate information 
Motor output
Establish and maintain mental thinking
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the structural divisions of the nervous system

A

Central nervous system- brain and spinal cord

Peripheral nervous system - somatic, autonomic, enteric

  • All have sensory and motor input and output
  • autonomic motor output divided into parasympathetic (rest and digest) and sympathetic (fight or flight)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a nerve

A

Bundles of axons and their sheaths

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

What is a ganglion

A

Collection of cell bodies located outside the CNS

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

What is a plexus

A

Extensive network of axons or cell bodies

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

Explain autonomic nervous system

A

Action occurs subconsciously (involuntary)
Action potentials in motor neutrons travel go cardiac muscle, smooth muscle and glands
Two neuron system: one from CNS to autonomic ganglion, other from autonomic ganglion to effector
Cell bodies located in both CNS and autonomic ganglion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Explain somatic nervous system

A

Actions taking place with conscious thought (voluntary)
Action potential in motor neutrons travel to skeletal muscles
Single neuron system
Cell bodies located inside CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain enteric division of nervous system

A

Found in digestive tract (controls digestive tract movement)
Interpreted with autonomic subdivision of PNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Difference between motor and sensory

A

Motor- away from CNS (the action)

Sensory- toward CNS (stimulus)

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

Describe neurons

A

Structural unit of CNS
Receive stimuli, transmit action potentials via axons and dendrites
Consists of cell body (soma), axon, dendrites

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

Describe dendrites

A

Short cytoplasm extensions, usually highly branched, emerge from cell body
Receive info from cells, other neurons, environment and direct towards cell body
Can contain dendritic spines to increase SA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe cell body

A

Only one large one

Contains nucleus, nucleolus, other organelles

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

Describe axon

A

Extends from cell body through axon hillock, then have initial segment, both of these make up the trigger zone (where an action potential is generated)

Can have branches coming off can axon collaterals which can lead to other cells or same cell body in which it extends from

End of axon called axon terminal or presynaptic terminal which contain terminal buttons or synaptic knobs

Transmit info away from cell body

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

Functional classification of neurons

A

Sensory
Motor
Interneurons

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

Structural classification of neurons

A

Multipolar, unipolar, bipolar

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

Explain multipolar neurons

A

Many dendrites
Single axon
Most neurons in CNS
All motor neurons (cell body in horns of grey matter of spinal cord)

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

Explain unipolar neurons

A

One process (axon from cell body divides into T shape one side with sensory receptor, other travels to CNS)
Most sensory neurons
Sensory receptors pick up info rather than dendrites

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

Explain bipolar neurons

A

One axon
One dendrite
Rare- only in special sense organs

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

What are neuroglia

A

Supporting cells in CNS and PNS

CNS: astrocytes, ependymal cells, microglia, oligodendrocytes

PNS: Schwann cells, satellite cells

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

Explain astrocytes

A

Form supporting framework for blood vessels and neurons (communication)

Help maintain blood brain barrier

Respond to tissue damage in CNS - create barrier around damage tissue so it can health faster and stop inflammation to healthy tissue, also limit axon regeneration of injured neurons

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

Explain ependmyal cells

A

Line central cavities of brain and spinal cord

Can be squamous, cuboidal or columnar shaped

Can be ciliated

Cavities filled with CSF - cells form lining and cilia assists in movement of fluid

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

Explain microglial cells

A

Monitor health surrounding neurons using their extensions

If detect injury, inflammation, unwanted substances then will turn phagocytic and move to affected neuron cell/unwanted substance and destroy it

23
Q

Explain oligodendrocytes

A

Wrap around axon forming insulating covering called myelin sheath

24
Q

Explain Schwann cells

A

Also called neurolemmocytes

Wrap around axon to form myelin sheath

25
Q

Explain satellite cells

A

Provide support and nutrition to cell bodies in ganglia

Protect cell bodies from harmful substances

26
Q

Difference between myelinated and unmyelinated axons

A

Myelinated: contain myelin sheath, have nodes of ranvier which are sections that don’t contain myelin sheath

Unmyelinated: no myelin sheath, may have one Schwann cell or oligodendrocytes covering more than one axon

27
Q

What is the purpose of a myelin sheath

A

Insulates, stops charges leaking out of axon, protects axon from damage, can speed up action potentials

28
Q

What is grey matter

A

Cell body and dendrites

Brain outer cortex and nuclei
Inner part spinal cord
Ganglion

29
Q

What is white matter

A

Axons

Deeper nerve tracts of brain
Outer part spinal cord
Nerves

30
Q

What is the method of communication in the nervous system

A

Action potential - an electrical signal transferring information from one part of neuron to the next

When ions flow across membrane it causes change in charge (one side more negative, one more positive) which is called a membrane potential

31
Q

What characteristics of the cell membrane allow action potentials to be generated

A

1) difference in ionic conc (mostly K and Na) across membrane
- number positive and negative ions in extracellular and intracellular fluid is considered electrically neutral as one same side, the number of positive and negative ions is around the same so charges cancel out –> doesn’t mean charge across whole membrane is neutral

2) ability of membrane to permeable to ions
- action potential results from movement of ions
- cannot occur unless membrane permits this

32
Q

What are non-gated ion channels

A

Also called leak channels
Open so ions can leak through at any time
Each leak channel is specific to a certain ion
Cell membrane has more K than Na leak channels
No signal required

33
Q

What are ion-gated channels

A

Requires signals to open, three types:

1) ligand gated: open when ligand/chemical binds to them (e.g. Neurotransmitter or hormone)
2) voltage gated: open in response to membrane potential change (voltage)
3) other gated: open in response to stimuli

34
Q

Explain the establishment of resting membrane potential

A

RMP: difference in charge across the cell membrane in a resting cell caused by Na/K pump and K leak channels

  • inside cell more negative than outside cell
  • RMP=-70mV

K is naturally abundant on intracellular side therefore leak through leak channels to extracellular fluid (down conc. gradient), the accumulation of K on extracellular side makes extracellular more positive

Same for Na which is naturally more abundant on extracellular side, however, less of them and their leak channels so no big difference to charge is made

Na/K works against conc. gradient to send 3 Na ions outside and bring 2 K inside which ensures large conc. gradient is maintained

35
Q

What three processes change the resting membrane potential

A

Depolarisation: when membrane potential becomes more positive e.g. Could go from -70mV to -30mV

Hyperpolarisation: when membrane potential becomes more negative

Repolarisation: membrane potential returns to normal

36
Q

What is a graded potential

A

Can lead to action potentials if the stimulus is strong enough

Short lived, localised (occur in one part of membrane) changes in membrane potential

Magnitude proportional to stimulus strength (strong stimulus = greater voltage change)

Often occurs in dendrites or cell body

Able to SUMMATE: effect produced by one gradient potential is added to effect produced by another graded potential (allows ions channels to open)

Decremental: not able to transfer info over long distance (hence start of action potential)

37
Q

When does an action potential occur

A

When a graded potential summates and membrane potential reaches a threshold of -55mV

Occurs in trigger zone of axon as it contains a large number of voltage ion chnanels

38
Q

List the path of an action potential

A

Resting membrane potential: all gated na and k channels are closed, K leak channels open so intracellular more negative, Na/K pump working

Depolarisation: once threshold reached, cell becomes more positive, Na gated channels open so Na moves inside cell, K gated channels closed so K remains in abundance in cell

Repolarisation: Na gated channels close, K gated channels open and K moves out of cell down conc. gradient so intracellular becomes more negative, less to negative membrane potential

Hyperpolarisation/afterpotential: Na gated channels closed, k gated channels slowly close so K continues to leave cell to create afterpotential, membrane potential becomes very negative

Resting membrane potential: Na and k gated channels closed, RMP re-established by Na/K pump, k lead channels continue to help re-establish RMP

39
Q

What is the all of none principle

A

Graded potential must reach threshold (-55mV) for action potential to be generated
If doesn’t reach then RMP returns to normal until next stimulus

40
Q

What is the refractory period

A

Occurs when part of a neuron generates an action potential, so neurons cannot respond to another stimulus at same sight

Absolute refractory period: stages of depolarisation and repolarisation which can’t have any interruptions (Na channels open)

Relative refractory period: stage where most voltage gated Na channels are closed, an action potential can occur but has to be a strong stimulus

41
Q

How do action potentials travel along unmyelinated fibres

A

Depolarisation of one part of neuron causes Na to move inside cell which creates current that will depolarise the area adjacent to it
Occurs along the whole length of the fibre
Following depolarisation each segment of axon becomes repolarised

42
Q

How do action potentials travel along myelinated fibres

A

Action potential generated at one node of randier which creates current that rapidly jumps to next node – called saltatory conduction

Continues along whole axon length very fast as skips large segments of axon

43
Q

What occurs at a synapse

A

An action potential is transmitted to another neuron, cell, muscle, effector gland, ect.

Electrical synapses - current
Chemical synapses - chemicals e.g. Neurotransmitters and hormones

44
Q

List steps of transmission across a chemical synapse

A

1) action potential arrives at pre-synaptic terminal
2) calcium channels open and calcium ions move down conc. gradient and diffuse into cell to act on vesicles
3) vesicles containing neurotransmitters, move to presynaptic membrane and fuse with it
4) neurotransmitters released into synaptic cleft via exocytosis
5) neurotransmitters diffuse across cleft
6) neurotransmitters bind to receptors of ligand gated Na channels on postsynaptic membrane
7) ion channels open allow diffusion of ions into post synaptic cell (Na moves in) - change in charge may trigger graded potential and so on
8) neurotransmitter removed from synapse by enzyme activity (must be removed or Na will keep entering cell and cause overstimulation)

Enzyme activity includes: released from receptor on post synaptic membrane and diffuse away from synapse, broken down by enzymes or remains whole, reabsorbed by pre synaptic membrane so can be reused when another impulse arrives

45
Q

Effect of drugs and alcohol

A

Antidepressants block reuptake of neurotransmitters (feel good ones) by presynaptic membrane so will continue to stimulate post synaptic neuron producing positive moods and emotions

Neurotransmitters have different effects depending on where they are released e.g. Can prevent neuron from being stimulated in one part or cause it to be active in another
-alcohol increases activity of inhibitory neurotransmitters in brain so brain function is slower as inhibitory input to brain is increased

46
Q

Describe the spinal cord

A

Facilitates transfer info from PNS to CNS and back
Protected by vertebral canal, CSF and meninges
Outer= white matter, inner = grey matter

Anterior an posterior of spinal cord have indentations that look like they split the cord in half

  • anterior median fissure
  • posterior median sulcus

White matter divides into 3 columns- dorsal (back), ventral (front) and lateral (side)

Grey matter divided into horns - dorsal, ventral, lateral

Middle of two halves called COMMISSURES which connects grey and white matter together

Hole right in centre called central canal which contains CSF

Rootlets branch directly off spinal cord which merge to from dorsal root at back and ventral root at front which merge to from spinal nerves (31 pairs arise)

47
Q

Explain sensory input through neurons in spinal cord and spinal nerves

A

Sensory receptor stimulated and stimulus travels along sensory neuron through spinal nerve to cell body in dorsal root ganglion
Then through rest of dorsal root to dorsal horn in grey matter
Can then cross synapse to an interneuron and then motor neuron of straight to a motor neuron
-synapse w/ interneuron will pass to somatic motor neuron and to skeletal muscle
-no interneuron will be to automatic motor neuron and then to smooth muscle or glands

48
Q

Explain motor output through neurons in spinal cord and spinal nerves

A

Once in motor neuron will travel through ventral root and then through body to effector

49
Q

What do horns of spinal cord mostly contain

A

Dorsal horns = interneurons
Ventral horns= some neurons but mostly cell body of somatic motor neuron
Lateral horns= cell body of automatic motor neuron

50
Q

What is a reflex

A

Automatic response to a stimulus that requires no contours thought
Can be somatic or autonomic
Homeostatic mechanism

51
Q

Explain reflex arc

A

The 5 components of a reflex make up a reflex arc:

1) sensory receptor
2) sensory neuron
3) internuron
4) motor neuron
5) effector

The FUNCTIONAL UNIT of the nervous system
Simplest arcs don’t contain interneurons and are called monosynaptic (ones that do called polysynaptic)

There are 3 types : stretch (monosynaotic), Golgi tension, withdrawal

52
Q

Explain stretch reflex

A

Receptor stimulated so signal sent via sensory neuron to spinal cord
Action potential synapses with motor neuron which sends action potential to effector muscle or gland

Action potential is also sent to brain so it is aware something has occurred, however, response initiated by lumbar region of spinal cord and not the brain

Common in knee, ankle, Achilles, tricep

53
Q

Example autonomic reflex - light shine in eyes

A

Eye light shinned in would constrict (direct reflex), however, other eye would too (called consensual reflex) as brain communicates and links are made between nerves controlling each eye

54
Q

What is a reaction

A

Have control over
Slower than a reflex -require conscious thought
Can become a learned behaviour e.g. Quicker responses through repetition

E.g. Burning hand on hot stove

HUMB1000 (13 decks)

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