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quiz 1 Flashcards

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Biology 101 flashcards
1
Q

define homoeostasis

A

-same (homo) stasis (state)
-body is in constant battle to maintain same state
-critical for survival because body can only survive within narrow range of conditions

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2
Q

role of the nervous system in homeostasis

A

-regulates body structures and processes to maintain homeostasis despite fluctuations in internal and external environment

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3
Q

what is the nervous system made of

A

-made of cells and organs that allows us to detect changes in external and internal environment and respond to them
-made up of brain, spinal cord, nerves
-has over 100 billion nerves in the brain alone
-responsible for memory learning

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4
Q

what are the two main cells in the nervous system

A

neurons and glial cells

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5
Q

what are neurons

A

-structural and functional unit of the nervous system
-responds to chemical and physical stimuli
-conduct electrochemical signals
-release chemicals that regulate body processes

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6
Q

what are nerves

A

-neurons are organized into tissues called nerves
-hundreds of nerves can bundled together to make nerve bundles

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7
Q

what are glial cells

A

-outnumber neurons 10-1
-glial means glue
-support and nourish neurons and remove waste
-non conducting cells so they won’t do anything
-defend against infection

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8
Q

what is the CNS

A

-has brain, spinal cord
-integrates and processes info sent by nerves

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9
Q

what is the PNS

A

-includes nerves that carry sensory messages to CNS and then the nerves send the message to muscles and glands
-PNS is divided into somatic and autonomic system

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10
Q

what is somatic system

A

-consists of sensory receptors in head and extremities and nerves carry sensory information to CNS and then nerves carry that info from CNS to skeletal muscles

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11
Q

what is the autonomic system

A

-controls glandular secretions and functioning of the smooth and cardiac muscles

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12
Q

what is sympathetic and parasympathetic divison

A

-this is a division from the autonomic system often working in opposition to each other to regulate involuntary processes of the body
-(heartbeat and peristalsis do not need control)

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13
Q

difference between myelinated and unmyelinated

A

-myelinated means that there is myelin sheath covering axon

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14
Q

what are sensory neurons

A

gather information from sensory receptors and transmit impulses to the CNS
-more specifically, transmit impulses from sensory receptors to the interneurons

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15
Q

photoreceptors

A

-sensory receptor in body
-detect radiant energy such as rods and cones

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16
Q

chemoreceptor

A

-sensory receptor in body
-detect presence of chemicals
-eg: smell in nose , o2 and co2 levels in blood, taste buds

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17
Q

mechanoreceptors

A

-detect mechanical stimuli
-touch on skin or hearing in the corti (inner ear)

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18
Q

sensory receptors

A

-they receive stimuli and form nerve impulse

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19
Q

interneurons

A

-found in brain and spinal cord (CNS) and act as integration centre
-Act as link between sensory and motor neurons
-Process and integrate incoming sensory info and relay outgoing motor info

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20
Q

motor neurons

A

-bring impulses from interneurons to the effectors
-Transmit information from CNS to muscles, glands and other organs (called effectors)

21
Q

effectors

A

-muscles and glands and other organs that respond to impulses from the motor neurons

22
Q

how long is a axon

A

1mm-1m

23
Q

what are reflex arcs

A

-connection of neurons that explain reflexive behaviours
-used to model the basic organization of nervous system

24
Q

how are reflexs so quick

A

-protect us
-reflex arcs use very few neurons to transmit messages so reflexes are very rapid.

25
Q

what are dendrites

A

-Extension of neuron that receives
information from receptors (in
case of sensory neurons) or other
nerve cells (motor neurons)
- Conduct impulse toward cell body
-highly branched so increases SA to receive info

26
Q

cell body

A

-Also called soma
-Contains nucleus
-site of metabolic reactions
-Processes info from dendrites
-if stimulus is large enough, info is passes on to axon
-

27
Q

how many axons does a neuron typically have

A

1

28
Q

axon

A

-Extends from the cell body and carries an impulse towards other neurons or effectors
-longest part in neuron
-terminal end of an axon branches into many fibres so to communicate with adjacent neurons, glands or muscles the axon terminal releases chem signals into space between it and the receptors/dendrites of neighboring cells

29
Q

axon terminal

A

-Also called axon bulb
-End of axon
-Where chemicals (called neurotransmitters) are released into the space between it an the receptors or dendrites of neighbouring cells

30
Q

mylin sheath

A

-A white, fatty, insulating layer
on an axon
-Axons with this are called
myelinated
-Protects neuron
-Speeds rate of nerve impulse transmission by acting as an electrical insulator
-can heal itself

31
Q

schwann cell

A

-A type of glial cell
-Form myelin sheath by wrapping
themselves around the axon
-Schwann cells in PNS
-Oligodendrocytes in CNS

32
Q

nodes of ranvier

A

-areas between myelin sheaths

33
Q

white matter

A

-In CNS neurons that are
myelinated are called white
matter
-Most neurons in PNS are
myelinated
-Myelin can repair itself so
damage isn’t necessarily
permanent

34
Q

grey matter

A

-In CNS neurons that are
NOT myelinated are called
grey matter
-No myelin so cannot repair
itself so damage is
permanent

35
Q

steps of reflex arc

A
  • Simplest neural pathway (fewer neurons involved, shorter distance for info to travel)
    -Impulse travels through
    spinal cord and out to
    effector
  • Does NOT need the brain
  • Another impulse (requiring
    greater time) is sent to the
    brain for processing
  • Involuntary/ no conscious
    control
  • Response is innate
    (automatic)
36
Q

how can neurons generate a neural impulse

A
  • neurons can establish a voltage difference between the inside and outside of the cell membrane. they use this voltage difference to generate a neural impulse.
37
Q

what happens to charges during resting membrane potential/state

A
  • There is always a charge separation
    across a membrane of an axon
     Resting membrane: -70mV
    -also called polarization, when have positive and negitive side
    -is the difference in electric potential
    between the interior and the
    exterior of a biological cell.
38
Q

during resting membrane potential/state what is Sodium-potassium exchange pump

A

-Uses energy
 Moves sodium out
 Moves potassium in
 Moves more sodium
out than potassium in
so get more positive
charge on outside of
axon

39
Q

during resting membrane potential/state what is happening to Sodium and potassium channels

A

Diffusion of ions
 No energy needed
 Sodium moves into cell
 Potassium moves out
of cell faster
 Build up of positive ions
outside axon

40
Q

Threshold Potential

A

Minimum amount of stimulus required to produce
a response
Each neuron has a set
amount of stimulation
needed to cause an action
potential.
Stimulation will cause the
axon to become more
permeable to sodium
Usually the threshold is
close to -55mV

41
Q

How Does an Action
Potential Occur?

A

Upon excitation (caused by a stimulus),
the nerve cell becomes more permeable
to Na+ than K+
 Na+ channels open and Na+ ions rush
into the cell via diffusion. Potassium
channels close.
* Charge of axon now
+35mV
* Takes only a
millisecond!

42
Q

Depolarization/ Action
Potentia

A

The axon’s charge going from -70mV to +35 mV is
called depolarization
* Sodium (Na+) is entering cell
* Once enough Na+ has entered the cell to
completely change the charge inside the cell from
being negative to being positive, an action
potential has occurred.

43
Q

Any depolarization between
-70mV and -55mV ___ cause
an action potential.

A

will not

44
Q

Any depolarization between
-55mV and 0 will produce
_____ action potentials for a
particular neuron.

A

identical

45
Q

A stronger stimulus ___produce a stronger
response. A nerve cell
will fire maximally or not
at all.

A

will not

46
Q

The intensity of the
stimulus determines
the

A

frequency (how
many) of impulses.

47
Q

Repolarization

A

The process of restoring the
original polarity.
* Due to change in membrane
potential:
1)Potassium moves out through
channels
2)Sodium channels close

48
Q

Hyperpolarization

A

Membrane potential overshoots to nearly -90mV
because too much K+ is released.

49
Q

Refractory Period

A

The time it takes a cell
to repolarize
 Lasts a few
milliseconds after an
action potential
 The nerve cell must
repolarize before it
can conduct another
action potential.

bio 30 (5 decks)

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