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Biology II > Chapter 44-The Nervous System > Flashcards

Chapter 44-The Nervous System Flashcards

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1
Q

Stimulus

A

Changes in the environment; all changes involve changes in energy

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2
Q

Sensory Receptors

A

detect stimulus

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3
Q

Motor effectors

A

respond to stimuli

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4
Q

The nervous system does what for an organism

A

allows organisms to detect changes and respond to environmental stimuli

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5
Q

Structure of Neurons

A
  1. Cell Body-enlarged part containing nucleus
  2. Dendrites-several short cytoplasmic extensions that receive stimuli
  3. Axon-usually 1, long extension that conducts impulses away from cell body
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6
Q

What do neurons do

A

produce the action potential

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7
Q

3 Types of Neurons

A
  1. Sensory Neurons
  2. Motor Neurons
  3. Interneurons
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8
Q

Sensory Neurons

A

(afferent neurons)

-carry impulses to CNS from sensory cells and organs

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9
Q

Motor Neurons

A
  • Efferent Neurons

- carry impulses from CNS to effectors (muscles and glands)

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10
Q

Interneurons

A
  • Association Neurons

- provide more complex reflexes and associative functions (learning and memory)

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11
Q

Central Nervous System

A

brain and spinal cord

-site of integration and higher processes

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12
Q

Peripheral Nervous System (PNS)

A
  • Sensory and motor neurons;sensory cells
  • somatic NS and Autonomic NS
  • -sympathetic and parasympathetic NS
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13
Q

Somatic NS

A

branch of PNS

-stimulates skeletal muscles

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14
Q

Autonomic NS

A

branch of PNS

  • stimulates smooth and cardiac muscles, as well as glands
  • divided into the Sympathetic and Parasympathetic NS that counterbalance each other
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15
Q

Neuroglia

A

-Support cell of NS
-supports neurons both structurally and functionally (nourish, remove wastes, assist in condition)
-Schwann cells, oligodendrocytes
-

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16
Q

Schwann cells and oligodendrocytes

A
  • Neuroglia
  • produce myelin sheaths surrounding axons
  • in CNS, myelinated axons form white matter
  • dendrites/cell bodies form gray matter
  • in PNS, myelinated axons are bundled to form nerves
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17
Q

Nerve impulse

A

the action potential, electrochemical in nature

  • electric-movement of charge
  • chemical-movement of ions
  • along cell membranes, b/c of separation of ions across the cell membrane, there is a form of electrical potential energy called a membrane potential. measured in volts
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18
Q

The electrical potential energy difference in reference to the two sides of the neurons plasma membrane

A

Negative pole=cytoplasmic side

Positive pole=extracellular fluid side

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19
Q

Resting potential

A

when a neuron is not actively being stimulated=resting neuron
-resting potential is about -70 mV

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20
Q

2 main forces that act on ions in establishing the resting membrane potential

A
  1. electrical potential produced by unequal distribution of charges
  2. Concentration gradient produced by unequal concentrations of molecules form one side of the membrane to the other
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21
Q

what 3 things make the inside of the neuron more negative than the outside

A
  1. Sodium-potassium pump
  2. Ion leakage channels
  3. Movement of intracellular negative ions to inside of membrane
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22
Q

Sodium-Potassium pump

A

(+ outside)

  • brings 2 K+ into cell for every three Na+ it pumps out
  • creates significant concentration gradient
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23
Q

Ion Leakage channels

A

(+ outside)

-allow more K+ to diffuse out than Na+ to diffuse in

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24
Q

The resting potential-how does it work

A

sodium potassium pump creates significant concentration gradient

  • concentration of K+ is much higher inside the cell so potassium diffuses out
  • membrane not permeable to negative ions
  • leads to buildup of positive charges outside and negative charges inside
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25
Q

2 types of changes to resting potential in neurons as a response to stimuli

A
  • Graded potentials

- action potentials-nerve impulse

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26
Q

Graded Potentials

A
  • Small transient changes in membrane potential due to activation of gated ion channels in response to a weak stimulus
  • each gated channel is selective for a specific ion
  • most are closed in the normal resting cell
  • voltage regulated
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27
Q

Depolarization

A

makes the membrane potential more positive

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28
Q

Hyperpolarization

A

makes membrane potential more negative

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29
Q

Action Potentials

A

Result when depolarization reaches the threshold potential (-55 mV)

  • Depolarizations bring a neuron further from the threshold
  • Hyperpolarizations move the neuron further from the threshold
  • caused by voltage-gated ion channels opening
  • a wave of depolarization followed by a wave of repolarization
30
Q

Voltage gated Na+ channels

A
  • have activation gate and inactivation gate
  • at rest, activation gate closed, inactivation gate open
  • transient influx of Na+ causes membrane to depolarize
31
Q

Voltage gated K+ channels

A
  • single activation gate that is closed in the resting state
  • K+ channel opens slowly
  • Efflux of K+ repolarizes the membrane
32
Q

Propagation of action potentials

A
  • each action potential, in its rising phase, reflects a reversal in membrane polarity
  • positive charges due to influx of Na+ can depolarize the adjacent region to threshold
  • and so the next region produces its own action potential
  • meanwhile, the previous region repolarizes back to the resting membrane potential
33
Q

2 ways to increase velocity of conduction

A
  • axon has a larger diameter

- axon is myelinated

34
Q

synapses

A

intracellular junctions of the axons of one neuron with the dendrites of other neurons, with muscle cells, or with gland cells

35
Q

Electrical synapses

A

Involve direct cytoplasmic connections between the two cells formed by gap junctions
-relatively rare in vertebrates

36
Q

Chemical Synapses

A
  • Have a synaptic cleft between the two cells

- end of presynaptic vesicles packed with neurotransmitters

37
Q

Chemical Synapses (in depth)

A

action potential triggers influx of Ca2+
-synaptic vesicles fuse with cell membrane
-neurotransmitter is released by exocytosis
Diffuses to other side of cleft and binds to chemical-or ligand-gated receptor proteins
-produces graded potentials in the postsynaptic membrane
-neurotransmitter action is terminated by enzymatic cleavage or cellular uptake

38
Q

Acetylcholine

A

Neurotransmitter (ACh)

  • crosses the synapse between a motor neuron and a muscle fiber
  • neuromuscular junction
  • binds to receptor in the postsynaptic membrane
  • causes ligand-gated ion channels to open
  • produces a depolarization called an excitatory postsynaptic potential (EPSP)
  • stimulates muscle contraction
39
Q

What causes muscle relaxation

A

Acetylcholinesterase (ACHe)

40
Q

Amino acids as Neurotransmitters

A
  1. Glutamate

2. Glycine and GABA

41
Q

Glutamate

A
  • Neurotransmitter, amino acid

- major excitatory neurotransmitter in the vertebrate CNS

42
Q

Glycine and GABA

A
  • Neurotransmitter, Amino Acid
  • Inhibitory nerotransmitters
  • open ligand-gated channels for Cl-
  • produce a hyperpolarizatoin called an inhibitory postsynaptic potential (IPSP)
43
Q

Biogenic amines

A

Neurotransmitters

  • epinephrine and norepinephrine are responsible for “flight or fight” response
  • Dopamine, used in areas of the brain that control body movements
  • seratonin is involved in regulation of sleep
44
Q

Three basic divisions of vertebrate brain

A
  • Hindbrain, or rhombencephalon
  • Midbrain, or mesencephalon
  • Forebrain, or prosencephalon
45
Q

Dominant brain feature in Vertebrates

A

forebrain

46
Q

2 elements that compose forebrain

A

Diencephalon
-Thalamus-integration and relay center
-hypothalamus-participates in basic drives and emotions, controls pituitary gland, regulates body temp.
Telencephalon (end brain)
-devoted largely to associative activity
-called cerebrum in mammals (brain basically)

47
Q

Corpus callosum

A

connects the right and left cerebral hemispheres

48
Q

Divisions of the brain hemispheres

A

Frontal, parietal, temporal, and occipital lobes

49
Q

Cerebral cortex

A

outer layer of the cerebrum

  • contains about 10% of all neurons in brain
  • highly convoluted
50
Q

3 regions of cerebral cortex (and one more)

A
  • Primary motor cortex-movement control
  • Primary somatosensory cortex-sensory control
  • Association cortex-higher mental functions
  • Basal ganglia
  • -aggregates of neuron cell bodies-gray matter
  • -participate in the control of body movements
51
Q

Thalamus

A

integrates visual, auditory and somatosensory information

52
Q

Hypothalamus

A

integrates visceral activities, controls pituitary gland

53
Q

Limbic system

A
  • hypothalamus, hippocampus, and amygdala

- responsible for emotional responses

54
Q

Left hemisphere

A

controls right side of body

-dominant in language

55
Q

Right hemisphere

A

adept at spatial reasoning

-primarily involved in musical ability

56
Q

Memory

A

short term memory is stored in form of transient neural excitations

  • long term memory involves structural changes in neural connections
  • hippocampus and amygdala involved in both parts
57
Q

Alzheimers disease

A
  • condition where memory and thought become dysfunctional
  • 2 causes
    1. nerve cells are killed from the outside in
    2. nerve cells are killed form inside out
58
Q

2 zones of spinal chord

A
  1. inner zone is gray matter, primarily consists of the cell bodies of interneurons, motor neurons, and neuroglia
  2. Outer zone is white matter, contains cables of sensory axons in the dorsal columns and motor axons in the ventral columns
59
Q

Functions of Spinal Chord

A
  • relays messages between the body and the brain
  • also functions in relexes
  • -knee jerk reaction is monosynaptic
  • -most reflexes in vertebrates involve a single interneuron
60
Q

The PNS

A

consists of nerves and ganglia
-function is to receive info from the environment, convey it to CNS, and to carry responses to effectors such as muscle cells

61
Q

Nerves

A

bundles of axons bound by connective tissue

62
Q

Ganglia

A

aggregates of neuron cell bodies

63
Q

Sensory Neurons

A
  • PNS
  • axons enter the dorsal surface of the spinal cord and form dorsal root of spinal nerve
  • cell bodies are grouped outside the spinal cord in dorsal root ganglia
64
Q

Motor Neurons

A
  • axons leave from the ventral surface and form ventral root of spinal nerve
  • cell bodies are located in the spinal cord
65
Q

Somatic nervous system

A

Somatic motor neurons stimulate the skeletal muscles to contract

  • in response to conscious command or reflex actions
  • antagonist of the muscle is inhibited by hyperpolarization (IPSPs) of spinal motor neurons
66
Q

Autonomic Nervous system

A

Composed of the sympathetic and parasympathetic divisions, plus medulla oblongata. The para and sympathetic divisions work to contrast each other

  • in both, efferent motor pathway has 3 neurons
  • -Preganglionic neuron
  • -Postganglionic neuron
67
Q

Preganglionic neuron

A
  • exits the CNS and synapses at an autonomic ganglion

- part of ANS

68
Q

Postganglionic Neuron

A

exits the ganglion and regulates visceral effectors

-smooth or cardiac muscle or glands

69
Q

Sympathetic Division

A

PNS, ANS

  • preganglionic neurons originate in the thoracic and lumbar regions of spinal chord
  • most axons synapse in two parallel chains of ganglia right outside the spinal cord
70
Q

Parasympathetic Division

A

PNS, ANS

  • preganglionic neurons originate in the brain and sacral regions of spinal cord
  • axons terminate in ganglia near or even within internal organs

Biology II (28 decks)

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