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BIOL155 > Nervous System - ANS & ENS > Flashcards

Nervous System - ANS & ENS Flashcards

1
Q

What are the three types of muscle tissue?

A

Skeletal muscle
Cardiac muscle
Smooth muscle

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2
Q

What gives skeletal muscles their striated appearance?

A

Skeletal muscles are made of repeating sarcomeres
= thin and thick filaments organized in a particular way that gives them a striated appearance

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3
Q

Do smooth muscles have a striated appearance? Why or why not?

A

In smooth muscles, there are still thin and thick filaments but they are not organized into sarcomeres for that striated appearance

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4
Q

Where can smooth muscle be found in the body?

A
  • Female reproductive system
  • Stomach
  • Blood vessels
  • Trachea
  • Iris
  • Bladder
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5
Q

How do skeletal muscles and smooth muscles differ in structure?

A

Skeletal Muscles are MULTINUCLEATED (many nuclei)
- striated from sarcomeres of thin and thick filaments

Smooth muscles only have ONE NUCLEUS
- have thick middles and then taper out at the ends
- have thick and thin filaments but are not arranged into sarcomeres (no striated pattern)

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6
Q

Skeletal muscles and smooth muscles differ by one key element: They do not have the same types of filaments: Elaborate

A

Skeletal muscles: thin and thick filaments

Smooth muscles: thin, thick, and intermediate filaments/microfilaments

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7
Q

Compare contraction in skeletal muscles and smooth muscles

A

Skeletal muscles
- contraction: sarcomeres shorten as muscles contract along one axis (through calcium-contraction cycle)

Smooth muscles
- contraction: contracts along many axes and bulges towards the middle

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8
Q

What are the two subtypes of smooth muscle tissue?

A
  1. Multi-unit smooth muscle
  2. Visceral smooth muscle
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9
Q

How does multi-unit smooth muscle differ from visceral smooth muscle?

A

They differ by their innervation and interconnection, affecting excitation

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10
Q

What is multi-unit smooth muscle?

A

Smooth muscle cells communicating with neurons, forming NMJs, and getting excited through communication directly from a neuron

  • involves many smooth muscles cells working together with neurons
  • webbing of neurons to communicate
  • carry out excitation through synapses
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11
Q

What is visceral smooth muscle?

A

AKA single-unit smooth muscle

Smooth muscle cells communicating with each other (and occasionally a pacesetter cell) through gap junctions

  • excitation can be spread through connecting muscle cells
  • have pacesetter cells
  • excitation through gap-junction coupling and pacesetter cells
  • can perform excitation or inhibition through neurotransmitters
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12
Q

What are pacesetter cells and which type of smooth muscle tissue is it found in?

A

These are special types of cells in visceral smooth muscle that can depolarize on its own

  • able to communicate through the gap junctions
  • excitation happens through gap junctions
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13
Q

True or False:

Smooth muscle excitation-contraction coupling is also calcium-dependent

A

TRUE!

Smooth muscle excitation-contraction coupling is very similar to skeletal muscle excitation-contraction in that they both require the use of Ca2+

However, the exact use of Ca2+ is slightly different in skeletal muscle fibres compared to smooth muscle fibres

Excitation requires an increased [Ca2+]

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14
Q

How does smooth muscle use Ca2+ in excitation-contraction coupling?

A

Instead of the Ca2+ binding to troponin, Ca2+ in smooth muscle binds to another protein called CALDESMON

Ca2+ is also involved in myosin head activation, turning of the head in the contraction cycle
- Compared to the skeletal muscle contraction cycle where ATP hydrolysis was in charge of activating the myosin head

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15
Q

What is caldesmon?

A

A protein that is present in smooth muscle in placement of troponin

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16
Q

What are the two main differences between Ca2+ roles in excitation-contraction coupling in smooth muscles and skeletal muscles?

A
  1. Caldesmon is present in smooth muscle instead of troponin in smooth muscle
  2. Calcium leads to myosin head activation in smooth muscle
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17
Q

True or False:

Smooth muscle can be found inside the eye

A

TRUE

The iris is an example of smooth muscle in the eye

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18
Q

True or False:

Smooth muscle is non-contractile

A

FALSE

Smooth muscle does contract – And it does so on many axes (forming into bulges in the center)

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19
Q

True or False:

Smooth muscle does contain myosin and actin filaments

A

TRUE

Smooth muscle contains myosin and actin filaments AND INTERMEDIATE FILAMENTS, but they are not arranged into sarcomeres

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20
Q

True or False:

Input from the nervous system is always required for smooth muscle excitation

A

FALSE

ALWAYS is a very strong word, and smooth muscles (specifically visceral smooth muscle) is capable of exciting without input from the nervous system because it has PACESETTER CELLS

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21
Q

True or False:

Input from the nervous system is never required for smooth muscle excitation

A

FALSE

NEVER is also another strong word and although pacesetter cells in visceral smooth muscles don’t require input from the nervous system, multi-unit smooth muscles do require input from the nervous system through neuronal connections

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22
Q

True or False:

Smooth muscle cells can be directly inhibited, as well as excited

A

TRUE

Through single-unit smooth muscle tissue, the smooth muscle cells are capable of being directly inhibited or excited (neurotransmitters)

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23
Q

True or False:

Smooth muscle cells in a tissue are always interconnected by gap junctions

A

FALSE

Multi-unit smooth muscle cells are interconnected by neurons… Visceral smooth muscle cells are interconnected by gap junctions, but not all smooth muscle cells are interconnected by gap junctions… Some are connected by neurons!

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24
Q

True or False:

Increases in intracellular calcium are required for smooth muscle contraction

A

TRUE

Just like skeletal muscle, smooth muscle also requires an increase in intracellular calcium for contraction!

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25
Q

What are the 3 anatomical divisions of the nervous system?

A
  1. Central Nervous System
  2. Peripheral Nervous System
  3. Enteric Nervous System
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26
Q

What are the 2 subdivisions of the peripheral nervous system?

A
  1. Autonomic Nervous System
  2. Somatic Nervous System
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27
Q

What are the 2 subdivisions of the autonomic nervous system?

A
  1. ANS - Parasympathetic division
  2. ANS - Sympathetic division
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28
Q

What is the peripheral nervous system?

A

Outside of the skull and spine, but directly connected to the CNS
- still forms synapses with the CNS

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29
Q

What is the autonomic nervous system?

A

Central and peripheral components of the neural circuits that control non-somatic organs
- division of the PNS that is in charge of forming neural circuits to visceral organs
- mostly involuntary

30
Q

What is the somatic nervous system?

A

Central and peripheral components of the neural circuits that skeletal muscles
- division of the PNS that is in charge of forming neural circuits to skeletal muscles
- mostly voluntary BUT not completely
- involves INVOLUNTARY SPINAL REFLEXES

31
Q

What is the enteric nervous system?

A

Associated with the digestive tract, and only indirectly connected to the CNS
- indirect connection to CNS through ANS

32
Q

How do you distinguish of the division is autonomic or somatic?

A

Look at the efferent neurons

If the efferent neurons go to skeletal muscles then it is SOMATIC (not necessarily voluntary because there are also reflexes that are involuntary)

If the efferent neurons go to visceral organs then it is AUTONOMIC

33
Q

The autonomic system’s efferent pathways control what kind of effectors? Visceral or skeletal?

A

VISCERAL!

34
Q

What does it mean for efferent pathways to be monosynaptic? Disynaptic?

A

Monosynaptic = efferent neurons forming single synapses (one NMJ) directly on the effector cell
Disynaptic = efferent neurons forming two synapses, extra stop in the circuit because one cell has to talk to a ganglion then another cell before it talks to the effector cell

35
Q

In the PNS, are somatic efferent pathways monosynaptic or disynaptic?

A

Somatic efferent pathways are MONOSYNAPTIC

36
Q

In the PNS, are autonomic efferent pathways monosynaptic or disynaptic?

A

Autonomic efferent pathways are DISYNAPTIC

37
Q

What are the two autonomic neurons called?

A

Preganglionic and postganglionic

38
Q

What is the preganglionic neuron?

A

The autonomic neuron leading to the autonomic ganglion, forms a synapse with the autonomic ganglion

39
Q

What is the postganglionic neuron?

A

The autonomic neuron leaving the autonomic ganglion to form a synapse with the effector cell

40
Q

True or False:

ANS efferent neurons often synapse onto neurons of the ENS rather than onto effector cells

A

TRUE!

Possible to see disynaptic pathways, but usually it goes

presynaptic < autonomic ganglion < postsynaptic < ANS < ENS < effector cell

41
Q

What kind of receptors do visceral effector cells use?

A

Visceral effector cells usually use metabotropic neurotransmitter receptors, which produce diverse, long-lasting cellular effects through biochemical cascades

Features of using metabotropic receptors:
1. longer-lasting responses
2. diverse biochemical effects (not just changes in membrane potential)
3. stimulatory or inhibitory responses to the same neurotransmitter

42
Q

What is the meaning of “dual innervation of target organs”?

A

Dual = two
Innervation = communication
Target organs = same organs

Parasympathetic and sympathetic divisions can talk to the same organs

And ** MOST OF THE TIME ** the parasympathetic and sympathetic divisions do opposite things (BUT NOT ALL THE TIME) They just usually stimulate opposite effects

43
Q

What physiological state correlates to parasympathetic activity?

A

High parasympathetic activity = REST AND DIGEST

In general, if one division becomes more active, the other will usually become less active

44
Q

What physiological state correlates to sympathetic activity?

A

High sympathetic activity = FIGHT OR FLIGHT

In general, if one division becomes more active, the other will usually become less active

45
Q

Parasympathetic

A

REST AND DIGEST

46
Q

Sympathetic

A

FIGHT OR FLIGHT

47
Q

Give two examples of when the two divisions of the ANS are not antagonistic

AKA They are not working in opposition to one another

A
  1. Male sexual response
    - parasympathetic neurons mediate arousal responses in erectile tissue
    - sympathetic neurons stimulate contractile ejaculatory/orgasmic reflexes
  2. Eye dilation/contraction
    - two divisions supposedly have opposite effects on pupil size
    - decreased light = implied increased sympathetic stimulation (DILATION)
    - increased light = implied increased parasympathetic stimulation (CONTRACTION)
    - pupillary reflexes are actually driven by light intensity, not stressful or reflexing situations
48
Q

Describe the chain structure of sympathetic ganglia

A

Sympathetic ganglia = fight or flight response

  • form an interconnected chain, which means the entire division can be activated at once
  • sympathetic activation refers to a situation where sympathetic ganglia are activated together, amplifying each others’ activity
49
Q

Compare and contrast the structure / activation of sympathetic vs parasympathetic ganglia

A

Sympathetic
- can spread to other ganglia
- become activated at one time because of the way the sympathetic ganglia are connected in a long chain

Parasympathetic
- do not see this in parasympathetic ganglia because they are separated (not communicating with each other or activating each other)

50
Q

The location of the preganglionic neuron cell bodies differ between the two ANS divisions:

Sympathetic division
Parasympathetic division

A

Sympathetic Division:
- preganglionic neurons are found in the lateral gray matter/ventral horn in the thoracic and superior lumbar spinal cord (very specific location)

Parasympathetic Division:
- preganglionic neurons are found in the brainstem and lateral gray matter in sacral spinal cord

51
Q

Differentiate the length of pre- and post-ganglionic axons between the ANS divisions

A

Sympathetic
- preganglionic neuron is located somewhere in the CNS
- preganglionic fiber is average length(?)
- sympathetic ganglia are located far from the target organ (mostly in the sympathetic chain)
- postganglionic fiber is long-ish to target organ

Parasympathetic
- preganglionic neuron is located somewhere in the CNS
- preganglionic fiber is long and far from the parasympathetic ganglia
- parasympathetic ganglia are located within or near the target organ
- very short postganglionic fiber because it is already so close to the target organ

52
Q

BOTH sympathetic and parasympathetic preganglionic axons are located somewhere in the __________

A

Central Nervous System (CNS)

53
Q

All preganglionic neurons (both sympathetic and parasympathetic divisions) release __________ just like somatic motor neurons (in the somatic nervous division)

A

All preganglionic neurons release ACETYLCHOLINE

54
Q

The neurotransmitters released by POSTganglionic neurons differ between the parasympathetic and sympathetic divisions:

What does each division release?

A
  1. Sympathetic division
    - releases ACh at preganglionic neurons
    - forms synapses in ANS
    - releases NOREPINEPHRINE at postganglionic neurons
  2. Parasympathetic division
    - releases ACh at preganglionic neurons
    - forms synapses in ANS
    - releases ACETYLCHOLINE at postganglionic neurons
55
Q

Each neurotransmitter can activate a different suite of neurotransmitter receptors, what effect does this have on its metabotropic effects?

A

Each neurotransmitter can activate a different suite of neurotransmitter receptors, which produces DIFFERENT METABOTROPIC EFFECTS

  • slightly different receptors can interact with the same neurotransmitter and have different effects
  • either inhibitory or excitatory
56
Q

How can one neurotransmitter be excitatory and/or inhibitory?

A

The same neurotransmitter can be excitatory or inhibitory depending on the subtype of receptor protein expressed by the postsynaptic cell (the effector organ)

57
Q

Parasympathetic postganglionic cells ALWAYS release ______________

A

Acetylcholine

58
Q

Sympathetic postganglionic cells ALWAYS release ______________

A

Norepinephrine

59
Q

Parasympathetic preganglionic cells ALWAYS release ______________________

A

Acetylcholine

60
Q

Sympathetic preganglionic cells ALWAYS release _____________________

A

Acetylcholine

61
Q

Visceral functions are mostly controlled by visceral reflexes, but do not ALWAYS involve the CNS

True or False

A

True!

Long visceral reflexes involve the CNS as it passes from the stimulus/receptors to the CNS then to the ANS (preganglionic and postganglionic neurons)/peripheral effector

Short visceral reflexes do not involve the CNS as they are still able to stimulate a response without passing through the CNS (found in the digestive system and associated with the ENS)

62
Q

Do long visceral reflexes involve the CNS?

A

YES!

Ex: The consensual pupillary light response involving the parasympathetic division
- in response to bright light, both pupils constrict

63
Q

Do short visceral reflexes involve the CNS?

A

NO!

Ex: gastroenteric reflex and gastroileal reflex
- stretching of the stomach wall if detected by mechanoreceptive visceral afferent neurons
- these synapse onto parasympathetic post-ganglionic neurons (and ENS neurons) enhancing smooth muscle contractions in the small/large intestine

64
Q

True or False:

Smooth muscle does not use actin or myosin filaments to generate tension

A

False!

Smooth muscles also have actin and myosin filaments (Thick and thin filaments) but they just aren’t arranged into sarcomeres

65
Q

True or False:

Smooth muscle does not have sarcomeres

A

True!

Smooth muscles do not have sarcomeres, they have thin and thick filaments but they are not arranged into sarcomeres

Thus smooth muscle does not have the striated appearance that skeletal muscles have

66
Q

True or False:

Smooth muscle contraction does not require intracellular calcium elevations

A

False!

Smooth muscle and skeletal muscle contraction both require intracellular calcium elevations = MUSCLE CONTRACTIONS ALL REQUIRE INCREASED CALCIUM LEVELS TO ACTIVATE

67
Q

True or False:

The ANS makes synapses on smooth muscle but not skeletal muscle

A

True!

The ANS works on making synapses with smooth muscles/visceral organs, whereas the somatic nervous system makes synapses on skeletal muscles

68
Q

True or False:

The ANS has both sensory and motor components

A

True!

The ANS has both afferent and efferent neurons, therefore having both a sensory and motor component to it

69
Q

True or False:

The parasymapthetic division of the ANS will be more active if you are lying down quietly than if you are exercising

A

True!

Parasympathetic = rest and digest
Sympathetic = fight or flight

70
Q

True or False:

The sympathetic and parasympathetic divisions of the ANS always act in opposition to each other

A

False!

In the case of the male sexual response, the sympathetic and parasympathetic divisions actually work together (same with the iris dilation/contraction)

71
Q

True or False:

Both divisions of the ANS make synapses in autonomic ganglia outside the CNS

A

True!

Have presynaptic neurons < autonomic ganglia < postsynaptic neurons

BIOL155 (34 decks)

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