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Dentistry BDS1 Sem 1 > Control & Communication > Flashcards

Control & Communication Flashcards

1
Q

What happens when chemical and electrical gradients for an ion are equal?

A

Nothing, there is no movements of ions across the mediums.

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2
Q

What can we say about the ions at resting membrane potentials?

A

They are NOT in equalibrium at resting membrane potentials

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3
Q

What is the resting membrane potential of a cell?

A

-70 mV

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4
Q

What is an action potential?

A

An action potential is a rapid change of the membrane potential inside the cell from negative to positive and back

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5
Q

What influence on neurons does action potential have?

A

Action potential enable neurons to perform 4 basic functions:

  1. Receive information
  2. Process information
  3. Propagate a signal
  4. Transmit a signal
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6
Q

What is an all-or-nothing law?

A

All-or-nothing law sates that if the membrane potential stays below the threshold (-50 mV, which causes opening of sodium channels), there will be no action potential.

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7
Q

What is the sequence of events that takes place after the threshold potential is reached?

A
  1. Na+ channels open and cause a fast increase in Na+ permiability - the inflow of sodium is increased - membrane potential is increasing rapidly - depolarisation
  2. After depolarisation - Na+ channels start to inactivate - Na+ permeability deacres - membrane start to repolarise
  3. Membrane depolarisation opens voltage gated K+ channels - K+ permeability increases - K+ outflow - hyperpolarisation
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8
Q

What is the example of a positive feedback loop in the process of membrane action potentials?

A

Na+ channels opening after membrane depolarisation

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9
Q

What is the example of a negative feedback loop in the process of membrane action potentials?

A

The opening of K+ channels slows down depolarisation and promotes membrane repolarisation.

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10
Q

What are the three different conformations of voltage-gated Na+ channels?

A
  1. Closed state
  2. Open state
  3. Inactive state
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11
Q

When are voltage-gated Na+ closed?

A

At resting membrane potential

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12
Q

When are voltage-gated Na+ open?

A

During depolarisation

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13
Q

When are voltage-gated Na+ are inactive?

A

Spontaneously, ball and chain theory

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14
Q

What happens when tetrodotoxin blocks the voltage-gated Na+ channels?

A

This would lead to inability to reach the threshold mark thus no action potential

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15
Q

What happens when tetraethylammonium blocks the K+ voltage-gated channels?

A

It increases the length of the action potential and no hyperpolarization would occur

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16
Q

What happens when the local anesthetic is introduced?

A

Some of the voltage-gated Na+ channels are locked in inactive state

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17
Q

What cell myelinated axons in the central nervous system?

A

Oligodendrocytes

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18
Q

What cells myelinated axons in the peripheral nervous system?

A

Schwann cells

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19
Q

What are the spaces between myelinated axons?

A

They are nodes, nodes of Ranvier

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20
Q

What is the significance of the nodes?

A

They have voltage-gated Na+ channels clusters

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21
Q

Why are nodes so important?

A

They make the electrical signal to jump from node to node increasing the speed

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22
Q

What is a refractory period?

A

It is a period of time where there is no response even to a large stimulus due to unavailability of Na+ channels.

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23
Q

What is a presynaptic response?

A

It is when an electrical signal becomes chemical

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24
Q

What is a postsynaptic response?

A

It is when a chemical signal becomes electrical

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25
Describe the presynaptic sequence of events in 4 steps.
1. Presynaptic depolarisation 2. Activation of voltage-gated Ca2+ channels 3. Ca2+ entry, and increased intracellular Ca2+ concentration 4. Vesicle fusion and transmitter release
26
What is acetylcholine?
It is a neurotransmitter released in synapses
27
What is nicotinic acetylocholine receptor?
It is a receptor on the neurons that recieves the acetylcholine
28
What is the function of acetylcholinesterase?
It is an enzyme that breaks down the access acetylcholine in neurotransmission
29
Describe the postsynaptic sequence of events in 3 steps.
1. Transmitter binds at postsynaptic receptors 2. Bound receptors regulate ion conductances 3. Transmitter is cleared by diffusion, enzymatic breakdown, or transport back into the presynaptic terminal or glia
30
What is the function of acetylcholine?
Acetylcholine binding causes a change in protein conformation in the nicotinic acetylcholine receptor which opens a central pore. The open pore allows Na+ flux. Entry causes depolarisation
31
What is shivering?
It is a thermoregulation process which leads to involuntary contraction of skeletal muscles using nAChR signaling
32
What happens during rigor mortis?
With no ATP available, Ca not be pumped back into the sarcoplasmic reticulum. Myosin finishes the last power stroke but fails to release from actin.
33
What ANS?
It is the autonomic nervous system
34
What are the functions of ANS?
Controls basic organ systems e.g. cardiovascular
35
How does ANS act?
It acts independently meaning it needs to conscious input.
36
What are the two divisions of the autonomic nervous system?
1. Sympathetic NS | 2. Parasympathetic NS
37
What is the sympathetic NS?
Fight or flight response. Catabolic in nature.
38
What is parasympathetic NS?
Housekeeping functions, Anabolic in nature
39
What is the afferent reflex arch?
It is the reflex arch that is going towards the central nervous system
40
What is the efferent reflex arch?
It is the reflex arch that is going away from the central nervous system
41
What some of the receptors within the afferent reflex arch?
1. Stretch receptors 2. Proprioceptors 3. Nociceptors
42
What is a ganglion?
A cluster of neurola cell bodies that exist outside of the CNS
43
What are the types of ganglionic fibers?
1. Preganglionic | 2. Postnglionic
44
What type of neurotransmitter do the SNS and PNS preganglionic fibres secrete?
Acetylcholine
45
What type of neurotransmitter do the sympathetic postganglionic fibres release?
Noradrenaline and adrenaline
46
What type of neurotransmitter do the parasympathetic postganglionic fibres release?
Acetylcholine
47
What are chromaffin cells?
they are postganglionic SNS neuron that lacks axons, they release adrenaline and noradrenaline
48
What are the three modes of communication between cells?
1. Gap junctions 2. Contact-dependent signals 3. Autocrine & paracrine signals
49
What is autocrine signaling?
Chemicals affect the same cells that secreted them
50
What is paracrine signaling?
Chemicals are secreted onto neighboring target cells
51
What is endocrine signaling?
Chemicals diffuse into the blood stream to reach target cells throughout the body
52
What are the three main types of hormones?
1. Peptides and proteins 2. Steroids 3. Amines
53
What are peptide hormones?
They are amino acids chains, stored in secretory vesicles, lipophobic - can not cross the plasma membrane
54
What are steroid hormones?
They are all derivatives of cholesterol, synthesised in SER, lipophilic - can cross the plasma membrane
55
What are amine hormones?
They are amino acids with modified groups
56
What are thyroid hormones?
They are amines but they behave more like steroids
57
What are the three modes of stimulating hormone release?
1. Hormonal 2. Neural 3. Humoral
58
What is the humoral response?
Response to the concentration of substances in blood
59
What are the functions of calcium?
1. Excitability of nerves 2. Control of Ca2+ channels 3. Cardiac, skeletal and smooth muscle contractility 4. Neurotransmitter release 5. Blood clotting 6. Maintenance of cellular integrity 7. Bone and teeth structure and strength
60
What is the trousseau sign?
1. Use of blood pressure cuff | 2. Hand bending
61
What hormones are used in regulation of Ca2+ concentration?
1. Parathyroid hormone 2. Activated Vitamin D 3. Calcitonin
62
What does parathyroid hormone action involve?
1. It increases the concentration of Calcium in blood by: - Bone dissolution via its indirect action of oseocytes - Tranfer of Ca2+ from bone fluid across osteocytes into central canal and circulation
63
What is the effect of parathyroid hormone on the kidneys?
1. Increase the reabsorption of the Ca2+ from the distal tubule 2. Enhances activation of vitamin D
64
What is vitamin D?
Vitamin D is synthesized from cholesterol when exposed to sunlight. Activated to calcitriol by liver. Increases Ca2+ absorption.
65
What is calcitonin?
1. Produced by the C cells of the thyroid 2. Protective against hypercalcemia 3. Plays part in protecting skeletal integrity when there is a high Ca2+ demand
66
What is a comprehensive periodontal examination?
1. Detect clinical signs of inflammation 2. Identify damage to the periodontium 3. Assign a periodontal diagnosis 4. Serve as baseline data for long term monitoring
67
What are the CCCTE signs?
Colour, consistency, contour, texture, exudate
68
How do we assess the colour of the gingiva?
1. Location 2. Colour 3. Extent
69
What is the contour of a healthy gingival margin?
Scalloped or knife-edged
70
What are some of the manifestations of diseased gingival margin?
Rolled, Recession, Cleft, Clefts
71
What is the contour of healthy papilla?
Sharp, pyramidal oe triangular
72
What are some of the manifestations of diseased papilla?
1. Bulbous 2. Blunted 3. Cratered
73
What is the consistency of healthy gingiva?
Firm, tight, well adapted
74
What are some of the manifestations of diseased gingiva in terms of consistency?
Soft, spongy, swollen, fluid-filled, retractable
75
What are some of the manifestations of the healthy texture of gingiva?
Matte with stippling (but not always)
76
What are some of the manifestations of diseased gingiva in terms of texture?
Shiny, smooth, loss of stippling (but not always)
77
What is a recession?
Apical shift of the gingival margin
78
How do we measure recession?
Measure from the cementoenamel junction to the gingival margin
79
What is a periodontal pocket?
A periodontal pocket is a pathological increase in depth of the gingival crevice or sulcus surrounding a tooth at the gingival margin
80
Where does the perio probe stop?
At the junctional epithelium
81
How do we measure mobility?
Using classifications such as Grade 1, Grade 2 and Grade 3
82
What is grade 1 mobility?
It is horizontal movement of less than 1 mm
83
What is grade 2 mobility?
It is the horizontal movement of more than 1 mm
84
What is grade 3 mobility?
Any vertical movement
85
How do we measure furcations?
By using degrees, such as degree I, II, III
86
What is a degree I furcation?
Horizontal loss of periodontal tissue support of less than 3 mm
87
What is a degree II furcation?
Horizontal loss of support above 3mm but no encompassing the total width of furcation area
88
What is a degree III furcation?
Horizontal through and through destruction of the periodontal tissue in the furcation

Dentistry BDS1 Sem 1 (15 decks)

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