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MS1 - MCBD > Week 5 Review > Flashcards

Week 5 Review Flashcards

1
Q

Which neurotransmitter is used at the first autonomic nervous system synapse?

A

acetylcholine

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2
Q

Post-ganglionic autonomic neurotransmitters are diffusely sprinkled from numerous _______ along the axons.

A

swellings/varicosities

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3
Q

Which neurotransmitter is predominantly used at sympathetic postganglionic synapses? What is the one exception?

A

norepinephrine, except for sweat glands (ACh - muscarinic M3)

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4
Q

Which neurotransmitter is used at the postganglionic parasympathetic synapse? Which receptor class?

A

ACh - muscarinic

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5
Q

In which tissues are alpha1 adrenergic receptors found and what is the normal physiologic effect of receptor binding?

A

smooth muscle (think blood vessels), binding causes vasoconstriction

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6
Q

In which tissues are alpha2 adrenergic receptors found and what is the normal physiologic effect of receptor binding?

A

alpha2 receptors are found at the nerve terminals/varicosities of preganglionic sympathetic neurons. Receptor binding causes auto-inhibition - stops release of norepinephrine.

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7
Q

In which tissues are beta1 adrenergic receptors found and what is the normal physiologic effect of receptor binding?

A

heart, kidneys

binding causes increased cardiac output and constriction of afferent arterioles

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8
Q

In which tissues are beta2 adrenergic receptors found and what is the normal physiologic effect of receptor binding?

A

smooth muscle (think lungs)

binding causes bronchodilation

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9
Q

In which tissues are beta3 adrenergic receptors found and what is the normal physiologic effect of receptor binding?

A

fat cells and bladder smooth muscle

binding causes lipolysis and bladder muscle relaxation

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10
Q

In which tissues are M3 receptors found and what is the normal physiologic effect of receptor binding?

A

glands, smooth muscle (bladder, GI), vasculature (endothelial cells)

binding causes contraction of glands and contraction of bladder and GI smooth muscle

in the vasculature, it causes NO release from endothelial cells –> vasodilation

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11
Q

In which tissues are M2 receptors found and what is the normal physiologic effect of receptor binding?

A

heart, presynaptic nerve terminals

binding causes decreased cardiac output in the heart, and auto-inhibition of ACh release from presynaptic nerves (similar to alpha2)

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12
Q

How are you going to remember the signaling pathways used by autonomic receptors?

A

QISSS IQ (G-protein types)

a1 = Q
a2 = I
B1 = S
B2 = S
B3 = S
M2 = I
M3 = Q
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13
Q

Which tissues use ATP as a neurotransmitter? What is the effect of binding?

A

arterioles, vas defrens, and sweet, bitter, umami gustatory receptors

ATP binding to purinergic receptors –> opening of nonselective cation channel –> Ca2+ entry –> binds to calmodulin –> MLCK activation –> MLCK phosphorylates myosin heads –> cross bridging –> constriction of arterioles and vas defrens

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14
Q

How do M3 receptors in endothelial cells cause vasodilation?

A

ACh binding –> PLC cleaves PIP2 –> IP3 + DAG –> IP3 releases Ca2+ from SR –> stimulation of NO synthase –> NO stimulates smooth muscle relaxation

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15
Q

Mechanoreceptors in the aortic arch and carotid sinus monitor blood pressure via arterial wall ______.

A

stretch

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16
Q

If carotid sinus cells sense too much stretch, parasympathetic tone is ________ (increased/decreased).

A

increased –> decreased cardiac output

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17
Q

Name three histological identifying traits of skeletal muscle.

A

nuclei are 1) long and 2) squished to the side of the fiber

3) striations

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18
Q

Name three histological identifying traits of cardiac muscle.

A

1) intercalated discs
2) branched myocytes
3) central, round nuclei

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19
Q

Name three histological identifying traits of smooth muscle.

A

1) fusiform fibers
2) nonstriated
3) central nuclei

looks like a flowing river

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20
Q

How can you tell the difference between dense regular CT and smooth muscle?

A

Smooth muscle will be more acidophilic (pink/red) and have more densely-packed nuclei.

CT will have super long, fusiform nuclei of fibroblasts.

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21
Q

What is found in the I band of a sarcomere?

A

actin filaments

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22
Q

What’s up with the H zone?

A

In between the thin filaments - only includes thick filaments.

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23
Q

During contraction, which structures in the sarcomere shorten? Select all that apply.

a) A band
b) H zone
c) I band
d) Entire sarcomere

A

H zone, I band, and entire sarcomere shortens during contraction

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24
Q

Within which connective tissue structure surrounding muscle fibers do motor nerves give off unmyelinated terminal branches?

A

perimysium

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25
Q

What is a junctional fold?

A

Invaginations of the sarcolemma at the neuromuscular junction to increase surface area for nACh receptors

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26
Q

What structures are found in an intercalated disc?

A

Gap junctions, desmosomes.

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27
Q

Which smooth muscle type looks wavy when contracted?

A

Smooth muscle

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28
Q

Which muscle fiber type has lots of myoglobin and mitochondria, and uses oxphos for energy?

A

Type I (slow, red)

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29
Q

What energy system is primarily used by type IIb fibers?

A

glycolysis

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30
Q

Is ATP released along with NE at presynaptic varicosities?

A

Yeah!

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31
Q

The basis for differences in muscle fiber twitch speed is due to how fast the myosin head can…?

A

how fast the myosin head can split/hydrolyze ATP

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32
Q

Describe the steps in skeletal muscle contraction.

A
  1. ACh binds NAChR.
  2. Non-selective cation channels open (graded potential).
  3. Big enough graded potential opens voltage-gated Na+ ion channels, propagating an action potential.
  4. Voltage gated Ca2+ channels (L-type/DHPR) in the t-tubule open.
  5. Ryanodine receptors in the SR open (mechanically linked to the L-type receptor), Ca2+ flows out of the SR.
  6. Ca2+ binds troponin C.
  7. Tropomyosin moves to expose myosin binding site on actin.
  8. Myosin + ADP + Pi binds to actin
  9. Pi is released and the power stroke happens.
  10. ADP is displaced by ATP and the cross-bridge is broken.
  11. ATP is hydrolyzed to ADP + Pi to start cycle again.
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33
Q

What is the difference between initiation of cardiac muscle contraction and skeletal muscle contraction?

A

The main difference is that the L-type/DHPR is NOT mechanically linked to the Ryanodine receptor in the SR. Ca2+ release from the SR via the Ryanodine receptor is chemically-gated by Ca2+ entry through the SR (calcium-induced calcium release, CICR)

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34
Q

Describe the steps in smooth muscle contraction.

A
  1. Ligand binds to GPCR alpha q.
  2. PLC hydrolyzes PIP2 –> IP3 + DAG.
  3. IP3 binds IP3R on SR, Ca2+ is released.
  4. Ca2+ binds calmodulin and activates it.
  5. Calmodulin activates myosin light chain kinase.
  6. MLCK phosphorylates myosin heads.
  7. Cross-bridge cycle happens.

OR

Action potential via gap junction causes Ca2+ entry and CICR, Ca2+ binds to calmodulin, etc.

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35
Q

Which fiber type uses a mix of aerobic and anaerobic metabolism?

A

Fast type IIa

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36
Q

For how long in a working muscle to ATP stores and creatine phosphate provide energy?

A

Stored ATP last for 3-5 seconds.

Creatine phosphate regenerates ATP for 30 seconds.

37
Q

In a muscle, after approximately 45 seconds of work, ________ metabolism peaks. After that, ________ metabolism increases and accounts for 75% of the energy load after around 90 seconds of work.

A

anaerobic peaks at 45 seconds, aerobic metabolism is at 75% of energy load at 90 seconds

38
Q

What is the preferred energy source and metabolic pathway of cardiac muscle?

A

Fatty acids, aerobic metabolism

39
Q

What is the preferred metabolic pathway for smooth muscle?

A

aerobic metabolism

40
Q

True or false:

Force of contraction in skeletal muscle is dependent on the amount of myosin and actin overlap.

A

true

41
Q

________ contraction occurs when afterload is too great for the muscle to shorten even though cross-bring cycling continues.

A

Isometric

42
Q

What is isotonic contraction?

A

When a muscle shortens at a constant tension.

43
Q

Myasthenia gravis is an autoimmune disorder that attacks __________ at the neuromuscular junction.

A

nicotinic ACh receptors

44
Q

The breakdown and release of myoglobin into the blood, causing kidney damage, is characteristic of what disease?

A

Rhabdomyolysis

45
Q

Malignant hyperthermia is an autosomal ________ mutation of the _______ _______. When given inhaled anesthetics, the ________ ______ is stimulated to release dangerously high levels of Ca2+, causing muscle contraction, ATP depletion, and an increase in temperature.

A

autosomal dominant

mutation of the ryanodine receptor

inhaled anesthetics trigger the ryanodine receptor to release Ca2+

46
Q

Which rib attaches at the sternal angle?

A

2nd

47
Q

At what spinal level is the sternal angle? Name 4 important anatomical considerations at this spinal level.

A

T4/5.

  1. limit of the superior portion of the pericardium
  2. aortic arch is located at this level
  3. brachiocephalic veins join to form the SVC
  4. bifurcation of the trachea
48
Q

What bony landmark marks the axial division between the superior and inferior mediastinum?

A

sternal angle

49
Q

Which intercostal muscles are used during inspiration?

A

External intercostals

50
Q

When performing a thoracocentesis, where in the intercostal space should you place the needle? Why?

A

Just above a rib to avoid the neurovascular bundle in the groove on the inferior edge of the rib.

51
Q

Intercostal nerves arise from the ______ primary rami.

A

ventral

52
Q

From what arteries do the superior epigastric arteries arise?

A

internal thoracic

53
Q

Superior epigastric arteries anastomose with the inferior epigastric arteries, which are branches off of the ______ ______ arteries.

A

external iliac arteries

54
Q

Spinal nerves from which level supply the dermatome at the pubic symphysis?

A

L1

55
Q

Name the spinal nerves that correspond to the dermatomes at the following landmarks:

nipple
xyphoid process
epigastric area
umbilicus

A

nipple: T4
xyphoid process: T5
epigastric area: T7
umbilicus: T10

56
Q

________ is characterized by a rubbing, crackling noise upon auscultation of the lungs caused by inflammation of the pleura.

A

Pleurisy

57
Q

In general, how much lower is the parietal pleura than the inferior extent of the lungs?

A

two ribs lower

58
Q

Which drug on our list is used to treat BPH? What else does it treat?

A

Prazosin (alpha1 antagonist) blocks smooth muscle contraction in the prostate to un-squish the prostatic urethra and increase urine flow. It also dilates blood vessels to treat hypertension.

59
Q

What are Merkel’s discs? What do they sense? Do they adapt?

A

Thin discs around nerve endings that sense pressure in skin and joints. They are slow-adapting.

60
Q

What do Meissner’s corpuscles sense? Do they adapt?

A

They sense fine touch, and kind-of adapt (faster than Merkel’s, slower than Pacinian)

61
Q

What do Pacinian corpuscles do? Do they adapt?

A

Sense vibration (>50 Hz), fast adapting.

62
Q

Ruffini’s endings sense _____.

A

stretch (of skin)

63
Q

Which nerve endings sense pain and temperature?

A

free nerve endings

64
Q

How do photoreceptors work?

A
  1. Photon hits receptor
  2. cis-retinal –> trans-retinal
  3. trans-retinal activates rhodopsin (rhodopsin –> metarhodopsin II)
  4. Metarhodopsin II activates Gs protein
  5. Gs activates phosphodiesterase
  6. Phosphodiesterase cleaves cGMP –> GMP
  7. cGMP-gated Na+ and Ca2+ channels close –> hyperpolarization
  8. Hyperpolarization prevents release of glutamate
  9. No glutamate neurotransmitter –> no action potential –> vision!
65
Q

Gustatory receptors for which tastes act through GPCRs? What is the signaling pathway?

A

Sweet, bitter, umami. Gq –> PLC –> IP3 and DAG –> Ca2+ release –> ATP released as a neurotransmitter to bind on afferent sensory neurons

66
Q

Which neurotransmitter is used by sour and salty gustatory receptors?

A

serotonin

67
Q

Hair cells are bathed in a ____-rich fluid. When the hair cells are bent, it causes opening of ____ channels –> depolarization, influx of Ca2+ –> release of the neurotransmitter _______.

A

K+ rich fluid. Bending opens a K+ channel –> depolarization and influx of Ca2+ –> release of glutamate.

68
Q

When there is mechanical damage to cells, proteases are released that cleave stuff to make _______, which binds to free nerve endings, stimulating the release of ________, which then binds to mast cells, stimulating release of ________.

A

bradykinin –> substance P –> histamine

69
Q

What is the significance of a positive Babinski sign?

A

Possible upper motor neuron lesion.

70
Q

Which nerve supplies sensation to the skin of the scrotum/labium majus?

A

Ilioinguinal nerve (L1)

71
Q

Which nerve provides motor innervation for the cremaster muscle?

A

Genital branch of the genitofemoral nerve

72
Q

The inferior epigastric arteries can be found between the rectus abdominis muscle and the ________ _______ within the ________ umbilical folds.

A

between rectus abdominis and transversalis fascia within the lateral umbilical folds

73
Q

Where is the pampiniform plexus located and what is its function?

A

Located in the spermatic cord, function is to cool blood in the testicular artery

74
Q

Name the layers of the testis/spermatic cord and their corresponding abdominal wall layers.

A

Superficial to deep:
skin - skin

Dartos fascia - superficial fascia (membranous layer/Scarpa’s)

External spermatic fascia - deep fascia of external oblique

Cremaster fascia/muscle - deep fascia and muscle of internal oblique

Internal spermatic fascia - transversalis fascia

tunica vaginalis - parietal peritoneum

note the transversus abdominis muscle does not contribute to anything in the scrotum

75
Q

Where is the femoral artery located with respect to the inguinal ligament?

A

Femoral artery is deep to the middle of the inguinal ligament

76
Q

Where is the deep inguinal ring located with respect to the femoral artery? From what did the deep inguinal ring arise?

A

Deep inguinal ring is just superior to the middle of the inguinal ligament, superficial to the femoral artery.

It arose from the transversalis fascia.

77
Q

Describe where a direct inguinal hernia occurs with respect to the rectus abominis muscle, the inguinal ligament, and inferior epitastric vessels.

A

Direct inguinal hernia occurs lateral to the rectus abdominis, medial to the inferior epigastric arteries, and superior to the inguinal ligament (this area is called the inguinal/Hasselbach’s triangle)

78
Q

Where does an indirect hernia happen with respect to the inferior epigastric vessels? What path does it take to exit the abdominal wall?

A

Lateral to the inferior epigastric vessels, through the deep inguinal ring, through the inguinal canal, and out the superficial inguinal ring into the scrotum.

79
Q

Describe the contents of the subinguinal space. Which one of these is not found in the femoral sheath?

A

NAVEL (lateral to medial)

nerve, artery, vein, empty, lymphatics

the nerve is not in the femoral sheath

80
Q

To place a line in the femoral vein, one should palpate the femoral artery, and place the line _______ to the artery.

A

the femoral vein is medial to the femoral artery

81
Q

What is the term for an accumulation of fluid in the tunica vaginalis?

A

Hydocele

82
Q

Your male patient notes a “heavy feeling” in his scotum, along with a dull ache. On PE you find a bag of worms. What is your Dx?

A

varicocele

83
Q

What is the name of the condition characterized by failure of testicular descent, which causes sterility and an increased risk of testicular cancer?

A

cryptorchidism

84
Q

Your patient comes to you and tells you that they have a mutated CIC-1 channel. You notice that they have hypertrophied muscles. What is your diagnosis?

A

myotonia congenita - mutated CIC-1 chloride channel slows repolarization, causing prolonged contraction and hypertrophy.

85
Q

How does intense exercise increase the risk for paralysis in someone that has hyperkalemic periodic paralysis?

A

Intense exercise can increase extracellular [K+] slightly because of all the action potentials that have involved K+ efflux from cells. This causes the resting membrane potential to become less negative, and therefore more Na+ channel inactivation gates are closed, exacerbating the inability to generate another action potential.

86
Q

Which gene is mutated in hyperkalemic periodic paralysis? What is the mechanism by which this defective protein causes disease?

A

SCN4A gene that encodes for the Na+ channel. The channel doesn’t close after an action potential is generated to allow for membrane repolarization.

87
Q

Malignant hyperthermia is characterized by a mutated _________ receptor. Inhaled anesthetics can trigger this receptor to release Ca2+ from muscle SR, causing constant muscle contraction, depletion of _____, and release of a lot of heat.

A

mutated ryanodine receptor

depletion of ATP, release of heat!

88
Q

What are the three stress biomarkers?

A
  1. Catecholamine levels
  2. Telomere length
  3. Cortisol levels

MS1 - MCBD (17 decks)

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