Histology Flashcards

1
Q

What are the characteristics of smooth muscle fibers with respect to myofibrils, location of nucleus and involuntariness of contraction?

A

Myofibrils not visible
Nucleus centrally located
Involuntary contraction

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2
Q

What are the characteristics of striated skeletal fibers with respect to myofibrils, location of nucleus and involuntariness of contraction?

A

Myofibrils visible
Peripheral nuclei (multinucleated)
Voluntary contraction

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3
Q

What are the characteristics of striated cardiac fibers with respect to myofibrils, location of nucleus and involuntariness of contraction?

A

Myofibrils visible
Centrally located nucleus
Involuntary contraction

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4
Q

What is the band letter at the center of the A band in striated cells?

A

H

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5
Q

What is the band letter at the center the I band in striated cells?

A

Z

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6
Q

What separates individual cells?

A

Endomysium

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7
Q

What separates a bundle of cells from one another?

A

Perymysium

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8
Q

What is the sheath that surrounds a muscle?

A

Epimysium

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9
Q

What is the name of the striated muscle cells that has a finger-like projection

A

Sarcolemma

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10
Q

What is the bundle of muscle fiber that lies before the perymysium

A

Fascicle

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11
Q

What is a sarcomere?

A

The repeating unit between two Z lines

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12
Q

What is the protein that holds the Z lines?

A

Alpha-actinin

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13
Q

What are the two types of filaments in a sarcomere?

A

Thin filament: F-actin

Thick filament: Myosin filament

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14
Q

What is found at the center of the H band?

A

The M-line, which is the site of the enzyme “Creatine Kinase”

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15
Q

What does the creatine kinase do?

A

Allows contraction

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16
Q

When does axon activation occurs?

A

When acetyl choline (Ach) gets to potassium/sodium receptors

17
Q

During contraction, what happens when myosin binds actin and cleaves ATP?

A

Myosin head bends, and the thin filament slides over the thick filament (contraction occurs)

18
Q

During the mechanism of contraction, what happens when calcium if removed by sarcoplasmic reticulum?

A

There’s relaxation

19
Q

Starting from the most external layer, what are the two division of the pericardium (and what are their subdivisions)?

A

External:
Fibrous pericardium
Serous pericardium
(Serous is further divided in parietal lamina, and visceral lamina)

20
Q

The endocardium is made of what?

A

Endothelium
Connective tissue
Smooth muscle tissue

21
Q

What is the myocardium made of?

A

Muscle fibers

22
Q

What is the other name of the epicardium?

A

Visceral layer of the serous pericardium

23
Q

In the heart’s sarcomeres, what does the zonula adherens do?

A

Transmit contractile forces

24
Q

In the heart’s sarcomeres, what does the macula adherens do?

A

Maintain stability

25
What is the Ehlers-Danlos syndrome?
Lack of collagens, affecting connective tissue. | This can cause walls to rupture (high risk of aneurysm)
26
Neuromuscular disease leading to muscle weakness Caused by antibodies preventing ACh receptors to get activated What is the Dx?
Myasthenia Gravis
27
What is muscular dystrophy (the Duchenne-Becker Dx)
Mutation of dystrophin gene leading to improperly formed muscle Caused by a lack of laminins that required dystroglycans, which themselves required dystrophins
28
You see a collapsed blood vessel on the histology image. Is it an artery or a vein?
A vein (arteries are thicker, and will therefore not collapse)
29
How do we call veins that fail to close to regulate the blood flow?
Varicose veins
30
What are the causes of varicose veins?
Obesity Smoking Pregnancy
31
Varicose veins can cause what?
High blood pressure
32
What is the intima made of in muscular arteries?
Endothelium (simple squamous) | Internal elastic limiting membrane
33
What is a vasa vasorum, and where can we find such a thing?
It's a small blood vessel that supplies the wall of larger blood vessels. We can find it in some blood vessels adventitia
34
What are the three types of capillaries, and their subdivisions?
Impermeable/continuous | Permeable (divided in "Fenestrated" and "Sinusoids")
35
What kind of capillaries allow the movement of RBC and WBC between its endothelial cells?
Sinusoid capillaries
36
How can you distinguish capillaries from post-capillaries venules?
Post-capillaries venules have pericytes around the lumen.
37
What are the vasoactive substances produced by the endothelium?
``` Endothelin (vasoconstriction) Nitric Oxide (vasodilatation) ```
38
By what metabolic means does the endothelium regulate the blood pressure?
Conversion of angiotensin 1 to angiotensin 2 | Inactivation of bradykinin