Histology

Question 1

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

Answer 1

Myofibrils not visible
Nucleus centrally located
Involuntary contraction

Question 2

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

Answer 2

Myofibrils visible
Peripheral nuclei (multinucleated)
Voluntary contraction

Question 3

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

Answer 3

Myofibrils visible
Centrally located nucleus
Involuntary contraction

Question 4

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

Answer 4

H

Question 5

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

Answer 5

Z

Question 6

What separates individual cells?

Answer 6

Endomysium

Question 7

What separates a bundle of cells from one another?

Answer 7

Perymysium

Question 8

What is the sheath that surrounds a muscle?

Answer 8

Epimysium

Question 9

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

Answer 9

Sarcolemma

Question 10

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

Answer 10

Fascicle

Question 11

What is a sarcomere?

Answer 11

The repeating unit between two Z lines

Question 12

What is the protein that holds the Z lines?

Answer 12

Alpha-actinin

Question 13

What are the two types of filaments in a sarcomere?

Answer 13

Thin filament: F-actin

Thick filament: Myosin filament

Question 14

What is found at the center of the H band?

Answer 14

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

Question 15

What does the creatine kinase do?

Answer 15

Allows contraction

Question 16

When does axon activation occurs?

Answer 16

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

Question 17

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

Answer 17

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

Question 18

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

Answer 18

There’s relaxation

Question 19

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

Answer 19

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

Question 20

The endocardium is made of what?

Answer 20

Endothelium
Connective tissue
Smooth muscle tissue

Question 21

What is the myocardium made of?

Answer 21

Muscle fibers

Question 22

What is the other name of the epicardium?

Answer 22

Visceral layer of the serous pericardium

Question 23

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

Answer 23

Transmit contractile forces

Question 24

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

Answer 24

Maintain stability

Question 25

What is the Ehlers-Danlos syndrome?

Answer 25

Lack of collagens, affecting connective tissue.

This can cause walls to rupture (high risk of aneurysm)

Question 26

Neuromuscular disease leading to muscle weakness
Caused by antibodies preventing ACh receptors to get activated
What is the Dx?

Answer 26

Myasthenia Gravis

Question 27

What is muscular dystrophy (the Duchenne-Becker Dx)

Answer 27

Mutation of dystrophin gene leading to improperly formed muscle
Caused by a lack of laminins that required dystroglycans, which themselves required dystrophins

Question 28

You see a collapsed blood vessel on the histology image. Is it an artery or a vein?

Answer 28

A vein (arteries are thicker, and will therefore not collapse)

Question 29

How do we call veins that fail to close to regulate the blood flow?

Answer 29

Varicose veins

Question 30

What are the causes of varicose veins?

Answer 30

Obesity
Smoking
Pregnancy

Question 31

Varicose veins can cause what?

Answer 31

High blood pressure

Question 32

What is the intima made of in muscular arteries?

Answer 32

Endothelium (simple squamous)

Internal elastic limiting membrane

Question 33

What is a vasa vasorum, and where can we find such a thing?

Answer 33

It’s a small blood vessel that supplies the wall of larger blood vessels.
We can find it in some blood vessels adventitia

Question 34

What are the three types of capillaries, and their subdivisions?

Answer 34

Impermeable/continuous

Permeable (divided in “Fenestrated” and “Sinusoids”)

Question 35

What kind of capillaries allow the movement of RBC and WBC between its endothelial cells?

Answer 35

Sinusoid capillaries

Question 36

How can you distinguish capillaries from post-capillaries venules?

Answer 36

Post-capillaries venules have pericytes around the lumen.

Question 37

What are the vasoactive substances produced by the endothelium?

Answer 37

Endothelin (vasoconstriction)
Nitric Oxide (vasodilatation)

Question 38

By what metabolic means does the endothelium regulate the blood pressure?

Answer 38

Conversion of angiotensin 1 to angiotensin 2

Inactivation of bradykinin