Histology

Question 1

From what kind of tissue does muscular tissue originate from?

Answer 1

Mesodermal (mesenchymal)

Question 2

What are the 3 kinds of muscular tissue

Answer 2

skeletal striated
cardiac
smooth

Question 3

Where are characteristics about the nucleus in the 3 kinds of muscular tissue?

Answer 3

skelatal = multiple and there are multiple per cell
cardiac= singular and centrally located
smooth = singular and centrally located

Question 4

in which of the 3 muscular tissues can we not see the striation?

Answer 4

smooth

Question 5

Which of the 3 musucular tissues has voluntary movement?

Answer 5

only skeletal

Question 6

Which of the 3 muscular tissues has weaker contractions?

Answer 6

smooth

Question 7

Which of the 3 muscular tissues has vigorous and rhythmic contractions

Answer 7

cardiac

Question 8

What muscular tissue is known to hypertrophy?

Answer 8

cardiac

Question 9

Which muscular tissue is known for hyperplasia?

Answer 9

smooth (since they are not terminally differentiated, they can easily divide)

Question 10

Which muscular tissue is the most abundant?

Answer 10

Skeletal

Question 11

What are the 3 layers of connective tissue found in skeletal muscle and where can we find them?

Answer 11

Epimysium = around muscle
perimysium = around fascicle
endomysium = around muscle fiber

Question 12

What can we find in the endomysium?

Answer 12

basement membrane
fibrocytes
reticular fibers
capillaries

Question 13

How do muscle fibers connect to other things (like tendons)?

Answer 13

they contain finger like projections made of actin (inside the muscular fiber) and the basement membrane (on the outside of the plasma membrane) that attaches to the collagen fibers of the tendon

Question 14

What are myofibrils and how many can be found inside a muscle fiber?

Answer 14

the main unit that contracts, there are ruffly 1500 of them in 1 muscle fiber

Question 15

What 2 kinds of filaments can be found in myofibrils and what are they made from?

Answer 15

3000 thin filaments (from actin)
1500 thick filaments (from myosin)

Question 16

On this image, identify:
Z disk
h band
m line
A band
I band
Actin
Myosin
Tropomyosin

Answer 16

Question 17

What is the smallest repetitive subunit of the muscle and what is it composed of?

Answer 17

Sarcomere, from one z line to the next one

Question 18

Where can we find Creatine Kinase and why is it important?

Answer 18

in the M line
it helps produce ATP during contraction

Question 19

What are the 2 subunits of Myosin, where can we find each of them and what are they used for?

Answer 19

LMM (light meromyosin) = is the tail end of myosin and it forms the backbone of the thick filament
HMM (heavy meromyosin) = is the head of the myosin filament and contains the ATPase site and is used during contraction

Question 20

What are the 2 subunits of HMM and where can we find them?

Answer 20

HMMS-1 = head where the ATPase is and is used during contraction
HMMs-2 = where the hinger aspect of the filament is

Question 21

What is troponin and what are it’s subunits?

Answer 21

A molecule that binds to actin and prohibits myosin attaches in it’s resting state?
TNI = inhibits actin myosin interaction
TNC = where Ca interacts
TNT = anchors to tropomypsin

Question 22

How does contraction work, what are the various steps and what is the main molecule needed to start the process?

Answer 22

1. influx of Ca from the ER
2. Ca will bind with TNC which will move troponin (and therefore tropmyosin) away from the binding site
   3.Myosin binds to actin (uses ATP)
   4.Myosin bends and causes slidding (gets rid of ADP)
3. ATP attaches again and removes myosin from actin

Question 23

During contraction, which bands get smaller and which stay the same?

Answer 23

I band gets smaller
A band stays the same length

Question 24

What is the role of Titan and Nebulin in the sarcomere?

Answer 24

titan = provides structural support to myosin
Nebulin = stabilizes actin

Question 25

Where can we find the neuromuscular junction?

Answer 25

on the sarcolema, the part that covers each cell. Not to be confused with the endomysium which is the layer just outside the sarcolema

Question 26

What neurotransmitter is used for muscle contraction?

Answer 26

Acetyl choline Ach

Question 27

What is the shape of the Ach receptor and what happens once it is activated?

Answer 27

there are 5 barrel shaped subunits. once it is activated, Na+ will flow in and K+ will flow out which will depolarize the membrane and cause the ER to release Ca and cause contraction

Question 28

What is the link between the sarcolema, t-tubules, cisternae and triad?

Answer 28

The t tubules are projections of the sarcolema that carry the action potential deep in the muscle to all the myofibrils. They are in close communication with the ER (also call cisternae when they are close to the t tubules) so they will release Ca when activated. Triad is the term used when talking about a t-tubule next to 2 cisternae

Question 29

How does Ca2+ get back into the ER once the contraction finished?

Answer 29

using Calcium ATPase which will pump the Ca2+ into the ER

Question 30

What are the 3 layers of the cardiac muscles?

Answer 30

epicardium (the most outer portion) Myocardium (the middle) the endocardium (the inside part)

Question 31

What is another name for the epicardium?

Answer 31

the visceral pericardium (the innermost part of the pericardium)

Question 32

What is the new structure found in between cardiac muscle cells not found in skeletal muscles cells

Answer 32

intercalated disk

Question 33

What are the 3 sections if intercalated disks?

Answer 33

Fascia Adherence Macula Adherance Gap junctions

Question 34

What is the fascia adherence? What is it made of?

Answer 34

the zone between 2 I bands (the Z line) composed of alpha-actinin that connect the actin filaments

Question 35

What is the macula adherence? What are they made of?

Answer 35

places in between the myofibrils made from desmosomes and intermediate filaments

Question 36

What is a gap junction and what is it made of?

Answer 36

A way for ions (Ca2+)to pass through the muscles fibers. Made from 2 connexons which are each made from 6 connexins (connexin 43)

Question 37

True or false, we onle see triads in the cardiac muscle fibers

Answer 37

false. We see diads as well where the ER crosses directly over the T-tubules

Question 38

True or false? smooth muscle cells, contract horizontally (like skeletal and cardiac cells)

Answer 38

false. since the actin is anchored everywhere in the cell. they compress in all directions

Question 39

True or false? We can see endomysium in smooth muscle cells?

Answer 39

False, Smooth cells don't have layers like the skeletal ones

Question 40

What is the comparison to T-tubules in smooth cells?

Answer 40

calveoli

Question 41

What are dense bodies and what is there purpose? What are they made of?

Answer 41

They line the inside of the cell and act as an anchoring point for the actin filaments alpha-actinin and dystoppin

Question 42

How do smooth cells contract?

Answer 42

1. Ca will attach itself to calmodulin 2. the Ca-Calmodulin (Ca++)will activated the Myosin light chain kinase 3. The MYCK will phophorylate the light chains on the myosin (LMM) which will stretch them out and activated them 4. Contraction continues like skeletal

Question 43

Where can we find the actin and myosin in smooth muscles?

Answer 43

Question 44

Where can we find fibrocytes in muscle fibers? and what do they do?

Answer 44

they are located at the edge of the endomysium, in between the muscle fibers, they maintain the connective tissue

Question 45

Starting from the heart, describe the passage of blood (afferent and efferent) until the blood goes back to the heart?

Answer 45

Question 46

What are the 3 sections (seperations) in the vessels?

Answer 46

intima media adventitia

Question 47

What can we find in the intima?

Answer 47

endothelium sub-endothelial layer (sometimes) internal elastic limiting membrane (only in afferent vessels)

Question 48

What can we find in the media?

Answer 48

Elastic membranes (in elastic arteries) smooth muscle

Question 49

What can we find in the adventitia?

Answer 49

Dense iregular connective tissue vasa vasorum (small capillaries that feed the outer layers)

Question 50

what are the main characteristics of the elastic arteries and how can we recognize them?

Answer 50

Presence of IELM and layers of smooth muscle and elastic membranes in the media

Question 51

How can we recognize muscular arteries?

Answer 51

presence of IELM and at least 4 layers of smooth muscle in the media. NO elastic fibers in media

Question 52

How can we recognize arterioles?

Answer 52

No IELM Only 1-2 layers of smooth muscles in media

Question 53

How can we recognize venules?

Answer 53

They do not have IELM or any smooth muscle, only a thin endothelium

Question 54

How do we recognize middle or large veins?

Answer 54

by their size, none of them will have IELM and they will only have 1-2 layers of smooth muscle with some connective tissue in between

Question 55

Between arteries and veins, which one tends to be more collapsed?

Answer 55

veins

Question 56

Where can we find fibrocytes in vessels?

Answer 56

in the adventitia

Question 57

true or false? The flow in the aorta in way less than in the capillaries and this causes there to be less volume in the capillaries as well

Answer 57

false 800 times more volume than in the aorta

Question 58

What are the 5 functions of the capillaries?

Answer 58

exchange nutrition thermoregulation blood pressure regulation inflammation

Question 59

How can we separate capillaries into groups?

Answer 59

permeable (fenestrated or sinusoids) impermeable or continuous

Question 60

What is the difference between fenestrated and continuous capillaries?

Answer 60

continuous = the molecules can pass only thoughthe channels and pinocytic vesicles fenestrated capillaries = the molecules can directly pass in between the cells

Question 61

What are sinusoid capillaries and where can we find them?

Answer 61

they are special capillaries found in the spleen that are not associated to a basement membrane. They have larger gaps in between the cells to allow for the passage of white and red blood cells

Question 62

what are the 4 functions of the endothelium?

Answer 62

permeablity metabolic function production of vasoactive substances anti-thrombogenic function

Question 63

What are 2 examples of metabolic function provided by the endothelium?

Answer 63

conversion of angiotensin 1 to angiotensin 2 inactivation of bradykinin, serotonin, protaglandins,...

Question 64

What are products that the endothelium produces for vasocontriction/dilation?

Answer 64

(endothelin (vasocontriction) and nitric oxide (vasodilation)

Question 65

Describe the lymphatic vessels

Answer 65

contain lymph veryt hin endothelial cells and no basement membrane anchored together with connective tissue fibers usually show valves and large vessles have smooth muscle cells in their walls