Histology plus Flashcards Preview

Cardiology > Histology plus > Flashcards

Flashcards in Histology plus Deck (56):
1

Where is the endocardium thicker?

Atrium

2

How are adhering jxns connected?

Actin filaments

3

What are purkinje cells?

Specialized cardiac myocytes connected via intercalated discs and gap jxns with fewer myofibrils and few mitochondria

4

What is the shape change associated with myocardium from endocardium to epicardium?

Longitudinal to oblique myocardium

5

What types of cells have intercalated disks?

Myocytes (connected in series) and purkinje fibers

6

What does titin attach to?

Connects thick filaments (myosin) to Z line

7

What is the difference between cardiac titin and skeletal titin?

Cardiac titin is shorter and stiffer. Can't lengthen past passive tension, ensuring you don't overstretch muscles

8

What is a thin filament?

2 strands of actin coiled together with tropomyosin and troponin

9

What is a thick filament?

About 200 myosin molecules

10

What is the Z line?

end of sarcomere

11

What is the I band?

Thin filaments only

12

What is the A band?

Thin and thick filaments

13

What is the M line

Middle of the sarcomere

14

What is the H zone

Myosin only

15

Which type of blood vessels only have intima?

capillaries

16

Aortic intima

Endothelium, connective tissue, internal elastic lamina

17

Aortic media

Many elastic laminae, much smooth m

18

Aortic adventia

Thinner than the media, external elastic lamina, vaso vasorum

19

Muscular artery intima

Endothelium, CT, internal elastic lamina

20

Muscular artery media

Some SM, no elastic laminae

21

Muscular artery adventia

Thinner than media, external elastic lamina is larger, fewer vas vasorum than aorta

22

Role of muscular arteries

Control regional blood flow (distributing vessels)

23

Arteriole intima

Endotehlium, CT, slight internal elastic lamina

24

Arteriole media

sl SM

25

Arteriole adventia

Very thin, no external elastic lamina or vaso vasorum

26

Capillary intima

Endothelium, basement membrane only
-->capillaries only have intima

27

Venule intima

Endothelium, sl CT

28

Venule media

None, sl SM

29

Venule adventia

Very thin, no EEL or vaso vasorum

30

Vein intima

Endothelium, CT

31

Vein Media

Some SM no elastic laminae

32

Vein adventia

Thicker than media, no EEL, few vaso vasorum

33

What do fibroblasts and smooth muscle have in common?

They both contribute to ECM

34

How does the adventitia of small BVs differ from that of larger BVs?

Not separated from surrounding CTs as it is in larger BVs

35

Why are elastic laminae of vessels perforated?

To allow for diffusion of nutrients
-Media is not well vascularized so receives nutrients by diffusion through intima

36

What property of sm cells allows for its decrease in energy expenditure?

Tonic SM has very slow cross bridge turnover. It can also enter latch state in which tension is maintained without cycling of cross bridges (maintains T with little energy, constant stim by SNS)

37

Compared to skeletal m, how does myosin bind in smooth muscle?

Binds with opposite polarity

38

What are the secretory functions of smooth muscle cells?

Secrete collagen, elastin, EC matrix

-->all can be altered in disease

39

Describe the process of contraction in sm cells

Ca/calmod complex-->MLCK-->RLC-->inc ATP binding capacity

40

3 ways to increase Ca2+ in SM cells

1. AP allows ca2+ to flow through plasma membrane via voltage sensitive channels
2. Ligand to GCPR-->IP3 allows ca2+ to exit SR
3. Stretch-->open Ca2+ channels in the plasma membrane

41

What can reduce MLCK activity?

1. Decrease of cytoplasmic Ca2+
2. Inactivation by ligand binding leading to inc in cAMP causes vasodilation (like epineph)

42

What activates MLC phosphatase activity?

NO

Takes phos group off of the RLC

43

What is the internal elastic lamina?

Boundary between intima and media

44

Do veins have an external elastic lamina?

No!

45

What layer do you look at to tell the dif between an artery and vein?

Media. Adventitia is thicker than the media

46

What are the 4 types of capillaries?

1. Continuous: tight jxns between endothelial cells, particles must pass through cytoplams and basal lamina to enter/exit lumen

2. Fenestrated: endothelial cells have holes, basal lamina is continuous

3. Discontinuous: Large gaps between endoth cells and basal lamina is incomplete

4. Sinusoids: giant capillary, not really a type, often have discontinuous endothelium

47

Where do you find fenestrated capillaries?

Kidney, endocrine organs

48

Where do you find discontinuous capillaries?

Spleen, lymph nodes, liver

49

What features allow for a greater degree and maintenance of contractility in smooth vs skel muscle?

1. Proportion of actin to myosin is much higher
2. SM lacks rigid organization into sarcomeres
3. Myosin heads bind to a dif actin filament with opposite polarity

50

List endothelial cell properties

1. Anti/prothrombotic properties in all vessels
2. Exchange of fluids, gases, solutes in capillaries
3. Modulation of cell migration, inflammatory and immune (venules)
4. Modulation of vasc SM contractility (arteries, arterioles)

51

What does endothelial dysfxn result in?

Abnormalities in vascular:
T=tone
G=growth
I=inflammation
F=fluidity

52

List mcs that cause vasoconstriciton

Endothelin
Angiotensin II
Thromboxane A2
Acetylcholine

53

List mcs that cause vasodilation

NO
Prostacyclin
Bradykinin
ACh

54

What is the annuli fibrosa of the heart?

-Composed of dense CT that forms aponeurosis
-Serves as a support structure of valves and ventricles
-Electrically isolates atria from ventricles
-Fibrous skeleton is an attachment for the myocardium

55

Role of delayed rectifier K+ channel

Repolarizes heart and therefore determines the maximum diastolic potential

56

What ion causes the upstroke in automatic APs?

Calcium (T and L channels)