Lecture 7: Cardiac Histology Flashcards

1
Q

What are some hallmarks of smooth muscle cells?

A
  • Non-striated (very smooth)
  • Smooth muscle cells occur as sheets/bundles of elongated fusiform cells
  • Centrally located nucleus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How are smooth muscle cells interconnected?

A

Gap junctions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What types of contractions do smooth muscle produce?

A
  • Continuous contractions of low force
  • Rhythmic contraction responsive to ANS stimulation
  • Sustain long contractions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What do smooth muscles anchor to during contractions?

A

Cytoplasmic Densities/Dense Bodies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Smooth muscles lack T-tubules. How does calcium enter the cell to initiate movement?

A

Caveolae: very similar to T-tubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are some of the key histological features of cardiac muscle?

A
  • Cells short, branched, Y shaped
  • Extensive capillaries
  • Intercalated discs/transverse junctions
  • Purkinje cells (may or may not be able to see depending on magnification)
  • Lipofuscin granules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is present in cardiac cells that allows the passage of electrical current?

A

Intercalated discs/transverse junctions

Specialized gap junctions only found in cardiac cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What type of cells are present in cardiac muscle that act as the “pacemaker” cells?

A

Purkinje Cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the two layers of pericardium?

A
  • Fibrous Pericardium: outer covering of dense CT
  • Serous Pericardium: provides fluid to reduce friction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the two layers of serous pericardium?

A
  • Parietal Serous Pericardium: lines inner surface of fibrous pericardium
  • Visceral Serous Pericardium (aka Epidcardium): covers outer surface of heart
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where is the pericardial cavity located?

A

Between parietal and visceral layers of serous pericardium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the key features of the epicardium/visceral serous pericardium?

A
  • Outermost layer of the heart wall (can be thick)
  • Lined with mesothelium (simple squamous)
  • Dense fibrocollagenous CT with elastic fibers
  • Branches of coronary arteries are embedded in adipose tissue
  • Can find nerves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are some key features of the myocardium?

A
  • Thickest layer of the heart
  • Contains
    • Striation
    • Intercalated discs
    • Dyad T tubule system
    • Lot of mitochondria
    • Lipofuscin granules
    • Atrial granules (myoendocrine cells)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the key features of the endocardium?

A
  • Simple squamous endothelium
  • Areolar CT
  • Reduce friction with blood vessles and valves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where are intercalated discs located?

A
  • At sites where cells meet end to end
    • Perpendicular to length of cell
  • Always coincide with Z lines
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the three types of membrane-membrane contact in cardiac muscle cells?

A
  • Fascia adherens (Transverse/perpendicular region)
  • Desmosomes (Transverse/perpendicular region)
  • Gap junctions (Longitudinal/parallel region)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the features of the fascia adherens?

A
  • Actin filaments at end of terminal sarcomeres
  • Transmit contractile forces between cells
18
Q

What are the features of desmosomes?

A
  • Provide anchorage for intermediate filaments of the cytoskeleton: structural support
  • Prevent tearing depending on the force of contraction
19
Q

What are the features of gap junctions?

A
  • Sites of low electrical resistance
  • Allow excitation and communication to pass between cells
20
Q

What makes up a Dyad T-tubule?

Where is it found

A
  • 1 T-tubule + 1 SR cisterna
  • Found at Z lines
21
Q

What is the function of Dyad T-tubules?

A

Permits uniform contraction of myofibrils within a single cardiomyocyte

22
Q

What are nodal cardiomyocytes?

A
  • Modified cells in SA/AV node that initiate and relay electrical signals
  • Lack interlacated disc
  • Only modify rate of intrinsic cardiac muscle contraction
23
Q

What are Purkinje fibers?

What are some of their histological features?

A
  • Conducting fibers that generate and transmit impulse
  • Located at periphery of myocardium/ adjacent to to endocardium
  • Lack T tubules
  • Cells larger and have larger nucleus
  • Few intercalated discs
  • Nuclei are more round in appearance
24
Q

What are lipofuscin granules?

A
  • Small bodies that accumulate with age in stable non-dividing cells
  • Contain material from residual bodies after lysosomal digestion
  • Pretty close to the nucleus on histology slide (if staining permits you to see them)
    • gold-ish color
25
Q

Describe atrial granules.

A
  • Atrial cardiomyocytes with membrane bound granules
    • Mostly in right atrium
  • Contain ANF
    • ​Increases GFR
    • Decrease Na+ and H2O retention in kidneys
26
Q

How does the endocardium differ between ventricles and atria?

A

​Ventricles

  • Subendocardial layer which contains Purkinje Fibers
  • Thin layer of CT and smooth muscles

Atria

  • Purkinje Fibers are closer to endothelium and intermixed with myocardium
27
Q

What are the histological features of the cardiac/fibrous skeleton?

A
  • Dense irregular CT located in endocardium
  • Anchors valves and surrounds AV valves to maintain shape, acting like a ligament
28
Q

What is function of the cardiac/fibrous skeleton?

A
  • Electrical insulator between atria and ventricles
  • Insertion of cardiac muscle
29
Q

What are the histological features of heart valves?

A
  • Core of fibroelastic CT (lamina fibrosa)
  • Covered by endothelium
  • Fibroelastic layer condenses to form valve ring (makes central portion of valve)
30
Q

Identify the tissue type.

A

Smooth muscle

31
Q

Identify the tissue types.

A

Top: longitudinal section of smooth muscle

Bottom: cross section of smooth muscle

32
Q

Identify the tissue type.

A

Cardiac muscle

33
Q

Identify the three arrows.

A

Top arrow: endocardium

Middle arrow: myocardium

Bottom arrow: epicardium

34
Q

Identify the tissue type shown.

A

Epicardium

35
Q

Identify the arrows.

A

Intercalated discs

36
Q

Identify features of this picture.

A

Top to bottom:

  • Desmosome
  • Desmosome
  • Fascia adherens
  • Gap junction
  • Fascia adherens
37
Q

Identify features of this picture.

A

Left (top to bottom)

  • Intercalated disc
  • Gap junction

Right

  • Terminal cisterna of SR
38
Q

Identify the tissue feature.

A

Lipofuscin granules

39
Q

Identify the circled structure.

A

Atrial granules

40
Q

Identify the features on the histological slides.

A
  • Ventricular endocardium (with subendocardium)
  • Atrial endocardium
  • M: myocardium
  • P: Purkinje Fibers
41
Q

Identify the cell type.

A

Purkinje Fibers

42
Q

Identify.

A

Left to Right (Top to Bottom)

  • Left atrium
  • Endocardium
  • Endothelium
  • Valve ring
  • Left ventricle
  • Endocardium
  • Endothelium
  • Lamina fibrosa