Heart Histology Flashcards
1
Q
Heart Structure
Left heart to all body except \_\_\_\_ (systemic) Right heart to \_\_\_\_ (pulmonary) Systemic arteries: \_\_\_\_ blood Pulmonary arteries: \_\_\_\_ blood Systemic veins: \_\_\_\_ blood Pulmonary veins: \_\_\_\_ blood Atria: receive blood from veins Ventricles: pump blood to arteries
A
lungs lungs oxygenated deoxygenated deoxygenated oxygenated
2
Q
Layers of the heart wall
1. Pericardium (external layer): • Homologous to the \_\_\_\_ of blood vessels. • Smooth, slippery texture to outermost surface. 2. Myocardium: • Continuous with the \_\_\_\_ of blood vessels. • 95% of heart is \_\_\_\_ muscle 3. Endocardium (inner layer) • Homologous to the \_\_\_\_ of blood vessels. • \_\_\_\_ lining.
• Heart wall > three layers ○ Pericardium § Tissues at level of tunica adventitia: \_\_\_\_, adipose, nerves, other blood vessels □ Likely that pericardium is composed of the same type of tissues as the blood vessels, specifically connective tissue ○ Myocardium (bulk) § Tunica media of large arteries □ Important difference: tunica media has \_\_\_\_ muscle, and myocardium is composed of \_\_\_\_ muscle ○ Endocardium (thin lining the interior of the myocardium) § Tunica intima > an endothelium that may be contain other tissues (\_\_\_\_ connective tissues)
A
tunica adventitia tunica media cardiac tunica intima endothelial
connective
smooth
cardiac
subendothelial
3
Q
Pericardium
- Membrane surrounding and protecting the heart.
- Confines while still allowing ____.
- 3 layers:
- Fibrous pericardium:
- Inelastic, dense ____ CT.
- Prevents ____, overfilling. • Anchors the heart.
- Serous pericardium:
- Thinner, more delicate CT.
- Double layer:
- ____ layer: fused to fibrous pericardium.
- ____ layer: also called epicardium.
• Pericardial cavity: Between parietal and visceral layers: contains pericardial fluid which reduces ____.
• Prevents the heart from overextending • Three components of pericardium is formed primarily of \_\_\_\_ tissue > allows it to have its function ○ Fibrous § Rich in collagen and poor in \_\_\_\_ (elastin allows contraction and elongation easily) ○ Serous (between the two layers > pericardial cavity) § Parietal § Visceral (epicardium) ○ Pericardial cavity § Allows movement of heart and prevents friction
A
free movement irregular overstretching parietal visceral friction
connective
elastin
4
Q
Pericardial cavity
- Serous pericardium:
- Thinner, more delicate CT. • Double layer:
- Parietal layer: fused to fibrous pericardium.
- Visceral layer: also called epicardium.
• Pericardial cavity: Between parietal and visceral layers: contains pericardial fluid which reduces friction.
• Fluid in pericardial cavity composed of \_\_\_\_ and polysaccharides ○ Same role that is played in \_\_\_\_ cartilage > gives the fluid ability to reduce friction • Also a a lot of \_\_\_\_
A
proteoglycans
articular
water
5
Q
Myocardium
• Thickest layer of the heart: • Thickest in \_\_\_\_ - to overcome high pressure of systemic circulation. • Thinnest in \_\_\_\_ - low resistance to back flow.
- Myocardial cell types:
- Contractile cardiocytes (a.k.a. cardiomyocytes):
- Specialized ____ cells.
- Myoendocrine cardiocytes:
- Secrete ____ – regulates diuresis and sodium excretion to control blood volume.
- Nodal cardiocytes:
- Control the ____ of heart contraction.• Amount of muscle correlates with ____ of blood
• Contractile cardiocytes
○ Closely related to ____ muscle cells (more than smooth), but behave like smooth muscle cells
• Myoendocrine cardiocytes
○ ANF - regulates production of ____
• Nodal cardiocytes
○ Present in cardiac ____
○ Heart contracts based on signals by NC, which are modified by ____ system that is influenced by other factors
§ Changes in relative charge of the membrane of these cells
A
left ventricle right atrium muscle atrial natriuretic factor rhythm pressure skeletal urine nodes autonomic
6
Q
The Cardiac Muscle Cell or Cardiomyocyte
Striated, branched cylinders, with a single, ____- located nucleus.
Wrapped around the ____ walls, increasing efficiency of blood ejection.
• Left ○ Section of cardiac muscle - \_\_\_\_ (looks like skeletal) § But the cells are histologically different > because of single centrally located nucleus • Right ○ Wrap around ventricular walls > by their contraction > pumping of blood
A
centrally
ventricular
striated
7
Q
Comparison of Skeletal, Cardiac and Smooth Muscle
TABLE!
• Cardiac cells are only present in the \_\_\_\_ ○ Similar in morphology to skeletal muscle cells due to striations § Striations depend on the contractile mechanisms of organization into \_\_\_\_ ○ Presence of densities (vertical bands) > \_\_\_\_ § Place where two different cardiac cells touch each other and fuse ○ Cardiac cells are \_\_\_\_ (skeletal is NOT) ○ Nuclei are \_\_\_\_ located (unlike peripherally like in skeletal) ○ Do not fuse into \_\_\_\_ cell (sinctitiam), like skeletal cells do ○ Cardiac looks very different from smooth cell, but the \_\_\_\_ is similar between the two § Contraction of cardiac cells is \_\_\_\_ which is controlled by the ANS (like the smooth muscle cell)
A
heart sarcomeres intercalated disks branched centrally multi-nucleated behavior involuntary
8
Q
Histology of the Cardiac Muscle
• Left ○ Intercalated disk § Two cells meet and fuse ○ Nucleus located \_\_\_\_ • Right ○ \_\_\_\_ § Thin CT that surrounds every cardiac fiber • Myocardium has same three levels of connective tissue that’s in \_\_\_\_ muscle ○ \_\_\_\_ - surrounds fibers ○ \_\_\_\_ - surrounds bundles ○ \_\_\_\_ - surrounds whole organ
A
centrally
endomysium
skeletal
endomysium
epimysium
perimysium
9
Q
Histology of the Cardiac Muscle
* Longitudinal section stained on the left, the blue arrows indicate the intercalated disks that are the limits between cells * Yellowish tissue with lots of nuclei is \_\_\_\_, it is connective tissue so those nuclei belong to \_\_\_\_ * On the right you have cross section of cardiac muscle cells
A
endomysium
fibroblasts
10
Q
Structure of the cardiomyocyte cell
- Organization of myofibrils similar to ____ muscle.
- Differences in the membrane system:
- Larger ____, found at the level of Z disk.
- ____ not as extensive.
- ____ (not triads): one T tubule interacting with one SR cisterna.
- More abundant ____.• Sarcomere made of thick and thin fibrils
○ Identical
• Cisternae of the SR
• Larger T tubules at level of Z disk
○ Allows a more efficient trafficking of ions, and during transmission of excitation signal > allows quicker liberation of ____ from SR
○ Contracting all the time, unlike skeletal which is only contracting some of the time
• In skeletal > triads > two cisternae and one T tubule; but in cardiac it’s a diad > one and one
A
skeletal t tubules SR diads mitochondria Ca++
11
Q
The Sarcomere
- Myofibrils are repeats of sarcomere units.
- I band:
- ____ – major component; two protein strands twisted around each other, contain “active sites”.
- Other proteins – ____, Troponins, ____.
• A band:
• ____ - flexible “heads” with ATPase activity protrude outward (except at ____), attach to “active” sites on actin (thin) filament.
• H band – contains ____; forms ____.
• M line – located in midline of the H band;
provides ____ support to myosin filaments.
• Z-disk (Z-line, Z-band)–where thin filaments attach; mostly ____.
• Everything at this level is identical between skeletal and cardiac ○ Even the Z disks are identical (where actin and filaments attach) • Question about this!
A
actin
tropomyosin
nebulin
myosin filament center creatine kinase ATP structural support
alpha-actinin
12
Q
Structure of the Cardiomyocyte Cell
• Organization of myofibrils similar to skeletal muscle.
• Differences in the membrane system: • Larger T tubules found at the level of Z
disk.
• Sarcoplasmic reticulum not as extensive.
• Diads (not triads): one T tubule interacting with one SR cisterna.
• More abundant mitochondria.
* In skeletal > T tubule is at junction of \_\_\_\_, but in cardiac cell they're at the \_\_\_\_ * Only one SR cisternae located > diad, instead of triad (one and one)
A
I-A band
Z disk
13
Q
Structure of the cardiomyocyte cell
• Cells are joined at the end by intercalated disks in a step-like arrangement:
• Transverse component: ____ link, transmission of contractile force.
• Desmosomes.
• Fasciae adherens (α-actinin and vinculin):
insertion site for ____.
- Longitudinal components: ionic (____) link, contraction coordination.
- ____, ion channels.
- Membrane receptors.• Reasons for joining of intercalated disk > heart must contract in coordinated manner > links cells mechanically and physiologically
• Mechanical link of ID > transverse component
○ Desmosomes
§ Serve to tightly bind to cells > common in ____
○ Fasciae adherens
§ ____ and vinculin > form the Z disks (myotendinous junction, junction between skeletal muscle and tendons)
• Mechanical contraction only works somewhat, the whole muscle organ contraction must be coordinated; in order to ensure that all cells in one seciton of heart contract (LV, for example) > functional link > longitudinal component
○ Ionic link; ions traffic from one cell to the next very rapidly
A
mechanical actin thin filaments functional gap junctions epithelia actinin
14
Q
Structure of the cardiomyocyte cell
• Blue arrows > electron dense regions > rich in proteins > \_\_\_\_ component
A
transverse
15
Q
Structure of the cardiomyocyte cell
• Longitudinal components DOES NOT mean that gap/ion channels are on side of cells > there are some in regions where transverse component is less \_\_\_\_ ○ More easily for \_\_\_\_ to travel through the cells ○ Enriched in the \_\_\_\_, most logical place for them to be located
A
dense
ions
intercalated disks
