Cardiac and Vascular Histo Flashcards
Describe the appearance of smooth muscle
Centrally located, elongated nucleus
- Tissue is NOT wavy
Describe the overall general features of cardiac muscle
- Intercalated discs
- Centrally located nucleus surrounded by an unstained portion
- lipofuscin granules near some of the nuclei
What is the order of the layers of the heart from superficial to deep?
Fibrous pericardium Parietal serous pericardium *Pericardial cavity* Visceral serous pericardium (epicardium) Myocardium Endocardium Cardiac skeleton
The epicardium (visceral serous pericardium) is loose CT that contains what 3 things?
- Autonomic nerves
- Adipose tissue
- Branches of coronary arteries in the adipose tissue
What lines the epicardium?
Mesothelium
What is the thickest layer of the heart?
Myocardium
What type of cells does the myocardium contain?
Cardiocytes
Nodal cardiocytes
Myoendocrine cardiocytes
What are the main histo features of the myocardium?
Intercalated discs
Striations
Lipofuscin granules
What type of T - tubule system does the myocardium have?
Dyad
What are intercalated discs?
Junctions between cardiocytes that allow spread of excitation and contraction
What are the 3 types of membrane - to - membrane contacts with the intercalated discs?
- Fascia adherens - most predominant
- Desmosomes
- Gap junctions
Which membrane - to - membrane contacts are transverse?
Fascia adherens
Desmosomes
Which membrane - to - membrane contacts are longitudinal?
Gap junctions
Actin filaments that insert into junction and transmit contractile force between cells
Fascia adherens
Low electrical resistance that allows excitation to spread between cells
Gap junctions
Anchorage for filaments of cytoskeleton
Desmosomes
Dyad T - tubules =
1 T - tubule + 1 SR cisterna
– permits uniform contraction
Purkinje fibers have an increased amount of?
Glycogen
What do Purkinje fibers lack?
T tubules
Where are Purkinje fibers larger at?
Periphery of myocardium
Where do most of the myoendocrine cardiocytes reside?
Right atrium
What do myoendocrine cardiocytes release?
Atrial natriuretic factor (ANF)
Job of Atrial Natriuretic Factor (ANF)?
- released from myoendocrine cardiocytes
Act on the kidney to decrease sodium and water retention
Endocardium =
Endothelium + layer of CT
In the ventricles, the endocardium has an extra layer known as?
Subendocardial layer
What is contained in the subendocardial layer of the endocardium of the ventricles?
CT with smooth muscle and branches of purkinje fibers
In the atrial endocardium, is there a subendocardial layer?
NO
Atria or ventricles, which endocardium has a subendocardial layer (CT with smooth muscle and purkinjes)?
Ventricles!
With no subendocardial layer in the atria, the purkinje fibers are closer to?
The endocardium
Purpose of cardiac skeleton?
Electrical insulator between the atria and ventricles
What are heart valves made of?
Fibroelastic CT covered by endothelium and continuous with the cardiac skeleton
What forms a valve ring (central portion of valve)?
Fibroelastic layer of endocardium
What are the 3 layers that comprise the walls of arteries and veins from innermost to outermost?
- Tunica Intima
- Tunica Media
- Tunic Adventitia
Arteries diameter decreases as they get _____ to the heart
Further
Veins diameter increases as they get ____ to the heart
Closer
What type of epithelium is in the tunica intima?
Simple squamous
What is in the subendothelial layer of the tunica intima?
Internal elastic membrane
The number of _____ between endothelial cells in the tunica intima alters permeability
Junctions
Endothelial cells in the tunica intima produce?
Collagen
Tunica Media
Circumferentially arranged layers of smooth muscle
In what is the tunica media the thickest?
Arteries
In arteries, between what 2 things is the tunica media?
Internal Elastic Membrane
External Elastic Membrane
Tunica Adventitia
Longitudinally arranged collagenous tissue
In what is the tunica adventitia the thickest?
Veins/venules
What 2 things can be found in the tunica adventitia?
- Vasa Vasorum
2. Nervi Vasorum
Vessels of tunica adventitia that supply blood to vascular tunics
Vasa vasorum
ANS input that controls contraction of vascular smooth muscle
- found in tunica adventitia
Nervi vasorum
Large arteries contain a lot of?
Elastin
Medium arteries (muscular) have a prominent?
Internal elastic membrane
Medium arteries have ____ smooth muscle and less elastin compared to large arteries
MORE
For large arteries, where does the elastin reside?
Between muscle cell layers
Small arteries and arterioles have ____ layers of smooth muscle
Many
Site of metabolic exchange; diameter often less than RBC
Capillaries
What cells promote the stability of capillaries and are controlled by NO?
Pericytes
What are the 3 types of capillaries?
- Continuous - most common; cells meet end to end with tight junctions
- Fenestrated - has pores amongst endothelial cells
- Discontinuous
Veins have ____ walls than arteries
Thinner
Veins have _____ lumen than arteries
Larger
