(4) Heart and Vascular System (Dennis) Flashcards
What type of muscle is this?
Describe
Striated or non-striated?
Voluntary or involuntary?
Skeletal Muscle
Striated & Voluntary
What type of muscle is this?
Describe
Striated or non-striated?
Voluntary or involuntary?
Cardiac Muscle
Striated
Involuntary
What type of muscle is this?
Describe
Striated or non-striated?
Voluntary or involuntary?
Smooth Muscle
Non-striated
Involuntary
What type of muscle is this?
How is it organized?
Smooth Muscle
Occurs as bundles or sheets of elongated fusiform cells
No visible striations
Interconnected by gap junctions
Describe smooth muscle contraction
Tension transmitted via densities to the membrane
Cells contract as one unit and assume a globular shape
***Anchor to cytoplasmitc densities/dense bodies
What is this muscle type?
Cardiac muscle
What are 2 distinguishing features of this type of muscle?
Cardiac Muscle
Intercalated discs
Purkinje cells
What are intercalated discs?
Transverse junctions at the ends of cells that allow passage of electrical current
What are purkinje cells?
Modified cardiac muscle cells that act as the ‘pacemaker’ for the heart
What is the fibrous pericardium?
Outer covering of dense connective tissue
What are the three components of the serous pericardium?
Parietal layer of Serous Pericardium
Visceral layer of serous pericardium
Pericardial cavity
Label the
Endocardium
Myocardium
Epicardium
Label the
Endocardium
Myocardium
Epicardium
What is this revealing?
What type of CT?
Epicardium
Dense fibrocollagenous CT with elastic fibers, lined with mesothelium
*Outermost layer of the heart wall
What is the notable structure of this tissue sample?
Branches of coronary arteries are embedded in adipose tissue of the
EPICARDIUM
What is the myocardium characterized by?
Striations
Intercalated discs
Dyad T-tubule system
Mitochondria
Lipofuscin granules
Atrial granules
What are the arrows pointing at?
Intercalated discs
*Specialized, interdigitating junctions b/w cardiomyocytes
Where are intercalated discs found?
At sites where cells meet end-to-end
ALWAYS COINCIDE WITH Z-LINES
Function of intercalated discs?
Binds cells
Transmit forces of contraction
Allow spread of excitation
Interdigitating junctions have 3 different types of membrane-to-membrane contacts:
What are they?
Transverse Region (Perpendicular)
- Fascia Adherens
- Desmosomes
Longitudinal region (parallel)
- Gap Region
Function of
Fascia adherens
Actin filaments at the ends of terminal sarcomeres insert into junction
- Transmit contractile forces b/w cells
- Most predominant
Function of
Desmosomes?
Provide anchorage for the
intermediate filaments of the cytoskeleton
Function of
Gap (nexus) junctions
Sites of low electrical resistance
Allows excitation to pass b/w cells
What is a dyad made of?
1 T-Tubule + 1 SR cisterna
What are these structures called?
Dyad T-tubules
Where are dyad T-tubules found?
Found at Z-lines
Permits uniform contraction of myofibrils within a single cardiomyocyte
What is this image revealing?
Lipofuscin Granules
What are lipofuscin granules?
- Small bodies that accumulate with age in stable non-dividing cells (i.e. cardiomyocytes)
- Contain material derived from residul bodies after lysosomal digestion
What are myoendocrine cells?
Atrial cardiomyocytes that contain membrane-bound granules
Contain precursor of atrial natriuretic factor (ANF)
Atrial Natriuretic Factor (ANF) targets _______ to _______ Na+ and H2O retention
Atrial Natriuretic Factor (ANF) targets kidneys to decrease Na+ and H2O retention
Ventricular endocardium has a ______________
Subendocardial layer
How do you distinguish b/w ventricular vs atrial endocardium?
In atria, purkinje fibers are often closer to the endothelium and intermixed with the myocardium
What are nodal cardiomyocytes?
Modified cells w/in SA/AV nodes that initiate/relay electrical signals
What is the order of the conduction system?
SA node –> AV node –> AV bundle –> R/L bundle branches –> Purkinje fibers
What is this?
Cardiac Skeleton
What is this?
Heart valve
