OSSF COMPREHENSIVE EXAM 2025/2026 QUESTIONS
WITH ANSWERS GRADED A+
✔✔What is the name of the separation between the ventricles and atria? -
✔✔Membranous septum
✔✔True/false: the heart needs a stimulus in order to beat - ✔✔False
✔✔What kind of cells make up the SA node? - ✔✔Modified cardiac myocytes
✔✔How are the cells of the SA node different from cardiac myocytes? - ✔✔Few
myofibers, no intercalated discs
✔✔What are the characteristics of the purkinje fibers? - ✔✔Few myofilaments, lots of
glycogen, conducts impulses much faster than muscle cells
✔✔What are the layers of vessels, from outside to inside? - ✔✔Tunica adventitia, tunica
media, tunica intima
✔✔What are the components of the tunica intima? - ✔✔Endothelium and basement
membrane, connective tissue, may or may not have internal elastic lamina
✔✔What is the function of the tunica intima? - ✔✔Regulate permeability
✔✔What are the components of the tunica media? - ✔✔Smooth muscle, external elastic
lamina
✔✔What is the function of the tunica media? - ✔✔Regulation of vessel compliance - by
number of elastic fibers and contractile state of smooth muscle
✔✔What are the components of the tunica adventitia? - ✔✔Connective tissue, adipose
✔✔What is the function of the tunica adventitia? - ✔✔Neuronal regulation of vessel wall
✔✔What is an example of a muscular artery? - ✔✔Coronary arteries
✔✔Are the internal and external elastic laminae visible in elastic arteries? - ✔✔They are
indistinct
✔✔Are the internal and external elastic laminae visible in muscular arteries? - ✔✔They
are prominent
✔✔Are the internal and external elastic laminae visible in small arteries? - ✔✔Only
internal, they don't have external elastic laminae
, ✔✔What layer is thinnest in arterioles? - ✔✔tunica adventitia
✔✔What layer is generally thinnest in veins? - ✔✔Tunica media
✔✔What layer is more prominent in veins? - ✔✔Tunica adventitia
✔✔Endothelium in which vessels is the target for vasoactive agents? - ✔✔Postcapillary
venules
✔✔What direction do lymph vessels flow in? - ✔✔Tissues to heart
✔✔True/false: Lymph vessels are more permeable than blood vessels - ✔✔True
✔✔What is the largest lymph duct? - ✔✔Thoracic duct
✔✔True/false: lymph vessels do not contain smooth muscle - ✔✔False
✔✔What are similarities between cardiac and skeletal muscle - ✔✔Striated, T tubules,
sarcomeres
✔✔What are characteristics of cardiac muscle that separate it from skeletal muscle? -
✔✔Intercalated discs, shorter, branched
✔✔What is the clinical importance of troponin? - ✔✔After a heart attack, they are
released to the blood
✔✔Mutations in what can cause hypertrophic cardiomyopathy? - ✔✔Myosin, Cardiac
myosin binding protein C
✔✔What is the concept of syncytium? - ✔✔Electrically coupled cells - passing AP from
one cell to another
✔✔What are the two types of cardiac myocytes? - ✔✔Contractile, conducting
✔✔What kind of myocyte make up the majority? - ✔✔Contractile
✔✔What is the key feature of conduction myocytes? - ✔✔They can spontaneously
depolarize
✔✔Why is the SA node the designated pacemaker? - ✔✔It has a faster conduction
velocity
WITH ANSWERS GRADED A+
✔✔What is the name of the separation between the ventricles and atria? -
✔✔Membranous septum
✔✔True/false: the heart needs a stimulus in order to beat - ✔✔False
✔✔What kind of cells make up the SA node? - ✔✔Modified cardiac myocytes
✔✔How are the cells of the SA node different from cardiac myocytes? - ✔✔Few
myofibers, no intercalated discs
✔✔What are the characteristics of the purkinje fibers? - ✔✔Few myofilaments, lots of
glycogen, conducts impulses much faster than muscle cells
✔✔What are the layers of vessels, from outside to inside? - ✔✔Tunica adventitia, tunica
media, tunica intima
✔✔What are the components of the tunica intima? - ✔✔Endothelium and basement
membrane, connective tissue, may or may not have internal elastic lamina
✔✔What is the function of the tunica intima? - ✔✔Regulate permeability
✔✔What are the components of the tunica media? - ✔✔Smooth muscle, external elastic
lamina
✔✔What is the function of the tunica media? - ✔✔Regulation of vessel compliance - by
number of elastic fibers and contractile state of smooth muscle
✔✔What are the components of the tunica adventitia? - ✔✔Connective tissue, adipose
✔✔What is the function of the tunica adventitia? - ✔✔Neuronal regulation of vessel wall
✔✔What is an example of a muscular artery? - ✔✔Coronary arteries
✔✔Are the internal and external elastic laminae visible in elastic arteries? - ✔✔They are
indistinct
✔✔Are the internal and external elastic laminae visible in muscular arteries? - ✔✔They
are prominent
✔✔Are the internal and external elastic laminae visible in small arteries? - ✔✔Only
internal, they don't have external elastic laminae
, ✔✔What layer is thinnest in arterioles? - ✔✔tunica adventitia
✔✔What layer is generally thinnest in veins? - ✔✔Tunica media
✔✔What layer is more prominent in veins? - ✔✔Tunica adventitia
✔✔Endothelium in which vessels is the target for vasoactive agents? - ✔✔Postcapillary
venules
✔✔What direction do lymph vessels flow in? - ✔✔Tissues to heart
✔✔True/false: Lymph vessels are more permeable than blood vessels - ✔✔True
✔✔What is the largest lymph duct? - ✔✔Thoracic duct
✔✔True/false: lymph vessels do not contain smooth muscle - ✔✔False
✔✔What are similarities between cardiac and skeletal muscle - ✔✔Striated, T tubules,
sarcomeres
✔✔What are characteristics of cardiac muscle that separate it from skeletal muscle? -
✔✔Intercalated discs, shorter, branched
✔✔What is the clinical importance of troponin? - ✔✔After a heart attack, they are
released to the blood
✔✔Mutations in what can cause hypertrophic cardiomyopathy? - ✔✔Myosin, Cardiac
myosin binding protein C
✔✔What is the concept of syncytium? - ✔✔Electrically coupled cells - passing AP from
one cell to another
✔✔What are the two types of cardiac myocytes? - ✔✔Contractile, conducting
✔✔What kind of myocyte make up the majority? - ✔✔Contractile
✔✔What is the key feature of conduction myocytes? - ✔✔They can spontaneously
depolarize
✔✔Why is the SA node the designated pacemaker? - ✔✔It has a faster conduction
velocity
