Histology Flashcards
Order of layers from superficial to internal
Epicardium - myocardium - endocardium
Endothelium of endocardium
Simple squamous endothelium
Layer under endothelium of endocardium
Subendocardial layer
Cells of endocardium endothelium
Elastic and connective fibers
Content of subendocardial layer
Microvasculature
Nerves
Purkinje fibers
Which layer is highly vascularized
Myocardium
Outermost layer
Epicardium
Epithelium of epicardium
Simple squamous epithelium
What surrounds the pericardium
An external layer of adipose tissue
Atrioventricular valves
Tricuspid valve (right atrium to right ventricle) Mitral valve (left atrium to left ventricle)
Semilunar valves
Pulmonary valve
Aortic valve
Central core of atrioventricular valves
Dense fibrous connective tissue
Structure with high dense connective tissue and a thin layer of endothelium
Aortic valve
What are the cells conducting the system of SA node
Modified cardiac muscle cells
Purkinje fibers are
Conducting myofibers
Cells rich in mitochondria and glycogen
Purkinje fibers
Which are larger, purkinje fibers or cardiac muscle fibers
Purkinje fibers
Order of veins from large to small
Large vein - medium sized vein - venule
Order of arteries from large to small
Elastic artery - muscular artery - arteriole
Difference between arteries and muscular arteries
Muscular arteries have an internal elastic lamina between tunica intima and media + an external elastic lamina between tunica media and tunica externa
Difference between large veins and medium sized veins
Medium sized veins have valves
Order of components in vascular wall arteries and veins
Endothelium - smooth muscle - connective tissue
Main structural difference between artery and veins
Arteries are round looking under microscope
Order of vessel wall layers from internal to external
Intima - media - adventitia
Epithelium of tunica intima of vessel wall
Simple squamous epithelium
Key characteristic of tunica intima - media
Internal elastic membrane separating both
Layer between tunica intima and media formed of
Smooth muscle cells
Function of myocytes
Modify blood flow / blood pressure
What system controls the contraction of myocytes
Autonomic nervous system + hormones + local chemicals
What is vasa vasorum in tunica adventitia
Small blood vessels that supply oxygen + nutrients to tunica media
Function of nervi vascularis in tunica adventitia
Small nerves controlling myocyte contraction
Take home message of tunica intima
Endothelium + basal lamina of CT
Take home message of tunica media
Layers of smooth muscle cells
Take home message of tunica adventitia
CT later, fibroblast, collagen + elastic fibers
Which are elastic arteries
Aorta, pulmonary arteries and their main branches
What separates smooth muscle cells in tunica media
Elastic lamellae
The number and thickness of lamellae related to
Blood pressure and age
Components of elastic arteries: tunica media
Smooth muscle
Fenestrated elastic lamellae
Collagen fibers
Elastic fibers tunica adventitia
Collagen fibers, elastic fibers, vasa vasorum, nervi vascularis, fibroblasts
Which arteries help reduce changes in pressure
Elastic arteries
What is missing in tunica media of muscular arteries that elastic arteries have
Elastic lamellae
What are muscular arteries
Distributing arteries
Which are the most abundant arteries
Muscular arteries
Muscular arteries have a thick
Tunica media
Which endothelium is thinner of tunica intima, in muscular or elastic arteries
In muscular arteries thinner due to thinner subendothelial CT
Collagen stains
Blue
Elastic lamellae stains
Purple
Function of arterioles
Regulate blood flow + at terminal vessels
Function of metarterioles
Channels of delivering blood to capillary bed
Metarterioles are surrounded by
Incomplete rings of smooth muscle
Slowest and thinnest vessels
Capillaries
Endothelium of capillaries
Single endothelial cells
What do pericytes look like
Small dark cells on the sides of capillaries
Function of pericytes
Communicate w/ endothelial cells
Involved in contractile cells and tissue regeneration
Continuous capillaries basement membrane
Continuous
Continuous capillaries basement membrane
Continuous
Function of continuous capillaries
Regulate exchange of materials
Main characteristic of continous capilaries
Continuous membrane and pinocytic vesicles
Fenestrated capillaries
Openings bridged by diaphragm
Function of fenestrated capillaries
A more extensive molecular exchange
Where are fenestrated capillaries found
Kidney, intestine… tissues of rapid exchange
Discontinuous capillaries function
Leakage between endothelial cells
Maximum macromolecule exchange occurs at which capillary
Discontinous capillary
What depends on size, charge and shape of trasversing molecules
The permeability of capillaries
What molecules cross through transcellular pathway (diffusion)
Small lipid-soluble (O2, CO2…)
What molecules cross through paracellular pathway (Water pores)
Small water soluble molecules (H2O, Aa, glucose)
What molecules cross through transcytosis (capillaries)
Macromolecules, Ab, albumin
Thoroughfare channel in capillary network are
Direct connections between metarteriole and venules
Precapillary sphincter are
Rings of smooth muscle that either open or close capillary flow
What controls the arteriovenous anastosomes
Thermoregulation
During cold temperatures:
Dilated anastomosis so blood does not pass to capillaries
During warm temperatures:
Constricted anastomosis so blood crosses to capillaries and releases heat
Arterial portal system ex.
Kidney portal system
Place at which white blood cells leave circulation
Postcapillary venules
Distinguish veins from arterioles
Veins are not round lookng and have red dots in center
Predominant layer in arteries
Tunica media
Predominant layer in veins
Tunica adventitia
Both media and adventitia layer in veins have
Elastic fibers
Valves in large veins are rich in
Elastic fibers
Function of valves
Prevent backflow
Why are valves in veins and not in arteries
Due to the low pressure in veins
Elastic lamina in veins are seen or not seen
NOT seen
Motor nerves are
Efferent
Sensory nerves are
Afferent
Principle site at which WBC leave circulation
Postcapillary venules
Is there an elastic membrane between tunica media and adventitia in VEINS
NO
More vasa vasorum in veins or in arteries
In veins
Carotid sinus has chemoreceptors or baroreceptors
Baroreceptor
Carotid body has baroreceptors or chemoreceptors
Chemoreceptors
Carotid body (chemoreceptors) responds to
Low O2 and pH
High CO2
Function of carotid sinus (baroreceptor)
Regulate blood pressure