1. When referencing a structure present in the interstitial septum, the prenatal

Question

1. When referencing a structure present in the interstitial septum, the prenatal structure is called the ________ (foramen ovale/fossa ovalis), whereas the postnatal structure is called the ______ (foramen ovale/fossa ovalis).
2. Describe how to determine if a histological crosssection of an artery is an elastic artery or a muscular artery.
3. Described the role arterioles play in regulation of blood flow. 1. When referencing a structure present in the interstitial septum, the prenatal structure is called the ________ (foramen ovale/fossa ovalis), whereas the postnatal structure is called the ______ (foramen ovale/fossa ovalis).
2. Describe how to determine if a histological crosssection of an artery is an elastic artery or a muscular artery.
3. Described the role arterioles play in regulation of blood flow.
2. Describe how to determine if a histological crosssection of an artery is an elastic artery or a muscular artery.
3. Described the role arterioles play in regulation of blood flow.

Explanation / Answer

1. When referencing a structure present in the interstitial septum, the prenatal structure is called the foramen ovale, whereas the postnatal structure is called the fossa ovalis.

Explanation: Foramen ovale (Foramen means opening) is the opening in the interatrial septum that divides the atrium into right and left atrium which is developed in the 7th week of developing fetus and closes at birth.

When it is closed it forms a depression or dent called as Fossa ovalis (fossa= dent).

Hence prenatal term is foramen ovale whereas postnatal term is fossa ovalis

2. Describe how to determine if a histological crosssection of an artery is an elastic artery or a muscular artery.

Elastic artery: The tunica interna has of elastic artery is very thicker and occupies 20% of the total wall thickness. Subendothelial tissue has more number of elastic fibres. The internal elastic layer is not distinct and has the same stucture of the elastic membranes of tunica media. There are more number of elastic fibres in tunica media

Muscular artery: The internal elastic layer of tunica interna is well differentiated. Smooth muscle is seen in the tunica media. The external elastic lamina is very prominent. Thickness of the Tunica adventitia is more and almost equal to the thickness of the tunica media

3. Described the role arterioles play in regulation of blood flow.

Vasoconstriction of arterioles reduces the radius of lumen and increases the resistance to the blood flow (reduces the blood flow) and increases the blood pressure

Vasodilation of arterioles increases the radius of lumen and decreases the resistance, thus increasing the blood flow and reducing the blood pressure

Stimulation of sympathetic system induces release of catecholamines causing Increase in blood pressure (due to vasoconstriction) and stimulation of parasympathetic system causes decrease in blood pressure by causing vasodilation

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