Orifices of heart, Biology

Assignment Help:

Atrio-ventricular Orifices

The right and left atrio-ventricular orifices are oval apertures. The openings lie in a plane that is almost vertical with a slight downward inclination. Each opening is directed forwards then left and slightly downwards. Each orifice is strengthened by a variable amount of fibrous tissue around it. It is guarded by a valve which allows flow of blood, only from atrium to ventricle but not in the reverse direction. The valves are made up of cusps which are thin leaflets of tissue. Each cusp consists of a double fold of endocardium within which is some fibrous tissue. It has two surfaces, ventricular and atrial. It has a base which is attached to the ring of fibrous tissue around the Atrio-ventricular orifice. It has an apex and free margins. The margins of adjoining cusps are fused to each other for some distance so that the cups form a continuous membrane. The apex and the margins give attachment to tendinous strands called the chordae tendinae. The chordae tendinae are also attached to the ventricular surfaces of the cusps which are therefore, rough in contrast to the atrial surface which are smooth. At their other end the chordae tendinae are attached to the apices of the papillary muscles. Each papillary muscle through the chordae tendinae is attached to the adjoining part of the two cusps. As a result the adjoining margins of the two cusps are drawn together when the papillary muscle contracts.

The features peculiar to each orifice are: the right orifice is larger than the left; it admits the tips of three fingers. In contrast the left orifice is smaller and admits the tips of two fingers. The arrangements of cusps and papillary muscles also differ.


Related Discussions:- Orifices of heart

Explain inhibition of cancer cell proliferation and growth, Explain Inhibit...

Explain Inhibition of cancer cell proliferation and growth? Vitamin D diminishes proliferation of abnormal intestinal, lymphatic, mammary and skeletal cells and provides a pote

Explain prevention of endocarditis, Explain prevention of endocarditis ...

Explain prevention of endocarditis Many physicians believe that antimicrobial prophylaxis before process that may cause transient bacteremia can stop endocarditis and prostheti

Explain the interaction of vitamin a with vitamin e, Explain the Interactio...

Explain the Interaction of Vitamin A with Vitamin E? Of the various nutrients, the interaction of vitamin E, proteins, zinc and iron with vitamin A is of significance. Know? Le

Assessment of tubercular meningitis, Assessment   For assessment of cli...

Assessment   For assessment of clinical manifestation of the disease you need to understand three stages of clinical course of the disease which are as follows:  Prodromal

Explain micafungin, Explain Micafungin It is an echinocandin indicated ...

Explain Micafungin It is an echinocandin indicated for treatment of esophageal candidiasis and prophylaxis of invasive Candida infections in patients undergoing hematopoietic s

Why enzymes work to speed up a chemical reaction, Enzymes work to speed up ...

Enzymes work to speed up a chemical reaction by: a. attaching coenzymes to the substrate b. heating up the substrate c. lowering the activation energy of the reaction d. supplyi

Explain the meaning of protein deficiency, Explain the Protein Deficiency? ...

Explain the Protein Deficiency? One of the most common nutritional disorders in the world today is the deficiency of protein. Both adults and children are affected, as the popu

Traumatology, Traumatology : This is the study of wounds. In other words we...

Traumatology : This is the study of wounds. In other words we can say that traumatology  is the study of wounds or injuries which can be caused by accidents or violence to a person

Anticodon, Anticodon is the series of three nucleotides on the transfer RN...

Anticodon is the series of three nucleotides on the transfer RNA molecule which recognizes and pairs with the specific codon on a messenger RNA molecule; it helps in controlling t

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd