Human Anatomy and Physiology: Cardiovascular, Reproductive and Immune Systems

Orifice of pulmonary trunk is also known as the opening of pulmonary trunk in mammals. It is the opening between the pulmonary trunk and the right ventricle of the mammalian heart.

The internal urethral orifice is defined as the opening of the urinary bladder into the urethra. It lies at the apex of the trigonum vesicae.

Human embryology is the branch of biology, which deals with the study of the development of embryo during the first eight weeks after fertilisation. The normal period of gestation (pregnancy) is nine months or 38 weeks.

These terminal components form a complex which inserts into the membrane to form a transmembrane ion channel which leads to lysis of the cell.

Meissner's corpuscles are the touch receptors located near the surface of the skin in human beings.The foreskin contains sensory receptors called Meissner corpuscles. These nerves provide pleasure as well as fine sensory perception.

C5a is a powerful chemotactic agent and also an anaphylatoxin.

This is a cell matrix component.

Activation of mast cells releases chemotactic factors for neutrophils and also vasoactive mediators such as histamine.

T-cells are derived from bone marrow stem cells and differentiate into immunocompetent cells in the thymus.

The alpha chain is specific for each VLA molecule (for example, VLA-1 is an alpha1beta1 molecule whilst VLA-6 is an alpha6beta1 molecule).

The high-walled endothelium of the post-capillary venules (HEV) in lymph nodes express vascular addressins, which are recognised by homing receptors on lymphocytes passing through the afferent lymphatics and which mediate entry of the lymphocytes into the lymph nodes.

Hematopoiesis originates in the early yolk sac, but as embryogenesis proceeds, this function is taken over by the fetal liver and spleen, and then later by the bone marrow, where it continues throughout life.

HIV infection is due to the transmission of the HIV virus, not the antibody. However, the presence of maternal anti-HIV IgG can lead to diagnostic difficulty. It is thus necessary to confirm HIV infection in the newborn by the presence of viral DNA or RNA using a polymerase chain reaction (PCR) method.

The coronary sinus is a major coronary vein. It returns the majority of the left ventricular blood flow to the right atrium. The coronary sinus orifice of the right atrium is the aperture via which approximately 90% venous drainage of the heart is returned to the circulation by the coronary sinus.

Pregnancies that share the placenta and amnion are at the highest risk of adverse outcome because of risk of twin-to-twin transfusion syndrome and cord entanglement.

Nearly all gamma delta T-cells in the skin express V gamma 5.