FATOR RH - Grupos Sanguíneos - Resumo | Biologia com Samuel Cunha

Summary

This video lesson explains the RH factor in blood types, focusing on the differences between RH positive and RH negative. It covers the genetic basis of RH compatibility, explaining how RH positive individuals can have either homozygous or heterozygous genotypes, while RH negative individuals are always homozygous recessive. The lesson also delves into blood donation compatibility, highlighting important aspects like the production of antibodies in RH negative individuals when exposed to RH positive blood. Additionally, it touches on the concept of erythroblastosis fetalis and provides practical examples to clarify the topic for students, especially for ENEM and vestibular exams.

Takeaways

• 😀 The Rh factor is important when donating blood and is either positive or negative, like the ABO blood type system.
• 😀 There are two types of Rh factor: Rh-positive (dominant) and Rh-negative (recessive). The Rh-positive gene is denoted as 'R' and the Rh-negative gene as 'r'.
• 😀 The Rh-positive blood type expresses the Rh factor on red blood cells, while Rh-negative blood lacks this factor.
• 😀 If a person is Rh-negative, their genotype must be homozygous recessive (rr). Rh-positive individuals can have either homozygous (RR) or heterozygous (Rr) genotypes.
• 😀 When an Rh-negative person receives Rh-positive blood, they may produce anti-Rh antibodies that can cause complications.
• 😀 Rh-positive individuals do not produce anti-Rh antibodies because they already have the Rh factor in their blood.
• 😀 Blood compatibility for donations includes both ABO and Rh systems. An Rh-negative person can donate blood to Rh-positive individuals, but the reverse is not true.
• 😀 The issue of erythroblastosis fetalis arises when an Rh-negative mother carries an Rh-positive baby, which can lead to complications if not properly managed.
• 😀 Today, with modern medical treatments, erythroblastosis fetalis is preventable through prenatal care, ensuring that there is no danger to the baby in such pregnancies.
• 😀 Understanding the genetics of Rh factor is crucial for predicting possible blood types in children, especially when one parent is Rh-negative and the other Rh-positive.

Q & A

What is the Rh factor, and how does it relate to blood types?

The Rh factor refers to a glycoprotein present in red blood cells. If a person has this protein, they are Rh positive; if not, they are Rh negative. It is important for blood transfusions and compatibility, alongside the ABO blood group system (A, B, AB, O).

What are the two types of Rh factors, and how are they inherited?

The two types of Rh factors are Rh positive and Rh negative. Rh positive occurs when an individual inherits at least one dominant 'R' allele (RZão). Rh negative results from inheriting two recessive 'r' alleles (rzinho).

What is the significance of the dominance and recessiveness of the Rh alleles?

The Rh positive allele (RZão) is dominant over the Rh negative allele (rzinho). This means that if a person inherits one Rh positive allele, they will express the Rh positive phenotype. Rh negative expression requires two Rh negative alleles.

How does the Rh factor affect blood donation and compatibility?

For blood donation, Rh positive individuals can donate blood to other Rh positive individuals, while Rh negative individuals can only donate to others who are Rh negative. However, Rh negative individuals can donate to both Rh negative and Rh positive recipients without problems.

What is the role of antigens and antibodies in Rh compatibility?

The Rh factor acts as an antigen on the surface of red blood cells. Individuals with Rh negative blood do not have this antigen and may produce anti-Rh antibodies if exposed to Rh positive blood. Rh positive individuals do not produce these antibodies because they already have the Rh antigen.

What is erythroblastosis fetalis, and how is it related to Rh incompatibility?

Erythroblastosis fetalis occurs when an Rh negative mother carries an Rh positive fetus. The mother may develop antibodies against the Rh antigen, potentially attacking the fetus's red blood cells in subsequent pregnancies. However, this condition is preventable with modern medical care, such as Rh immunoglobulin injections.

What are the possible outcomes of a cross between two heterozygous Rh positive individuals?

A cross between two heterozygous Rh positive individuals (RZão rzinho) results in a 75% chance of an offspring being Rh positive and a 25% chance of being Rh negative, due to the possible inheritance of the recessive Rh negative allele.

Can two Rh negative parents have an Rh positive child?

No, two Rh negative parents (both having the genotype rzinho rzinho) cannot have an Rh positive child. The child would inherit an Rh negative allele from each parent, resulting in an Rh negative phenotype.

How does a Rh negative woman with an Rh positive partner affect their child’s Rh factor?

If a Rh negative woman (rzinho rzinho) is partnered with an Rh positive man (RZão rzinho or RZão RZão), their child could be Rh positive if they inherit the Rh positive allele (RZão) from the father.

Why is it important to know both ABO and Rh blood types for blood donation?

It is crucial to know both the ABO blood type and the Rh factor for blood donation because compatibility depends on both systems. A person with Rh positive blood can receive from both Rh positive and Rh negative donors, but an Rh negative person can only receive blood from Rh negative donors.