The study of blood, the blood-forming organs, along with blood diseases and their treatment.

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Is there any advantage to one blood type over another?

All humans can be grouped into ABO and Rh+/- blood groups (at a minimum). Is there any advantage at all to one group or the other? This article hints that there are some pathogens that display a ...
26
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3answers
6k views

Why draw blood from veins rather than arteries?

Why draw blood from veins rather than arteries? Is it more convenient or safer?
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3answers
34k views

Why do mammalian red blood cells lack a nucleus?

How did the red blood cell in humans get to lose its nucleus (and other organelles)? Does the bone marrow just not put the nucleus in, or is it stripped out at some stage in the construction of the ...
21
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1answer
610 views

Are lymphocyte sizes clustered in two groups?

Tortora writes in Principles of Anatomy and Physiology: Lymphocytes may be as small as 6–9 μm in diameter or as large as 10–14 μm in diameter. Those ranges are quite close to each others. Should ...
18
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4answers
2k views

Why do we need red blood cells?

From what I know, the main function of red blood cells is hemoglobin transport. So, why do we need cells packed with hemoglobin: why can't it travel freely in the bloodstream? My own thoughts were: ...
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5answers
9k views

Origin, or source, of rhesus negative in human blood

This is my first post here, so please be gentle. I recently learned that I have Rh- blood (I'm A-), and was idly looking into blood types on Wikipedia. I was surprised to find that relatively few ...
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2answers
9k views

Why do people have antibodies against other blood types?

The ABO blood type divides each blood type according to whether they have the "A" and "B" antigen(s) (AB has both, O has none). People also have antibodies against the antigens they don't have (AB has ...
12
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1answer
2k views

Why does oxygen bind to hemoglobin in an specific angle?

There is an specific angle of the bond between oxygen and hemoglobin in lungs, which I don't know, but what interests me more is the question, why is it specific?
10
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1answer
807 views

Where is the aneurysm in this picture?

I'm a curious person, I've never had any medical training, but I wish to know some more about aneurysms. Aneurysms are basically weakened spots in the elastic artery wall. This can eventually result ...
9
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2answers
2k views

What percent of your blood can you lose before you need a transfusion

Losing a little blood is okay. If your a normal healthy person, and got into an accident, how do they know if you need a transfusion or if you'll be okay? This is hypothetical.
9
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1answer
140 views

Why do so many people have group O blood?

Please forgive me in case my question wouldn't make much sense. I was reading about ABO blood groups on Wikipedia, where I learnt that O is a recessive allele, and that it seems the A allele predates ...
9
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1answer
194 views

What are the clotting factors' effect on avascular necrosis development?

Do clotting factors tpa and pai-1 lead to degenerative osteoarthritis in the same way that lupus anticoagulant and prothrombin might? Is one of these pathways particularly detrimental during formation ...
8
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3answers
1k views

What is this microscopic image from Peter Gabriel's New Blood album cover?

This image appears on the cover of Peter Gabriel's album New Blood. It appears to be a photograph of some microscopic biological cell. But it doesn't look like a blood cell to me. What kind of ...
8
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2answers
2k views

Is blood an organ according to biology?

It consist approximately 7 percent of body weight. By definition organ is composed of multiple tissues. Blood is a fluid, a circulating tissue. Therefore can we call this fluid system a liquid ...
8
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1answer
215 views

Does the oxygen concentration equilibrate between red blood cells in the liver sinusoids?

In the sinusoids of the liver, venous blood from the hepatic portal system mixes with arterial blood from the hepatic arteries. Do oxygen molecules move between oxygenated RBCs and non-oxygenated ...
8
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2answers
798 views

Fate of erythrocytes after splenectomy

The spleen is considered a graveyard for red blood cells. So in case of Splenectomy (complete surgical removal of the spleen), what would be the fate of red blood cells? Would this cause Polycythemia? ...
7
votes
1answer
416 views

When giving blood, what is the specific Iron measurement they take?

I went to give blood the other day, and they take an "iron" measurement prior to actually drawing the blood. My level was 16.4 -- but what specific type of iron were they measuring? I've heard of ...
7
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2answers
101 views

Do other animals have different blood types?

Humans have the ABO and Rhesus blood typing systems. I have two questions about it: Why have we evolved these blood types? Do other animals have different blood types as well?
6
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2answers
14k views

Can positive and negative blood type of a couple lead to miscarriage?

I want to know can $+ve$ and $-ve$ blood group of a couple could be a cause of miscarriage in pregnancy?
6
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1answer
68 views

Why ml scale blood retrieval is required to run a blood test?

Substances found in blood are present at microscopic scale and tend to be invisible to the unaided eye. Why is a whole vial of blood (at ml scale) is required to assess the presence and concentration ...
6
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1answer
439 views

Does a blood transfusion cure disease?

Does transferring blood between two people also transfer all the white blood cells? Why can't AIDS victims with low t-cell count just get blood transfusions till they have more t-cells? Why can't ...
6
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1answer
80 views

Blood cells penetration

Is there a type of blood cell that can reach all other body cells? By "reach", I mean to "touch" the surface of the target cell. If we look at the red blood cell for example, that moves in blood ...
6
votes
1answer
867 views

Why extract DNA from certain white blood cells instead of whole blood?

In my lab, human DNA is extracted from whole-blood samples. I don't actually do the extractions and I am not familiar with the specific protocol but I understand that platelets and red blood cells ...
6
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1answer
94 views

Time lapse between fresh blood's exposure to air and that same blood turning darker red-brown

For investigative purposes, I'm searching for a tool that can be used as a quick visual assessment of the the length of time that blood has been exposed to air after the blood flow has stopped.. Let's ...
5
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1answer
245 views

How can the child and the mother have different blood types?

As far as I know the fetus is fed by the umbilical cord which basically connects his/her circulatory system with the mother's in order to supply oxygen and nutrients. But how is this possible if they ...
5
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2answers
1k views

Why do men have a higher hematocrit (red blood cell count) than women?

The hematocrit, also known as packed cell volume (PCV) or erythrocyte volume fraction (EVF), is the volume percentage (%) of red blood cells in blood. It is normally 45% for men and 40% for women. ...
5
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1answer
313 views

Are tongues red because they contain blood?

Many animals have red tongues, though not all of them - blue-tongued skinks and giraffes come to mind. Are they red because of the blood (and therefore haemoglobin) in them? It sounds plausible, but ...
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1answer
2k views

Why does blood come from mouth when people are shot in the chest area?

In almost every movie scene when a character is shot in the chest area, some blood comes from his mouth or sometimes even coughs blood before he dies. Are these kind of scenes realistic/possible? If ...
4
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1answer
210 views

Besides hemoglobin, what proteins are present in red blood cells?

I knew that mature red blood cells (RBCs) lacked nuclei, but I wasn't aware until just now that they also lacked ribosomes and mitochondria. Most cells in the human body all contain a common laundry ...
4
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1answer
79 views

Blood consumption

Is consumption of blood more "dangerous" compared to meat? There was a news-article about unnatural chemicals found in the blood of mothers. This reminded me about a question I have pondered upon ...
4
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1answer
206 views

Does Blood Loss Shorten Telomeres?

If blood loss necessitates immediate cell division to replace lost cells, does the increase in cell division correlate to shortening of telomeres? Does it further cause the Hayflick Limit to be ...
4
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1answer
82 views

Why don't individuals with sickle cell trait suffer from sickle cell anemia?

Ostensibly, in people with sickle cell trait, half of the hemoglobin in their body would be defective. Is it actually the case that sickle cell hemoglobin is produced in equal amounts? If not, how ...
4
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2answers
1k views

What happens when you mix type A with type B blood (and v.v)

What happens when you mix different blood types that are not compatible? For example, if a patient has type A blood and receives type B blood, or v.v.?
4
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1answer
1k views

why does blood when oxidized over time become bluish green?

Oxygenated blood is bright red and deoxygenated blood is dark red or brown. If you take oxygenated blood and leave it in the air it will turn dark red, then brown, then finally a bluish green from ...
4
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1answer
46 views

Parents are Rh +ve and child Rh -ve

Suppose the two parents of a child have blood groups A+ve and O+ve, and the child has O-ve type. For blood group, there are two alleles. Since the child has O, the father must have one 'A' allele and ...
4
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1answer
170 views

Why isn't Rh disease present in other mammals?

I have read about Rhesus D Hemolytic Disease of the Newborn, sometimes called "Rh disease". It's rare, but it can happen when an Rh+ baby is conceived by an Rh- mother. This raises many questions. I ...
4
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1answer
119 views

Is it possible to condition the body to reduce bruising?

I do combat sports, and in these sports there are a lot of hits that can cause bruising. I've found that, over time, physical conditioning can reduce and/or eliminate the bruising to the point where ...
4
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1answer
120 views

What percentage of human capillaries are located in the skin?

As in the subject line, what percentage of capillaries in a human (expressed in terms of total length, I suppose) are located in the skin, as opposed to internal organs? Google scholar has not turned ...
3
votes
1answer
322 views

Possible genotypes for blood types?

If I am blood type B, what are all the possible genotypes that could be expressed by my parents? I think it might be 16 but I was reading online and saw this: Similarly, someone who is blood type ...
3
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1answer
2k views

How much does donating blood affect the amount of oxygen in your blood stream at high altitude?

I am a regular blood donor and I am also a skydiver. We normally go to around 13,000 feet AGL (above ground level). Depending on how high above sea level the ground is, altitudes could be as high as ...
3
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1answer
43 views

In which of the following diseases structure of haemoglobin produced is normal but their amount reduced?

The options provided are- Chronic blood loss Sickle cell anaemia Haemolytic anaemia Thallasaemia Transfusion reactions - *Q-15: pg-785; **Review of Medical Physiology - William F. ...
3
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1answer
56 views

How does Hemocytoblast constantly get formed into so many blood cells and yet remains there in the bone marrow throughout the lifetime?

I mean, Hemocytoblast is a stem cell which is constantly being differentiated into daughter cells and leads to formation of all the blood cells (having short and limited life spans), so how come those ...
3
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2answers
3k views

Presence of MHC on red blood cells

Do red blood cells have no MHC? (I have often heard that they do not.) If so why are they not destroyed by immune cells?
3
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1answer
80 views

Any evolutionary explanation for human blood groups?

What is the explanation of people having blood types from an evolutionary perspective?
3
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1answer
27 views

External tissues, connected to the body?

Some cancer tumors suppress themselves from spreading. When such tumors are removed by surgery, the metastasis process is accelerated. Isn't it possible to put such tumors into external device like ...
3
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2answers
2k views

What is the genetic basis of blood type (ABO) system?

What is the genetic basis of the A/B/B+/O/etc. blood type system? Are there definitive loci that correspond to each or can multiple different genotypes produce the same antigen profile? Also, is the ...
3
votes
1answer
80 views

Why oxLDL accumulate to form foam cells?

In atherosclerosis, why macrophage store all the cholesterol from oxLDL inside, and turns to foam cell, and not just degrade it and going back to blood? (there are some amount that leave the plaque, ...
3
votes
1answer
101 views

How do CO₂ and carbonic acid (H₂CO₃) work in buffering the blood?

Been struggling with this for the past few days even after reading half of the acid base tutorial here, if someone could help me that'd be great. What I don't understand is how HCO3- is supposed to ...
3
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1answer
95 views

How do genetic chimeras with different blood types not die?

If a person is a chimera and has two different blood types in his veins, how does he not die? Shouldn't the immune system attack one of the blood types? In 1953 a human chimera was reported in the ...
3
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1answer
244 views

When was the purpose of bone marrow discovered?

I'm currently reading William Cheselden's book Osteographia or The Anatomy of the Bones, which was published in 1733 (for the pretty pictures, naturally; not up to date anatomy). When he addresses the ...