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Certain hormones, such as androgens, epinephrine, thyroid hormones, and growth hormone, can affect the oxygen–hemoglobin saturation/disassociation curve by stimulating the production of a compound called 2,3-bisphosphoglycerate (BPG) by erythrocytes. BPG is a byproduct of glycolysis. Because erythrocytes do not contain mitochondria, glycolysis is the sole method by which these cells produce ATP. BPG promotes the disassociation of oxygen from hemoglobin. Therefore, the greater the concentration of BPG, the more readily oxygen dissociates from hemoglobin, despite its partial pressure.

The pH of the blood is another factor that influences the oxygen–hemoglobin saturation/dissociation curve (see [link] ). The Bohr effect    is a phenomenon that arises from the relationship between pH and oxygen’s affinity for hemoglobin: A lower, more acidic pH promotes oxygen dissociation from hemoglobin. In contrast, a higher, or more basic, pH inhibits oxygen dissociation from hemoglobin. The greater the amount of carbon dioxide in the blood, the more molecules that must be converted, which in turn generates hydrogen ions and thus lowers blood pH. Furthermore, blood pH may become more acidic when certain byproducts of cell metabolism, such as lactic acid, carbonic acid, and carbon dioxide, are released into the bloodstream.

Hemoglobin of the fetus

The fetus has its own circulation with its own erythrocytes; however, it is dependent on the mother for oxygen. Blood is supplied to the fetus by way of the umbilical cord, which is connected to the placenta and separated from maternal blood by the chorion. The mechanism of gas exchange at the chorion is similar to gas exchange at the respiratory membrane. However, the partial pressure of oxygen is lower in the maternal blood in the placenta, at about 35 to 50 mm Hg, than it is in maternal arterial blood. The difference in partial pressures between maternal and fetal blood is not large, as the partial pressure of oxygen in fetal blood at the placenta is about 20 mm Hg. Therefore, there is not as much diffusion of oxygen into the fetal blood supply. The fetus’ hemoglobin overcomes this problem by having a greater affinity for oxygen than maternal hemoglobin ( [link] ). Both fetal and adult hemoglobin have four subunits, but two of the subunits of fetal hemoglobin have a different structure that causes fetal hemoglobin to have a greater affinity for oxygen than does adult hemoglobin.

Oxygen-hemoglobin dissociation curves in fetus and adult

This graph shows the oxygen saturation versus the partial pressure of oxygen in fetal hemoglobin and adult hemoglobin.
Fetal hemoglobin has a greater affinity for oxygen than does adult hemoglobin.

Carbon dioxide transport in the blood

Carbon dioxide is transported by three major mechanisms. The first mechanism of carbon dioxide transport is by blood plasma, as some carbon dioxide molecules dissolve in the blood. The second mechanism is transport in the form of bicarbonate (HCO 3 ), which also dissolves in plasma. The third mechanism of carbon dioxide transport is similar to the transport of oxygen by erythrocytes ( [link] ).

Carbon dioxide transport

This figure shows how carbon dioxide is transported from the tissue to the red blood cell.
Carbon dioxide is transported by three different methods: (a) in erythrocytes; (b) after forming carbonic acid (H 2 CO 3 ), which is dissolved in plasma; (c) and in plasma.

Questions & Answers

action of gluteus medius and minimus
Green Reply
Lateral rotation of the hip joint
Hertzo
Briefly explain location of ecg on a patient
Prince Reply
it is a machine that gives a graphical representation of heart beat
Nani
Briefly explain location of ecg leads on a patient?
Prince
in ecg we use electrical leads over the chest ,ancle and wrist
Nani
what is the anatomical and function difference between paravertebral and prevertebral ganglia ?
Rada Reply
types of tissue in human
Preety Reply
charactetistic Of cartilaginous tissue
Preety
what is theRecurrent infection?
pankaj Reply
what do you mean about recurrent infection
pankaj
Recurrent or persistent infection is a manifestation of primary immuno deficiency
Kedha's
weakens the immune system, allowing infections and other health problems to occur more easily
Kedha's
lysis of RBC
Abdirizack
What is barometric pressure
Kedha's Reply
what is the agglutination advantage
Gopal Reply
the functions of the liver
Nana Reply
it produces bile juice which is used to make the food smaller
Kedha's
it also plays an important role in conversion of amino acid into urea
Komal
it also has role in gluconeogenesis in which amino acids and lipids convert into glucose.
Komal
during fetal life it's a center for hemopoiesis (formation of blood cells)
Komal
it filters, or removes, harmful substances from the blood
Kedha's
It stores nutrients, such as vitamins and iron,for the body
Kedha's
what is the largest gland in human body
Shahid Reply
liver
rachna
correct
Said
correct
dominic
thyroid gland
Kedha's
thyroid is largest endocrine gland
Komal
describe microscopic structures of the kidney
Nana Reply
kidney is covered by fibrous capsule, consists of an outer cortex and inner medulla with medullary pyramids. The microscopic structure is seen as 1-2 millions of nephrons and collecting tubule.
Komal
identify the four major tissue types
Binkheir Reply
connective epithelial
Nana
two ramining
Binkheir
muscle nervous
Nana
epithelial, connective, muscle, and nervous tissue
Mel
tell me about urine formation
Nana Reply
it includes three steps. ultrafiltration selective reabsorption tubular secretion
Komal
ultrafiltration also known as glomerular filteration. All solutes up to 4nm size and water can freely pass through the filtering membrane.
Komal
selective reabsorption : About more than 99% of water ,electrolytes and other substances are reabsorbed by the tubular epithelial cells. The reabsorbed subtances move into interstitial fluid and then into blood of peritubular capillaries .
Komal
The substances like water ,glucose,amino acids and electrolyte are reabsorbed
Komal
tublar secretion: the substances are transported from blood to again into the renal tubules
Komal
and then those are excreted out as urine
Komal
internal and external structures of the kidney
Nana Reply
how the kidney works
Nana
on the bases of pressure and filtration
Said
General
Nana
excretion of wasts, role in hb, role in vit D synthesis
Said
care to explain?
Okoye
yes plx
Nana
the differences between eukaryotic and prokaryotic
Binkheir Reply
eukaryotic don't have nucleus and prokaryotic have nucleus.
Emmmanuel
no, the eukaryotic has well enveloped nucleus and prokaryotic has nucleus without membrane which is also known as nucleoid
Komal
Eukaryotes have organized nucleus and prokaryotes don't have organized nucleus
Kedha's
what is staphylococcus?
Binkheir Reply
Its a bacteria
kannan
they also cause staph infections
Nana
on the skin
Nana
the definition of staphylococcus?
Binkheir
pathogenic organism
Frank
Spherical shaped bacteria arranged in different rows causing infections
PL
type of bacteria
Kedha's
gram negative or positive?
Peter
gram positive
Komal

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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