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Not all organisms use hemoglobin as the method of oxygen transport. Invertebrates that utilize hemolymph rather than blood use different pigments to bind to the oxygen. These pigments use copper or iron to the oxygen. Invertebrates have a variety of other respiratory pigments. Hemocyanin, a blue-green, copper-containing protein, illustrated in [link] b is found in mollusks, crustaceans, and some of the arthropods. Chlorocruorin, a green-colored, iron-containing pigment is found in four families of polychaete tubeworms. Hemerythrin, a red, iron-containing protein is found in some polychaete worms and annelids and is illustrated in [link] c . Despite the name, hemerythrin does not contain a heme group and its oxygen-carrying capacity is poor compared to hemoglobin.

Molecular model A shows the structure of hemoglobin, which is made up of four protein subunits, each of which is coiled into helices. Left right, bottom and top parts of the molecule are symmetrical. Four small heme groups are associated with hemoglobin. Oxygen is bound to the heme. Molecular model B shows the structure of hemocyanin, a protein made up of coiled helices and ribbon-like sheets. Two copper ions are associated with the protein. Molecular model C shows the structure of hemerythrin, a protein made of coiled helices with four iron ions associated with it.
In most vertebrates, (a) hemoglobin delivers oxygen to the body and removes some carbon dioxide. Hemoglobin is composed of four protein subunits, two alpha chains and two beta chains, and a heme group that has iron associated with it. The iron reversibly associates with oxygen, and in so doing is oxidized from Fe 2+ to Fe 3+ . In most mollusks and some arthropods, (b) hemocyanin delivers oxygen. Unlike hemoglobin, hemolymph is not carried in blood cells, but floats free in the hemolymph. Copper instead of iron binds the oxygen, giving the hemolymph a blue-green color. In annelids, such as the earthworm, and some other invertebrates, (c) hemerythrin carries oxygen. Like hemoglobin, hemerythrin is carried in blood cells and has iron associated with it, but despite its name, hemerythrin does not contain heme.

The small size and large surface area of red blood cells allows for rapid diffusion of oxygen and carbon dioxide across the plasma membrane. In the lungs, carbon dioxide is released and oxygen is taken in by the blood. In the tissues, oxygen is released from the blood and carbon dioxide is bound for transport back to the lungs. Studies have found that hemoglobin also binds nitrous oxide (NO). NO is a vasodilator that relaxes the blood vessels and capillaries and may help with gas exchange and the passage of red blood cells through narrow vessels. Nitroglycerin, a heart medication for angina and heart attacks, is converted to NO to help relax the blood vessels and increase oxygen flow through the body.

A characteristic of red blood cells is their glycolipid and glycoprotein coating; these are lipids and proteins that have carbohydrate molecules attached. In humans, the surface glycoproteins and glycolipids on red blood cells vary between individuals, producing the different blood types, such as A, B, and O. Red blood cells have an average life span of 120 days, at which time they are broken down and recycled in the liver and spleen by phagocytic macrophages, a type of white blood cell.

White blood cells

White blood cells, also called leukocytes (leuko = white), make up approximately one percent by volume of the cells in blood. The role of white blood cells is very different than that of red blood cells: they are primarily involved in the immune response to identify and target pathogens, such as invading bacteria, viruses, and other foreign organisms. White blood cells are formed continually; some only live for hours or days, but some live for years.

Questions & Answers

Describe the process of protein sythesis?
Kizito Reply
What is a ploidy level
Francis Reply
Ploidy refers to the number of chromosomes. We have 23 pairs of chromosomes in somatic cells. Sex cells are haploid thus 23 chromosomes vs. 46 Chromosomes.
Evolution is evolvement according to one's environment. Let's use humidity as an example. A person from a very cold environment would not be used to hot humid weather. But over time their body would slowly, slowly adapt.
Give me (3) types of biodiversity
Hi guys 🇧🇪
hello boy
what do you guys understand about evolution?
Kiana Reply
it's a process or analayzing some program
but am not sure if some know plz let share
is a study of
unfolding or unrolling hence the process of development of growth
is the periodic change of the structural features of an organism
I think
process of developing
hi guiz
hello guys
why are diagrams not available
Evans Reply
How can nucleotide molecules of DNA be constructed?construct a six molecules of DNA?
Julia Reply
You take a Deoxyribose sugar. The Deoxyribose sugar has a hydrogen on the second carbon vs. an OH group. The nitrogenous base binds to the #1 Carbon and a phosphate binds to the 5'. When the 2nd NBase bonds, it does so on the 3' Carbon. Thus you have 5' to 3' directional growth.
what is the explanation of local biomes in Nigeria
It would be savanna, tropical grassland.
describe the breathing mechanism in the body fish.
Jackson Reply
what is genetics.
the study of hereditary
state the importance of biodiversity of organisms in an area?
Chris Reply
Let's compare The Brazilian Rain Forest to Antarctica. There many, many types of flora and fona in The Rain Forest. So many that we are still discovering them vs. the variety in Antarctica.
it boosts the ecosystem where each species has an important tole
what is biology
Adam Reply
Biology is the study of living things.
what are some of the branches of biology?
what is meosis
Mabatho Reply
did you mean meiosis? meiosis this is the type of cell division where one diploid parent cell produces two daughter cells that are haploid and genetically different from the parent cell.
I'm struggling to understand genetics
Am also struggling as well
nothing comes on a silver platter, you need to put effort in everything you are doing not forgetting God. study as if there is no tomorrow. "Suffer now and enjoy the future"
true bro
exactly brother
Glory to God
Thanks Pat🙏
you're welcome
what's a nervous system
tessy Reply
what's the human brain
The human brain consist of the cerebrum, cerebellum and brain stem. The cerebral cortex is composed of neuronal cell bodies, which is the gray matter. The white matter is composed of neuronal axons. The brain is the motherboard of our system.
the structure of paramecium
Charity Reply
It is a unicellular, eukaryotic, autotrophic, organism whose movement is done by cilia.
what is codominant
what is endocytosis
Stephen Reply
Endocytosis is when the cell membrane surrounds and engulfs an antigen, viral particles, etc. This forms a vesicle which moves through the cytoplasm. And merges with a designated organelle.
what is the meaning of adrenocorticotropic
Abigail Reply
adrenocorticotropic is stimulating or acting on the adrenal cortex.
ok thanks
What is science of biology
Thando Reply
The study 📓 of leaving things
how does a parasite benefit from its mode of living?
Abuk Reply
why are the images n diagrams unable to be seen?
where are the illustrations
a parasite gets protection, food, shelter
human being

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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