Lecture 1 – Intro & Red Blood Cells

Main topics: Functions of blood, liquid component of blood and its constituents (plasma, plasma

proteins), the solid components of blood (all formed elements), hematopoiesis & its sites, different kinds

of cytokines & their actions, red blood cell properties & breakdown, RBC conditions (hyperbilirubinemia,

anemia, polycythemia)

Why are we learning this? The blood is a critical component of the body’s functioning: it allows all of

our vital organs to receive oxygen, combats pathogens when they enter our body and attempt to initiate

disease, moderates our fluid volume, and enables us to heal our wounds, among other things. As such,

it’s integral to understand in learning physiology, which deals with how bodily structures enable bodily

functions!

What are the functions of blood?

Most of us are probably pretty familiar with general information about blood: it’s red and blue, for one, and it courses through our veins! If you’ve taken basic high school biology, you may also know that blood carries oxygen and carbon dioxide, that it is useful in furthering one’s immunity, and that it As much as this is true, however, blood has a range of other functional properties – some of which may be obvious to you, and some of which you may have never previously heard about. Let’s talk a closer look at these. Firstly, blood carries many things – gases, nutrients, hormones, and wastes!

For one, blood transports gases like CO2 and O2 – it takes carbon dioxide (a gas that many of our

cells exude as a result of cellular respiration) into the lungs, so that it may be exhaled and

thereby removed from the body. Conversely, blood transports oxygen after it enters the body

via the lungs, taking it to tissues that require oxygen to proceed in metabolic activity. Blood

carries both CO2 and O2 via hemoglobin, a globular protein with four subunits

Blood also moves nutrients (if you took PSL300, you’ll remember that we spoke of blood

glucose, or blood sugar, and talked about how hormones like insulin and glucagon can modify

the amount of glucose you have in your blood at any given time)

Blood also carries hormones, like ADH, ACTH, oxytocin, FSH, insulin, glucagon, and so on!

Remember, a hormone is basically any substance that travels in the blood and has some effect

on a target organ or tissue; the blood is full of these, then!

Finally, blood carries metabolic wastes. What are these? Basically, anything the body doesn’t

want, but produces (e.g., we really don’t like having too much nitrogen, so blood carries it in the

form of urea to prevent it from poisoning us, and it is expelled via the urine, as we’ll find out in

the TIP: Always make and memorize lists, in PSL. Here, for example, we are told

that blood carries many things – namely, gases, nutrients, hormones, and wastes.

Hereafter, you should be able to ask yourself something like, “What are the four

things blood can carry?”, and come up with “Gases, nutrients, hormones, and

wastes!” as an answer. Think in terms of lists!

(I’ll try to help you do this by providing a list of lists at the end of each chapter, but

you should do this in all cases.)

renal lectures)

Secondly, blood has a relatively intimate relationship with the interstitial (or “tissue”) fluid. If you, again, took PSL300, you’ll know that the interstitial fluid is the fluid sitting in our tissue – the fluid, in other words, that’s outside of our cells, but not in blood vessels. If not, check out its anatomical position here:

Why is

this

important? Well, as you may notice, the diagram indicates that water, for one, moves easily between

interstitial fluid and the blood’s fluid component (the plasma). Sodium also appears to do so! This

brings us to an important conclusion – blood quite frequently exchanges contents with the interstitial

fluid, regulating the ion, water, and pH content of the interstitial fluid!

Thirdly, as we mentioned earlier, you may well have learnt that blood helps you heal. More specifically, it allows your wounds to clot. How does it do this? Via blood cells called thrombocytes, or platelets, which we’ll learn more about later in this lecture. By allowing your wounds to seal over, blood also prevents you from losing too much fluid; this is important, because maintaining a healthy blood volume in our bodies is integral to proper health. Blood also facilitates immunity (i.e., your body’s ability to defend itself from incoming foreign agents). How does it accomplish this? Among other things, it contains white blood cells (leukocytes) like neutrophils (the cells that are our very first line of innate immune defense, creating inflammation to fight infections), lymphocytes (T and B cells, which travel in the lymph, as their name suggests), basophils, eosinophils, monocytes, macrophages, and dendritic cells, all of which we’ll learn more about soon. Because these cells float around in the blood’s fluid component (plasma), blood is said to provide us with humoral immunity (i.e., immunity that’s conveyed via liquids). Finally, as you may remember from BIO120 and PSL300, blood is responsible for temperature regulation – if you want to get rid of heat, you shuttle your blood to your extremities (i.e., the outer-reaching

segments of your body, including legs and arms) to allow the environmental to absorb your heat; conversely, if you want to conserve heat, you ensure that it doesn’t travel to your skin! How much blood, precisely, do we have? This depends on our weight and our gender. Males, on average, have about five liters of blood; females have about four.

What’s inside blood?

Now that we know a little bit about the function of blood, let’s consider its structure! As we mentioned

in our intro to physiology, a body part’s function is really typically a direct consequence of its structure;

this, of course, is true of blood. The blood’s cells, fluids, ions, proteins, and other components ensure

that it can carry out everything discussed in the section above.

So, what does blood contain?

Plasma (46-63% of the total volume of blood): Most of blood is, in fact, liquid – specifically, a

liquid called plasma! Plasma is essentially water with a few things, like blood cells and plasma

proteins, floating inside it

o Water makes up 92% of the plasma!

o The remainder of the plasma (8%) is made up of:

Ions

Trace elements & vitamins

Gases

Namely, CO2 and O2

Organic molecules, including:

Amino acids

Glucose

Lipids

Nitrogenous waste

Proteins (most of which are made by the liver), including:

o Albumins (60% of all blood proteins)

o Globulins (35% of all blood proteins)

o Fibrinogen (4% of all blood proteins)

Formed elements (37-54%): The rest of the blood is made up of solids, or formed elements (to

remember this name, think: “They’re solid things, so they’re elements that have a form”). These

are, basically, the blood cells (both red and white)

o Most of the formed element portion of blood is made up of red blood cells! RBCs are,

in fact, responsible for basically 99.9% of the formed elements, whereas WBCs and

thrombocytes make up only 0.1% of all elements

The hematocrit is the percent of the total blood volume occupied by red blood

cells – remember, not the percent of the total blood volume occupied by all

TIP: Unless otherwise noted, remember numbers in PSL! It may seem like an

ordeal to remember “5 liters for males, 4 liters for females”, but do it if you want an

A in the course!

formed elements… just the percent of the total blood volume occupied by red

blood cells! Red blood cells really are a massive component of the blood

Focus on blood contents: plasma proteins Now that we’ve taken a general look at all the contents of blood, let’s zoom in on one portion of the plasma – the plasma proteins! As their name suggests, these are just proteins (i.e., collections of amino acid) that float around in the plasma; they play a range of roles. Namely, plasma proteins:

1. Generate colloid osmotic pressure. Albumins are pretty big (66 kD); as such, their presence in

blood vessels compels water to enter the blood vessels from the tissue. This force of albumins –

i.e., their ability to pull water into the blood – is known as colloid osmotic pressure; it is

counteracted by hydrostatic pressure.

2. Plasma proteins also act to buffer pH – they bind to small amounts of acid in the blood,

removing it before it changes the blood’s pH.

TIP: To remember things like the constituents of blood, make branching charts (hierarchical

diagrams, in other words).

So, for example, I’d do the following:

This is immensely useful to memorizing complex relationships between many structures.

Blood

Formed elements (37-54%)

Thrombocytes (part of same

0.1% as WBCs)RBCs (99.9%)

WBCs (0.1%)

Lymphocytes (20-40%)

Monocytes (2-8%)

Neutrophils (50-70%)

Eosinophils (1-4%)

Basophils (<1%)

Plasma (46-63%)

Water (92%) Other (8%)

Ions Gases (CO2, O2)Trace elements,

vitaminsOrganic molecules

Amino acids Glucose LipidsNitrogenous

wasteProteins

Albumins (60%)

Globulins (35%)

Fibrinogen (4%)

You should also know that there’re three kinds of plasma proteins, as was highlighted in our breakdown of the plasma:

1. Albumins – big proteins that, as was mentioned above, create colloid osmotic pressure (i.e., pull

water into vessels)

2. Globulins – globular (i.e., large surface area) proteins that act as clotting factors (sealing

wounds), enzymes (all kinds of metabolic functions), carriers, and, of course, antibodies.

Antibodies are gamma globulins, specifically.

3. Fibrinogen – a protein that is cleaved by thrombin to create fibrin, the protein that wraps

around thrombocytes to create a thrombus (blood clot)

You should remember another relatively important thing about plasma proteins: Although plasma proteins are solids, they are not regarded as formed elements – they’re counted as part of the 46-63% of blood volume that’s made up of plasma (liquid), though they’re theoretically not water, exactly. Only blood cells are called formed elements.

Focus on blood contents: formed elements Now that we’ve taken a closer look at some of the contents of plasma, the liquid portion of blood, let’s consider the other 37-54% of blood volume: the formed elements! The formed elements are, essentially, all the cells contained within blood. These include:

1. Red blood cells (“erythrocytes” – to remember this name, realize that it has an r in it, and think

“RBCs”). 99.9% of formed elements.

a. These make up a huge proportion of blood volume (99.9%). There’s only one kind of

RBC! Their main purpose? Shuttling oxygen to the cells of the body! Each RBC contains

millions of molecules of haemoglobin, and each molecule is capable of binding to four

oxygen molecules! That’s quite a bit.

b. These guy lack a nucleus and most organelles to maximize space for their haemoglobin

molecules; they’re also flexible, to allow for easy movement through blood vessels, and

are oval, biconcave disks (this shape optimizes their surface area, again allowing

maximal oxygen absorption). Red blood cells are made and matured in the bone

marrow; afterwards, they travel our circulation for approximately 120 days, eventually

being recycled by macrophages (phagocytic, tissue-based monocyte-derivatives).

c. RBCs are the cells we’re referring to when we discuss blood types! You can have A, B,

AB, or O red blood cells, as well as Rh- or Rh+ red blood cells (so, your type could, for

example, be something like B-). Remember, then – blood type refers to RBCs, not

WBCs!

2. White blood cells (“leukocytes”). 0.1% of formed elements, when paired with thrombocytes.

These guys’ primary focus is to protect us from invading pathogens! They’re our real immune

cells, as we’ll soon find out. WBCs include:

a. Lymphocytes. 20-40% of WBCs. Any of three types of WBCs in the immune system, all

of them agranulocytes (i.e., cells that do not contain granules in their cytoplasm). The

three possible types of lymphocytes are T cells, B cells, and NK cells. Lymphocytes span

both the innate and acquired immune systems, and carry out a range of functions:

some of them kill foreign cells, some of them kill our own malfunctioning cells, some of

them release chemical signals called cytokines, and some of them make antibodies

(i.e., molecules used to bind invaders and prepare them for phagocytosis). Lymphocytes,

as their name suggests, don’t just travel in the blood – they also travel in the lymph

(i.e., the clear fluid contained within the lymphatic vessels – the network of vessels that

transports fat and excess fluid through the body). Lymphocytes can participate in both

cell-mediated (i.e., a response involving cells, such as phagocytes, cytotoxic T cells, and

cytokines) and humoral (i.e., a response involving antibodies) immunity.

b. Monocytes. 2-8% of WBCs. These guys reside in the blood, and give rise to

macrophages and dendritic cells as their derivatives. Monocytes are the largest of all

WBCs; they’re involved in innate immunity. They’re also agranulocytes, just like

lymphocytes. They participate in inflammation. Note that monocytes exist only in the

blood – once they enter the tissue, they become macrophages! Monocytes & their

derivatives are phagocytes.

c. Neutrophils. 50-70% of WBCs. Most abundant! These guys are granulocytes, just like

eosinophils and basophils (you can remember this by noting that all the –phils are filled

with granules). They predominantly respond right away to infections, arriving at the site

of injury or invasion within minutes. They’re innate immune cells! Neutrophils are

phagocytes.

d. Eosinophils. 1-4% of WBCs. Eosinophils are granulocytes, too, though less common

ones! They primarily work with mast cells and IgE to control allergy and asthma.

They’re also quite short-lived.

e. Basophils. <1% of WBCs. Least abundant! Another kind of granulocyte. These guys

store histamine, a chemical involved in innate immune responses.

3. Platelets (“thrombocytes”). 0.1% of the formed elements, in combination with WBCs. The flat

blood cells, derived from megakaryocytes, that are responsible for building blood clots, which

help us stop bleeding! We’ll learn more about these in Lecture Five, so no “spoilers” for now.

Focus on formed elements: hematopoiesis It’s clear, then, that we have quite a diversity of formed elements! How are all these different blood cells made, however, and where? The easiest answer in terms of a “where” is “the bone marrow”! Most blood cells, as we’ll see soon, are derived from pluripotent hematopoietic stem cells (HSCs); these dominantly exist in the bone marrow. However, blood cells can be made in a range of locations; where they’re made differs with age, too! They can be created in:

In the embryo (i.e., the not-as-yet-born child):

o Yolk sac: a part of the embryo that stores nutrients (like a bird’s egg yolk)

o Liver: detoxification, protein synthesis, digestive organ

o Spleen: an example of an encapsulated lymphoid tissue – filters blood

o Bone marrow: Inner component of bones; the tissue inside is called the stroma, and it is

fed by both radial arteries (stemming from the central canal inside the bone) and

nutrient arteries (arteries that enter the bone from the outside). Deoxygenated blood is

removed from the bone marrow via the venous sinuses, which branch into larger,

central sinuses that exit the bone

In the child:

o Bone marrow: inner component of bones

In the adult:

o Pelvis: the part of the skeleton that holds the lower trunk

o Spine: the series of bones that runs down the center of our back

o Ribs: the thoracic bones that surround the heart and lungs

o Cranium: the skull (the bones surrounding the brain)

o Proximal end of long bones: the end of the bone that is closest to the center of our

bodies

How are blood cells made, now? All of them, it turns out, are created via a process known as hematopoiesis. This process begins, in all cases, with a pluripotent hematopoietic stem cell (1 in every 100 000 cells): a cell that, as its name suggests, can give birth to a range of different blood cells.

Here are all the things you should be deriving from these three diagrams: Diagram 1 Insights

1. A pluripotent HSC becomes: a) a multipotent progenitor (uncommitted stem cell from Diagram

2), OR b) a lymphoid progenitor (lymphocyte stem cell from Diagram 2).

2. Multipotent progenitors are uncommitted, really, just like Diagram 2 says! Even though they

appear to be dedicated to myeloid cells, not all multipotent progenitors become myeloid

precursors – some rededicate themselves to lymphocyte production! So, really, at this point,

they are uncommitted.

3. Megakaryocytes & erythrocytes share a progenitor not shown on 2, 3.

4. Granulocytes, monocytes, & mast cells share a progenitor (not shown on 2, 3).

Pluripotent hematopoieti

c stem cell

Multipotent progenitor

("uncommitted stem cell")

If it doesn't become

myeloid, it'll go help the

lymphocytes!

Myeloid progenitor cell (one of the "committed

precursors - not shown on diagram)

Megakaryo/erythro

progen.

Erythro. progen. #1

Erythro. progen. #2

Erythroblast

Reticulocyte

Erythrocyte

Megakaryo. progen.

Megakaryocyte

Platelets

Granulocyte/macrophage

progen.

Mast cell Myeloblast

Monocyte

Macrophage

Dendritic cell

Neutrophil progen. #1

Neutrophil

Eosinophil progen. #1

Eosinophil progen. #2

Eosinophil

Basophil progen. #1

Basophil progen. #2

Basophil

Lymphoid progenitor cell ("lymphocyte stem cell")

B cell progen.

B cell

T cell progen.

Cytotoxic T Helper T

Many different helpers!

NK T

NK cell progen.

NK cell

5. Proceeding even more specifically, monocytes & granulocytes share the myeloblast.

6. Monocytes become macrophages or dendritic cells!

7. NK, T, and B cells are all lymphocytes.

8. There is a kind of T cell called an NK T cell. This is not the NK cell we’ve previously learnt

about.

9. A lot of progenitors are not shown on Diagrams 2 & 3.

Diagrams 2 & 3 Insights

1. According to this diagram (in reality, there may be more), erythrocytes have four committed

progenitors specific to them. Platelets, neutrophils, eosinophils, and basophils each have two

committed progenitors specific to them.

2. Reticulocytes, erythrocytes, platelets, neutrophils, monocytes, basophils, eosinophils, and

lymphocytes exist in the circulation. Their precursors are found in the bone marrow.

So, now we know where and how hematopoiesis happens. But what actually causes it to happen? How is it regulated? As it turns out, signalling chemicals called cytokines mediate hematopoiesis. These include:

Interleukins – released from white blood cells; make all kinds of cells

Colony-stimulating factors (CSF) – released from endothelial cells and WBCs

o Granulocyte-colony-stimulating factor (G-CSF) – make phils

Erythropoietin (EPO) – released from the kidney in response to low oxygen; make erythrocytes

Thrombopoietin (TPO) – released from the liver; make megakaryocytes

Focus on formed elements: red blood cells Because red blood cells make up such a huge proportion of blood volume (up to 45% of it, typically), and have so many important functions, let’s take a closer look at them, for a moment. As we’ve mentioned previously, RBCs:

Function via anaerobic metabolism

Have no nucleus, no new transcription, and not many organelles

Have a cytoskeleton linked to actin and attachment proteins that helps them achieve their

unique oval, biconcave disk shape

Can change shape

Have a life span of about 120 days

Are made at a rate of 2-3 million per second

Exist in the blood at ~5 x 106 cells/microliter concentration

Have haemoglobin inside them, as well as some enzymes

Haemoglobin deserves a bit of excess consideration as well:

Four-subunit (two alpha chains, two beta chains) globular protein

Each subunit has one heme group, which can bind to one oxygen via the iron at its center – this

means that one haemoglobin can carry four oxygen molecules

TIP: To remember new names, rewrite them many times! You may have noticed that I

have rewritten the term “pluripotent hematopoietic stem cell” several times in the above

paragraph instead of, as good form would mandate, referring to it by an acronym (e.g.,

“pluripotent HSC”) or a pronoun (e.g., “it”). Why did I do this? So that you’d have to hear

the word in your head several times while reading these notes, and fully understand it to

move forward in your reading! Long, often not-so-intuitively-remembered names are

crucial to remember for PSL exams – if you’re having trouble remembering one, use it in

conversation or in writing as often as possible!

In understanding red blood cells, we need to look at one more thing – when their 120-day life is up, what happens to them? We definitely don’t want a heap of dead cells floating in the blood, so RBCs must somehow be removed. Here, then, is the RBC life-and-death cycle!

1. RBCs are made in the bone marrow.

2. RBCs are released into the circulation. 90% of them proceed to live life, while 10% are instantly

broken down (via hemolysis – literally, “blood cutting”).

a. Those that survive post-birth annihilation live for 120 days.

i. After 120 days, they (while still whole) enter a macrophage (found in the

spleen, lvier and bone marrow). Here, they are broken down. Specifically, inside

the macrophage:

1. Their amino acids are sent back to the bone marrow for RBC formation.

2. Their iron is:

a. Sent back to the bone marrow for RBC formation, travelling via

transferrin, or:

b. Transferred (haha, transferred) to the liver in ferritin to be

stored.

3. Their heme is converted to biliverdin, then bilirubin. This bilirubin is

transported to the liver.

a. From the liver, bilirubin goes to:

i. The small intestine, and then the large intestine, where

it is converted into bilirubin-derived products, which:

1. Become urobilins and stercobilins, and are

eliminated in feces, or:

2. Are absorbed into the circulation, travel to the

kidney, and are eliminated in the urine.

ii. The kidney, where it is eliminated in the urine.

b. Those that do not survive have their parts sent to the macrophage (for the same

processing as described above – the only difference is that they enter the macrophage

already in parts, so their haemoglobin has escaped), and have their haemoglobin (Hb)

sent to the kidney for elimination in the urine.

Red blood cell conditions: hyperbilirubinemia (jaundice), anemia, polycythemia We’re almost through – what a lecture! Just a last few points to go through. We just discussed RBC breakdown above. What happens when we get too many RBCs being broken down? Well, we get a lot of bilirubin floating around; when there’s so much of it that it cannot be effectively processed, it begins to enter our circulation. Because bilirubin is yellow, and because we’ve fewer RBCs than usual that are still intact, we take on a more yellowish condition: in particular, our skin and the whites of our eyes become yellow. This can be caused either by liver disease (if the liver cannot process bilirubin, it’ll bother us), or bile duct obstruction (in which the duct connecting the liver, small intestine, gall bladder, and pancreas gets stopped up – this prevents bilirubin from being excreted, too).

Because jaundice involves more bilirubin than is usual, it is also called hyperbilirubinemia (literally, “more bilirubin in the blood”). If hyperbilirubinemia happens in newborn babies, right away after birth, it is known as neonatal jaundice. Sometimes, this doesn’t mean the liver is dysfunctional – it just means that it hasn’t as yet been able to remove bilirubin sufficiently quickly! It may well do so without a few days. To fix the problem in the short term, babies are expose to blue light (420-470 nm), which oxidizes bilirubin to biliverdin; this is known as phototherapy. Another famed RBC condition is anemia, in which we just… don’t have enough haemoglobin. This probably means we don’t have enough RBCs, which can happen for a couple of reasons:

1. Low production. Not many RBCs are made, to begin with.

a. This can be caused by destruction of HSCs via drugs and radiation (aplastic anemia),

inadequate iron, folic acid, and Vitamin B12 from the diet (nutritional/pernicious

anemia), or low EPO (remember, EPO is the cytokine that makes RBCs – this is known as

renal anemia, because the kidney makes EPO).

2. High removal. RBCs are made normally, but removed too quickly.

a. This can be caused by genetic defects in RBC proteins, parasites, drugs (antibiotics and

anti-seizure drugs), autoimmune reactions (in which your body kills your own cells), and

haemorrhage (i.e., excessive blood loss).

Finally, sometimes the problem isn’t too few RBCs: it’s too many. If our hematocrit makes up over 54% of our blood volume, there’s an issue; we call this polycythemia. Polycythemia usually means too many RBCs are being made – this could be because of abnormal erythrocyte precursors (primary polycythemia), or because of too little oxygen’s being delivered to the tissues, which signals for more RBCs (secondary polycythemia).

Know these terms! If you want to make total sense of this lecture, you should know these terms! If you don’t know them, or don’t understand what other terms fit under them, look them up now. There’s no better time, and you’ll be able to orient much better! Hormones, metabolic wastes (urea), pH, ions (sodium, potassium), plasma, hematocrit, formed elements, centrifugation, organic molecules, amino acids, plasma proteins, glucose, lipids, trace elements and vitamins, albumins, globulins, fibrinogen, colloid osmotic pressure, protein carriers, buffers, clotting factors, enzymes, antibodies, gamma-globulins, beta-globulins, alpha-globulins, RBCs, erythrocytes, WBCs, leukocytes, thrombocytes, platelets, lymphocytes, monocytes, macrophages, neutrophils, basophils, eosinophils, granulocytes, phagocytes, yolk sac, liver, spleen, bone marrow, stroma, bone cortex, central sinus, nutrient artery, radial artery, venous sinuses, pelvis, spine, ribs, cranium, proximal, distal, long bones, flat bones, embryo, hematopoiesis, pluripotent hematopoietic stem cell, uncommitted stem cell, progenitor, precursor, blast, committed progenitor cell, lymphocyte stem cell, megakaryocyte, erythroblast, reticulocyte, circulation, colony stimulating factors, endothelial cells, interleukins, cytokines, proliferation, differentiation, EPO, erythropoietin, thrombopoietin, TPO, kidney, G-CSF, granulocyte colony-stimulating factor, transplant, cytoskeleton, filament, actin, haemoglobin, anaerobic, aerobic, transcription, bilirubin, heme, biliverdin, urobilins, stercobilins, bile,

small intestine, large intestine, feces, Hb, hemolysis, Fe2+, ferritin, jaundice, hyper, hypo, hyperbilirubinemia, anemia, ischemia, turnover, bile duct, neonatal, fetus, phototherapy, aplastic anemia, pernicious anemia, nutritional anemia, renal anemia, genetic,, autoimmune, polycythemia, viscosity, primary polycythemia, secondary polycythemia

Key lists & groups in this chapter E.g.: Phagocytes:

Monocytes

Their derivatives (macrophages, dendritic cells)

Neutrophils

Granulocytes:

Basophils, neutrophils, eosinophils (phil, phil, phil)

Numbers in this chapter, in order of appearance All quantities discussed in this lecture. Remember these if you want maximal marks!

5L of blood in 70-kg male

4L of blood in 58-kg female

Hematocrit (red blood cell volume) = 37-54% of all blood volume (usually 45%)

Plasma (liquid volume) = 46-63% of all blood volume

Formed elements (all blood cell volume) = 37-54% of all blood volume (notice, most formed

elements = hematocrit)

Water = 92% of plasma

Other stuff (ions, organic molecules, trace elements, vitamins, gases) = 8% of plasma

o Of this, proteins are important! They come in three kinds!

Albumins = 60% of all plasma proteins

Globulins = 35% of all plasma proteins

Fibrinogen = 4% of all plasma proteins

RBCs = 99.9% of all formed elements

WBCs + platelets = 0.1% of all formed elements

o Lymphocytes = 20-40% of all WBCs

o Monocytes = 2-8% of all WBCs

o Neutrophils = 50-70% of all WBCs

o Eosinophils = 1-4% of all WBCs

o Basophils = <1% of all WBCs

Pluripotent HSC = 1 in every 100 000 cells in the blood

In bone marrow, 25% of cells are developing erythrocytes, 75% are developing leukocytes

Hemoglobin has four subunits, can carry four oxygen molecules

Each RBC has millions of haemoglobin molecules

Life span of RBC = 120 days

We can make 2-3 million RBCs per second

We have ~5 x 106 RBCs/microliter

When they leave the bone marrow, 90% of new RBCs live out their lives; 10% undergo hemolysis

right away

Blue light = 420-470 nm

Hematocrit is too high if it is >54%

Miscellaneous facts you may forget, & key ideas you may have been confused about All not-so-connected facts mentioned in this lecture. Remember these if you want maximal marks!

Most plasma proteins (i.e., albumins, globulins, fibrinogen) are made in the liver

“Differential white count” refers to a

1 in every 100 000 cells is a pluripotent HSC

75% of all cells developing in the bone marrow at a given time are leukocytes; 25% are

developing erythrocytes, even though there are, in the end, far more erythrocytes than

leukocytes