18.3 Erythrocytes

what is the most common formed element

erythrocyte

how much erythrocytes does a single drop of blood contain

millions of erythrocytes

how much leukocytes does a single drop of blood contain

thousands of leukocytes

how many erythrocytes per microliters of blood do males have

5.4 million erythrocytes per microliter

how many erythrocytes per microliters of blood do females have

4.8 million erythrocytes per microliter

erythrocytes make up about how much percent of total cells in the body

25

what is the diameter of RBCs

7-8 micrometers

what is the primary function of erythrocytes

pick up inhaled oxygen from the lungs and transport to the body tissues and to pick up some carbon dioxide waste at the tissues and transport it to the lungs for exhalation to facilitate gas exchange in the body.

what happens as a erythrocyte matures in the red bone marrow

it extrudes (forces out) its nucleus and other organelles

what is an immature erythrocyte called

reticulocyte

what is a reticulocyte

immature erythrocyte that still contain fragments of organelles

what percentage of the erythrocyte count should reticulocytes compromise

approximately 1-2 percent

what do reticulocyte counts indicate

a rough estimate of the rate of RBC production

how do mature erythrocytes generate energy

through anaerobic respiration

why dont erythroctyes utilize the oxygen they are transporting

because they lack mitochondria and rely on anaerobic respiration

what structural proteins help erythrocytes maintain their shape and squeeze through capillaries

proteins like spectrin

what is spectrin

a cytoskeletal protein element

what is anaerobic respiration

metabolic process that generates energy without using oxygen to produce ATP from glucose

what do cells break down to generate energy in anaerobic respiration

glucose or other nutrients to produce energy in the form of ATP

what remnants do reticuloytes typically contain

networks, reticulum, of ribosomes

what happens to these remnants of reticulocytes as they mature

they are quickly shed

what is the shape of erythrocytes

biconcave disks

explain the shape of biconcave disks of erythrocytes

plump at their periphery and very thing in the center

why do erythrocytes have more interior space (center)

they lack most organelles

what is the benefit of the biconcave shape of erythrocytes

provides a greater surface area across which gas exchange can occur

what happens to oxygen in the capillaries

oxygen diffuses out of the erythocytes and into the cells

what happens to carbon dioxide in the capillaries

carbon dioxide diffuses into the erythrocytes

why do erythrocytes slow down in capillary beds

cappilarry beds are extremely narrow

what allows erythrocytes to bend and fold in narrow capillaries

their structural proteins, like spectrin are flexible

what happens to erythrocytes when they enter wider vessels after passing through narrow capillaries

they spring back into their normal shape

in wider vessels, what happens to erythrocytes

they stack up like a roll of coins, rouleaux

what is a rouleaux

a stack of erythroytes that resemebls a roll of coins

what are hemoglobins and what are they composed of

large molecule, made up of proteins and iron

what is the structure of hemoglobin

four folded chains of a protein called globin

what are the specific types of globin chains in hemoglobin

alpha 1, and 2, and beta 1, and 2

what is bound to each globin molecule

a red pigment molecule called heme

what ion is contained within the heme molecule

an ion of iron (Fe2+)

what is hemoglobin

molecule in RBCs that carries oxygen

what is heme

red, iron containing PIGMENT that binds to hemoglobin

how many hemoglobin molecules can an individual erythrocyte contain

300 million

how many oxygen molecules can an erythrocyte bind to and transport

1.2 billion

how many oxygen molecules can each hemoglobin molecule transport

4 oxygen molecules

what happens to hemoglobin in the lungs

it picks up oxygen and forms oxyhemoglobin

what happens to oxyhemoglobin in the body tissues

it releases some oxygen and becomes deoxyhemoglobin

what determines the amount of oxygen released by hemoglobin

the need for oxygen in the surrounding tissues

what is oxyhemoglobin

molecule of hemoglobin to which oxygen is bound

what is deoxyhemoglobin

molecule of hemoglobin without an oxygen molecule bound to it

what color is oxyhemoglobin

bright red

what color is deoxyhemoglobin

darker red

whats the process of hemoglobin, oxyhemoglobin, and deoxyhemoglobin

hemoglobin picks up oxygen in the lungs becoming oxyhemoglobin, then releases oxygen to body tissues, becoming deoxyhemoglobin

what is deoxyhemoglobin sometimes referred to

reduced hemoglobin

what happens to carbon dioxide in the capillaries

some dissolves in plasma, some binds to hemoglobin forming carbaminohemoglobin

what percentage of carbon dixodie is dissolved in the plasma

76

if not all CO2 is dissolved, what does the left over dissolved CO2 become

bicarbonate ion

what is carbaminohemoglobin

bound form of hemoglobin and carbon dioxide

what happens to CO2 bound to hemoglobin

it is carried back to the lungs and released

what can happen if theres a change in the levels of RBCs

it can affect the bodys ability to deliver oxygen to tissues

what happens when hematopoiesis is ineffective

insufficient numbers of RBCs are produced leading to anemia

what is polycythemia

a condition where theres an over production of RBCs

why is dehydration linked to polycythemia

plasma is composed of mostly water which is a decrease in plasma which causes there to be a higher concentration of RBCs

why is plasma important in blood, esp polycythemia

to dilute RBCs

what is the primary drawback of polycythemia

increased blood viscocity, making it harder for the heart to circulate blood

what is hematopoiesis

process of producing new blood cells that occurs in bone marrow

what happens if tissues dont receive sufficient oxygen due to insufficient hemoglobin

it can result in another form of anemia

what is the most important value in determining oxygenation of tissues

percent saturation

what is percent saturation

percentage of hemoglobin sites occupied by oxygen

how is percent saturation typically monitored

using a pulse oximeter device

how does a pulse oximiter work

it sends light through a thing body part like the finger and measures the light absorbed by hemoglobin

what is considered a normal pulse oximeter reading

95-100

what does a lower percentage reading indicate

hypoxemia, low blood oxygen

what is hypoxemia

below normal level of oxygen saturation of blood

what is the difference between hypoxemia and hypoxia

hypoxemia refers to low blood oxygen while hypoxia refers to low oxygen levels in general

what is hypoxia

lack of oxygen supply to the tissues

how can oxygen levels be directly monitored

through an arterial stick, measuring partial pressure of oxygen (Po2 or PO2)

what units are used to record partial pressure of oxygen

millimeters of mercury (mm Hg)

how much blood do kidneys filter daily

about 180 liters (~ 380 pints)

why are kidneys ideal sites for oxygen saturation receptors

because they filter a significant volume of blood (20% of resting volume)

what happens in response to hypoxemia in the kidneys

interstitial fibroblasts secrete EPO, increaasing erythrocyte production

what is erythropoietin (EPO)

hormone that stimulates the production of RBCs

how does EPO secretion respind to changes in oxygen saturation

its a negative feedback loop

what happens in the negative feedback loop of EPO responding to oxygen saturation

EPO secretion falls when oxygen saturatuin rises and vice versa

why do people living at high elevations have higher hematocrits (RBCs)

due to lower oxygen levels in the atmosphere

what symptoms may people experience when traveling to high elevations

fatigue, headache, and shortness of breath (altitude sickness)

how do kidneys respond to hypoxemia at high elevations

they secrete EPO to increase erythrocyte production

why do mountain climbers rest at increasing elevations

to allow EPO levels and erythrocyte counts to rise, avoiding altitude sickness

why do mountain climbers use bottled oxygen on tall peaks

to cope with low oxygen levels near the summit

what is altitude sickness

happens when the body cant adapt quickly enought ot high elevations with lower oxygen levels

at what rate are erythrocytes produced in the bone marrow

more than 2 million cells per second

what raw materials are necessary for erythrocyte production

nutrients like glucose, lipids, and amino acids

what trace elements are necessary for erythrocyte production

iron, copper, zinc, and B vitamins

what are trace elements

essential nutrients that the human body needs in small amounts to function properly

what are trace elements also known as

trace minerals

what B vitamins are needed for erythrocyte production

folate and vitamin B12

what role does iron play in erythrocyte production

iron is a part of the heme group in hemoglobin

how is iron absorbed and transported in the body

iron is absorbed from food, stored in ferritin and hemosiderin, and transported by ferroportin and transferrin

what is ferritin

the main storage protein for ion that stores them in a usable form and helps regulate iron levels

what is hemosiderin

the secondary storage site for excess iron and stores iron in a less usable form

how are ferritin and hemosiderin the same

both are protein containing storages form of iron found in the bone marrow, liver and spleen

what is the role of copper in erythrocyte production

enable iron absorption and oxidation

what two plasma proteins is copper a component of

Hephaestion and ceruloplasmin