<< Chapter < Page Chapter >> Page >
By the end of this section, you will be able to:
  • Trace the generation of the formed elements of blood from bone marrow stem cells
  • Discuss the role of hemopoietic growth factors in promoting the production of the formed elements

The lifespan of the formed elements is very brief. Although one type of leukocyte called memory cells can survive for years, most erythrocytes, leukocytes, and platelets normally live only a few hours to a few weeks. Thus, the body must form new blood cells and platelets quickly and continuously. When you donate a unit of blood during a blood drive (approximately 475 mL, or about 1 pint), your body typically replaces the donated plasma within 24 hours, but it takes about 4 to 6 weeks to replace the blood cells. This restricts the frequency with which donors can contribute their blood. The process by which this replacement occurs is called hemopoiesis    , or hematopoiesis (from the Greek root haima- = “blood”; -poiesis = “production”).

Sites of hemopoiesis

Prior to birth, hemopoiesis occurs in a number of tissues, beginning with the yolk sac of the developing embryo, and continuing in the fetal liver, spleen, lymphatic tissue, and eventually the red bone marrow. Following birth, most hemopoiesis occurs in the red marrow, a connective tissue within the spaces of spongy (cancellous) bone tissue. In children, hemopoiesis can occur in the medullary cavity of long bones; in adults, the process is largely restricted to the cranial and pelvic bones, the vertebrae, the sternum, and the proximal epiphyses of the femur and humerus.

Throughout adulthood, the liver and spleen maintain their ability to generate the formed elements. This process is referred to as extramedullary hemopoiesis (meaning hemopoiesis outside the medullary cavity of adult bones). When a disease such as bone cancer destroys the bone marrow, causing hemopoiesis to fail, extramedullary hemopoiesis may be initiated.

Differentiation of formed elements from stem cells

All formed elements arise from stem cells of the red bone marrow. Recall that stem cells undergo mitosis plus cytokinesis (cellular division) to give rise to new daughter cells: One of these remains a stem cell and the other differentiates into one of any number of diverse cell types. Stem cells may be viewed as occupying a hierarchal system, with some loss of the ability to diversify at each step. The totipotent stem cell    is the zygote, or fertilized egg. The totipotent (toti- = “all”) stem cell gives rise to all cells of the human body. The next level is the pluripotent stem cell    , which gives rise to multiple types of cells of the body and some of the supporting fetal membranes. Beneath this level, the mesenchymal cell is a stem cell that develops only into types of connective tissue, including fibrous connective tissue, bone, cartilage, and blood, but not epithelium, muscle, and nervous tissue. One step lower on the hierarchy of stem cells is the hemopoietic stem cell    , or hemocytoblast    . All of the formed elements of blood originate from this specific type of cell.

Questions & Answers

explain how blood acts as a connective tissue in the body
Rymz Reply
how does blood act as a connective tissue in the body
Rymz
what is anatomy
Victoriah Reply
fat deficiency in the body
Agbor Reply
Explain how body exercise regulates blood pressure
dranimva Reply
thank you
Thelma
what is cillia and flangella
Kalah Reply
what are the proceduers of condactive system ?
Salua Reply
please, is cell the only smallest particle in de human body
Chibuzor Reply
what are the function of the epithelial tissues
Vaidah Reply
write short notes on following hypervolemia hypovolemia hypo tension oedema DVT shock embolism tachycardia bradycadia varicose veins stroke thrombosis vertigo
Zulpha
secretion, absorption ,protection
Nakyondwa
meaning of ossification
Nakyondwa
osteogenesis or bone formation
Veterinary
pls what is DVT
Ngwani
deep vein thrombosis
Angel
throbbing or cramping pain in 1 leg (rarely both legs), usually in the calf or thigh. swelling in 1 leg (rarely both legs) warm skin around the painful area. red or darkened skin around the painful area. swollen veins that are hard or sore when you touch them.
zinet
Epithelial tissues are widespread throughout the body. They form the covering of all bodysurfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption,excretion, filtration, diffusion, and sensor
Ziya
diagram of a neuron
Emmanuel Reply
go to Google and see hear
Ziya
from where the mixture(collagen & glycoprotein) of basal lamina is secreted?
kiran Reply
epssed
Muktar
what
Ziya
hhhhhmmmm
muhammad
I hope all we enjoy this moment
Muktar
I am together with u brothers
kanaku
what a the 4 proximal bones
kanaku
The proximal end of the radius articulates in both the elbow and proximal radioulnar joints. ... Neck – A narrow area of bone, which lies between the radial head and radial tuberosity. Radial tuberosity – A bonyprojection, which serves as the place of attachment of the biceps brachii muscle.
Ziya
why is the pancreas refer to as an endocrine and exocrine gland
tang Reply
what is a malignancy
tang
malignancy" refers to the presence of cancerous cells that have the ability to spread to other sites in the body (metastasize) or to invade nearby (locally) and destroy tissues
muhammad
Hi, pancreas is a basic organ
Douglas
the intramembranous ossification are developed from membrane whiles the endochondral ossification developed from cartilage
Helena Reply
primary ossification begins at the center of diaphysis while the secondary is the bone growth after birth that occurs at the epiphyseal disc
Helena
Hi
Bashar
hii
Urmila
good to see you
Bashar
hii
Ziya
Yo
Amoako
Hi
rapisanai
good morning guys
Sushma
your all members which countries?
Sushma
I am from Ethiopia
Rama
hi
Sushma
from India 🇮🇳
Sushma
from Bangladesh.
Rashed
hello 👋
Sanam
hii
JUNIOR
what are you doing everyone?
Sanam
listening chemistry class
Sushma
what's corona going on in your country's ?
Sushma
kindly discuss for mi....epithelial tissues
Nabirye
hy
Lal
hii gys
Ziya
hi😊
abdiyu
hello every one
Qaisar
hii gys
Priya
hii
Nigel
why is interstitial fluid refered to as the internal environment of a body?
SAID Reply
?
Vincent
this is because it contains 95% of water which can the body tissues
korobe
because it's located inside the cells
Chimkaha
It makes up ground substance
Douglas
what is meant by the word anatomy and physiology
Vincent Reply
anatomy is about the structures that make up the human body. physiology is about the normal function of the human body
Chimkaha
anatomy is the study of body structures and their parts while physiology is the study of body parts works/function.
Douglas
correction, anatomy is the study of body structures and their parts while physiology is the study of how body parts works/function.
Douglas
what is lipid
Freeman
how one treat patient with heart attack
Freeman
ion pumps and phagocytosis are both example of
Ibrahim Reply
endocytosis
Miriam
The process by which the plasma membrane of a cell folds inwards to ingest material.
Frimpong
hey guys
Vincent
Hello Vincent
Yunus
guys I'm a beginner in public health what can you advise me?
Vincent
Hello members,I'm a beginner in nursing,I need ur advises
Fatou
hey guys,so do i and i need ur advice on how to study pharmacology of nursing
Emnet
Hello guys I'm also beginners in Public Health and your advice needed me
Hero

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Anatomy & Physiology' conversation and receive update notifications?

Ask