WEEK 1: CELLULAR COMPONENTS, DEVELOPMENT AND FUNCTIONS Flashcards
List the 4 main components of blood
- erythrocytes
*leukocytes
*thrombocytes
*plasma
What is hematocrit?
Packed cell volume
Outline functions of ions found in blood plasma
*role in membrane excitability
* maintains osmotic distribution of fluid between ECF and ICF
*Buffer pH changes
State the percentage of Erythrocytes, plasma, platelets and Leukocytes in blood sample
Erythrocytes: 45%(42%F)
Plasma: 55%( 58% F)
Platelets and Leukocytes: less than 1%
Hematocrit: erythrocytes+ platelets+leukocytes
Describe platelets and their functions
Are cell fragments
Important in hemostasis, stopping of bleeding from an injured vessel
State the function of leukocytes
Immune system ‘s mobile defense units, are transported in the blood to sites of injury and platelets or at invasion by defense causing microorganism
State the functions of erythrocytes
Transport of oxygen around the body
Outline components of plasma
90% water
ORGANIC SUBSTANCES
*Plasma protein: 6-8% of plasma weight
*Nutrients: glucose, amino acids, lipids and vitamins
*Waste products: creatinine, bilirubin and nitrogenous wastes such as Urea)
*Dissolved gases: oxygen and carbon dioxide
* Hormones
INORGANIC SUBSTANCES 1% weight of plasma
*Abundant electrolytes: sodium and chloride ions
*Smaller amounts: potassium, bicarbonate ions, calcium ions
Name the 3 plasma proteins
*albumin
*globulin
*fibrinogen
State the functions of albumin
*Transport of insoluble compounds
*Contribute mostly in coloid osmotic pressure
State the functions of globulins
Alpha and beta:
*transport but highly specific
* Involved in blood clotting
*Act as inactive precursor which need to be activated to carry out function e.g Angiotensinogen»>angiotensin
Gamma
* Are antibodies or immunoglobulins which are crucial to the body’s defense mechanism
State the average blood volume in males and females
Males: 5.5L
Females:5L
How much percentage does blood account for our body weight?
8%
State the functions of fibrinogen
A key clotting factor in blood
What is the lifespan of erythrocytes?
120 days
Why is the lifespan of erythrocytes short?
They do not have DNA, RNA and ribosomes so they cannot synthesize proteins for cell repair, growth and division or for renewing enzyme supplies
What is erythropoiesis?
Formation of erythrocytes
What is hematopoiesis?
Formation of blood cells
What does reticulocytes of 0.5% to 1.5% above normal indicate?
High rate of erythropoietic activity
Briefly describe hematopoiesis
1.Hematopoietic sterm cells arise from the mesodermal cells.All blood cells are derived initially from pluripotent
haemopoetic stem cells in the bone marrow.
2.Mesodermal cells are acted on by FGF2 (fobroblast growth factor 2) forming hemangioblast
3.Hemangioblast cells are acted on by VEGF (vascular endothelial growth factor)
4.differentiate into vascular endothelium
5. undifferentiated hemangoiblasts will participate in
*angiogenesis
*hematopoiesis
What is hypoxia?
Low oxygen
Describe the control of erythropoiesis
1.Kidneys detect reduced oxygen carrying capacity of blood
2.When less oxygen is delivered to the kidneys, they secrete erythropoietin into blood
3.Erythropoietin stimulates erythropoiesis by red bone marrow
4.Additional circulating erythrocytes increase oxygen carrying capacity of blood
5. Increased oxygen carrying capacity relieves initial stimulus that triggered erythropoietin secretion
Describe 2 ways in which erythropoietin secretion controls erythropoiesis
*stimulates up the mitosis of erythroid sterm cells and erythroblasts
* It speeds up hemoglobin synthesis , thus speeding up erythrocyte maturation
State other substances that can be binded by Hemoglobin
*carbon dioxide: to the lungs for excretion
* Hydrogen ion
* Carbon monoxide
*Nitrogen monoxide: dilate arterioles
Name the 2 enzymes found in erythrocytes and their functions
*Glycolytic enzymes: Energy metabolism for fuelling the active transport mechanisms involved in maintaining proper ionic concentrations within the cell
- Carbonic anhydrase: converts carbon dioxide to bicarbonate ions ( HCO3-) which is the primary form in which CO2 is transported in blood
Name the growth factor that stimulates erythropoiesis
Erythropoietin (EPO)
State the characteristics of hematopoietic stem cells
*they are the parental cell type for all blood cells
*usually present in the bone marrow only
*probably able to divide indefinitely or at least a very large number of times
Describe the life cycle of erythrocytes
pluripotent stem cells
myeloid stem cell
pro-erythroblast
erythroblast
reticulocyte
erythrocyte
1.Erythroid stem cells divide and mature to form erythroblasts. These are nucleated cells which actively synthesise haemoglobin.
2.These mature, differentiate and divide for about four days, then lose their nucleus, becoming reticulocytes.
3.Reticulocytes are distinguishable from mature erythrocytes because a network of internal cell structures can be seen. They mature in the bone marrow for a further two days, and are then released into the circulation.
4.They are still recognisable as reticulocytes for about one day, (just less than 1% of circulating erythrocytes are still recognisable as reticulocytes).
5. After this their maturation is complete and they are fully mature erythrocytes.
*Folate and vitamin D are involved in changing erythroid stem cell to pro-erythroblast
*Hemoglobin synthesis occur during changing pro-erythroblast to erythroblast
*Iron binds to transferrin and ferritin to be transported in reticulocytes which lose nucleus, they stay for 1 day in blood and mature to erythrocyte
Which part in the life cycle of red blood cells produce hemoglobin?
Reticulocytes
What do blood groups depend on?
Surface antigens on erythrocytes
What is an antigen?
A large , complex molecule that triggers a specific immune response against itself when it gains entry to the body
What is an antibody?
a blood protein produced in response to andcounteractinga specificantigen. Antibodies combinechemicallywith substances which the bodyrecognizesas alien, such as bacteria,viruses, and foreign substances in the blood.
*Bonds with the specific antigen against which it is produced and leads to the antigen’s destruction by various means
Where are antigens found?
In surface membrane of erythrocytes
Where are antibodies found?
In plasma
State the 4 main blood groups / types
A,B, AB, O
Describe the antigens and antibodies found in the blood types
A:, A antigens, anti-B antibodies
B: B antigens, anti-A antibodies
AB: A and B antigens, no antibodies
O: No antigens, anti-A and anti-B antibodies
What happens in a transfusion reaction?
antibody reaction with erythrocyte-bound antigen results in agglutination or hemolysis of the attacked erythrocytes in the recepients plasma in mismatched transfusions which can lead to death
Effects of mismatched blood transfusion
- results in blockage of blood vessels by the agglutination erythrocytes
- May result in acute kidney caused by the release of large amounts of hemoglobin from ruptured donor erythrocytes
Which blood type is a universal donor?
Type 0
Why is blood type O called a universal donor?
It has no A or B antigens so it cannot be attacked by either anti-A or anti-B antibodies .
However type O individuals can receive only type O blood, because the anti-A and anti-B antibodies in their plasma will attack either A or B antigens in incoming blood
Why is blood type AB called a universal recipient?
They lack anti-A or anti -B antibodies,they can accept donor blood of any type, although they can donate blood only to other AB people.Because their erythrocytes have both A and B antigens, their cells would be attacked if transfused into individuals with antibodies against either of these antigens.
What is Rh factor?
The Rh factor is a protein that can be found on the surface of red blood cells.
If your blood cells have this protein, you are Rh positive.
If your blood cells do not have this protein, you are Rh negative.
The “positive” or “negative” part of your blood type, such as O positive or A negative, refers to your Rh status.
Why can Rh negative people be given Rh negative blood only whereas Rh positive people van receive either Rh positive or Rh negative blood?
Because Rh negative people produce anti-Rh antibodies when exposed to the foreign Rh-positive blood.
What is erythroblastosis fetalis or hemolytic disease of the newborn?
This is whereby an Rh-negative mother develops antibodies against the erythrocytes of an Rh-positive fetus
The maternal antibodies destroy many foetal erythrocytes,the bone marrow cannot keep pace with the rate of destruction and releases immature reticulocytes and eventually erythroblasts. Hence the name of the condition.
What is immunity?
the body’s ability to resist or eliminate potentially harmful foreign materials or abnormal cells.
What is the immune system?
an internal system that recognizes and either destroys or neutralizes materials that are foreign to the ‘normal self’
Outline the functions of the immune system
*defend against invading disease-producing micro-organisms such as bacteria and viruses
*functions as a ‘‘clean up’’ that removes worn out cells such as old red blood cells and tissue debris paving the way for wound healing and tissue repair
*identifies and destroys cancer cells that arise in the body
State the 5 types of leukocytes
*Neutrophils
*Eosinophils
*Basophils
*Monocytes
*Lymphocytes
The leukocytes are divided into 2 main groups
Name them
*Granulocytes; CONTAIN PREFORMED stored chemicals that are released by exocytosis on appropriate stimulation for carrying out the granulocyte’s function
The 3 cells are distinguished on the basis of their granule’s affinity for dyes
*EOSINOPHILS: red dye
*BASOPHILS: blue dye
*NEUTROPHILS: neutral
POLYMORPHONUCLEAR: many shaped nucleus
*Agranulocytes: lacking granules
*Mononuclear: single nucleus
*MONOCYTES; LARGER, OVAL OR KIDNEY-SHAPED NUCLEUS
*LYMPHOCYTES: smallest, large spherical nucleus that occupies most of the cell
Describe neutrophils and their functions
*are phagocytic specialists
*the first defenders on the scene of bacterial invasion
*has 3-5 lobes
*can undergo oxidative burst
*NEUTROPHILS: neutral
*an increase in neutrophils typically accompanies acute bacterial infections
What happens in NETosis?
It is a programmed cell death of neutrophils
Neutrophils use their vital cellular materials to prepare a web of fibers dubbed NEUTROPHIL EXTRACELLULAR TRAPS( NET’S), which they release into the ECF on their death.
These fibers contain granule proteins from the neutrophil’s cytoplasm and chromatin from it’s nucleus , bind with the bacteria and contain bacteria killing chemicals, enabling NETs to trap and then destroy bacteria extracelullarly.
Describe eosinophils and their functions
*They secrete substances that kill worms and internal parasites (cationic peptide an major basic protein)
* play a role in allergic reaction
* nucleus is bi-lobed
*EOSINOPHILS: red dye
An increase in eosinophils is associated with internal parasites infestations and allergic conditions ( asthma and hay fever)
Describe Basophils and their functions
- are the least numerous and most poorly understood leukocytes
*have affinity for blue dye
*has s-shaped or u-shaped nuclei
*similar structurally and functionally to mast cells which never circulate in blood but are dispersed in connective tissue throughout the body
*Release histamines which are important in allergic reactions
*They also release heparin which speeds up removal of fat particles from the blood after a fatty meal - Heparin can also prevent blood clotting ( coagulation) of blood samples drawn for clinical analysis and is used extensively as an anti-coagulant drug
State the functions of Heparin released by the Mast cells and Basophils
*They also release heparin which speeds up removal of fat particles from the blood after a fatty meal
* Heparin can also prevent blood clotting ( coagulation) of blood samples drawn for clinical analysis and is used extensively as an anti-coagulant drug
What is the lifespan of GRANULOCYTES?
3-4 days
Describe the monocytes and their functions
*are professional phagocytes
*They migrate to the connective tissue as immature cells and enlarge to form MACROPHAGES
*
What is the lifespan of a macrophage?
months to years
Describe lymphocytes and their functions
- provide immune defense against targets for which they are specifically programmed
B-lymphocytes: produce antibodies, which are released into blood and carry out ANTIBODY-MEDIATED or HUMORAL IMMUNITY
T-lymphocytes: they directly destroy their specific target cells by releasing chemicals that punch holes in the victim cell in a process called CELL-MEDIATED IMMUNITY
What is the lifespan of lymphocytes?
100-300 days
What are lymphoid tissues?
they are lymphocyte containing tissues
Describe the life-cycle of monocyte
- hematopoitic stem cell
- myeloid stem
3.pro-monocyte
4.monocyte
NOTE: Myeloid stem cell s stimulate by interleukin 3 an 5 agranulocyte colony stimulating factor
Describe the life-cycle of GRANULOCYTES
- Hematopoietic stem cell
- myeloid stem cell
- myeloblast
- Basophilic, eosinophilic and neutrophilic pro-myelocyte
- Basophilic , eosinophilic an neutophilic myelocyte
- Basophilic, eosinophilic an nutrophilic band cell
- Basophilc, eosinophil and neutrophil
NOTE; myeloid stem cell is stimulate by interleukin 3 and 5, along with granulocyte colony stimulating factor
Describe the life-cycle of thrombocytes
- Hematopoietic stem cell
- Myeloid stem cell
3.Megakryoblast - pro-megakaryoyte
- Megakaryocyte
- Platelets
NOTE: the myeloid stem cell is stimulate by thrombopoietin from the liver
the platelets are formed when the megakaryocyte fragments into small pieces as it expode when trying the pass through the sinusoidal capillaries
Describe the life cycle of lymphocytes
- Hematopoietic stem cell
- Lymphoid stem cell
- lymphoblast
- pro- lymphocyte
- lymphocyte
B- lymphoyte mature in the bone marrow whereas the T-lymphocyte mature in the THYMUS
NOTE: myeloid stem cell is stimulated by interleukin 3 and 5 along with the agranulocyte colony stimulating factor
Describe the structure o hemoglobin
*Each hemoglobin molecule is a tetramer made of four polypeptide globin chains.
*Each globin subunit contains a heme moiety formed of an organic protoporphyrin ring and a central iron ion in the ferrous state (Fe2+).
State the different types o hemoglobin
During pregnancy, the fetus primarily produces fetal hemoglobin (HbF). HbF comprises two a and two gamma-globin subunits. HbF has a stronger oxygen affinity than HbA, allowing oxygen to flow from maternal to fetal circulation through the placenta. Production of HbF drops significantly after birth, reaches low, near-adult levels by two years, and ultimately makes up 2 to 3% of hemoglobin in adults.
HbA, the most common adult form of hemoglobin, comprises two alpha and two beta-globin subunits. Inversely to HbF, HbA production explodes after birth and ultimately makes up 95-98% of hemoglobin in adults.
HbA2 is a less common adult form of hemoglobin. It comprises two alpha and two delta-globin subunits and makes up 1 to 3% of hemoglobin in adults
Describe heme synthesis
Eight enzymes accomplish this process, four of which work in the mitochondria and four in the cytosol.
1.The process starts in the mitochondria, where ALA (aminolevulinic acid) synthase links glycine and succinyl coenzyme A to form ALA.
Steps 2 through 5 occur in the cytosol.
- Next, ALA dehydratase takes two molecules of ALA and produces porphobilinogen (PBG).
3.In the third step, porphobilinogen deaminase takes four molecules of PBG and produces hydroxymethylbilane.
4.Next, uroporphyrinogen III cosynthase takes hydroxymethylbilane and produces uroporphyrinogen III.
5.In the fifth step, uroporphyrinogen decarboxylase takes uroporphyrinogen III and produces coproporphyrinogen III.
The final three steps of heme synthesis occur in the mitochondria.
6.Coproporphyrinogen III is then transformed to protoporphyrinogen IX by coproporphyrinogen oxidase.
7.The seventh step occurs when protoporphyrinogen oxidase converts protoporphyrinogen IX to protoporphyrin IX.
8.The eighth and final step of heme synthesis is the addition of Fe to protoporphyrin IX by ferrochelatase, producing a heme molecule.[2][4]
Name the enzyme that adds Fe to the protoporphyrin IX to form a heme molecule
ferrochelatase
Describe the globin synthesis
*Globin chain production occurs in the cytosol of erythrocytes and occurs by genetic transcription and translation.
*Many studies have shown that the presence of heme induces globin gene transcription.
*Genes for the alpha chain are on chromosome 16, and genes for the beta chain are on chromosome 11.
