fluid connective tissues 1

what is blood often defined as in histology? why is it referred this way?

it is often described as a special connective tissue, in which the intercellular substance is a fluid. it is referred to as this way because the intercellular substance of blood lacks a fibrous component

where is most of the intercellular proteins of the blood produced?

it is produced by cells in other tissues, primarily the liver, not by the blood cells

how much blood do humans contain?

they contain about 5 liters of blood, accounting for about 7% of body weight

what are some of the functions of blood?

1. transport of O2, nutrients and hormones to the tissue

2. carrying CO2 to the lungs, as well as waste products to the kidneys to be excreted

3. contributes to the regulation of body temperature

4. pH and electrolyte concentrations is maintained through constant exchange of molecules with interstitial fluids

5. helps with immune defense through production of antibodies

6. blood regulation of blood clotting, preventing blood loss

what is blood composed of?

plasma (55%) and formed elements (45%)

what is plasma? what is it composed of?

• plasma is a straw-colored clear liquid which makes 55% of blood. cellular elements and dissolvable substances (solutes) are suspended

• it is approximately 92% water and 8% solids, which is a mix of organic and inorganic substances.

what are the 3 major proteins present in plasma?

1. albumin (4.5 g/dl)

2. globulin (2.5 g/dl)

3. fibrinogen

characteristics and function of albumin

• smallest and most abundant protein in plasma

• maintains colloidal osmotic (oncotic) pressure

• formed in the liver

characteristics and function of globulin

• alpha, beta and gamma

• includes several proteins of different sizes

• involved in transport of hormones, ions, metals and lipids

what are gamma globulins?

they are immunoglobulins (antibodies) that are synthesized by cells of the lymphatic organs and tissues

characteristics and functions of fibrinogen

• produced by the liver

• takes place in hemostasis system

• essential component for blood clotting and prevention of bleeding

what does the plasma also contain?

hormones from various endocrine organs, metabolites, nutrients and several other substances

functions of plasma proteins

1. maintaining osmotic balance

2. buffering pH changes

3. transport of materials through blood (ex: water insoluble hormones)

4. antibodies (gamma globulins, immunoglobulins

5. clotting factors (fibrinogen)

what are the 3 types of formed elements in blood?

1. erythrocytes (RBC)

2. leukocytes (WBC)

3. thrombocytes (platelets)

what is hematocrit?

the result of elements which are separated by centrifugation done in calibrated tubes. it gives an estimate of the volume of the formed elements

what is the heaviest component in hematocrit?

erythrocytes, which form the lower layer. they make up about 45% of the blood volume

what layer are the platelets and leukocytes present in hematocrit?

in buffy coat, a grayish white layer immediately above the erythrocyte layer, forming about 1% of total blood volume

what is the uppermost layer of hematocrit consist of?

plasma

how is plasma obtained from the blood?

following treatment by an anticoagulant, containing all components of the fluid portion of blood

how is serum obtained?

from clotting or defibrinated blood, and it does not contain fibrinogen, but it does contain all the other components elaborated during the process of blood clotting

what is serum?

plasma that lacks fibrinogen and other clotting factors

what are erythrocytes?

also known as red blood cells (RBCs), they are the body’s most numerous blood cells. their main function is to transport oxygen and CO₂ through circulation using hemoglobin

what are the normal RBC levels for males and females?

• females: 4.60 × 10⁶/μL (4.60 million/ μL)

• males: 5.20 x 106 /μL (5.20 million/μL)

why is RBC count slightly lower in women?

primarily due to the menstruation cycle. hormones also play a large factor, as testosterone increases RBC production, and is a hormone that is much higher in men compared to women

how many hemoglobin molecules does each RBC contain?

about 280 hemoglobin molecules, with each hemoglobin containing 4 iron atoms.

how do RBC circulate?

as RBCs pass through the lungs, the iron atoms combine with oxygen molecules. RBCs travel the circulatory system until, at the tissues, iron atoms release oxygen into interstitial fluid and

hemoglobin molecules take up carbon dioxide. Back at the lungs, RBCs release

carbon dioxide and take up oxygen again.

at rest, how much oxygen do humans use?

about 250 ml of oxygen, producing almost 200 ml of carbon dioxide per minute. with activity, these quantities can increase 10 to 20 fold

what is hemoglobin?

the main component of the blood cell, it is a conjugated protein that serves as the vehicle for transportation of oxygen and CO₂. the hemoglobin molecule consists of two primary structures, which are Haem and Globin

how is haem produced?

by the combination of iron with a porphyrin ring. the iron atoms are in a ferrous state, Fe²⁺ , because iron in the ferric state, Fe³⁺, cannot bind oxygen. the porphyrin ring is a structure formed in the precursor nucleated erythroblasts

what does globin consist of?

amino acids linked together to form four polypeptide chains of globin.

what are the most significant chains for adult hemoglobin?

the alpha and beta chains

what are the 3 types of hemoglobin synthesized?

1. embryonic hemoglobin (Gower and Portland)

2. fetal hemoglobin (hemoglobin F)

3. adult hemoglobin (hemoglobin’s, A, A2 and F)

what is hemoglobin A?

it is a tetramer with two α and two β chains (α2, β2). it is most prevalent in adults, accounting for about 96% of total hemoglobin

what is hemoglobin A2?

it consists of two α and two delta δ chains (α 2 δ 2). accounts for 1.5% to 3% of total hemoglobin count in adults

what is hemoglobin F?

it consists of two α and two gamma γ chains (α2 γ2). it is the principle form of hemoglobin in the fetus. it accounts for less than 1% of total hemoglobin in adults

what is majority of the hemoglobin circulating in the blood?

oxyhemoglobin and reduced hemoglobin

what are other hemoglobin derivatives found in the normal circulating blood?

1. methemoglobin

2. sulfhemoglobin

3. carboxyhemoglobin

what is methemoglobin?

a hemoglobin derivative in which the iron has been oxidized from the ferrous (Fe²⁺) to the ferric (Fe³⁺) state, and is therefore, incapable of combining reversibly with oxygen. it is dark-colored, and when present in large quantities in the circulation, can cause a dusky discoloration of the skin resembling cyanosis

what is sulfhemoglobin?

a hemoglobin derivative that can be formed by exposure to agents such as sulfonamides or sulfa containing drugs. the affinity of sulfhemoglobin for oxygen is 100 times lower than that of normal hemoglobin

what is carboxyhemoglobin?

a hemoglobin derivative where carbon monoxide reacts with hemoglobin to form carboxyhemoglobin. levels of it are increased in smokers and certain industrial workers. the affinity for O2 is much lower than its affinity for carbon monoxide, which consequently displaces O2 on hemoglobin, reducing oxygen carrying capacity of blood