BSCI202: Circulatory System

Dr. Justicia Opoku

The Circulatory System consists of 2 organ systems which fluid circulates:

Cardiovascular and Lymphatic system

Cardiovascular system

blood circulates in blood vessels

Lymphatic system

lymph circulates in lymphatic vessels

What is 1?

Carotid artery

What is 2?

Right lung

What is 3?

Vena cava

What is 4?

Aortic artery

What is 5?

Subclavian artery and vein

What is 6?

Left lung

What is 7?

Heart

hypovolemic shock

caused from severe blood loss

Lymph

fluid contained within the lymphatic system

What is lymph similar to?

interstitial fluid

Where is diffuse lymphatic tissue found in the body?

Tonsils, mucosa associated lymph tissue, and red bone marrow

What are the lymph organs?

thymus, spleen, and lymph nodes

What is the main function of lymphocytes?

Immunity

What is the approximate blood volume as a percentage of body weight?

About 6-8% of body weight (in kg)

What is the typical total blood volume range for adults?

4.5-6.0 liters

What is the blood volume for adult males?

5-6 L

What is the blood volume for adult females?

4-5 L

Why do males generally have higher blood volume than females?

Due to larger body size, greater muscle mass, and hormonal differences (ie. testosterone increases red blood cell production)

What are two main factors that contribute to males having more blood volume than females?

Greater muscle mass and higher testosterone

What is this?

Body Fluid Compartments

What is the first step in visualizing the composition of blood?

withdraw blood and place it in a tube, then centrifuge it

What are the three main layers formed when blood is centrifuged (top to bottom)?

Plasma, Buffy Coat, Erythrocytes

What percentage of whole blood is make up of plasma?

55%

What is found in the buffy coat, and what percentage of whole blood does it represent?

Leukocytes (white blood cells) and platelets; it makes up <1% of whole blood

What percentage of whole blood is made up of erythrocytes?

45%

What term describes the percentage of blood volume occupied by erythrocytes?

Hematocrit

What are the two main components of Plasma?

Water (90%) and dissolved substances (proteins, electrolytes, nutrients, gases, wastes)

What are the two main components of Blood?

Plasma and Formed Elements

What are the three major types of Formed Elements in blood?

Erythrocytes (Red Blood Cells), Leukocytes (White Blood Cells), and Platelets

What are the three major types of Plasma Proteins?

Albumin, Globulin, and Fibrinogen

What are the two main categories of Leukocytes?

Granulocytes and Agranulocytes

Which three leukocytes are classified as Granulocytes?

Neutrophils, Eosinophils, and Basophils

Which two leukocytes are classified as Agranulocytes?

Lymphocytes and Monocytes

What are the functions of plasma proteins?

• Maintaining blood osmotic pressure

• Transporting substances

• Immune function

• Blood clotting

• Regulation of pH

Which plasma protein is most abundant and helps maintain osmotic pressure?

Albumin

What do Albumin and globulins help prevent?

fluid from leaking out of the blood vessels into the surrounding tissues

What do plasma proteins transport?

various substances such as hormones, nutrients, and waste products

How do plasma proteins help with immunity?

Immunoglobulins play a vital role in the immune system by fighting infections

What plasma protein helps with blood clotting?

Fibrinogen

What is the most commonly ordered blood test?

Complete Blood Count

What is the blood volume equation?

What is the key structural feature of an erythrocyte (RBC) and what is its functional advantage?

Biconcave disc shape; it provides a huge surface area-to-volume ratio, maximizing gas exchange efficiency

What major cellular components are absent in mature erythrocytes?

Nucleus and cytoplasmic organelles (including mitochondria)

What percentage of an RBC's content is hemoglobin?

More than 97%

Why is the absence of mitochondria in RBCs functionally beneficial?

It means RBCs use anaerobic respiration and do not consume the oxygen they carry, making them perfect oxygen transporters

What is the primary function of erythrocytes?

To transport oxygen in the blood

What are the two main structural components if a hemoglobin molecule?

Globin protein (4 polypeptide chains) and 4 Heme groups

What are the four polypeptide chains called?

Two alpha and two Beta polypeptide chains

How many hemoglobin molecules are in a single red blood cell (RBC)?

About 250 million hemoglobin molecules

How many oxygen molecules can one hemoglobin molecule carry at maximum?

Four oxygen molecules (one per heme group)

What is the total oxygen-carrying capacity of one RBC?

Up to 1 billion oxygen molecules

What is the main function of hemoglobin?

To transport oxygen from the lungs to peripheral tissues.

What percentage of oxygen in the blood is carried by hemoglobin?

More than 98%

What is hemoglobin called when it is bound to oxygen, and what is its color?

Oxyhemoglobin (HbO₂) – bright red.

What is hemoglobin called when it has released oxygen, and what is its color?

Deoxyhemoglobin (reduced hemoglobin) – dark red

What is hemoglobin called when it is bound to carbon dioxide?

Carbaminohemoglobin (HbCO₂).

Can hemoglobin bind both O₂ and CO₂ at the same time?

Yes, at different binding sites

What is this?

Oxyhemoglobin (O2-Hb) Dissociation Curve

Bohr’s Effect

Presence of CO2 decreases the affinity of Hb for O2

Haldane Effect

Combination of O2 with Hb displaces CO2 from Hb

Bohr happens when what?

unloading

Haldane happens when what?

Loading

What is Erythropoiesis?

formation of red blood cells

What feedback loop is the hormonal regulation of erythropoiesis?

A negative feedback loop

What is the hormonal regulation of erythropoiesis based on?

Oxygen levels and Erythropoietin (EPO) levels in the blood

What is Erythropoietin (EPO) synthesized by?

peritubular cells of the kidney

What happens to EPO when in the presence of oxygen?

They are hydroxylated and digested by proteosomes

When do EPO always synthesize?

When EPO levels are decreased by sufficient levels of oxygen and when EPO levels are increased by hypoxemia/hypoxia

What are the steps in how Erythropoietin (EPO) mechanism for regulating erythropoiesis?

What is the life span of RBC?

Only 100-120 days, short

What stimulates the production of erythropoietin?

Low O2 levels in blood stimulate kidneys to produce erythropoietin

What promotes erythropoiesis in red bone marrow?

Erythropoietin and necessary raw materials in blood promotes erythropoiesis as new erythrocytes enter the bloodstream

What happens to older and damaged red blood cells? What happens to the hemoglobin?

engulfed by macrophages of spleen, liver, and bone marrow; the hemoglobin is broken down?

When the hemoglobin is broken down, what happens to the raw materials?

They are made available in blood for erythrocyte synthesis

Hemoglobin is broken into what two pathways?

Heme and Globin

What does globin provide back to the bloodstream?

Its amino acids are used for other protein synthesis

Heme splits into two different pathways, what are they?

Iron portion and non-iron portion

In the iron portion of Heme, what is iron stored as?

ferritin or hemosiderin

What is iron bound to? What happens after?

Transferrin; released to blood from liver as needed for erythropoiesis

What is the non-iron portion called? Where is it picked up?

Bilirubin; picked up by the liver

Where is Bilirubin released and secreted?

released in bile, secreted into blood

Bilirubin when in bile is metabolized to what by bacteria?

urobilinogen

Anemia

decrease in the oxygen-carrying capacity of blood

What are causes to Anemia?

Decrease in RBC number; Decreased hemoglobin content in RBC; Abnormal hemoglobin

What are three classifications of decrease in RBC number anemia?

Hemorrhagic anemia, Aplastic anemia, Hemolytic anemia

What are three types of anemia that has decreased hemoglobin content in RBC?

Sideroblastic anemia, Iron-deficiency anemia, Pernicious anemia

Iron-deficiency anemia

An adult requires 1 mg to 2 mg per day of iron. As the newly produced RBCs contain less amount of hemoglobin, they are relatively of small size when compared to normal RBCs, thus the name, microcytic

Pernicious anemia

Vitamin B12 deficiency causes a failure of DNA syntehsis and resultant impaired cell division

What are two types of abnormal hemoglobin?

Sickle-cell anemia and Thalassemia

What are severe symptoms of anemia?

Fainting, Chest pain, Angina, Heart attack

Hypoxemia

decreased blood O2 levels

Hypoxia

Inadequate oxygen supply to tissues/organs

What gene is prevalent in areas with high incidence of malaria?

Sickle-cell gene

Normal erythrocyte has normal hemoglobin amino acid sequence in the beta chain while sickled erythrocyte has how many amino acid changes in the beta chain of hemoglobin?

one

What treatment is there for sickle cell?

Hydroxyurea

What form of hemoglobin is present in fetus and small infants?

fetal hemoglobin (HbF), most disappear early in childhood but some persist