Bio-Circulatory System I

What are the main components of the circulatory system?

The heart, blood vessels, and blood.

What is hematology?

The study of blood.

What are the functions of blood?

1. Transport

oxygen, carbon dioxide, nutrients, metabolic waste, and hormones

2. Protection

white blood cells destroy microorganisms and cancer cells

platelets intitate blood clotting

3. Regulation

maintains fluid balance

stabilizes pH of extracellular fluid

regulates body temperature

What is blood plasma?

a clear, light-yellow fluid that forms the extracellular matrix of blood, making up 55% of blood volume

What are the formed elements of blood?

red blood cells (RBCs), white blood cells (WBCs), and platelets

Blood osmolarity

the concentration of particles in the blood that cannot pass through the vessel walls determined by albumin, RBCs, and sodium

Albumin

smallest and most abundant type of plasma protein

transports various solutes and maintains optimal viscosity and osmolarity of the blood

Hemopoiesis

The production of the formed elements of blood, occurring in the red bone marrow

What are the functions of erythrocytes (RBCs)?

they pick up oxygen from the lungs and transport it to the tissues, and they pick up carbon dioxide from the tissues to unload in the lungs

ex. severe deficiency can be fatal; incapable of self-repair

Describe the structure of erythrocytes.

Discoidal cells with a thick rim and thin center, lacking organelles, which allows them to flow smoothly through vessels.

Blood viscosity

the thickness or stickiness of blood from the ratio of albumin and RBCs

ex. determinant of blood flow through vessels

What is sickle-cell disease?

A hereditary defect in hemoglobin causing RBCs to become sickle-shaped, leading to clogged blood vessels and reduced blood flow.

What is the average lifespan of erythrocytes?

120 days

What happens to RBCs as they age?

their membrane proteins deteriorate, leading to fragility and eventual rupture (hemolysis) as they pass through small blood vessels

ex. die in the spleen

What is polycythemia?

An excess of RBCs that increases blood viscosity, potentially leading to hypertension and heart attack.

What is the role of globulins in blood?

They play roles in immunity, clotting, and transport.

What is the function of fibrinogen?

It is a soluble precursor of fibrin, which forms the framework of a blood clot.

What is blood viscosity?

The thickness or stickiness of blood, primarily due to the presence of RBCs and albumin.

What determines blood osmolarity?

The concentration of particles in the blood that cannot pass through vessel walls, mainly determined by Na, proteins, and RBCs.

How are old erythrocytes removed from circulation?

They are removed by the spleen, where macrophages digest the empty membranes and recycle components like iron

What is anemia?

A condition characterized by a deficiency of red blood cells (RBCs) or hemoglobin.

What are the three main causes of anemia?

Reduced erythropoiesis, rapid RBC destruction, and hemorrhage.

What is iron-deficiency anemia?

A type of anemia caused by insufficient iron in the diet.

What is pernicious anemia?

An autoimmune condition that destroys stomach tissue responsible for producing intrinsic factor, leading to vitamin B12 absorption issues.

How can gastric bypass surgery affect anemia?

It can lead to pernicious anemia by reducing intrinsic factor production.

Antigens

occur on the surface of RBCs to help the body distinguish 'self' from 'foreign' blood and trigger immune response

ex. if the body detects an antigen of foreign origin, it activates an immune response

What are the four main human blood types?

• Type A

• Type B

• Type AB

• Type O

What antibodies does a Type A person have?

Anti-B antibodies.

What happens during a blood transfusion if a Type A patient receives Type B blood?

The patient's anti-B antibodies attack the transfused Type B RBCs, causing agglutination and potentially leading to hemolysis.

What is the Rh blood group?

A classification based on the presence (Rh-positive) or absence (Rh-negative) of Rh antigens on RBCs.

What is hemolytic disease of the newborn?

A condition where Rh-negative mothers produce anti-Rh antibodies that attack the RBCs of an Rh-positive fetus in subsequent pregnancies.

What are leukocytes?

white blood cells (WBCs) that protect the body from pathogens and contain many organelles

What are the two main categories of leukocytes?

granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).

Neutrophils

granulocyte

the most abundant WBCs that are attracted to infection sites to phagocytize and release toxic chemicals that kill bacteria

ex. the chemicals kill the neutrophils, so they have a short lifespan

What role do eosinophils play in the immune response?

They destroy large parasites and dispose of antigen-antibody complexes.

Basophils

granulocyte

secretes histamine (vasodilator) and heparin (inhibits blood clotting) promoting blood flow to injured tissues

important in allergies and inflammation

ex. an elevated number occurs in those with diabetes and chicken pox

What is leukopenia?

A condition characterized by too few WBCs, making the body vulnerable to infections.

Monocytes

agranulocyte

formed in the bone marrow, they migrate to tissues to protect against disease and turn into macrophages

ex. largest of the WBCs

What are platelets?

circulating fragments of bone marrow cells called megakaryocytes that are formed by thrombopoiesis

ex. involved in blood clotting and wound healing

What are the three steps of hemostasis (control of bleeding)

1. vascular spasm

prompt constriction of the broken vessel, triggered by serotonin

2. platelet plug

sticky mass of platelets close small breaks in the vessel and adhere to collagen of broken vessel walls, contracting to pull the wall together

3. coagulation

involves many chemical reactions and clotting factors

What are the stages of hemostasis?

Vascular spasm, platelet plug formation, and coagulation (clotting).

What is thrombosis?

Abnormal clotting of blood in an unbroken vessel, which can lead to strokes or heart attacks.

What is an embolus?

A piece of a thrombus that breaks off and travels in the bloodstream, potentially blocking blood flow.

What is the role of platelet-derived growth factor (PDGF)?

It stimulates the replacement of damaged tissue by promoting mitosis in fibroblasts and smooth muscle cells.

What is the significance of differential WBC count?

It measures the relative counts of different types of WBCs, helping to diagnose infections or other conditions.

Type A blood

type A antigen

anti-B antibodies

Type B blood

type B antigen

anti-A antibodies

Type O blood

neither antigen

both antibodies

Type AB blood

both antigens

neither anti-A nor anti-B antibodies 

How does blood transfusion work?

if a type A patient is given type B blood, the patients anti-B antibodies attack the transfused type B blood cells

What determines if a blood type is positive or negative?

Rh-positive people have RhD antigens on their RBCs while Rh negative people have no RhD antigen on their RBCs

What type of blood can you receive based on whether you are Rh positive or negative?

if Rh-positive, you can receive both Rh+ and Rh- blood

if Rh-negative, you can only receive Rh- blood

How does oxygen get transported?

two ways

1. RBCs contain hemoglobin, a protein made of four iron containing heme groups that each bind one oxygen molecule

so, when blood passes through the lungs, oxygen binds to hemoglobin which delivers it to tissues

2. a small amount of oxygen gets dissolved in the plasma