Blood overview and Blood diffusion

What is blood?

Complex connective tissue

• only fluid connective tissue in body

What are the components of blood?

Formed elements (RBCs, WBCs, Platelets) and matrix (plasma)

Why do veins look blue?

Due to how light penetrates the skin

• blood is always red

  • bright red when oxygen rich

  • Dark red when oxygen poor

What is plasma?

liquid matrix of blood, making up 55% of blood

What is plasma made of?

90% water and 10% solutes (ions, proteins)

When centrifuged, how does blood separate?

• plasma = 55%

• Buffy coat (WBC + Platelets) = <1%

• RBCs = 45%

Functions of plasma?

• pH buffering

• osmotic pressure control

• clotting support

• transport medium

What is albumin and what is its function?

Most abundant plasma protein (60%) made in liver

• controls osmotic pressure and acts as a carrier protein

What are the formed elements of blood?

• Red blood cells (RBCs)

• White blood cells (WBCs)

• Platelets

What is a hematocrit?

The percentage of RBCs in a blood sample

• Normal is about 45%

What are the functions of blood?

1. Transport: O2, nutrients, waste, hormones

2. Regulation: pH, body temp, solute concentration

3. Defense: immune system (WBCs), clotting (platelets)

What is the primary functions of RBCs?

Carry oxygen and carbon dioxide using hemoglobin

What are the anatomical features of RBCs?

• anucleate

• No mitochondria

• Filled with hemoglobin (97%)

• Small and flexible to pass through capillaries

What cofactor is needed for hemoglobin?

Iron (Fe)

Hematopoiesis

Formation of blood cells in bone marrow

What is the stem cell for all blood cells?

hematocytoblast (hematopoietic stem cell)

What happens to RBCs during development?

Lose nucleus/organelles, fill with hemoglobin, become highly specialized

Why must RBCs be constantly produced?

They can’t repair themselves and only last 120 days

Bilirubin

breakdown product of hemoglobin

• Yellow pigment in urine

• Brown in feces

Erythropoietin

Hormone from kidney/liver that stimulates RBC production in low O2 conditions

Anemia

low O2 carrying capacity due to lower % of RBCs in hematocrit

Causes of anemia

• Blood loss (injury, menstruation)

• Decreased RBC production (iron deficiency)

• Increased RBC destruction (infection, mismatched transfusion)

What is sickle cell anemia?

Genetic defect in hemoglobin causing sickled RBCs that rupture, clog vessels, cause pain and organ damage

• carriers are resistant to malaria

General function of white blood cells

Immune defense: fight infection, inflammation, allergies, parasites

Unique capabilities of WBCs

• Diapedesis: move out of blood vessels

• Positive chemotaxis: move toward damage

• Amoeboid movement in tissues

Causes of abnormal WBC growth?

• Viral infections (Mono, HIV/AIDS)

• stress hormones

• Drugs

What causes increased/decreased WBC count?

• Increased: infection, cancer (leukemia)

• Decreased: viruses, stress, drugs

What is leukemia?

Cancer of WBCs

• acute: starts from stem cells = rapid

• Chronic: later stages = slower

• Named by location: myeloid vs lymphoid

General functions of platelets?

Clotting (hemostasis) , respond to vessel damage

Unique traits of platelets?

Fragments of megakaryocytes, no nucleus, aggregate at damage sites

3 steps of blood clotting

1. Vascular spasm - smooth muscle contracts

2. Platelet plug formation - platelets stick to collagen

3. Coagulation - fibrinogen becomes fibrin (mesh traps RBCs)

Platelet plug vs blood clot

• Plug = just platelets

• Clot = fibrin + trapped cells

Fibrinogen Vs Fibrin

• Fibrinogen = soluble protein

• Fibrin = insoluble mesh used in clotting

Hemophilia

inherited clotting disorder

• body can’t properly form clots

White blood cells are callled

leukocytes

Red blood cells are called

erythrocytes