2.6 : Blood, Vessels & Clotting

What are Arteries and Arterioles

Arteries transport blood AWAY from the heart and have thick walls to withstand high BP

Arteries branch off into arterioles

What are Capillaries

Smallest vessels amongst the three being only 1 cell thick

RBC’s move single file within them

All somatic cells are 2 cell-widths away from one at all times

What are Veins and Venules

Transport blood TOWARD heart and have thin walls due to low BP

Have semi-lunar valves to prevent backflow

What are the two parts blood consists of

1) Plasma : fluid suspension of protein and dissolved nutrients

2) Cells/formed elements :

• Erythrocytes

• Leukocytes

• thrombocytes

(all three are made in bone marrow)

What are Erythrocytes (RBC)

Red blood cells

purpose: transport O2 and some CO2

Life span: about 120 days

special features: enucleated (nucleus removed), no mitochondria

What are Leukocytes (WBC)

white blood cells

purpose: cells of the immune system (protects)

Life span: ranges from hours to years

special features : many types, can be mobile, phagocytic (can engulf things) and requires maturation

What are Thrombocytes (platelets)

Platelets

purpose: blood clotting

life span: 8 - 10 days

Special features: not actual cells (bud off massive parent cells)

Blood clotting first step

Damaged cells release clotting factors (triggers the process)

Blood clotting second step

Clotting factors are released from platelets (amplifies the signal/accelerates the reaction chain)

Blood clotting third step

Prothrombin is converted into thrombin

Thrombins job is to cut fibrinogen into sticky fibrin threads

Blood clotting fourth step

Soluble fibrinogen is converted into the protein fibrin

Blood clotting fifth step

Fibrin protein collects at the site of damage

Blood clotting last sixth step

The network of fibrin proteins fibres collect traps erythrocytes and forms a clot

what is interstitial fluid

interstitial fluid or tissue fluid is the fluid that bathes cells

How is it made in the capillaries

The high BP from the arteriole end pushes fluid into nearby tissue through the little holes (fenestrations) in the capillaries

• 90% is reabsorbed at the venous (venule) end because low BP

• 10% enters lymphatic vessels

What are Lymphatic vessels

vessels that transport TF (now lymph) to lymph nodes for filtration and screening

What are the wall components of a blood vessel

tunica Media, eterna and intima

Tunica externa is made of collagen

Media is smooth muscles

Intima is made of endothelium