Blood

Components of the Circulatory System

Includes cardiovascular and lymphatic
systems

Heart pumps blood thru cardiovascular system

Blood vessels carry blood from heart to cells
and back

Lymphatic system

picks up excess fluid filtered
out in capillary beds and returns it to veins

Functions of the Circulatory System
• Plays roles in

Transportation of respiratory gases, delivery
of nutrients and hormones, waste removal,
temperature regulation, clotting, and immune
function

Three functions and properties of blood:

transport, regulation, protection

Blood transports oxygen, carbon dioxide,

nutrients, hormones, heat, and waste products

Three functions and properties of blood:

transport, regulation, protection

Blood regulates homeostasis of all body fluids,

pH, body temperature, and water content of

cells

Three functions and properties of blood:
transport, regulation, protection

Blood protects against excessive loss by

clotting, and uses white blood cells to protect

against infections

Functions and properties of blood

Blood is a liquid connective tissue consisting of

cells surrounded by a liquid matrix (plasma), ~ 5L

total in humans

The plasma (liquid) portion of blood

Consists of water, proteins, and other solutes

The cellular components (formed elements)

Consists of red blood cells, white blood cells,

and platelets

3 types of plasma proteins

albumins, globulins,

and fibrinogen

Albumin accounts for 60-80%

Creates colloid osmotic pressure that draws

H2O from interstitial fluid into capillaries to

maintain blood volume and pressure

Globulins carry lipids

Gamma globulins are antibodies

Fibrinogen serves as clotting factor

Converted to fibrin

serum

Plasma minus clotting factors

Red blood cells

Ery = red

Thro = related to blood clotting

Cyte = cell

Red blood cells

have no nucleus or other

organelles and are biconcave discs (donut

without the hole)

Red blood cells

This shape allows them to carry oxygen more

efficiently

• Increased surface area for gas exchange

• Flexibility for squeezing into capillaries

• About 300 billion RBCs are made each day

Hematocrit

The total amount of red blood cells in blood, on average 38-53% is normal

Red blood cells

contain hemoglobin

molecules (~280 million of them!), used to carry O2 to

all cells and to carry some CO2 to the lungs

Each hemoglobin molecule contains an iron ion

which allows each molecule to bind four oxygen

molecules

White blood cells

Leuko = white

Cytes = cell

White blood cells (leukocytes)

contain a nucleus

and organelles, but no hemoglobin

Leukocytes

Granular or Agranular

Granular

containing vesicles/granules that appear

when the cells are stained

Examples: neutrophils, eosinophils, basophils

Agranular

(containing no vesicles/granules)

• Examples : lymphocytes, monocytes

Granulocytes

Neutrophil: phagocytosis

Granulocytes

Eosinophil: fight against allergic reactions and parasitic

infections

Granulocytes

Basophil: releases heparin (an anticoagulant) and triggers

allergies (granules contain histamines)

Agranulocytes:

Lymphocytes: immune defense (become B- and T-

lymphocytes

Monocytes

phagocytosis

Platelets

Thrombo- = related to blood clotting

Cyte = cell

Platelets (thrombocytes)

used to clot the blood via

hemostasis

Hemostasis

is a sequence of responses that

stops bleeding

Platelets

make up most of the mass of blood

clots

Hemostasis

Step 1. Vascular spasm

Hemostasis

Step 2.Platelet plug formation

Hemostasis

Step 3. Blood clotting

Coagulation through the formation of fibrin

Hemostasis: Vascular spasm

When a damaged vessel vasoconstricts to reduce

quantity of blood that can enter the blood vessel

• Vasoconstriction happens because the smooth muscle

of the blood vessel contracts

• This reduces blood loss from several minutes to hours

so that the next two steps of hemostasis can begin

Hemostasis: Platelet plug formation

Three steps:

1. Platelet adhesion

2. Platelet release reaction

3. Platelet aggregation

Blood clotting (coagulation) involves several

clotting factors

The blood clotting cascade can be activated in

one of 2 ways: extrinsic or intrinsic pathway

Blood clotting

can be activated in

one of 2 ways: extrinsic or intrinsic pathway

Blood clotting

Both pathways lead to the formation of

prothrombinase from which the common

pathway continues

Blood clotting final output

Fibrin

Extrinsic pathway:

tissue trauma

Intristic pathway:

Blood internal trauma

ex:when blood is left in a tube it will clot

Pathways

Both use Ca2+ as a clotting factor

and lead to the common pathway

The common pathway

Blood clotting (coagulation) involves several

clotting factors and it’s a positive feedback loop!

• End of common pathway: creates loose and then

strong fibrin threads.

• Source of many clotting factors vitamin K and

liver

Clots

unwanted clots are usually dissolved by

plasmin

Breaks down the clots

an enzyme that is part of the

fibrinolytic system

Thrombus

Stationary

Embolus

Travels

Tissue plasminogen activator

activates the

fibrinolytic system – can be synthesized given to

patients to break down/dissolve clots

Anticoagulants

Prevents clots

Anemia

Reduced capacity of blood to carry O2,reduced hematocrit and or amount of hemoglobin

Anemia

Sickle cell anemia (genetic)

• Pernicious anemia, iron deficiency anemia,

others

Polycythemia:

increased hematocrit

Blood doping (Lance Armstrong!

erythropoietin

(EPO), synthetic oxygen carriers, and blood

transfusions