Transcript Document

Cardiovascular System
Components- blood, heart, and blood
vessels
1st system to become fully operational
(heart beats at the end of the 3rd week
of development)
Functions of Blood
Transportation of dissolved gases,
nutrients, hormones, and wastes
Regulation of pH and ion composition
of interstitial fluids
Restriction of fluid loss (blood clots)
Defense against toxins and pathogens
Stabilization of body temperature
Composition of Blood
Fluid connective tissue with a matrix
called plasma
Formed elements- RBC transport
oxygen, WBC defend body, platelets
help clot the blood
Blood Facts
Blood Temperature is 38 C
Blood is 5 times as viscous as water
pH is slightly alkaline averaging 7.4
Body contains between 4-6 liters of
blood
Plasma
Composed of 92% water
7% plasma proteins
1% other solutes
Plasma Proteins
Albumins- most common, maintain
osmotic pressure, transport fatty acids,
steroid hormones, and cholesterol
Globulins- antibodies
Fibrinogens- blood clotting
Peptide hormones- insulin, thyroid
stimulating hormones, etc.
Formed Elements
Red Blood Cells (RBC)- make-up 99% of
formed elements
 Hemoglobin- red pigment that binds to
oxygen
 One drop contains 260 million RBCs, account
for 1/3 of all cells of the body
 Each RBC can carry more than a billion
molecules of oxygen
 No nuclei, mitochondria, or ribosomes
 Don’t divide or make proteins, life span about
120 days
RBC continued
Cells of the liver, spleen, and bone marrow
monitor blood for damaged cells
RBC’s are formed in the red bone marrow
Biconcave shape
 Provides larger SA to volume ratio, allows
oxygen to be absorbed and released quicker
 Allow RBC to stack on top of each other, this
makes it easier to flow through narrow areas
 Allows bending and flexing through very
small capillaries
Blood Types
Blood types are determined by the type of
antigen present on RBCs
Antigens are proteins on the surface of the cell
that mark the cell as being “self”
The main surface antigens of RBCs are A, B,
and Rh

A person can have A, B, AB, or neither A or B and
be type O. In addition you either have a Rh (+), or
not (-)
Blood type cont.
Your body will produce antibodies (called
agglutinins) to combat antigens not found on
your own cells. When these agglutinins attack
foreign RBC they bind to them and clump in a
process called agglutination
People w/out the Rh antigen (Rh-) don’t
necessarily carry an antibody against Rh. This
antibody is produced when a person is exposed
to Rh.
White Blood Cells “leukocytes”
Have nuclei and other organelles, but
lack hemoglobin
Defend body against invasion by
pathogens
Circulate for only a short portion of
their lifespan
Function of WBC
Neutrophils- difficult to stain, digest
bacteria that have been marked by
antibodies and then join w/ lysosomes
that break down pathogens
Short life span- 10 hours in blood, or
only 30 minutes when attacking
bacteria
Eosinophils and Basophils
Stain darkly, attach object with
antibodies, use endocytosis, defend
against large multicellular parasites
Basophils- Stain darkly, rare 1%,
release histamine, which dilates blood
vessels and heparin, which prevents
blood clotting
Monocytes
Circulate in the blood for only 24
hours, then enter tissues and become
macrophages, which engulf debris, and
microorganisms in cells
Lymphocytes
20-30% of WBCs,
T cells- cell mediated immunity
B cells- make antibodies to attack
foreign material in the blood
NK cells- natural killer cells, immune
surveillance, important in preventing
cancer
Hemostasis- cessation of bleeding
Prevents loss of blood when there is
damage to vessel walls at the same
time providing a framework for tissue
repair
3 Phases
 Vascular
 Platelet
 Coagulation
Vascular Phase
As soon as there is a cut in the wall of a
blood vessel, smooth muscle fibers in the
wall contract, lasts for 30 minutes
 Decreases diameter of blood vessel,
restricting blood flow
 Stimulates release of chemical factors
that accelerate division of new cells to
help in repair
Platelet Phase
Platelets in the blood stick to the walls of
the vessel surrounding cut as well as
collagen fibers exposed to the cut, 15
seconds after injury
Platelet plug
Platelets release compounds that stimulate
contraction of smooth muscle and more
platelets to stick to plug, positive feedback
Coagulation Phase
30 seconds after injury
Complex sequence of steps, fibinogens that
circulate in blood are changed into fibrin which
is an insoluble fiber
Fibrin forms over platelet plug
Clotting requires Ca2+ and 11 different proteins
(clotting factors)
Some of these clotting factors create a positive
feedback loop to increase rate of coagulation