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