Download Circulatory System Notes File

Cardiovascular System Notes
I. Blood
 Liquid portion: plasma
 Solids: red blood cells (RBC), white blood cells (WBC) and
platelets
 55% liquid and 45% solid
 average adult has 4-5 Liters of blood.
A. Plasma- a sticky straw colored liquid which is about 90% H2O
 cells receive substances carried in the plasma
 carries hormones and transports wastes
 proteins in plasma are used for clotting, homeostasis and
antibodies
B. Red Blood Cells- Erythrocytes
 transport oxygen to the cells
 Formed in red bone marrow
 Synthesize (make) hemoglobin (molecule that actually
transports oxygen)
 During formation, cell nucleus and organelles
disintegrate
 A mature RBC is only a sac containing hemoglobin
 Survive 120-130 days, they can’t reproduce
 30 trillion in the body, when they “die” their parts (iron)
are recycled to form new RBC’s
C. White Blood Cells – Leukocytes
 one of the body’s defenses against disease
 formed in red marrow, lymph and spleen
 WBC are larger than RBC and there are fewer in the
body
 WBC can squeeze through openings in walls of vessels
into intercellular fluid to get to the site of an infection.
 WBC are irregularly shaped, may last several years
 Phagocytes- type of WBC
engulf invading organism
 Antibodies-produced by WBC to help destroy pathogens
D. Platelets
 essential to forming blood clots
 a blood clot is a mass of interwoven fibers and blood
cells that prevent excess loss of blood
 not whole cells, fragments of very large cells formed in
marrow
 no nucleus
 last 7-11 days
 when the vessel tears or rips, platelets congregate at the
site and form a plug, clotting factors are released which
trigger production of fibrin (a protein) and forms a scab.
D. Blood Types (ABO)
 determined by an antigen on the surface of RBC
 antigen- a protein or carbohydrate that acts as a signal
which helps the body identify foreign substances
 antigens produce no response, foreign antigens trigger
antibody production
 4 blood types were found initially because a doctor
noticed that certain blood types didn’t mix
E. Blood Types (Rh Factor)
 antigen present on RBC
 first observed in the Rhesus monkey
 85% of population is Rh+ (have the antigen)
 if an Rh- person gets Rh+ blood antibodies will cause
agglutination
 Rh incompatability
II. The Circulatory System
A. Anatomy of the Heart
 Central organ of the circulatory system
 Pumps blood throughout the body through a network of
vessels
 Ave adult heart beat is 60-80 beat/min - children are
higher
 Surrounded by a saclike membrane called the
pericardium - reduces friction as the heart beats
 A septum divides the the heart vertically into left and
right sides
 Atrioventricular (AV) valves divide the heart
horizontally into upper and lower chambers
 Semilunar (SL) valves separate ventricles from major
blood vessels
 Upper chambers are referred to as atria (atrium- singular)
 Lower chambers are referred to as ventricles
 Veins carry blood from the body to the atrium
 Arteries carry blood from the ventricles to the body
B. Circulation
•Deoxygenated blood enters the RIGHT ATRIUM from the
SUPERIOR AND INFERIOR VENA CAVAS
•Blood passes through the TRICUSPID VALVE (an AV valve)
to the RIGHT VENTRICLE
•Blood then moves through the PULMONARY VALVE (an SL
valve) to the PULMONARY ARTERIES that carry the blood to
the lungs to be reoxygenated
•Blood reenters the heart from the lungs through the
PULMONARY VEINS to the LEFT ATRIUM
•It then passes through the MITRAL VALVE (an AV valve) to
the LEFT VENTRICLE
•From the LEFT VENTRICLE it passes through the AORTIC
VALVE (an SL valve) to the AORTA
•The AORTA send the blood throughout the body
C. Circuitry of the Heart
•Heartbeat is controlled by electrical impulses
•Starts with the SINOATRIAL (SA) NODE
•a specialized group of cells that can initiate an impulse
•causes contraction of the atria
•known as the PACEMAKER
•Impulse travels to the ATRIOVENTRICULAR (AV) NODE -group
of specialized cells in the upper septum
•cells here delay the signal
•Then impulse travels through the BUNDLE OF HIS down the
septum
•PURKINJIE FIBERS then carry the impulse to the ventricles causing
them to contract
•Delay ensures full contract of atria before ventricles contract
D. Blood Vessels
1. Arteries carry blood away from the heart
a. they are thick walled, with 3 layers:
– inner: endothelial
– middle: smooth muscle
– outer:connective tissue
b. Typically carry oxygenated blood
2. Veins carry blood to the heart
a. thinner and less muscular than arteries
b. contain valves that prevent blood from flowing backwards
c. Typically carry deoxygenated blood
E. Blood Flow Pattern
1. Arteries
2. Arterioles
3. Capillaries
4. Venules
5. Veins
F. Blood Pressure
1. Blood pressure is the pressure blood exerts on the blood vessels
during contraction
2. Systolic pressure – pressure blood exerts when the ventricles
contract
3. Diastolic pressure – relaxed pressure of blood flowing through
arteries
G. Circulation Patterns
1. Circulation in the body is a closed system that is divided into
branches
a. pulmonary circulation: blood flow from heart to lungs and
back to heart
b. systemic circulation: blood flow from the heart to all other
body tissues and back to the heart
o Hepatic portal circulation – to liver
o Renal circulation – to kidneys